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Keywords:

  • Humans;
  • Hypothermia [*prevention & control];
  • *Infant, Low Birth Weight;
  • Infant, Newborn;
  • Infant, Premature;
  • Infant, Premature, Diseases [*prevention & control];
  • Perinatal Care [methods];
  • Randomized Controlled Trials

Abstract

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Background

Hypothermia incurred during routine postnatal resuscitation is a world-wide issue (across all climates), with associated morbidity and mortality. Keeping vulnerable preterm infants warm is problematic even when recommended routine thermal care guidelines are followed in the delivery suite.

Objectives

To assess efficacy and safety of interventions, designed for prevention of hypothermia in preterm and/or low birthweight infants, applied within 10 minutes after birth in the delivery suite compared with routine thermal care.

Search strategy

The standard search strategy of The Cochrane Collaboration was followed. Electronic databases were searched: MEDLINE (1966 to May Week 4 2004 ), CINAHL (1982 to May Week 4 2004), EMBASE (1974 to 09/07/04), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2004), Database of Abstracts of Reviews of Effects (DARE 1994 to July 2004), conference/symposia proceedings using ZETOC (1993 to July 2004), ISI proceedings (1990 to 09/07/2004) and OCLC WorldCat (July 2004). Identified articles were cross-referenced. No language restrictions were imposed.

Selection criteria

All trials using randomised or quasi-randomised allocations to test a specific intervention designed to prevent hypothermia, (apart from 'routine' thermal care) applied within 10 minutes after birth in the delivery suite to infants of < 37 weeks' gestational age or birthweight ≤2500 g.

Data collection and analysis

Methodological quality was assessed and data were extracted for important clinical outcomes including adverse effects of the intervention by at least three independent reviewers. Authors were contacted for missing data. Data were analysed using RevMan 4.2.5. Relative risk (RR), risk difference (RD) and number needed to treat (NNT) with 95% confidence limits were calculated for each dichotomous outcome and mean differences (MD) with 95% confidence limits for continuous outcomes.

Main results

Six studies giving a total of 304 infants randomised and 295 completing the studies were included. Four comparisons to 'routine care' were undertaken within two categories:

  • 1)
    barriers to heat loss (four studies): plastic wrap or bag (three), stockinet caps (one) and
  • 2)
    external heat sources (two studies): skin-to-skin (one), transwarmer mattress (one).

Plastic barriers were effective in reducing heat losses in infants < 28 weeks' gestation (three studies, n = 159; WMD 0.76 °C; 95% CI 0.49, 1.03) but not in the 28 to 31 week group. There was insufficient evidence to suggest that plastic wrap reduces the risk of death within hospital stay (three studies, n = 161; typical RR 0.63; 95% CI 0.32, 1.22; typical RD -0.09; 95% CI -0.20, 0.03). There was no evidence of a significant difference in major brain injury, mean duration of oxygen therapy or hospitalisation for infants < 29 weeks' gestation. Stockinet caps were not effective (borderline significant for infants < 2000 g birthweight) in reducing heat losses.

Skin-to-skin care was shown to be effective in reducing the risk of hypothermia when compared to conventional incubator care for infants 1200 to 2199 g birthweight (one study, n = 31; RR 0.09; 95% CI 0.01, 0.64; NNT 2; 2 to 4). The transwarmer mattress significantly kept infants ≤1500 g warmer and reduced the incidence of hypothermia on admission to NICU

(one study, n = 24; RR 0.30; 95% CI 0.11, 0.83; NNT 2 range 2 to 4).

Authors' conclusions

Plastic wraps or bags, skin-to-skin care and transwarmer mattresses all keep preterm infants warmer, leading to higher temperatures on admission to neonatal units and less hypothermia. Given the low NNT, consideration should be given to using these interventions in the delivery suite. However, the small numbers of infants and studies and the absence of long term follow-up mean that firm recommendations for clinical practice cannot be given. There is a need to conduct large, high quality randomised controlled trials looking at long-term outcomes.

PLAIN LANGUAGE SUMMARY

Synopsis pending. Copyright © 2006 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.


BACKGROUND

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Neonatal hypothermia after birth is a world-wide issue (Costeloe 2000) across all climates (Christensson 1988; Johanson 1992; Tafari 1973) and if prolonged can lead to harm and in severe cases death. Keeping preterm infants sufficiently warm immediately after birth, especially during resuscitation, is problematic even when routine thermal care guidelines are followed. The newborn cannot shiver (Scopes 1963), and relies on interventions to protect it against exposure to cold. The ability to maintain an equilibrium between heat loss and heat gain (Bickmann 1992) despite variation in environmental temperatures is restricted during the first 12 hours of life (Smales 1978). After birth, deep body and skin temperature of the term newborn can drop at a rate of approximately 0.1 °C and 0.3 °C per minute respectively unless immediate action is taken (Adamsons 1965a). Silverman 1958 and Day 1964 showed that reducing heat losses in preterm infants in the first few days after birth increased survival rates. Early intervention in the delivery suite is therefore of high priority if hypothermia is to be prevented.

What are the clinical implications of cold stress?

Although cold stress may be important for initiating breathing (Harned 1970) and induced cooling may help protect the brain of asphyxiated term newborns, prolonged exposure to cold should be avoided. Extended periods of cold stress can lead to harmful side effects, which include hypoglycaemia (Elliott 1957), respiratory distress (Pomerance 1974), hypoxia, metabolic acidosis (Gandy 1964), coagulation defects (Chadd 1972), delayed readjustment from fetal to newborn circulation (Stephenson 1970), acute renal failure, necrotizing enterocolitis, failure to increase weight or weight loss (Glass 1968) and in extreme cases death (Elliott 1957). Factors that increase the risk of hypothermia include prematurity, intrauterine growth retardation (Borse 1997; Hey 1975), asphyxia, certain congenital anomalies such as gastroschisis and damage to the central nervous system (Bickmann 1992).

What causes hypothermia immediately at birth?

Rapid postnatal fall in body temperature is attributable to a combination of the physical characteristics of the infant (e.g. large surface area in relation to body weight and a thin layer of insulating fat) and environmental factors in the delivery suite. Extent of total heat loss and the four modes of heat exchange (conduction, convection, radiation and evaporation) are influenced by the ambient air temperature, pressure and relative humidity, and temperature of surrounding surfaces (Capobianco 1980; Thomas 1994). Increased rate of heat loss is mainly caused by evaporation of amniotic fluid from the skin surface (Hammarlund 1980) when the wet newborn moves from the warm environment of the uterus (Adamsons 1965a) into a cool, dry delivery suite.

The term infant, in an attempt to maintain core body temperature within the normal range of 36.5 to 37.5 °C (skin temperature of 0.5 to 1.0 °C lower) (Hey 1970; Oliver 1965), responds mainly by production of heat from the breakdown of brown fat (non-shivering thermogenesis) (Stern 1970) and peripheral vasoconstriction. When skin temperature falls to 35 to 36 °C non-shivering thermogenesis is initiated (Bruck 1961). The World Health Organisation classifies a core body temperature for newborns of 36 to 36.4 °C as mild hypothermia, 32 to 35.9 °C as moderate and < 32 °C as severe (WHO 1997). The preterm infant has the combined disadvantages of decreased fat for heat production and insulation, decreased glycogen stores, immature skin which increases water loss and poor vascular control. They experience even higher evaporative heat losses than term infants in the first day, especially at low ambient relative humidities (Hammarlund 1979). Five hundred and sixty calories of heat are lost for each millilitre of water which evaporates from the skin (Rutter 2000). Currently, there is no accepted formal definition of 'normal' temperatures for preterm infants and methods and accuracy of temperature measurement continue to be debated (Bailey 2000; Smith 2004).

The external (skin-environment) temperature gradient is pivotal in influencing the infant's response to cold (Adamsons 1965) and it is here that health professionals can intervene in the delivery suite to minimise the risk of hypothermia.

What preventative action can be taken?

Standard care includes providing a warm delivery room at a minimum of 25 °C (although rarely achieved in practice) (WHO 1997), drying the infant thoroughly, especially the head, immediately after birth (Bloom 1994), removing any wet blankets, wrapping in a prewarmed blanket, prewarming any contact surfaces, eliminating drafts and close proximity to outside walls (Capobianco 1980). Radiant warmers (if available) for resuscitation and stabilization allow easy access and are effective in preventing heat losses, provided that the infant is immediately dried and placed under the prewarmed heater (Du 1969; Dahm 1972). Although the infant gains heat by radiation, there are increased potential losses through convection and evaporation and these are exacerbated if the infant is inadequately dried. Servocontrol is advantageous for the avoidance of overheating or underheating if absorption of heat is being obstructed by coverings.

Studies to investigate the effectiveness of additional measures to reduce heat loss in the immediate postnatal period fall into two groups:

  • (1)
    barriers to heat loss and
  • (2)
    external heat sources.

Interventions in the first group focus mainly on reducing evaporative heat losses (LeBlanc 1991) and have included wraps and/or headcoverings made from a variety of materials (Chaput 1979; Coles 1979; Holzman 1985). Baum 1968 tested a polyester suit lined with aluminum, known as the 'silver swaddler', designed to prevent hypothermia by reducing all modes of heat transfer to the environment and this was effective for infants with birthweights > 3000 g but, since the material is opaque, it is not practical during resuscitation. Transparent plastic coverings such as bubble wrap (Besch 1971) and single layer gowns (Hobbs 1975) are effective in the delivery suite for full-term healthy newborn infants and those with birthweights > 2000 g respectively and where the intervention was polyethylene wrap for infants of < 33 weeks' gestation (Lenclen 2002). Hoods or heat shields which are not in contact with the infant's body have also been used in conjunction with a radiant warmer or incubator (Baumgart 1981; Bell 1980). Barrier creams, waxes or protective films such as Aquaphor ® (Nopper 1996) have also been utilised to reduce heat losses in immature infants but are not normally applied within 10 minutes of birth.

Interventions in the second group have included heated mattresses (Almeida 2000) and as an alternative to radiant warmers, for a healthy term newborn skin-to-skin contact, (where the infant is thoroughly dried and placed on the mother's chest and abdomen with a light blanket around them), can reduce radiant and conductive heat loss and promote temperature stabilization (Britton 1980; Christensson 1992).

All of these interventions have potential disadvantages, for example Newton 2003 reported that significantly more infants (with gestational ages < 30 completed weeks), wrapped in polythene bags were hyperthermic (> 37 °C) when compared to unwrapped historical controls. Brun 1997 noted that a chemical hot pack during resuscitation of a newborn infant resulted in third degree burns and recommended that these should not be used unless the peak temperature of the pack is < 44 °C.

Review focus

Interventions should therefore either decrease total heat losses or provide external heat without compromising accessibility during resuscitation and should have minimal side effects (such as hyperthermia, burns, maceration, or infection). This review focuses on individual interventions applied within 10 minutes after birth in the delivery suite and is limited to preterm and/or low birthweight infants since these are most susceptible to the adverse effects of hypothermia. Longer term thermal management and spatial or environmental strategies for increasing warming are beyond the scope of this review.

OBJECTIVES

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

PRIMARY OBJECTIVE

To assess the efficacy and safety of interventions, designed for the prevention of hypothermia in preterm and/or low birthweight infants, and applied within 10 minutes after birth in the delivery suite, compared with routine thermal care.

Subgroup analyses to be carried out by intervention, by birthweight/gestational age and by developmental status of the country of study, to determine whether effectiveness varies according to:

  • The interventions applied

  • Birthweight and gestational age within the following categories:

    • birthweight (< 1500 g), (1500 g to 2500 g)

    • gestational age (< 28 wk), (28 to 32 wk) and (33 to 37 wk)

  • The developmental status of the country in which the trial was conducted based upon the UNICEF classification of a developing country (UNICEF 2002).

However, the subgroups reported in the included studies were not compatible with those pre-specified. Therefore, post facto subgroup analyses based on reported gestational age and birthweight subcategories were carried out where appropriate within each comparison group.

SECONDARY OBJECTIVES

To assess effects on complications associated with preterm birth, hypothermia, and adverse outcomes.

CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Types of studies

All trials using randomised or quasi-randomised allocation to test a specific intervention designed to prevent hypothermia immediately after birth.

Types of participants

Preterm infants of less than 37 weeks' gestational age (according to best obstetric estimate at time of delivery) or low birth weight infants of ≤2500 g, where the intervention to prevent hypothermia is applied within 10 minutes after birth in the delivery suite. Both appropriate and small-for-gestational age infants were eligible.

Exclusions

Infants with major congenital malformations, especially abdominal wall defects.

