Prophylactic intravenous calcium therapy for exchange blood transfusion in the newborn

  • Protocol
  • Intervention


  • Tinuade A Ogunlesi,

    Corresponding author
    1. Obafemi Awolowo College of Health Sciences, Olabisi Onabanjo University, Department of Paediatrics (Neonatal Unit), Sagamu, Ogun State, Nigeria
    • Tinuade A Ogunlesi, Department of Paediatrics (Neonatal Unit), Obafemi Awolowo College of Health Sciences, Olabisi Onabanjo University, Sagamu, Ogun State, 121001NG, Nigeria.

    Search for more papers by this author
  • Foluso EA Lesi

    1. College of Medicine of the University of Lagos, Department of Paediatrics, Lagos, Nigeria
    Search for more papers by this author


This is the protocol for a review and there is no abstract. The objectives are as follows:


To determine whether the use of prophylactic calcium reduces the risk of hypocalcaemia-related morbidities and death among newborn infants receiving EBT.


We will perform subgroup analysis to address:

  1. preterm (< 37 weeks gestation) versus term (≥ 37 weeks gestation);

  2. the type of anticoagulant in the blood transfused (comparison will be made between citrate and heparin);

  3. the volume of blood used (comparison will be made between single-volume and double-volume EBT);

  4. timing of administration of calcium (comparison will be made between administration during EBT or administration immediately after EBT).


Exchange blood transfusions (EBT) have been reported as accounting for close to two-thirds of blood transfusions among newborns in low- and middle-income countries (Pam 2004; Ogunlesi 2011). On the contrary, centres in high-income countries rarely employ EBT in the care of newborn infants (MacLennan 2001; Flaherman 2012). This difference is due to the varying pattern of indications for EBT (such as haemolytic diseases and other causes of hyperbilirubinaemia (increased levels of bilirubin in the blood) in the newborn infants) in the low- and middle-income countries compared to high-income countries.

Description of the condition

EBT is a form of whole blood transfusion in which the total blood volume is replaced within a period of 24 hours. In perinatal and neonatal medicine, EBT is most often used for rapid removal of toxins (such as bilirubin and sensitised red cells), or to replace red blood cells. Two types of EBT are commonly used in the newborn; single-volume or double-volume exchange transfusion. Single-volume EBT implies transfusion with 80 ml/kg to 85 ml/kg of blood - which is the estimated total blood volume of the infant - whereas double-volume EBT implies transfusion with double the estimated total blood volume of an infant (160 ml/kg to 170 ml/kg) (Maisels 2001). Traditionally, double-volume EBT is used in the management of severe hyperbilirubinaemia, while single-volume EBT is commonly used in the management of severe neonatal anaemia, especially within the first week of life. Double-volume EBT is used in infants with severe hyperbilirubinaemia arising from haemolytic (blood) diseases such as blood group incompatibilities (particularly ABO and Rhesus), enzymopathies (such as glucose-6-phosphate dehydrogenase deficiency) and membranopathies (causing red blood cell anomalies such as erythrocytosis and elliptocytosis). Other indications include septicaemia, prematurity, cephalohematoma or sub-galeal hematoma (collections of blood in the head), disseminated intravascular coagulation (clotting anomaly) and metabolic derangements such as intractable hypoglycaemia (low blood sugar levels).  

Description of the intervention

Fresh whole blood, usually preserved with acid-citrate-dextrose or citrate-phosphate-dextrose, is used for EBT. The calculated volume of blood is administered in small aliquots of 5 ml to 10 ml, depending on the weight of the infant, using a special three-way valve. The valve is connected to an umbilical venous catheter through which the transfusion is performed over about two hours. When done effectively, the double-volume procedure replaces between 85% and 90% of the red cells in circulation, and reduces the serum bilirubin level to about 60% of the pre-EBT level, while the single-volume procedure raises the haematocrit (level of red blood cells) of the infant close to that of the blood used for the procedure (Maisels 2001). Complications during EBT may arise from the process of umbilical catheterization, the biochemical properties of the anti-coagulant used, as well as the presence of microbes in the blood.

EBT-related morbidities include hypocalcaemia (low blood calcium), hypothermia (low body temperature), hypoglycaemia, metabolic acidosis (over-production of acid), hyperkalaemia (high blood potassium), thrombocytopaenia (low platelet concentration), cardiac arrhythmias (irregularities), air embolism, apnoea (cessation of breathing), septicaemia and omphalitis (infections of the blood and umbilical stump, respectively), necrotising enterocolitis (tissue death in the bowel) and intestinal perforation (Patra 2004; Sanpavat 2005; Gharehbaghi 2010; Sakha 2010). 