Types of intervention

Any intervention applied within 10 minutes after birth in the delivery suite apart from ROUTINE THERMAL CARE which was defined as any of the following routine practices: providing a warm delivery suite at a minimum of 25 °C (rarely achieved in practice), drying the infant immediately after birth, removing any wet blankets and wrapping in a pre-warmed blanket, pre-warming any contact surfaces, avoiding draughts and in developed countries the use of radiant warmers or incubators. The control intervention comprised any elements of routine thermal care.

The interventions studied were to include:

  • (1)
    Barriers to heat loss applied to any part of the body of the preterm and/or low birthweight infant within 10 minutes after birth in the delivery suite
    • Coverings such as transparent plastic wraps and bags made of low density polyethylene (LDPE) or linear low density polyethylene (LLDPE) or polyvinylidene chloride (PVDC)

    • Semi-permeable membranes such as Opsite® or Tegaderm®

    • Other additional swaddling materials or wraps (excluding delivery room blankets) such as the 'silver swaddler'.

  • (2)
    External heat sources (non-routine) initiated within 10 minutes after birth in the delivery suite
    • Skin-to-skin care

    • Heated/gel/chemical mattresses.

Types of outcome measures

PRIMARY OUTCOMES

The temperature of the infant taken on admission to the Neonatal Intensive Care Unit (NICU) or up to two hours after birth. Temperature was assessed as both continuous and dichotomous variables.

Rectal, axillary, oral or tympanic temperature measurements were accepted as equivalent core body temperature and abdominal skin temperature was accepted for skin temperature. Where both core temperature and skin temperature were recorded core temperature took priority. Where multiple temperatures were recorded (i.e. within different time frames up to two hours after birth) the lowest temperature recorded took priority.

A core body temperature of < 36.5 °C or a skin temperature of < 36 °C indicated the presence of hypothermia within the control and intervention groups.

For hypothermia, core body temperature and skin temperature subgroupings as defined by WHO 1997 were used to determine three levels of severity

  • Mild hypothermia or cold stress: core body temperature 36 to 36.4 °C or skin temperature of 35.5 to 35.9 °C

  • Moderate hypothermia: core body temperature 32 to 35.9 °C or skin temperature of 31.5 to 35.4 °C

  • Severe hypothermia: core body temperature of < 32 °C or skin temperature < 31.5 °C.

SECONDARY OUTCOMES

These were categorised as (1) morbidity and (2) adverse outcomes due to the intervention.

  • (1)
    Morbidity
    • Hypoglycaemia as defined by a blood glucose level of < 2.0 mmol/L within two hours of birth

    • Respiratory distress syndrome (RDS) as defined by clinical signs of grunting, flaring, retractions, cyanosis in room air, tachypnoea and a radiological picture of reticulogranular mottling and air bronchogram

    • Surfactant given at any time

    • Intubation in delivery room

    • Requirement for ventilation and duration of ventilation (days)

    • Length of stay (days)

    • Mortality: death within seven days, death within 28 days and/or death during hospital stay

    • Severe metabolic acidosis as defined by pH < 7.20 and/or base deficit > 10 mmol/L within the first three days of life

    • Intraventricular haemorrhage as defined according to the criteria of Papile et al from head ultrasound performed before 14 days of life (Lee 2000; Papile 1978)

    • Patent ductus arteriosus as defined by clinical diagnosis plus treatment with indomethacin or surgical ligation or both (Lee 2000)

    • Chronic lung disease as defined by oxygen dependency at 36 weeks' corrected gestational age for an infant who was born at ≤32 weeks' gestation (Lee 2000; Shennan 1988)

    • Necrotizing enterocolitis as defined according to the criteria of Bell et al (Bell 1978) stage 2 or higher and classified as medical (clinical symptoms and signs plus evidence of pneumatosis on abdominal radiographs) or surgical (histological evidence of NEC on surgical specimen of intestine) (Lee 2000)

    • Acute renal failure as defined by a serum creatinine level of more than 1.5 mg/dL (Stapleton 1987) and oliguria (urine output < 1 ml/kg/hr)

  • (2)
    Adverse outcomes due to the intervention
    • Hyperthermia as defined by an admission temperature to NICU or within two hours of birth of ≥38 °C

    • Burns within three days of birth

    • Maceration within three days of birth

    • Skin or systemic infection secondary to intervention within the first week of birth as defined by a culture of pathogenic bacteria from normally sterile body tissue or fluid

    • Antibiotic course of five days or more started within the first seven days of birth

    • Interference with resuscitation and other practices (e.g. UV catheter placement for fluid replacement, chest tube insertion)

    • Fluid problems such as dehydration or fluid overload, electrolyte imbalance such as hypernatraemia (serum sodium > 150 mmol/L) or hyponatraemia (serum sodium < 130 mmol/L)

    • Any other unexplained adverse outcome attributed to the intervention within seven days of birth

    • Negative psychological outcomes (perception of care by parents).

SEARCH METHODS FOR IDENTIFICATION OF STUDIES

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

See: Neonatal Group methods used in reviews.

The standard search strategy of the Cochrane Collaboration was used (Clarke 2002). This included searches of electronic databases: MEDLINE (1966 to May Week 4 2004 ), CINAHL (1982 to May Week 4 2004), EMBASE (1974 to 09/07/04), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2004) and the Database of Abstracts of Reviews of Effects (DARE 1994 to July 2004), conference/symposia proceedings using ZETOC (1993 to July 2004) and ISI proceedings (1990 to 09/07/2004). In addition OCLC WorldCat (July 2004) was searched and identified articles were cross referenced. No language restrictions were imposed. The MEDLINE search strategy is detailed below and similar search strategies were devised using appropriate terminology for each electronic database.

  • 1.
    plastic barrier*.ab,ti.
  • 2.
    polyethylene*.ab,ti.
  • 3.
    (bubble wrap* or bubble-wrap* or bubblewrap*).ab,ti.
  • 4.
    (clingfilm* or cling film* or cling-film*).ab,ti.
  • 5.
    (plasticwrap* or plastic-wrap* or plastic wrap*).ab,ti.
  • 6.
    exp Polyethylenes/
  • 7.
    exp Polyvinyls/
  • 8.
    (polyvinyl* or poly-vinyl*).ab,ti.
  • 9.
    (low density polyethylene* or low-density polyethylene*).ab,ti.
  • 10.
    (gladwrap* or glad wrap* or glad-wrap*).ab,ti.
  • 11.
    (polybag* or poly bag* or poly-bag*).ab,ti.
  • 12.
    (saranwrap* or saran-wrap* or saran wrap*).ab,ti.
  • 13.
    transparent baby bag*.ab,ti.
  • 14.
    baby bag*.ab,ti.
  • 15.
    (headwrap* or polyester headwrap*).ti,ab.
  • 16.
    silver swaddling*.ti,ab.
  • 17.
    (silver and swaddling*).ti,ab.
  • 18.
    swaddling*.ti,ab.
  • 19.
    exp Incubators, Infant/
  • 20.
    radiant warmer*.ti,ab.
  • 21.
    exp Membranes, Artificial/
  • 22.
    (semi-permeable membrane* or semipermeable membrane*).ti,ab.
  • 23.
    exp POLYURETHANES/
  • 24.
    polyurethane*.ti,ab.
  • 25.
    kangaroo care*.ti,ab.
  • 26.
    skin to skin contact*.ti,ab.
  • 27.
    heat* mattress*.ti,ab.
  • 28.
    chemical gel mattress*.ti,ab.
  • 29.
    gel mattress*.ti,ab.
  • 30.
    chemical mattress*.ti,ab.
  • 31.
    head hood*.ti,ab.
  • 32.
    head insulation*.ti,ab.
  • 33.
    swaddl*.ti,ab.
  • 34.
    plastic bag*.ti,ab.
  • 35.
    early suck*.ti,ab.
  • 36.
    Breast Feeding/
  • 37.
    (breast feed* or breastfeed*).ti,ab.
  • 38.
    skin-to-skin.ti,ab.
  • 39.
    suckl*.ti,ab.
  • 40.
    bath*.ti,ab.
  • 41.
    radiant heater*.ti,ab.
  • 42.
    radiant heat lamp*.ti,ab.
  • 43.
    (mother* adj5 (bab* or infant*) adj5 (contact* or hold*)).ti,ab.
  • 44.
    heated bed*.ti,ab.
  • 45.
    resuscitat*.ti,ab.
  • 46.
    exp RESUSCITATION/
  • 47.
    (intervention* or procedure* or method*).ti,ab.
  • 48.
    exp Infant, Low Birth Weight/
  • 49.
    ((birth* or bab* or infant) and (premature or pre-mature or preterm or pre-term or low weight or low birth weight or very low birth weight or VLBW or LBW)).ab,ti.
  • 50.
    Infant, Newborn/
  • 51.
    Body Temperature Regulation/ or Body Temperature/
  • 52.
    HYPOTHERMIA/
  • 53.
    (hypothermia or cold stress or heat loss or temperature regulation or body temperature).ab,ti.
  • 54.
    temperature drop*.ti,ab.
  • 55.
    heat loss.ti,ab.
  • 56.
    or/1-47
  • 57.
    or/48-50
  • 58.
    or/51-55
  • 59.
    56 and 57 and 58

METHODS OF THE REVIEW

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

The standard method of The Cochrane Collaboration for conducting a systematic review as described in The Cochrane Reviewers' Handbook (Clarke 2002) was followed.

SELECTION AND QUALITY ASSESSMENT

The search strategy was designed and electronic databases searched in association with the Medical Faculty Librarian, Queen's University Belfast. At least three reviewers independently assessed the full list of titles and abstracts for eligibility and the full texts of those considered to be relevant were retrieved. Reasons for exclusion of studies were clearly stated by each reviewer. Formal translation of studies was not required.

At least three independent reviewers assessed those studies which fulfilled the criteria for inclusion for quality and extracted data using prepared proformas. Methodological quality was judged according to: (1) blinding of randomisation, (2) blinding of intervention, (3) completeness of follow-up and (4) blinding of outcome measurement. There was complete agreement among team members. Additional information was sought from investigators for three included trials (Vohra 2003; Vohra 1999; Wimmer 2002). The information retrieved is detailed in the Table of “Characteristics of included studies”.

Reviewers were not blinded to authors or to institution. In two papers a team member was also an author of a selected trial so that team member was excluded from the study appraisal process.

ANALYSIS

Meta-analysis was carried out using the fixed effect model. Relative risk (RR) and 95% confidence limits were calculated for dichotomous outcomes. From the risk difference (RD), the number needed to treat (NNT) or the number needed to harm (NNH) and 95% confidence limits for each homogenous subgroup were calculated. Mean differences (MD) and 95% confidence limits were calculated for continuous outcomes.

The influence of the trial quality on the findings of the review would have been explored, had there been more studies, by conducting a sensitivity analysis of adequate versus unclear versus inadequate allocation concealment as outlined in The Cochrane Reviewers' Handbook (Clarke 2002).

Where heterogeneity was identified, subgroup analyses were carried out for gestational age and birthweight. Had there been sufficient studies sensitivity analyses would have provided valuable information on the role of variations in methodological quality, definitions of hypothermia, type of patient group and intervention.

DESCRIPTION OF STUDIES

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Seventy-four studies potentially eligible for inclusion in our review were identified. Of these, 48 were randomised or quasi-randomised controlled studies and 26 were non-randomised studies. On assessment, six studies were identified as fulfilling all of our criteria for inclusion. Forty-two randomised or quasi randomised studies did not fulfill our criteria for inclusion and are detailed in the Table of “Characteristics of excluded studies”. We decided not to include in the Table of “Characteristics of excluded studies” non-randomised studies. Further details of these non-randomised trials can be obtained from the authors on request. In all, six studies involving 304 randomised infants were included in this review: two theses (Brennan 1996; Roberts 1981), two published papers (Bergman 2004; Vohra 1999) and two abstracts (Vohra 2003; Wimmer 2002 ). The Vohra 2003 and the Wimmer 2002 manuscripts have been accepted by the Journal of Pediatrics and the Journal of Perinatology respectively and are currently 'In press'. Full data will be available on publication.

Four studies compared barriers to heat loss to no barriers (Roberts 1981; Vohra 1999; Vohra 2003; Wimmer 2002) and two studies compared external heat sources (non-routine) to no external heat sources (Bergman 2004; Brennan 1996). There were two comparison groups within the barriers to heat loss category : plastic wrap or bag versus routine care (Vohra 1999; Vohra 2003; Wimmer 2002) and stockinet cap versus routine care (Roberts 1981). There were also two comparison groups within the external heat source category: skin-to-skin care versus routine care (Bergman 2004) and transwarmer mattress versus routine care (Brennan 1996).

All interventions were applied immediately after birth in the delivery suite. Participants were categorised by gestational age (all preterm) in four studies and by birthweight (all low birthweight) in two studies. One study was conducted in a developing country, (South Africa) (Bergman 2004), and all other studies took place in developed countries (USA: Brennan 1996; Roberts 1981; Wimmer 2002 and Canada: Vohra 1999; Vohra 2003). Routine external heat sources were utilised as part of care (control group and/or intervention group) in all studies : servo controlled incubator (Bergman 2004), radiant warmer (Brennan 1996; Vohra 1999; Vohra 2003 ), warmer table (Wimmer 2002) and radiant warmer ± transport incubator (Roberts 1981). The main outcome measure (temperature of the infant on admission to NICU or up to 2 hours after birth) was reported as a continuous variable in five studies and as a dichotomous variable only in one study (Bergman 2004). Five studies reported core body temperature (rectal:3, axillary:2) and in one study skin temperature was reported. In addition, three studies also provided dichotomous data pertaining to incidence of hypothermia in the intervention and control groups. Definitions of hypothermia were not consistent across studies. There was limited reporting of pre-specified secondary outcomes.

SUMMARY DESCRIPTIONS OF INDIVIDUAL STUDIES

Further details for each study are given in the Table of “Characteristics of included studies.”

BARRIERS TO HEAT LOSS

ROBERTS 1981

Participants

Forty inborn infants of 32 to 36 completed weeks' gestation born between 7 am to 5 pm on weekdays were included in this single centre study conducted at Parkland Memorial Hospital in Dallas, Texas, USA. Infants were excluded from the study if they were: not appropriate for gestational age, had an Apgar score < 7 at 5 minutes, signs of central nervous system defect, developed sepsis or where the maternal temperature > 37.8 °C during labour.

Intervention

Stockinet cap (CAP) - sterile headpiece made of stockinet which covers the forehead, the ears, underneath the occipital bone and all the area above this plane.

CAP group(n = 17): infants received a stockinet cap after delivery as soon as possible after being dried under a radiant warmer.

Control group (n = 23): infants received the same treatment as the intervention group but did not receive a stockinet cap.

All infants weighing < 2500 g were transported to the nursery in a transport incubator.

Outcomes

Core body temperature (axillary °C) was measured within 10 minutes of admission to the neonatal unit. The amount of heat lost from the time the axillary temperature was taken in the delivery room until the temperature was taken in the neonatal unit was also reported.

Vohra 1999

Participants

Sixty-two inborn infants of < 32 completed weeks' gestation, where the neonatal resuscitation team were present, were included in this single centre study conducted at the Grace Hospital (later the IWK Grace Health Centre) in Halifax, Nova Scotia, Canada. Infants were excluded from the study if they had: major congenital anomalies with open lesions and where the infant was considered “previable” by the attending Obstetrician.

Intervention

Polyethylene bag (WRAP) - 20cm x 50cm manufactured by Eastern Paper, a Division of EPC Industries.

WRAP group(n = 27): a transparent polyethylene bag was opened at resuscitation under a radiant warmer and the infant was placed on it from the shoulders down. Only the head of the infant was dried; the body was wrapped without drying.

Control group(n = 32): infants were managed with the protocol described by the Neonatal Resuscitation Program. Infants were routinely dried under the radiant warmer.

All infants were transferred to NICU in incubators.

Outcomes

Core body temperature (rectal °C) was measured on removal of the bag/wrap on admission to the neonatal unit. Incidence of mortality, hyperthermia, infection, skin maceration and interference with resuscitation were also reported.

VOHRA 2003

Participants

Fifty-five inborn infants of < 28 completed weeks' gestation, where the neonatal resuscitation team were present, were included in this single centre study conducted at McMaster University Medical Center in Hamilton, Ontario, Canada. Infants were excluded from the study if they had: major congenital anomalies that were not covered by the skin and blistering skin conditions.

Intervention

Polyethylene wrap (WRAP) - 20cm X 50cm manufactured by Eastern Paper, a Division of EPC Industries.

WRAP group(n = 26): infants were placed on polyethylene, wrapped from the neck down, only the head was dried and stabilized under a radiant warmer.

Control group(n = 27): infants were dried completely according to the International Guidelines for Neonatal Resuscitation and stabilised under a radiant warmer.

All infants were carried by one member of the neonatal team from the delivery room to the neonatal unit and placed in a single walled incubator with 60 percent humidity.

Outcomes

Core body temperature (rectal °C) on removal of the bag/wrap on admission to the neonatal unit, core body temperature (rectal °C) 1 hour later and incidence of mortality from all causes were reported. Additional outcomes are also reported in the full manuscript and will be available for data extraction on publication: Apgar score at 1 minute, Apgar score at 5 minutes, blood gas pH, Bicarbonate (mmol/L), Glucose mmol/L, hyperthermia (rectal °C > 37.5) and interference with resuscitation).

WIMMER 2002

Participants

Eighty-eight infants of < 29 completed weeks' gestation were included in this single centre study conducted at Pitt County Memorial Hospital, Greenville, NC, USA. Infants were excluded from the study if they had: congenital anomalies with open lesions, meconium staining of the amniotic fluid or if they were considered previable or subsequent assessment indicated that the infant was ≥29 completed weeks' gestation.

Intervention

Polyurethane bag (WRAP).

WRAP group (n = 41): infants were placed immediately into a polyurethane bag, while still wet, up to their necks and resuscitated according to the guidelines for Neonatal Resuscitation.

Control group (n = 47): infants were resuscitated according to these guidelines without the bags.

All infants were taken to the neonatal unit on a warmer table, (with the heat off) with warm blankets on top of the infant.

Outcomes

Core body temperature (rectal°C) and incidence of hypothermia (rectal °C < 36.4) on admission to the neonatal unit, incidence of mortality, major brain injury, duration of oxygen therapy and hospitalisation.

Further details will be available on publication of the full manuscript.

EXTERNAL HEAT SOURCES (NON-ROUTINE)

BERGMAN 2004

Participants

Thirty-five inborn infants delivered, (excluding caesarean sections), having a birthweight between 1200 and 2199g were included in this study conducted at two secondary level referral hospitals (Mowbray Maternity Hospital and Karl Brenar Hospital) in Cape Town, South Africa. Infants were excluded from the study if they had a birthweight below 1200 g or above 2199 g, an Apgar score below six at five minutes, congenital malformations detected at birth or where the mother was too severely ill to be able to look after herself or the infant, was known to have a positive HIV status or had given up the infant for adoption.

Intervention:

Skin-to-skin care (SSC)

All infants were delivered onto a theatre cloth on the mother's abdomen/chest, dried, assessed, then placed on the mother's naked chest and covered with double layered cotton cloth. The bed was then placed in the semi-Fowlers position.

SSC group (n = 18): the infant remained in skin-to-skin contact, was secured to the mother's chest, hips and arms were flexed and placed in a 'frog' position.

Control group (n = 13): the infant was immediately transferred to a pre-warmed servo-controlled closed incubator which remained with the mother in the delivery ward for the first hour. A cap, booties and heat shield were applied if the infant skin temperature fell below 36 °C.

Outcomes

Infant stability was measured in terms of a set of pre-defined physiological parameters. Observations for heart rate, oxygen saturation and body temperature (skin °C) were recorded at five minute intervals in the first half hour, then 15 minute intervals. Continuous observations for apnoea and signs of respiratory distress, and blood sugar were measured at one, three and six hours.

BRENNAN 1996

Participants

Twenty-four inborn infants having a birthweight ≤1500 g were included in this single centre study conducted at Shands Hospital located in north-central Florida, USA. Infants were excluded from the study where the maternal temperature at delivery was > 38.0 °C, the infant had: an obvious neural tube defect, an omphalocele, gastroschisis, extrophy of the bladder, cloacal exstrophy, any other open lesion that would cause greater than normal heat loss at delivery, sacral teratoma, or any other lesion that would prevent the infant from being positioned and evaluated in the normal manner.

Intervention:

Transwarmer Infant Transport Mattress (TM) manufactured by Prism Technologies, San Antonio, Texas. These are filled with a gel of sodium acetate, water and thickeners. Once activated they heat to approximately 40 °C for two hours.

TM group (n = 12): the mattress was activated and placed on the radiant warmer surface with blankets on top of it when delivery was imminent. The newborn infant was immediately placed on the blankets and dried. Blankets were removed and the infant was then placed directly onto the warming mattress.

Control group (n = 12): infants received the same care as the intervention group but without the warming mattress.

Both groups were evaluated and resuscitated according to the Neonatal Resuscitation Program and transported to the neonatal unit on the radiant warmer surface. The infants in the intervention group remained on the mattress until the admission temperatures were taken.

Outcomes

Core body temperature (axillary °C) was measured as soon as possible after arrival at the neonatal unit. Incidence of interference with resuscitation was also monitored. Individual patient data was reported in this study.

METHODOLOGICAL QUALITY

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

BARRIERS TO HEAT LOSS

The generation of allocation sequence was adequate (computer randomisation or lot drawing) in three studies and unclear in one. Allocation concealment was adequate in three studies using varying degrees of sealed/opaque/double enclosed envelopes and in one study the method was unclear. No attempt was reported in any of the studies to blind participants or care providers to the intervention. Follow-up was complete in two studies. In the remaining two studies Vohra 1999 (3 of 62 or 5%) and Vohra 2003 (2 of 55 or 4%) of infants randomised were lost to follow-up. Reasons for loss to follow-up were reported adequately in each study. No studies reported any attempt to blind the outcome assessors to the intervention.

EXTERNAL HEAT SOURCES (NON-ROUTINE)

The generation of allocation sequence was adequate (computer randomisation or lot drawing) in both studies, however, the method of allocation concealment for each study was unclear. No attempt was reported in any of the studies to blind participants or care providers to the intervention. Follow-up was complete in one study. In the remaining study Bergman 2004 (4 of 35 or 11%) of infants randomised were lost to follow-up. Reasons for loss to follow-up were adequately reported. Only one study Bergman 2004 reported any attempt to blind the outcome assessors to the intervention where the principal investigator and data analysis team were blinded.

In all, no studies in either category fulfilled all the methodological quality criteria. Further details for each study are given in the Table of “Characteristics of included studies.”

RESULTS

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

RESULTS OF META-ANALYSES

Six studies were identified which fulfilled our criteria for inclusion giving a total of 304 infants randomised and 295 infants completing the studies. Four studies compared barriers to heat loss to no barriers giving a total of 245 infants randomised and 240 infants completing the studies (Roberts 1981; Vohra 1999; Vohra 2003; Wimmer 2002). Two studies compared external heat sources (non-routine) to no external heat sources giving a total of 59 infants randomised and 55 infants completing the studies (Brennan 1996; Bergman 2004). There were two comparisons within the barriers to heat loss category: plastic wrap versus routine care (Vohra 1999; Wimmer 2002; Vohra 2003) and stockinet cap versus routine care (Roberts 1981). There were also two comparisons group within the external heat source category: skin-to-skin care versus routine care (Bergman 2004) and transwarmer mattress versus routine care (Brennan 1996). There were insufficient studies to carry out subgroup analysis according to developmental status of the country.

BARRIERS TO HEAT LOSS

COMPARISON 01 PLASTIC WRAP VERSUS ROUTINE CARE

Primary outcomes

01.01 Core body temperature (°C) of the infant taken on admission to NICU or up to 2 hours after birth

Three studies comprising 200 infants (Vohra 1999; Vohra 2003; Wimmer 2002) reported core body temperature (rectal °C) on admission to NICU. Each individual study showed a significant effect in favour of the intervention (plastic wrap) group for infants with a gestational age < 28 completed weeks. Although the infants in the Wimmer 2002 study had a gestational age < 29 completed weeks, these infants were included in the < 28 completed week subgroup for meta-analysis.

Overall

For infants with a gestational age < 32 completed weeks, a statistically significant difference was shown in core body temperature on admission to NICU favouring the intervention (plastic wrap) group when compared to those who received routine care immediately after birth in the delivery suite (three studies, n = 200; WMD 0.60°C 95% CI 0.37, 0.83).

However, the overall test for homogeneity and for the subgroup of infants with a gestational age < 32 completed weeks fails with I2values > 75%. We note the most likely reason for this failure is the contribution of the small Vohra 1999 study for the subgroup of infants < 28 completed weeks which gives rise to a 95% CI range somewhat outside the range suggested by the other studies. Rather than excluding this study purely on statistical grounds the possible reasons for this heterogeneity are explored in the discussion section of this review.

01.01.01 For infants with a gestational age < 28 completed weeks a statistically significant difference was shown in core body temperature on admission to NICU favouring the intervention (plastic wrap) group when compared to those who received routine care immediately after birth in the delivery suite (three studies, n = 159; WMD 0.76 °C; 95% CI 0.49, 1.03).