Hypocalcaemia (defined as serum total calcium less than 8 mg/dl (2 mmol/l) or serum ionised calcium less than 4.4 mg/dl (1.1mmol/l)) is routinely prevented with calcium administration during or immediately after EBT (Nelson 1988; Maisels 2001). However, studies have shown that not all newborn infants with EBT-related hypocalcaemia get calcium treatment (Steiner 2007). Hypocalcaemia may be asymptomatic, but some of the common manifestations include jitteriness, abnormal cry, lethargy, irritability, apnoea, hypotonia (low muscle tone), carpopedal spasm (affecting hands and feet) or seizures (Maisels 2001). These clinical features do not reflect severity of calcium deficiency, and may occur in any combination. Evidence of a prolonged QTc interval on electrocardiography is suggestive of severe hypocalcaemia requiring treatment. The use of clinical assessment for hypocalcaemia may be justifiable in low- and middle-income countries where laboratory facilities required for the detection of hypocalcaemia may not be available.

In practice, hypocalcaemia is frequently treated by the intravenous administration of 10% calcium gluconate containing 9.3 mg of elemental calcium per millilitre. This is administered as 1 ml (100 mg) for every 100 ml of blood transfused. This intervention may be administered in pulses during the procedure, or as a slow bolus (dose) immediately after the procedure.

As a result of the risk of significant morbidity and mortality associated with hypocalcaemia, some practitioners - and even standard textbooks of neonatal medicine - suggest routine prophylactic administration of calcium to infants undergoing EBT as described above. Although, some practitioners still advocate routine prophylactic calcium administration for EBT, most current guidelines on transfusion practices are silent on the need for routine calcium administration to infants requiring EBT or stipulate that routine administration of calcium is not recommended (NICE 2010). It has yet to be proven that this practice is necessary, safe and effective. 

How the intervention might work

Hypocalcaemia that occurs during EBT is thought to arise from the chelating (metal binding) effects of the citrate commonly used as an anti-coagulant in the transfused blood. Serum calcium levels have been shown to fall significantly during EBT without accompanying clinical manifestations, and to rise transiently to hypercalcaemic (high calcium level) ranges following calcium administration (Nelson 1988; Lo 1990). The two extremes of this fluctuation pose great risk of cardiac arrhythmias to the infant undergoing EBT. However, there have been suggestions that changes in ionised serum calcium level during EBT are not remarkable (Kreuger 1975; Jasso-Gutierrez 1982). Furthermore, serum calcium levels have been reported to normalise within 24 hours of EBT, even without calcium therapy (Nelson 1988). 

The interaction between the chelating agent and serum calcium is complex. When blood containing citrate is administered, the citrate binds calcium and forms un-ionised calcium complexes. Citrate causes a fall in ionised serum calcium levels resulting in a compensatory stimulation of parathormone secretion and mobilisation of calcium and phosphorus in order to normalise the serum calcium level. However, use of heparin as an anticoagulant for blood preserves the serum ionised calcium levels, in addition to those of albumin and parathyroid hormone, during EBT (Milner 1975). As citrate is more commonly used as an anti-coagulant than heparin, newborn infants receiving EBT are expected to develop hypocalcaemia. Therefore, newborn infants receiving EBT with citrated blood should benefit from routinely-given prophylactic intravenous calcium to prevent EBT-related hypocalcaemia. 

Potential adverse effects

The adverse effects of intravenous calcium include vomiting, constipation, rapid vasodilation with hypotension (widening of blood vessels causing low blood pressure), bradycardia (slow heart rate), cardiac dysrhythmias (irregular heartbeat) and possibly cardiac arrest in severe cases. It also causes intense irritation at the site of administration and ultimately, tissue necrosis if extravasation (leakage from the vein) occurs.

Why it is important to do this review

Infants undergoing EBT may develop extremely low serum levels of total and ionised calcium. Some infants undergoing EBT may develop hypocalcaemia and require treatment during EBT, while others may not require treatment with calcium (Steiner 2007). Fluctuations in serum calcium levels may cause dangerously high serum calcium levels with the risk of cardiac toxicity.

It is important to know the extent to which hypocalcaemia, which requires treatment, occurs during EBT, and if it is necessary and safe to administer prophylactic intravenous calcium routinely to infants requiring EBT.