01.01.02 For infants with a gestational age of 28 to 31 completed weeks no statistically significant difference in the effects of the two interventions (plastic wrap and routine care) for core body temperature on admission to NICU was shown (one study, n = 41; MD 0.17 °C; 95% CI -0.27, 0.61).

01.02 Core body temperature taken 1 hour after initial admission temperature to the NICU was taken

This outcome was reported in one small study (Vohra 2003) in terms of core body temperature (rectal °C) one hour after the initial admission temperature was taken. This was not pre-defined at review protocol stage. The reason stated for collection of this outcome measure was to ascertain whether the intervention (plastic wrap) prevented rather than delayed the post natal fall in body temperature immediately after birth.

01.02.01 For infants with a gestational age < 28 completed weeks no statistically significant difference in the effect of the two interventions (plastic wrap and routine care) was shown for core body temperature one hour after the initial admission temperature to NICU was taken, although the direction was in favour of the intervention (one study, n = 53; MD 0.20 °C; 95% CI -0.24, 0.64).

01.03 Hypothermia on admission to NICU (core body temperature < 36.5 °C or skin temperature < 36 °C)

01.03.01 Wimmer 2002, in addition to reporting core body temperature on admission to NICU as a continuous variable, also provided data in a dichotomous format in terms of incidence of hypothermia in intervention and control groups (plastic wrap and routine care). Hypothermia was defined in this study as a core body temperature (rectal) < 36.4 °C on admission to NICU. For infants of gestational age < 29 completed weeks, (classed as < 28 wk for previous subgroup analysis for 01.01.01), plastic wrap significantly reduces the risk of hypothermia on admission to NICU (one study, n = 88; RR 0.63, 95% CI 0.42, 0.93; RD -0.26; 95% CI -0.46, -0.06).

This finding is consistent with those for the outcome measure 01.01.01. Four infants would need to be wrapped in plastic in order to prevent one infant from becoming hypothermic (NNT 4, 95% CI 3 to 17).

Secondary outcomes

01.04 Mortality (death within hospital stay)

Three studieswhich included 112 infants (Vohra 1999;Vohra 2003; Wimmer 2002) reported this outcome in terms of death within hospital stay. Mortality figures for the Vohra 2003 study included two infants who died in the delivery room. The test for homogeneity passed with an I2value of 3.6%.

01.04.01 For infants with a gestational age < 28 completed weeks the results of the meta-analysis are in the direction in favour of the intervention group (plastic wrap). However, this is being pulled by the (Vohra 1999) study with five events in the control group and showing borderline significance. Overall there is insufficient evidence to suggest that plastic wrap reduces the risk of death within hospital stay for this group of infants (three studies, n = 161; typical RR 0.63; 95% CI 0.32, 1.22; typical RD -0.09; 95% CI -0.20, 0.03).

01.04.02 For infants with a gestational age of 28 to 31 completed weeks there were no deaths within hospital stay in either group. Data were provided from one study Vohra 1999 (41 infants).

01.05 Major brain injury

This outcome was reported in one study (Wimmer 2002) but it was not pre-defined at review protocol stage.

01.05.01 For infants of gestational age < 29 completed weeks there was no evidence of a difference in risk of major brain injury (one study, n = 88; RR 1.15; 95% CI 0.36, 3.68; RD 0.02; 95% CI -0.12, 0.15).

01.06 Duration of oxygen therapy (days)

This outcome was reported in one study (Wimmer 2002) but it was not pre-defined at review protocol stage.

01.06.01 For infants of gestational age < 29 completed weeks, there is no significant difference in duration of oxygen therapy (one study, n = 88; MD -6.51 days; 95% CI -23.30, 10.28).

01.07 Duration of hospitalisation (days)

This outcome was reported in one study (Wimmer 2002).

01.07.01 For infants of gestational age < 29 completed weeks, there was no significant difference in duration of hospitalisation (one study, n = 88; MD -5.49 days; 95% CI -19.93, 8.95).

Other secondary outcomes

The following secondary outcome measures were not available for any of the included studies for this comparison: hypoglycaemia, respiratory distress syndrome, surfactant given at any time, intubation in the delivery room, requirement for ventilation, duration of ventilation, severe metabolic acidosis, intraventricular haemorrhage, patent ductus arteriosus, chronic lung disease, necrotizing enterocolitis, acute renal failure, burns, antibiotics or negative psychological outcomes.

Data regarding Apgar scores at one and five minutes, blood gas pH, bicarbonate (mmol/L), glucose are reported in the Vohra 2003 full manuscript and will be available in the next update of this review.

Adverse occurrences

There were no occurrences of adverse events attributable to the intervention (i.e. hyperthermia, infection, skin maceration or interference with resuscitation) for infants in the intervention and control groups in the Vohra 1999 study.

Data regarding interference with resuscitation and hyperthermia are reported in the Vohra 2003 full manuscript and will be available in the next update of this review.

COMPARISON 02 STOCKINET CAP VERSUS ROUTINE CARE

Primary outcomes

02.01 Core body temperature (°C) on admission to NICU or up to 2 hours after birth

Roberts 1981 reported core body temperature (axillary °C) on admission to NICU in a study of 40 infants. This study reported figures for all infants with a gestational age 32 to 36 completed weeks, and also for the subgroup of infants < 2000 g birthweight. We have tried to disaggregate the data using the information available, in order to obtain data for the subgroup of infants weighing 2000 g or more at birth. These subgroup analyses by birthweight class were not pre-specified in the protocol for this review.

Overall:

The I2 value of 65.8% indicates that there is a moderate degree of heterogeneity of effect across these two birthweight subgroups. Overall, the results show no statistically significant difference in the effects of the two interventions (stockinet cap versus routine care) on core body temperature on admission to NICU (one study, n = 40; MD 0.15 °C; 95% CI -0.18, 0.48).

02.01.01 For infants with a birthweight < 2000 g a borderline statistically significant difference was shown in core body temperature on admission to NICU favouring the intervention (stockinet cap) group when compared to those who received routine care (one study, n = 10; MD 0.70 °C; 95% CI -0.01, 1.41).

02.01.02 For infants with a birthweight ≥2000 g no statistically significant difference in the effects of the two interventions (stockinet cap versus routine care) for core body temperature on admission to NICU was shown (one study, n = 30; MD 0.00 °C; 95% CI -0.37, 0.37).

02.02 Hypothermia on admission to NICU (core body temperature < 36.5 °C or a skin temperature < 36 °C)

02.02.01Roberts 1981, in addition to reporting core body temperature on admission to NICU as a continuous variable, also provided data in a dichotomous format in terms of incidence of hypothermia in both groups (stockinet cap and routine care). Hypothermia was defined in this study as a core body temperature (axillary ) < 36 °C on admission to the NICU. For infants with a gestational age 32 to 36 completed weeks (birthweight range 1360 to 2965g), there was no significant difference in risk of hypothermia (as defined by the study) between those infants who received stockinet cap and those who received routine care (one study, n = 40; RR 0.90; 95% CI 0.48, 1.71; RD -0.05; 95% CI -0.36, 0.26).

Secondary outcomes

The following secondary outcome measures were not reported for this comparison: hypoglycaemia, respiratory distress syndrome, surfactant given at any time, intubation in delivery room, requirement for ventilation, duration of ventilation, length of stay, mortality, severe metabolic acidosis, intraventricular haemorrhage, patent ductus arteriosus, chronic lung disease, necrotizing enterocolitis, acute renal failure and adverse events due to the intervention (hyperthermia, burns, maceration, skin or systemic infection, antibiotics, interference with resuscitation and other practices, fluid problems, negative psychological outcomes).

EXTERNAL HEAT SOURCES (NON-ROUTINE)

COMPARISON 03 SKIN-TO-SKIN CARE VERSUS ROUTINE CARE

Primary outcomes

03.01 Hypothermia (skin temperature < 35.5 °C for two consecutive recordings)

Bergman 2004 reported this outcome in terms of skin temperature remaining below 35.5 °C for two consecutive readings (five minute intervals for the first hour, thereafter 15 minute intervals during the six hour observation period). This outcome was not pre-specified at review protocol stage.

03.01.01 For infants with a birthweight between 1200 and 2199 g evidence suggests that skin-to-skin contact significantly reduces the risk of hypothermia (as defined by the study) within 6 hours of birth when compared to conventional incubator care (one study, n = 31; RR 0.09; 95% CI 0.01, 0.64; RD -0.56; 95% CI -0.84, -0.27). Two infants would need to receive skin-to-skin contact in order to prevent one infant from becoming hypothermic (NNT 2, 95% CI 1 to 4).

Secondary outcomes

03.02 Hypoglycaemia (blood glucose < 2.6 mmol/L)

Bergman 2004 reported this outcome which was confirmed by laboratory estimation within the 6 hour observation period where blood glucose was measured by heel prick at one, three and six hours. This was not our pre-specified definition of hypoglycaemia at review protocol stage.

03.02.01 For infants with a birthweight between 1200 and 2199 g there is no significant difference in risk of hypoglycaemia (as defined by the study) between those infants who received skin-to-skin contact and those who received conventional incubator care (one study, n = 31; RR 0.24; 95% CI 0.03, 2.06; RD -0.18; 95% CI -0.43, 0.08).

Other secondary outcomes

This study reported the following additional outcome measures: heart rate below 100, or above 180 beats per minute for two consecutive recordings, apnoea longer than 20 s, oxygen saturation below 87% for two consecutive recordings despite supplementation with nasal prong oxygen, FiO2 up to 0.60 and CPAP up to 5 cm water, and overall data (transfers to NICU, exceeded parameters, mean SCRIP score within first 6 hours and number of perfect scores, mean SCRIP score in the sixth hour and number of perfect scores).

The following secondary outcome measures were not reported for this comparison group: respiratory distress syndrome, surfactant given at any time, intubation in delivery room, requirement for ventilation, duration of ventilation, length of stay, mortality, severe metabolic acidosis, intraventricular haemorrhage, patent ductus arteriosus, chronic lung disease, necrotizing enterocolitis or acute renal failure.

Adverse occurrences

Bergman 2004 reported that “there were no adverse events related to the intervention”.

COMPARISON 04 TRANSWARMER (SODIUM ACETATE) MATTRESS VERSUS ROUTINE CARE

Primary outcomes

04.01 Core body temperature (°C) on admission to NICU or up to two hours after birth

Brennan 1996 reported core body temperature (axillary °C) on admission to NICU in a study of 24 infants.

04.01.01For infants with a birthweight ≤1500 g a statistically significant difference was shown in mean c favouring the intervention (transwarmer mattress) group when compared to those who received routine care (one study, n = 24; MD 1.60 °C; 95% CI 0.83, 2.37).

04.02 Hypothermia on admission to NICU (core body temperature < 36.5°C or skin temperature < 36°C)

Brennan 1996 in addition to reporting core body temperature on admission to NICU as a continuous variable, also provided data in a dichotomous format in terms of incidence of hypothermia in the intervention and control groups (transwarmer mattress and routine care). Hypothermia was defined in this study as a core body temperature (axillary °C) < 36.5 on admission to NICU.

04.02.01 For infants with a birthweight ≤1500 g evidence suggests that the transwarmer mattress significantly reduces the risk of hypothermia on admission to NICU (one study, n = 24; RR 0.30 95% CI 0.11, 0.83; RD -0.58; 95% CI -0.91, -0.26). Two infants would need to receive a sodium acetate mattress in order to prevent one infant from becoming hypothermic (NNT 2, 95% CI 1 to 4 ).

Secondary outcomes

The following secondary outcome measures were not reported for this comparison group: hypoglycaemia, respiratory distress syndrome, surfactant given at any time, intubation in delivery room, requirement for ventilation, duration of ventilation, length of stay, mortality, severe metabolic acidosis, intraventricular haemorrhage, patent ductus arteriosus, chronic lung disease, necrotizing enterocolitis, acute renal failure and adverse events due to the intervention (hyperthermia, burns, maceration, skin or systemic infection, antibiotics, fluid problems, negative psychological outcomes).

Adverse occurrences

Brennan 1996 reported that the intervention did not at any time interfere with the care of the infants.

DISCUSSION

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Hypothermia (body temperature below normal) on admission to neonatal units is a problem world-wide across all climates, particularly for small infants and those born too early. Early intervention in the delivery room is vital. This review focused on individual interventions to prevent hypothermia applied immediately at birth apart from 'routine' care in comparison to 'routine care' only. The studies fell into two major groups: barriers to prevent heat losses and additional external heat sources. The strengths of the review lie in the fact that a comprehensive literature search was undertaken encompassing both published and unpublished studies. In addition, strict inclusion criteria were adhered to ensuring that the review was focused on interventions that were applied within the first 10 minutes after birth for preterm and/or low birthweight infants as opposed to bigger infants or long-term thermal management. Limitations of the review were dictated by the number and size of the relevant studies and by the lack of reported data for the pre-specified secondary outcomes.