To determine whether the use of prophylactic calcium reduces the risk of hypocalcaemia-related morbidities and death among newborn infants receiving EBT.


We will perform subgroup analysis to address:

  1. preterm (< 37 weeks gestation) versus term (≥ 37 weeks gestation);

  2. the type of anticoagulant in the blood transfused (comparison will be made between citrate and heparin);

  3. the volume of blood used (comparison will be made between single-volume and double-volume EBT);

  4. timing of administration of calcium (comparison will be made between administration during EBT or administration immediately after EBT).


Criteria for considering studies for this review

Types of studies

Randomised controlled trials and quasi-randomised controlled trials (individually or cluster-randomised) comparing the outcome of newborn infants undergoing EBT who received or did not receive prophylactic calcium.

Types of participants

Newborn infants aged from birth to 28 days requiring EBT (single- or double-volume) for any reason and irrespective of postmenstrual age (whether or not the infant was premature).

Types of interventions

The intervention arm will include infants who received prophylactic intravenous calcium irrespective of the dose and type of calcium salt administered and the time of calcium administration (during or within an hour of EBT). The control arm will include infants who did not receive intravenous calcium or received placebo.

Types of outcome measures

Primary outcomes
  1. All-cause death until discharge

  2. Presence of cardiac dysrhythmias within a week of EBT

  3. Number of infants with serum calcium levels (total < 8 mg/dl (2 mmol/l) or ionised < 4.4 mg/dl (1.1 mmol/l)) within a week of EBT

Secondary outcomes
  1. Number of infants with serum magnesium under 1.5 mg/dl within a week of EBT

  2. Number of infants with serum parathormone under 10 pg/ml within a week of EBT

  3. Number of infants with serum calcitonin over 10 pg/ml within a week of EBT

  4. Duration of hospitalisation (in days)

  5. Incidence of partial or generalised seizures within a week of EBT (clinically diagnosed as tonic extension of limbs or clonic, jerky movements of the limbs or electroencephalographically diagnosed)

  6. Incidence of carpopedal spasms within a week of EBT (clinically diagnosed as sustained contraction of the muscles of the extremities)

  7. Incidence of jitteriness within a week of EBT (clinically diagnosed as brief myoclonic twitching of the muscles of the extremities occurring in clusters)

  8. Incidence of prolonged QTc interval on electrocardiography within a week of EBT

  9. Adverse reactions to calcium therapy within a week of EBT (skin necrosis, vomiting, constipation, hypotension, apnoea, cardiac arrest) occurring singly or in combination.

    1. Skin necrosis is defined as an obvious discontinuity in the skin layer at the site of calcium administration

    2. Vomiting is defined as a reflex act of expelling the gastric contents

    3. Constipation is defined as a frequency of bowel opening that is less than three times per week

    4. Hypotension is defined as mean arterial pressure < 30 mmHg

    5. Apnoea is defined as cessation of breathing for more than 20 seconds associated with cyanosis (blue tinge to skin) and bradycardia

    6. Cardiac arrest is defined as a sudden cessation of cardiac output and effective circulation

Search methods for identification of studies

Electronic searches

We will search the Cochrane Neonatal Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1966 to date), EMBASE (1966 to date), the African Index Medicus (1993 to date), SCISEARCH (Science Citation Index) (1990 to date) and LILACS (1987 to date). We will search the metaRegister of Controlled Trials (mRCT) ( to identify unpublished or ongoing trials. The studies of interest may be published or unpublished from both low- and middle-income countries as well as high-income countries. We will not apply any language restriction. If we identify a study in an abstract form only, we will assess it for possible inclusion in the review and will attempt to contact the study authors for more details to guide our final decision on whether or not to include it.

We will use the search strategy as instructed by the Cochrane Neonatal Review Group. The key words will include: [newborn] OR [neonate] OR [infant] AND [exchange transfusion] OR [exchange blood transfusion] AND [intravenous] AND [calcium] AND [clinical trials] OR [randomised controlled trials].

Searching other resources

We will handsearch journals, published abstracts and proceedings of major conferences such as the International Neonatology Conference, conferences of the Royal College of Paediatrics and Child Health and the American Academy of Pediatrics. We will search the reference lists of articles obtained. We will search the Web of Science for relevant citations in journal databases and in the conference proceedings citation index. If we identify trials for inclusion, we will enter the first known trial in Web of Science to see whether any new trials have quoted the original trials. We will make contact with experts in the field to find out about any ongoing studies that we might include in the review.