Six studies were identified which fulfilled our criteria for inclusion giving a total of 304 infants randomised and 295 infants completing the studies. Four studies compared barriers to heat loss to no barriers (Roberts 1981; Vohra 1999; Vohra 2003; Wimmer 2002) and two studies compared external heat sources (non-routine) to no external heat sources (Brennan 1996; Bergman 2004). There were two comparisons within the barriers to heat loss category: plastic wrap versus routine care (Vohra 1999; Vohra 2003; Wimmer 2002) and stockinet cap versus routine care (Roberts 1981). There were also two comparisons within the external heat source category: skin-to-skin care versus routine care (Bergman 2004) and transwarmer (sodium acetate) mattress versus routine care (Brennan 1996). Each technique was successful to a greater or lesser degree in increasing temperature on admission to NICU.

Barriers to heat loss

Plastic barriers were effective in reducing heat losses for the younger group of infants with gestational ages of < 28 completed weeks. The results showed that there was a high level of heterogeneity within this subgroup of infants. Possible causes may lie within the variations in methods used in the three studies (Vohra 1999; Vohra 2003; Wimmer 2002). The authors of these studies were contacted and potential differences were explored. In both the Vohra 1999 and Vohra 2003 studies the study sample represented all preterm infants within the eligible gestational age range born at the institution. The intervention consisted of a polyethylene bag which was cut into a wrap, only the head of the infant was dried, the body was wrapped from the neck down, a radiant warmer was used, and no parental consent was sought. No attempt was made to change standard delivery room temperatures during the studies. Infants were transferred to the NICU in incubators in the first study (Vohra 1999) and in the arms of one of the neonatal team in the second (Vohra 2003). In contrast, in Wimmer 2002, the study sample excluded infants for whom no consent was given (and who might have been smaller or more ill and thus more prone to heat loss); and the intervention consisted of polyurethane bag with a drawstring, and the body was wrapped from the neck down while still wet. Attempts to control delivery room temperatures, as recommended by the World Health Organisation, failed and resulted in a wide spread of delivery room temperatures. Infants were transferred to the NICU down a very long, drafty hallway on an open warmer with its heat off with warm blankets over the infants. All three studies followed the NRP protocol and exclusion criteria were similar. An additional point of interest was the reported imbalance of birthweight between study groups in the Vohra 1999 study. The birthweight-adjusted difference in rectal temperatures for infants with a gestational age of < 28 completed weeks remained significant but decreased from 1.90 °C, SD(0.43 °C) to 1.54 °C, SD(0.42 °C).

There was limited reporting of secondary outcomes for this group of studies. There was insufficient evidence to suggest that plastic barriers reduce the risk of death within hospital stay for the younger infants and no deaths were reported for the older group of infants. Similarly, there was no evidence of a significant difference in major brain injury, mean duration of oxygen therapy or hospitalisation, for infants with a gestational age < 29 completed weeks.

Where the barrier to heat loss was stockinet caps, a borderline statistically significant difference in temperature on admission to NICU in favour of the intervention group was shown for those infants with a birthweight < 2000 g but no difference for those infants ≥2000 g. This finding is consistent with those reported by Greer 1988 in which various head coverings were compared under radiant warmers for infants > 2500 g. Where head coverings were applied within one minute of birth, results showed that infants wearing 'stockinettes' had lower mean core body temperatures at 5, 15 and 30 minutes after delivery than either the hatless group or the group wearing an insulated fabric bonnet. As a result, 'stockinettes' were not recommended for use in conjunction with a radiant warmer.

External heat sources (non-routine)

Skin-to-skin care was shown to be effective in reducing the risk of hypothermia when compared to conventional incubator care for infants with a birthweight between 1200 and 2199 g and the transwarmer mattress significantly kept infants ≤1500 g warmer and reduced the incidence of hypothermia on admission to NICU. There was no evidence that skin-to-skin care reduced the risk of hypoglycaemia. There was limited reported of secondary outcomes.

Overall

Despite the variations in interventions applied, definitions of 'routine care', definitions of hypothermia and groups of infants included, across all studies there is a similar pattern emerging showing that infants in the intervention group are significantly warmer (or show a non-significant trend in that direction) when compared to infants receiving 'routine care'. There is also an indication from these studies that the effect is greater in the lightest and most immature infants. Babies of < 28 weeks or those weighing ≤1500 g appeared to derive most benefit from interventions in the delivery suite to prevent hypothermia. These are also the infants most likely to suffer from the adverse effects of hypothermia and in whom further studies should be undertaken.

There was limited reporting of pre-specified secondary outcomes across all studies. Two of the studies reported that there were no adverse events due to the intervention and one study reported that the intervention did not at any time interfere with the care of the infants. Data regarding interference with resuscitation, hyperthermia, Apgar scores at one and five minutes, blood gas pH and bicarbonate (mmol/L), glucose are reported in the Vohra 2003 full manuscript and will be available in the next update of this review. There is a need for the measurement of hyperthermia in neonatal units where such interventions are adopted as routine practice. Clarification on 'normal' temperatures for these populations of infants is also essential as is better data correlating axillary versus rectal versus other temperatures.

Paradoxically hypothermia is more of a problem in the developing world where climates are generally warmer. Only one of the included studies was conducted in a developing country, South Africa (Bergman 2004). Although South Africa is classified as developing, the units participating in this study carried out in Cape Town provided secondary level care for inborn babies and is therefore not truly representative of the developing world.

Further studies are needed of interventions such as plastic bag wrapping for infants under 30 weeks' gestation with adequate sample size to assess both short-term and long-term neurodevelopmental outcomes. Such a multicentre study (HeLP) is currently underway (FYI, funded by Canadian Institute of Health Research and conducted in partnership with the Vermont Oxford Network). Intended sample size is 1600 preterm infants < 28 weeks gestational age with all cause mortality as the primary outcome. The plastic wraps utilised in this study cost approximately 157 Canadian Dollars for 5000 wraps which when calculated per infant is approximately three cents.

AUTHORS' CONCLUSIONS

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Implications for practice

Health professionals strive to minimise risk of cold stress for newborn infants immediately after birth by adhering to good practice guidelines such as: providing a warm delivery room at a minimum of 25 °C (although this is difficult to achieve in practice), drying the infant, removing any wet blankets and wrapping in a prewarmed blanket, prewarming any contact surfaces, avoiding draughts and in developed countries, using radiant warmers or incubators. Despite this hypothermia remains a world-wide problem, especially for small infants and those born too early (Costeloe 2000). Any additional intervention designed for prevention of hypothermia in very preterm and/or low birthweight infants, and applied within 10 minutes after birth in the delivery suite, compared with routine thermal care may be beneficial in practice. The interventions in this review (plastic wraps and bags, skin-to-skin contact, and transwarmer mattresses) keep infants warmer and lead to higher temperatures on admission to the NICU and to decreased incidence of hypothermia. As hypothermia increases the risk of morbidity and mortality in preterm infants, consideration should be given to using these interventions in the delivery suite. However, given the small numbers of infants and the small numbers of studies in this review and the fact that no long-term data on follow-up are available, firm recommendations for clinical practice cannot be given at this time.

Implications for research

Due to the small numbers and size of trials in this review there is a need conduct high quality randomised controlled trials where the specifically designed intervention to prevent hypothermia is applied within the first few minutes after birth in the delivery suite. These studies should be large enough to look at long-term neurodevelopmental outcomes and could also include economic evaluations to assess feasibility for use in poorer countries where cost is a fundamental concern. We report in the Table of “Characteristics of ongoing studies” that a large multicentre randomised controlled trial of heat loss prevention (HeLP) in the delivery room commenced in September 2004 (Vohra 2004). This trial will include infants < 28 weeks' gestational age, the intervention will be polyethylene skin wrap and the study will look at mortality as its primary outcome. Eighteen-month neurodevelopmental follow-up is also planned.

POTENTIAL CONFLICT OF INTEREST

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

SV is principal investigator on two studies that met the review eligibility criteria (one published and one 'In press' ). This team member was excluded from the study appraisal process.

SV is also co-leading the current multicentre HeLP study.

Acknowledgements

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Mr Diarmuid Kennedy, Faculty Librarian - Medicine and Health Sciences, Queen's University Medical Library, Mulhouse Building, Belfast, BT12 6DP.

Mr Mike Stevenson, Senior Statistician - Clinical Research Support Centre, Royal Group of Hospitals Trust, Grosvenor Road, Belfast, BT12 6BA.

Ms Suzanne Sweeney, Texas Woman's University Library, Texas Woman's University, Box 23717, TWU Station, Denton, Texas 76204.

TABLES

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES
Characteristics of included studies
StudyBergman 2004
MethodsRandomised.
Multicentre (2).
Blinding of randomisation: unclear.
Generation of allocation sequence: adequate, (computer minimisation method).
Allocation concealment: unclear, (“… a computer minimisation method determined allocation in a concealed manner”, “.. second hospital… minimisation factors and subsequent allocation by the computer were exchanged by mobile telephone, with no delays”).
Blinding of intervention: participants - no/unfeasible, care providers - no/unfeasible.
Blinding of outcome measurement: yes, after the pilot phase, the principal investigator and data analyses team were blinded. A statistician, blinded to the allocation, performed the statistical analyses.
Complete follow-up: no, (31 of 35 infants randomised completed the study, 1 infant was excluded after 2 hours when the mother required a caesarean section for a second twin, 3 further infants 'bailed out' within the first 3 hr requiring additional respiratory support and moved to neonatal intensive care).
Room temperature, maternal temperature and incubator temperature were recorded.
Ethical approval was obtained.
Informed consent.
ParticipantsInfants delivered with a birthweight 1200 to 2199 g.
35 infants randomised: intervention group (n = 21), control group (n = 14), 31 completed study: intervention group (n = 18), control group (n = 13).
Setting: South Africa.
Exclusion criteria:
Mother: 1) delivered outside the unit, 2) had a caesarean section, 3) too severely ill to be able to look after themselves or their infants, 4) known to have positive HIV status, 5) giving their babies up for adoption.
Infant: 1) birthweight below 1200 g or above 2199 g, 2) Apgar score below 6 at 5 min, 3) congenital malformations detected at birth.
Intervention group (skin-to-skin care) characteristics:
Mothers: gravidity mean (1.9), parity mean (1.8), race African (8), race Coloured (12), smoking in pregnancy (7), alcohol use(6), opiate in labour (9), Oxytocin in labour (3), hypertension (3), antepartum steroids (5).
Infants: male (12), resuscitation (4), birthweight (g) mean (1813) SD(260), gestational age (wks) mean (34.2) SD(1.9), appropriate for GA (13), small for GA (7).
Control group (conventional care) characteristics:
Mothers: gravidity mean (1.9), parity mean (1.6), race African (4), race Coloured (10), smoking in pregnancy (4), alcohol use (2), opiate in labour (6), Oxytocin in labour (1), hypertension (1), antepartum steroids (3).
Infants: male: (7), resuscitation baby (1), birthweight (g) mean (1866) SD(258), gestational age (wks) mean (35.3) SD(1.9), appropriate for GA (10), small for GA (5).
InterventionsINTERVENTION: SKIN-TO-SKIN CARE
All infants were delivered onto a theatre cloth on the mother's abdomen/chest, dried gently and assessed. They were then placed naked on the mother's naked chest and covered with double layered cotton cloth. The bed was placed in semi-Flowers position.
Intervention group:
The infant remained in skin-to-skin contact, was secured to the mother's chest, the hips were flexed and placed in a 'frog position', arms also flexed.
Control group:
The infant was immediately transferred to a prewarmed servocontrolled closed incubator which remained with the mother in delivery ward for the first hour. If the infant temperature was below 36 degrees centigrade, a cap and booties were applied along with a heat shield placed over the infant. If this was insufficient a sheet of plastic was framed over the foot end of the heat shield and the outlet of the warm air funnelled over the infant.
OutcomesInfant stability in terms of a set of predetermined physiological parameters. Observations for heart rate, respiratory rate, oxygen saturation and temperature were recorded at 5 minute intervals in the first hour, then 15 minute intervals. Continuous observations for apnoea and signs of respiratory distress, blood sugar measured at 1, 3 and 6hr.
Primary Outcomes:
1) neonatal intensive care admissions
2) number of exceeded parameters
3) composite stabilization score (SCRIP) (1-6h)
4) composite stabilization score (SCRIP) (6th h)
Secondary outcomes:
1) skin temperature degrees centigrade remaining below 35.5 C for 2 consecutive readings
2) heart rate below 100 or above 180 beats per minutes for 2 consecutive readings
3) apnoea longer than 20 seconds
4) oxygen saturation below 87% for 2 consecutive recordings, despite supplementation with nasal prong oxygen, FiO2 up to 0.6 and CPAP up to 5cm water
5) blood glucose below 2.6 mmol/L reading confirmed by laboratory.
Notes
Allocation concealmentB
StudyBrennan 1996
MethodsRandomised.
Single centre.
Blinding of randomisation: unclear.
Generation of allocation sequence: adequate, (lot drawing - pulling cards from an envelope in which 24 cards had been placed. Equal numbers of cards had either 'mattress' or 'no mattress' written on them).
Allocation concealment: unclear.
Blinding of intervention: participants: no/unfeasible, care providers: no/unfeasible.
Blinding of outcome measurement: no.
Complete follow-up: yes, all 24 infants randomised completed the study.
Gestational age, birthweight, and the time temperature taken after birth were recorded.
The proposal for the study underwent a full review by the Institutional Review Board of the University of Florida, Health Science Centre.
Informed consent.
ParticipantsInfants delivered with a birthweight less than or equal to 1500 g.
24 infants randomised: intervention group (n = 12), control group (n = 12).
Setting: USA.
Exclusion criteria:
1) the maternal temperature at delivery was greater than 38.0 degrees Centigrade, 2) the infant had an obvious neural tube defect,
3) the infant had an omphalocele, gastroschisis, exstrophy of the bladder, cloacal exstrophy, or any other open lesion than would cause greater than normal heat loss at delivery, 4) the infant had a sacral teratoma, or any other lesion that would prevent the infant from being positioned and evaluated in the normal manner.
All infants characteristics: gestational age range (wks) 24 to 32, birthweight range (g) 531 to 1498.
Intervention group (transwarmer mattress) characteristics: gestational age (wks) mean (27.8), birthweight (g) mean (1033).
Control group characteristics: gestational age (wks) mean (27.3), birthweight (g) mean (1027).
InterventionsINTERVENTION: TRANSWARMER INFANT TRANSPORT MATTRESS (Prism Technologies, San Antonio, Texas). These mattresses are filled with a gel of sodium acetate, water and thickeners. Once activated they heat to approximately 40 degrees centigrade for 2 hours.
Intervention group:
The NICU nurse activated the mattress when delivery was imminent and placed it on the radiant warmer surface with blankets on top of it and the newborn infant was immediately placed on the blankets, dried and the blankets removed, then placed directly onto the warming mattress.
Control group:
Infants received the same care as the intervention group but without the warming mattress.
Both groups were evaluated and resuscitated according to the Neonatal Resuscitation Program and transported to NICU on the radiant warmer surface. The infants in the intervention group remained on the mattress until the admission temperatures were taken in the NICU.
OutcomesPrimary outcomes:
1) core body temperature degrees centigrade (axillary) was measured using the IVAC 2080A Temp Plus 11 (IVAC, San Diego, California) as soon as possible after arrival at NICU.
Secondary outcomes:
1) interference to resuscitation.
NotesIndividual patient data was reported in this study therefore dichotomous data for hypothermia on admission to NICU for the control and intervention group was calculated.
Allocation concealmentB
StudyRoberts 1981
MethodsRandomised.
Single centre.
Stratified randomisation by gestational age 32 to 34 and 35 to 36 completed weeks' gestation.
Blinding of randomisation: unclear.
Generation of allocation sequence: adequate, (lot drawing - index cards were utilised to pre-arranged randomisation - random number tables).
Allocation concealment: unclear.
Blinding of intervention: participants - no/unfeasible, care providers- no/unfeasible.
Blinding of outcome measurement: no
Complete follow-up: yes, all 40 infants randomised completed the study.
Delivery room, transport incubator, highest maternal temperatures, birthweight, gestational age, method of delivery, time elapsed from birth to onset of drying and time elapsed from birth to arrival in nursery were recorded.
Informed consent.
ParticipantsInfants delivered from 7am until 5 pm Monday through Friday with a gestational age of 32 to 36 completed weeks.
40 infants randomised: intervention group (n = 17), control group (n = 23).
Setting: USA.
Criteria for exclusion:
1) infant not appropriate birthweight for gestational age, 2) Apgar score @ 5 min less than 7, 3) signs of central nervous system defect, 4) infant dropped from study on development of sepsis, 5) maternal temperature greater than or equal to 37.8 degrees centigrade, 5) delivered outside of delivery room.
Intervention group (stockinet cap) characteristics: male (4), female (13), white (6), black (5), Mexican - American (6), vaginal delivery (15), caesarean section (2), gestational age (wks) (32 to 34 (5), 35 to 36 (12)), gestational age (wks) mean (34.9 ), birthweight (g) range (1420 to 2890), birthweight (g) mean (2253.4), Apgar score @ 5 min equal to 9 (16), infants transported in incubator (7), highest maternal temperature (degrees centigrade) range (36.6 to 37.7) mean (37.1).
Control group (conventional care) characteristics: male (12), female (11), white (8), black (13), Mexican - American (2), vaginal delivery (18), caesarean section (5), gestational age (wks) (32 to 34 (4), 35 to 36 (19)), gestational age (wks) mean (35.2), birthweight (g) range (1360 to 2965), birthweight (g) mean (2276.8), Apgar score @ 5 min equal to 9 (22), infants transported in incubator (12), temperature (degrees centigrade) transport incubator range (33 to 37) mean (35.2), highest maternal temperature (degrees centigrade) range (36.2 to 37.8) mean (37.2).
InterventionsINTERVENTION: STOCKINET CAP - a sterile headpiece made of stockinet (a material used to protect skin under orthopedic casts) which covers the forehead, the ears, underneath the occipital bone, and all the area above this plane.
Intervention group:
Infants received a stockinet cap after delivery as soon as possible after being dried under a radiant warmer.
Control group:
Infants received the same treatment as the intervention group but did not receive a stockinet cap.
All infants weighing less than 2500 g were transported to the nursery in a transport incubator.
OutcomesPrimary outcomes:
1) core body temperature degrees centigrade (axillary) within 10 minutes of admission to NICU (IVAC electric thermometer Model 821)
Core body temperatures degrees centigrade (axillary) in the delivery room were also recorded to enable calculation of the “amount of heat lost from the time the axillary temperature was taken in the delivery room until the axillary temperature was taken in the nursery”.
Secondary outcomes:
None reported.
Notes
Allocation concealmentB
StudyVohra 1999
MethodsRandomised.
Single centre.
Prognostic stratification was by gestational age 23 to 27 and 28 to 31 completed weeks' gestation.
Blinding of randomisation: yes.
Generation of allocation sequence: adequate, (computer generated random sequence).
Allocation concealment: adequate, (double-enclosed, opaque, sealed, and sequentially numbered envelopes).
Blinding of intervention: participants - no/unfeasible, care providers - no/unfeasible.
Blinding of outcome measurement: no.
Complete follow-up: no, (59 of 62 infants randomised completed the study, 1 infant was excluded as no rectal temperature was recorded, two infants were excluded due to an imperforate anus).
Delivery room, nursery temperatures and other potential confounding variables, (birthweight, maternal temperature, illnesses, medications, length of second stage of labour, length of time to arrival at nursery) were recorded.
Ethics approval was obtained.
No informed consent.
ParticipantsInfants delivered with a gestational age of less than 32 completed weeks.
62 infants randomised: 59 completed study, intervention group (n = 27), control group (n = 32).
Setting: Canada.
Exclusion criteria:
1) major congenital anomalies with open lesions, 2) infants whom the attending obstetrician considered “previable”.
Intervention group (polyethylene wrap) characteristics < 28 wks: birthweight (g) mean (914) SD (163), gestational age (wk) mean (26.1) SD (1.4) Apgar score @ 1min mean (5.0) SD (3.0), Apgar score @ 5 min mean (6.7) SD (1.7), ruptured membranes (min) mean (186) SD (471), length 2nd stage (min) mean (26) SD (55).
Control group (conventional care) characteristics < 28 wks: birthweight (g) mean (742) SD (206), gestational age (wks) mean (25.7) SD (1.5), Apgar score @ 1 min mean (4.3) SD (2.1), Apgar score @ 5 min mean (7.1) SD (1.4), ruptured membranes (min) mean (10) SD (21), length 2nd stage (min) (18) SD (24).
Intervention group (polyethylene wrap) characteristics >= 28 wks: birthweight (g) mean (1251) SD (282), gestational age (wk) mean (29.6) SD (1.1) Apgar score @ 1min mean (6.5) SD (1.8), Apgar score @ 5 min mean (8.5) SD (1.1), ruptured membranes (min) mean (105) SD (310), length 2nd stage (min) mean (15) SD (25).
Control group (conventional care) characteristics >= 28 wks: birthweight (g) mean (1265) SD (206), gestational age (wks) mean (29.4) SD (1.5), Apgar score @ 1 min mean (6.0) SD (2.1), Apgar score @ 5 min mean (8.0) SD (1.4), ruptured membranes (min) mean (108) SD (21), length 2nd stage (min) (13) SD (24).
InterventionsINTERVENTION: POLYETHYLENE BAG - measured 20 cm x 50 cm and was manufactured by Eastern Paper, a Division of EPC Industries.
Intervention group:
A transparent polyethylene bag was opened at resuscitation under a radiant warmer and the infant was placed on it from the shoulders down. Only the head of the infant was dried; the body was wrapped without drying.
Control group:
Controls were managed with the protocol described by the Neonatal Resuscitation Program. Infants were routinely dried under the radiant warmer.
Infants were transferred to the neonatal unit in an incubator.
OutcomesPrimary outcome:
1) core body temperature degrees centigrade (rectal) was measured with a digital rectal thermometer on removal of the bag/wrap on admission to NICU.
Secondary outcomes:
1) mortality
2) hyperthermia
3) infection
4) skin maceration
5) interference with resuscitation.
Notes42 infants who met the inclusion criteria were not enrolled in the study reasons were as follows: still birth (1), 34wks gestational age (2), failure to reach delivery in time (8), failure of staff to pick up envelope on the way to the delivery room (31). The non-enrolled infants did not differ significantly from those in the study population.
Allocation concealmentA
StudyVohra 2003
MethodsRandomised.
Single centre.
Blinding of randomisation: yes.
Generation of allocation sequence: adequate, (computer generated random sequence balanced in blocks of 4 subjects). Concealment of allocation: adequate, (double enclosed, opaque, sealed and sequentially numbered envelopes).
Blinding of intervention: participants - no/ unfeasible, care provider - no/unfeasible.
Blinding of outcome measurement: no.
Complete follow-up: no, (53 of 55 infants randomised completed the study, 2 infants died in the delivery room).
No further information available.
ParticipantsInfants delivered with a gestational age less than 28 completed weeks where the birth was attended by the neonatal team.
55 infants randomised: intervention group (n = 28), control group (n = 27), 53 completed study: intervention group (n = 26), control group (n = 27).
Setting: Canada.
Exclusion criteria:
1) neonatal team did not attend the delivery, 2) major congenital anomalies that were not covered by skin e.g. gastroschisis, meningomyelocele, 3) blistering skin conditions.
Intervention group (polyethylene wrap) characteristics: female (14), birthweight (g) mean (858) SD (199), gestational age (wks) mean (26) SD (1.5).
Control group (conventional care) characteristics: female (13), birthweight (g) mean (825) SD (270), gestational age (wks) mean (26) SD (1.4).
InterventionsINTERVENTION: POLYETHYLENE WRAP - measured 20 cm x 50 cm and was manufactured by Eastern Paper, a Division of EPC Industries LTD.
Intervention group:
Infant placed on polyethylene, wrapped from the neck down, only the head was dried, stabilised under radiant warmer.
Control group:
Control infants were dried completely according to the International Guidelines for Neonatal Resuscitation and stabilised under a radiant warmer.
All infants were carried by one member of the neonatal team from the delivery suite to the neonatal unit and placed in a single walled incubator with 60 percent humidity.
OutcomesPrimary outcomes:
1) core body temperature degrees centigrade (rectal) on admission to NICU following removal of wrap.
Secondary outcomes:
1) core body temperature degrees centigrade (rectal) taken one hour later.
2) mortality - death before discharge.
Further secondary outcomes are reported for Apgar scores, blood gas pH, Bicarbonate (mmol/L), Glucose (mmol/L), hyperthermia and interference with resuscitation.
NotesFurther details will be reported on publication of the full trial. The author (SV) kindly supplied additional information for methodological quality.
Allocation concealmentA
StudyWimmer 2002
MethodsRandomised.
Single centre.
Blinding of randomisation: yes.
Generation of allocation sequence: unclear.
Allocation concealment : adequate, (opaque envelopes).
Blinding of intervention: participants - no/unfeasible, care provider - no/unfeasible.
Blinding of outcome measurement: no.
Complete follow-up: yes, all 88 infants randomised completed the study.
Delivery to admission time was also recorded.
ParticipantsInfants delivered with a gestational age less than 29 completed weeks.
88 infants randomised: intervention group (n = 41), control group (n = 47).
Setting: USA.
Exclusion criteria:
1)congenital anomalies with open lesions (e.g. gastroschisis, meningomyelocele), 2) resuscitation not undertaken because of previability, 3) meconium staining of amniotic fluid, 4) subsequent assessment indicated that infant had a gestational age greater than or equal to 29 completed weeks.
Intervention group (Polyurethane bag) characteristics: birthweight (g) mean (918) SD (259), gestational age (wks) mean (26.5), SD (1.4).
Control group (conventional care) characteristics: birthweight (g) mean (850) SD (253), gestational age (wks) mean (26.1) SD (1.4).
InterventionsINTERVENTION: POLYURETHANE BAG.
Intervention group:
Infants were placed immediately into a polyurethane bag, while still wet, up to their necks and resuscitated according to the guidelines for Neonatal Resuscitation.
Control group:
Controls were resuscitated according to these guidelines without bags.
Both groups were taken to the neonatal intensive care unit on a warmer table, (with the heat off) with warm blankets on top of the infant.
OutcomesPrimary outcome:
1) core body temperature degrees centigrade (rectal) on admission to the NICU.
2) hypothermia on admission to the NICU defined by a core body temperature (rectal) < 36.4 degrees centigrade.
Secondary outcomes:
1) mortality.
2) major brain injury.
3) duration of oxygen therapy.
4) duration of hospitalisation.
NotesFull details will be reported on publication of the full trial. The author (RK) kindly supplied additional information regarding methodological quality and quantitative data for main and secondary outcome measures.
Allocation concealmentA
Characteristics of excluded studies
Almeida 2000Query over randomisation, (40 participants in the intervention group and 75 participants in the control group) unable to contact authors for clarification.
Baum 1968Participants had a birthweight greater than or equal to 6 lb.
Besch 1971Participants had a birthweight greater than 2000 g.
Brice 1981Intervention not applied immediately at birth (within 10 mins) in the delivery suite.
Bystrova 2003Participants had a birthweight greater than 2500 g.
Cattaneo 1998Intervention was not applied immediately at birth (within 10 mins) in the delivery suite.
Chaput 1979Participants had a birthweight greater than 2000 g.
Christensson 1992Participants were term.
Christensson 1996Participants were term delivered by caesarean section.
Christensson 1998Intervention was not applied immediately at birth (within 10 mins) in the delivery suite.
Chwo 2002Intervention was not applied immediately at birth (within 10 mins) in the delivery suite but on the day following birth.
Coles 1979Participants were term.
Dahm 1972Participants were term.
Day 1964Intervention not applied immediately at birth (within 10 mins) in the delivery suite.
Fardig 1980Participants were term.
Gray 2004Intervention was not applied immediately at birth (within 10 mins) in the delivery suite. Participants were at least three days old.
Green-Abate 1994Intervention was not applied immediately at birth (within 10 mins) in delivery suite. Participants were less than 1 week old.
Greer 1988Participants were term and had a birthweight greater than 2500 g.
Grover 1994Participants were term and the intervention was not applied immediately at birth (within 10 mins) in the delivery suite. Participants were aged 11 to 95 days.
Hellin Martinez 2000Participants were term.
Hobbs 1975Participants were term.
Holzman 1985Participants were term.
Huang 2002Participants had a birthweight greater than or equal to 2500 g.
Johanson 1992Participants were term with a mean gestational age 39.1 weeks. Randomised controlled intervention study compared to a prospective observational study.
Legault 1993Intervention was not applied immediately at birth (within 10 mins) in the delivery suite. Participants were aged one week or more.
Ludington-Hoe 1994Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Participants in intervention group averaged 18 days old and control participants averaged 13 days old.
Ludington-Hoe 2000Participants had a postnatal age of 6 to 53 days on enrollment to the study.
Marks 1985Participants had a gestational age of 36 plus or minus one week. Intervention was not applied immediately at birth (within 10 mins) in the delivery suite. Participants were aged 14 to 68 days.
Mazurek 1999Participants were term.
Meyer 2001Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Intervention applied on arrival at NICU.
Monterosso 1999Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Participants were at least one week of age at time of study.
Nopper 1996Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Participants enrolled within the first 96 hours after birth.
Nuntnarumit 2004This study compared plastic wrap and plastic bag to plastic wrap only. Plastic wrap only was not considered to be 'routine care' as pre-specified in the review inclusion criteria.
Omene 1978Participants were term.
Raman 1992Participants were term.
Roberts 2000Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Participants were born at 30 or more weeks' gestation or corrected age.
Ruiz 1998Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Temperature was not an outcome measure.
Sarman 1989Intervention not applied immediately at birth (within 10 mins) in the delivery suite.
Sarman 1992Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Participants were 3 to 32 days of age during the study.
Short 1998Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Participants day of life 32.9 plus or minus 15.9 days.
van den Bosch 1990Participants were term.
van den Bosch 1996Intervention not applied immediately at birth (within 10 mins) in the delivery suite. Intervention applied after 48 hours in the NICU.
Characteristics of ongoing studies
StudyMeyer 2003
Trial name or titleHow should preterm infants be kept warm during transport to NICU - in incubators or under radiant warmers?
ParticipantsInfants less than 29 weeks gestation.
InterventionsPlastic wrap applied immediately at delivery.
OutcomesAxillary temperature on arrival to NICU. Low admission temperature defined as less than 36.5 degrees centigrade.
Starting dateSeptember 2003
Contact informationDr M Meyer
Middlemore Hospital
Auckland
New Zealand
Email: MMeyer@middlemore.co.nz
Notes40 infants randomised to date. Aiming for 60 plus.
StudyVohra 2004
Trial name or titleMulticentred randomised controlled trial of heat loss prevention (HeLP) in the delivery room.
ParticipantsInfants less than 28 weeks gestation.
InterventionsPolyethylene occlusive skin wrap applied immediately following birth in the delivery suite.
OutcomesMortality, axillary temperature, rectal temperature (in some) and clinically important variables including: APGAR scores, incidence of acidosis, hypotension, hypoglycaemia, seizures, patent ductus arterious, respiratory distress syndrome/chronic lung disease, necrotizing enterocolitis, intraventricular haemorrhage. Also length of stay and cause of death.
Starting dateSeptember 2004
Contact informationDr Sunita Vohra
Director CARE (Complementary and Alternative Research and Education) Program
Stollery Children's Hospital
Associate Professor of Pediatrics
University of Alberta
Email: svohra@cha.ab.ca
NotesThis multicentre trial will involve 40 centres, Canada, US and UK, all part of the Vermont-Oxford Network.

ANALYSES

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES
Table Comparison 01. Plastic wrap versus routine care
Outcome titleNo. of studiesNo. of participantsStatistical methodEffect size
01 Core body temperature (degrees C) on admission to NICU or up to 2 hours after birth4200Weighted Mean Difference (Fixed) 95% CI0.60 [0.37, 0.83]
02 Core body temperature (degrees C) 1 hour after the initial admission temperature to the NICU was taken153Weighted Mean Difference (Fixed) 95% CI0.20 [-0.24, 0.64]
03 Hypothermia on admission to NICU: core body temperature < 36.5 C or skin temperature < 36 C188Relative Risk (Fixed) 95% CI0.63 [0.42, 0.93]
04 Death within hospital stay4202Relative Risk (Fixed) 95% CI0.63 [0.32, 1.22]
05 Major brain injury188Relative Risk (Fixed) 95% CI1.15 [0.36, 3.68]
06 Duration of oxygen therapy (days)188Weighted Mean Difference (Fixed) 95% CI-6.51 [-23.30, 10.28]
07 Duration of hospitalisation (days)188Weighted Mean Difference (Fixed) 95% CI-5.49 [-19.93, 8.95]
Table Comparison 02. Stockinet cap versus routine care
Outcome titleNo. of studiesNo. of participantsStatistical methodEffect size
01 Core body temperature (degrees C) on admission to NICU or up to 2 hours after birth240Weighted Mean Difference (Fixed) 95% CI0.15 [-0.18, 0.48]
02 Hypothermia on admission to NICU: core body temperature < 36.5 C or skin temperature < 36 C140Relative Risk (Fixed) 95% CI0.90 [0.48, 1.71]
Table Comparison 03. Skin-to-skin care versus routine care
Outcome titleNo. of studiesNo. of participantsStatistical methodEffect size
01 Hypothermia: skin temperature < 35.5 C for 2 consecutive recordings131Relative Risk (Fixed) 95% CI0.09 [0.01, 0.64]
02 Hypoglycaemia: blood glucose level < 2.6 mmol/L131Relative Risk (Fixed) 95% CI0.24 [0.03, 2.06]
Table Comparison 04. Transwarmer mattress versus routine care
Outcome titleNo. of studiesNo. of participantsStatistical methodEffect size
01 Core body temperature (degrees C) on admission to NICU or up to 2 hours after birth124Weighted Mean Difference (Fixed) 95% CI1.60 [0.83, 2.37]
02 Hypothermia on admission to NICU: core body temperature < 36.5 C or skin temperature < 36 C124Relative Risk (Fixed) 95% CI0.30 [0.11, 0.83]
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Figure Analysis 01.01. Comparison 01 Plastic wrap versus routine care, Outcome 01 Core body temperature (degrees C) on admission to NICU or up to 2 hours after birth

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Figure Analysis 01.02. Comparison 01 Plastic wrap versus routine care, Outcome 02 Core body temperature (degrees C) 1 hour after the initial admission temperature to the NICU was taken

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Figure Analysis 01.03. Comparison 01 Plastic wrap versus routine care, Outcome 03 Hypothermia on admission to NICU: core body temperature < 36.5 C or skin temperature < 36 C

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Figure Analysis 01.04. Comparison 01 Plastic wrap versus routine care, Outcome 04 Death within hospital stay

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Figure Analysis 01.05. Comparison 01 Plastic wrap versus routine care, Outcome 05 Major brain injury

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Figure Analysis 01.06. Comparison 01 Plastic wrap versus routine care, Outcome 06 Duration of oxygen therapy (days)

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Figure Analysis 01.07. Comparison 01 Plastic wrap versus routine care, Outcome 07 Duration of hospitalisation (days)

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Figure Analysis 02.01. Comparison 02 Stockinet cap versus routine care, Outcome 01 Core body temperature (degrees C) on admission to NICU or up to 2 hours after birth

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Figure Analysis 02.02. Comparison 02 Stockinet cap versus routine care, Outcome 02 Hypothermia on admission to NICU: core body temperature < 36.5 C or skin temperature < 36 C

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Figure Analysis 03.01. Comparison 03 Skin-to-skin care versus routine care, Outcome 01 Hypothermia: skin temperature < 35.5 C for 2 consecutive recordings

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Figure Analysis 03.02. Comparison 03 Skin-to-skin care versus routine care, Outcome 02 Hypoglycaemia: blood glucose level < 2.6 mmol/L

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Figure Analysis 04.01. Comparison 04 Transwarmer mattress versus routine care, Outcome 01 Core body temperature (degrees C) on admission to NICU or up to 2 hours after birth

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Figure Analysis 04.02. Comparison 04 Transwarmer mattress versus routine care, Outcome 02 Hypothermia on admission to NICU: core body temperature < 36.5 C or skin temperature < 36 C

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COVER SHEET

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES

Title

Interventions to prevent hypothermia at birth in preterm and/or low birthweight babies

Authors

McCall EM, Alderdice FA, Halliday HL, Jenkins JG, Vohra S

Contribution of author(s)

The review was conceived by the Northern Ireland Neonatal Intensive Care Outcomes Research and Evaluation Group (NICORE).

The review was co-ordinated and the manuscript prepared in RevMan version 4.2.5 by the contact reviewer (EC). The search strategy was designed by EC and the QUB Medical Faculty Librarian. The data extraction proforma was drafted by EC and edited by FA, HH, JJ and SV.

FA, HH, JJ, and EC screened abstracts and papers against the inclusion criteria, appraised the quality and extracted the data. Entry onto RevMan was carried out by EC.

HH, JJ and SV provided clinical input at all stages of the review process. FA and HH also provided methodological input.

All reviewers were involved equally in the development of the content of the final manuscript.

Issue protocol first published

2003/2

Review first published

2005/1

Date of most recent amendment

14 March 2005

Date of most recent SUBSTANTIVE amendment

13 November 2004

What's New

Information not supplied by author

Date new studies found and included/excluded

Information not supplied by author

Date authors' conclusions section amended

Information not supplied by author

Contact address

Ms Emma McCall, Research Fellow, Department of Child Health, Queen's University Belfast, Institute of Clinical Sciences, Grosvenor Road, Belfast, Northern Ireland, BT12 6BJ, UK, E-mail: e.mccall@qub.ac.uk, Tel: +44 02890 635056, Fax: + 44 02890 236455

DOI

10.1002/14651858.CD004210.pub2

Cochrane Library number

CD004210

Editorial group

Cochrane Neonatal Group

Editorial group code

HM-NEONATAL

REFERENCES

  1. Top of page
  2. Abstract
  3. BACKGROUND
  4. OBJECTIVES
  5. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW
  6. SEARCH METHODS FOR IDENTIFICATION OF STUDIES
  7. METHODS OF THE REVIEW
  8. DESCRIPTION OF STUDIES
  9. METHODOLOGICAL QUALITY
  10. RESULTS
  11. DISCUSSION
  12. AUTHORS' CONCLUSIONS
  13. POTENTIAL CONFLICT OF INTEREST
  14. Acknowledgements
  15. SOURCES OF SUPPORT
  16. TABLES
  17. ANALYSES
  18. COVER SHEET
  19. REFERENCES
  • References to studies included in this review
  • Bergman 2004 {published data only}
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  • Brennan 1996 {published data only}
  • Brennan AB. Effect of sodium acetate transport mattresses on admission temperatures of infants <= 1500 grams [dissertation]. Gainesville (FL): University of Florida, 1996.
  • ROBERTS 1981 {published data only}
  • Roberts JR. Use of a stockinet cap on premature infants after delivery [dissertation]. Denton (TX): Texas Woman's University, 1981.
  • Vohra 1999 {published data only}
  • Vohra S, Frent G, Campbell V, Abbott M, Whyte R. Effect of polyethylene occlusive skin wrapping on heat loss in very low birth weight infants at delivery: a randomized trial. Journal of Pediatrics 1999;134:547-51.
  • Vohra 2003 {unpublished data only}
  • Vohra S, Roberts R, Zhang B, Janes M, Schmidt B. HEat Loss Prevention (HELP) in the delivery room: a randomized clinical trial (RCT) in very preterm infants. Pediatric Research 2003;53:374A [Abstract 2126].
  • Wimmer 2002 {published data only}
  • Wimmer J, Knobel R, Ahearn C, Morton M, Holbert D. Placing infants < 29 weeks gestation in polyurethane bags after birth to reduce hypothermia. Journal of Perinatology 2002;22:602-3.
  • References to studies excluded from this review
  • Almeida 2000
  • Almeida PG, Chandley JM, Rubin LP. Improving admission temperature of very low birth weight (VLBW) newborns: an interventional trial. Pediatric Research 2000;47:282A [Abstract 1661].
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  • Baum JD, Scopes JW. The silver swaddler. Device for preventing hypothermia in the newborn. Lancet 1968;1:672-3.
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  • Bystrova K, Widstrom AM, Matthiesen AS, Ransjo-Arvidson, Wells-Nystrom B, Wassberg C, et al. Skin-to-skin contact may reduce negative consequences of “the stress of being born”: a study on temperature in newborn infants, subjected to different ward routines in St. Petersburg. Acta Paediatrica 2003;92:320-6.
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  • Christensson 1998
  • Christensson K, Bhat GJ, Amadi BC, Eriksson B, Hojer B. Randomised study of skin-to-skin versus incubator care for rewarming low-risk hypothermic neonates. Lancet 1998;352:1115.
  • Chwo 2002
  • Chwo MJ, Anderson GC, Good M, Dowling DA, Siau SH, Cho DM. A randomized controlled trial of early kangaroo care for preterm infants: effects on temperature, weight, behaviour and acuity. Journal of Nursing Research 2002;10:129-42.
  • Coles 1979
  • Coles EC, Valman HB. Hats for the newborn infant. British Medical Journal 1979;2:734-5.
  • Dahm 1972
  • Dahm LS, James LS. Newborn temperature and calculated heat loss in the delivery room. Pediatrics 1972;49:504-13.
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  • Day LD, Caliguiri L, Kamenski C, Ehrlich F. Body temperature and survival of premature infants. Pediatrics 1964;34:171-81.
  • Fardig 1980
  • Fardig JA. A comparison of skin-to-skin contact and radiant heaters in promoting neonatal thermoregulation. Journal of Nurse-Midwifery 1980;25:19-28.
  • Gray 2004
  • Gray PH, Paterson S, Finch G, Hayes M. Cot-nursing using a heated, water-filled mattress and incubator care: a randomized clinical trial. Acta Paediatrica 2004;93:350-5.
  • Green-Abate 1994
  • Green-Abate C, Tafari N, Rao MR, Yu K, Clemens JD. Comparison of heated water-filled mattress and space-heated room with infant incubator in providing warmth to low birthweight newborns. International Journal of Epidemiology 1994;23:1226-33.
  • Greer 1988
  • Greer PS. Head coverings for newborns under radiant warmers. Journal of Obstetric, Gynecological and Neonatal Nursing 1988;17:265-71.
  • Grover 1994
  • Grover G, Berkowitz CD, Lewis RJ, Thompson M, Berry L, Seidel J. The effects of bundling on infant temperature. Pediatrics 1994;94:669-73.
  • Hellin Martinez 2000
  • Heillin Martinez MJ, Lopez Terol E, Perez Lopez M, Vidagany Escrig I. Maintain the temperature of a healthy newborn infant. Revista Rol de Enfermeria 2000;23:63-5.
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  • Holzman IR. A method to maintain infant temperature. American Journal of Diseases of Children 1985;139:390-2.
  • Huang 2002
  • Haung L, Chwo M, Chu D, Chang Y. Effects of very early kangaroo care on infants' extrauterine adaptation. Journal of Nursing (China) 2002;49:37-51.
  • Johanson 1992
  • Johanson RB, Spencer SA, Rolfe P, Jones P, Malla DS. Effect of post-delivery care on neonatal body temperature. Acta Paediatrica 1992;81:859-63.
  • Legault 1993
  • Legault M, Goulet C. Comparative study of two methods of holding premature infants: the kangaroo method versus traditional method [Etude comparative de deux methodes de sortie du premature: methode kangourou versus methode traditionnelle]. Canadian Journal of Nursing Research 1993;25:67-80.
  • Ludington-Hoe 1994
  • Ludington-Hoe S, Thompson Coon J, Swinth J, Hadeed AJ, Anderson GC. Kangaroo care: research results and practice implications and guidelines. Neonatal Network 1994;13:19-27.
  • Ludington-Hoe 2000
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  • Marks 1985
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  • Mazurek 1999
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  • Meyer 2001
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  • Monterosso 1999
  • Monterosso L, Percival P, Cole J, Evans SF. Effect of nappy liners on temperature stability in very preterm infants. Journal of Paediatrics and Child Health 1999;35:363-6.
  • Nopper 1996
  • Nopper AJ, Horri KA, Sookdeo-Drost S, Wang TH, Mancini AJ, Lane AT. Topical ointment therapy benefits premature infants. Journal of Pediatrics 1996;128:660-9.
  • Nuntnarumit 2004
  • Nuntnarumit P, Deesomchok A. Efficacy of polyethylene occlusive skin wrapping with plastic bag in preventing hypothermia in infants less than 32 weeks' gestational age at delivery. Marathon Multimedia LLC [http://www.pas.meeting.org/], editor(s). 2004 Pediatric Academic Societies' Annual Meeting. May 1-4, 2004, San Francisco, (CA). Pediatric Academic Societies, 2004.
  • Omene 1978
  • Omene JA, Diejomaoh FM, Faal M, Diakparomre MA, Obiaya M. Heat loss in Nigerian newborn infants in the delivery room. International Journal of Gynaecology and Obstetrics 1978-79;16:300-2.
  • Raman 1992
  • Raman S, Shahla A. Temperature drop in normal term newborn infants born at the University Hospital, Kuala Lumpar. Australian and New Zealand Journal of Obstetrics and Gynaecology 1992;32:117-9.
  • Roberts 2000
  • Roberts KL, Paynter C, McEwan B. A comparison of kangaroo mother care and conventional cuddling care. Neonatal Network 2000;19:31-5.
  • Ruiz 1998
  • Ruiz JG. Kangaroo mother versus 'traditional' care for newborn infants <= 2000 grams: a randomised control trial. Journal of Clinical Epidemiology 1998;51 Suppl:125.
  • Sarman 1989
  • Sarman I, Tunell R. Providing warmth for preterm babies by a heated, water filled mattress. Archives of Disease in Childhood Fetal and Neonatal Edition 1989;64:29-33.
  • Sarman 1992
  • Sarman I. Thermal responses and heart rates of low-birth-weight premature babies during daily care on a heated, water-filled mattress. Acta Paediatrica 1992;81:15-20.
  • Short 1998
  • Short MA. A comparison of temperature in VLBW infants swaddled versus unswaddled in a double- walled incubator in skin control mode. Neonatal Network 1998;17:25-31.
  • van den Bosch 1990
  • van den Bosch CA, Bullough CH. Effect of early suckling on term neonates' core body temperature. Annals of Tropical Paediatrics 1990;10:347-53.
  • van den Bosch 1996
  • van den Bosch CA, Nhlane C, Kazembe P. Trial of polythene tobacco-wrap in prevention of hypothermia in neonates less than 1500 grams. Tropical Doctor 1996;26:26-8.
  • References to ongoing studies
  • Meyer 2003
  • How should preterm infants be kept warm during transport to NICU - in incubators or under radiant warmers?. Ongoing study September 2003.
  • Meyer M. How should preterm infants be kept warm during transport to NICU - in incubators or under radiant warmers?. Personal communication June 03 2003 and update July 08 2004.
  • Vohra 2004
  • Multicentred randomised controlled trial of heat loss prevention (HeLP) in the delivery room. Ongoing study September 2004.
  • Vohra S. Multi centered randomised controlled trial of heat loss prevention (HeLP) in delivery room. Personal communication 08 July 2004.
  • Additional references
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  • Adamsons K, Gandy GM, James LS. The influence of thermal factors upon oxygen consumption of the newborn human infant. Journal of Pediatrics 1965;66:495-508.
  • Adamsons 1965a
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  • Bailey 2000
  • Bailey J, Rose P. Temperature measurement in the preterm infant: A literature review. Journal of Neonatal Nursing 2000;6:28-32.
  • Baumgart 1981
  • Baumgart S, Engle WD, Fox WW, Polin RA. Effect of heat shielding on convective and evaporative heat losses and on radiant heat transfer in the premature infant. Journal of Pediatrics 1981;99:948-56.
  • Bell 1978
  • Bell MJ, Ternberg JL, Feigin RD, Keating JP, Marshall R, Barton L, et al. Neonatal necrotizing enterocolitis. Therapeutic decisions based on clinical staging. Annals of Surgery 1978;187:1-7.
  • Bell 1980
  • Bell EF, Weinstein MR, Oh W. Heat balance in premature infants: comparative effects of convectively heated incubator and radiant warmer, with and without plastic heat shield. Journal of Pediatrics 1980;96:460-5.
  • Bickmann 1992
  • Buczkowski-Bickmann MK. Thermoregulation in the neonate and the consequences of hypothermia. CRNA: The Clinical Forum for Nurse Anesthetists 1992;3:77-82.
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  • Borse 1997
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  • Britton 1980
  • Britton GR. Early mother-infant contact and infant temperature stabilization. JOGN Nursing 1980;9:84-6.
  • Bruck 1961
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  • Christensson 1988
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  • Glass 1968
  • Glass L, Silverman WA, Sinclair JC. Effects of the thermal environment on cold resistance and growth of small infants after the first week of life. Pediatrics 1968;41:1033-46.
  • Hammarlund 1979
  • Hammarlund K, Sedin G. Transepidermal water loss in newborn infants. III. Relation to gestational age. Acta Paediatrica Scandinavica 1979;68:795-801.
  • Hammarlund 1980
  • Hammarlund K, Nilsson GE, Oberg PA, Sedin G. Transepidermal water loss in newborn infants. V. Evaporation from the skin and heat exchange during the first hours of life. Acta Paediatrica Scandinavica 1980;69:385-92.
  • Harned 1970
  • Harned HS Jr, Herrington RT, Ferreiro JI. The effects of immersion and temperature on respiration in newborn lambs. Pediatrics 1970;45:598-605.
  • Hey 1970
  • Hey EN, Katz G. The optimal thermal environment for naked babies. Archives of Disease in Childhood 1970;45:328-34.
  • Hey 1975
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  • LeBlanc 1991
  • LeBlanc MH. Thermoregulation: incubators, radiant warmers, artificial skins and body hoods. Clinics in Perinatology 1991;18:403-22.
  • Lee 2000
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