Data collection and analysis

Selection of studies

Independently, both authors will assess the eligibility of trials identified through searching for inclusion in the review. We will retrieve full reports of the potentially relevant trials, and independently determine if they meet the inclusion criteria using a pre-tested eligibility form. We will list all excluded studies, along with the reasons for excluding them. We will ensure that trials with multiple publications are included only once, but where the multiple publications include different but relevant outcomes, we will include all the publications in the review. Any disagreement will be resolved through discussion. We will consult the Cochrane Neonatal Review Group for further advice where necessary.

Data extraction and management

A data extraction form will be designed and tested before use. We will extract data from eligible studies independently using the data extraction form. One author (TAO) will enter the data into Review Manager (RevMan) (Review Manager 2013), the Cochrane Collaboration's review writing software, while the second author (FEAL) will cross-check the data for completeness and accuracy. Data will be extracted from the number of participants randomised and the number analysed in each group for each reported outcome.

For continuous outcomes, we will extract the number of participants for each treatment arm, arithmetic means and standard deviations (SDs). If we encounter data with skewed distribution, where the data have been reported as geometric means, we will extract geometric means and SDs on the log scale, or, if medians have been used, medians and ranges. For rate and count outcomes (such as participants with outcomes that occur more than once over the period of trial), we will extract the number of events or episodes experienced in each trial arm and person-time over which the events were experienced for each group. We will extract hazard ratios (HRs) and SDs for time-to-event outcomes. We will extract data on reported adverse events.

We will attempt to contact the trial authors where the relevant details are not recorded or were unclear. Discrepancies will be resolved through discussion.

Assessment of risk of bias in included studies

Independently, both authors will assess risk of bias for every eligible study using the guidelines provided in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will assess the risk of bias within each included study in relation to the following five domains (allocation sequence generation, allocation concealment, blinding, handling of incomplete outcome data and selective outcome reporting), giving ratings of 'low risk of bias', 'high risk of bias' and 'unclear risk of bias' for each domain of each trial. Disagreements will be resolved through discussions.   

Randomisation sequence generation

For each included study we will describe the method used to generate the allocation sequence to allow an assessment of whether it should produce comparable groups.

The assessment will be graded as follows:

  1. low risk of bias (truly random processes such as the use of a table of random numbers or computer-generated random numbers);

  2. high risk of bias (non-random processes such as use of hospital record numbers or dates of birth);

  3. unclear risk of bias.

Allocation concealment

For each included study we will describe the method used to conceal allocation to interventions prior to assignment and will assess whether intervention allocation could have been predicted before or changed after recruitment. The methods will be graded as follows:

  1. low risk of bias (use of central allocation which may be web-based or pharmacy-controlled; sequentially-numbered, opaque, sealed envelopes);

  2. high risk of bias (unsealed, non-opaque assignment envelopes or not sequentially-numbered, allocation by alternation or rotation;

  3. unclear risk of bias (method of concealment not described in significant detail to allow a definite judgement).

Blinding of participants and researchers

For each included study we will describe the methods used to blind study participants and researchers from knowledge of which intervention a participant received. Blinded studies, or studies in which non-blinding was not likely to have affected the results significantly, will be classified as having a low risk of bias. Non-blinded studies will be classified as having a high risk of bias. 

Incomplete outcome data

For each included study we will describe the methods used to account for incomplete outcome data, with regard to the amount, nature and handling of incomplete outcome data. In instances where studies do not report complete outcome data, we will attempt to obtain missing data by contacting the study authors. We will extract and report on data on attrition and exclusions as well as the numbers involved (compared with total randomised), reasons for attrition/exclusion where reported or obtained from investigators, and any re-inclusions in analyses performed by review authors. Unbiased follow-up will be considered to have happened when at least 80% of the participants were followed up. Based upon this, we will judge whether the researchers dealt with incomplete data.

Selective outcome reporting

We will attempt to assess the possibility of selective outcome reporting by investigators in the included trials by, where available, examining the study protocols; based upon this, we will judge whether reports of the study were free from suggestion of selective outcome reporting.

We will also explore other sources of bias, particularly the sources of funding of the included studies and other study peculiarities.

Measures of treatment effect

The type of treatment effect to be used in describing each of the listed outcomes will depend on the type of data extracted for the specific outcome.

Continuous data 

If means and SDs are available, continuous data will be analysed. We will extract and utilise this for the analysis irrespective of provision of mean and SD if mean difference is provided. We will be interested in post intervention values. We will re-calculate the SD in instances where the standard error is reported. We will extract data from studies that reported adequately on skewed continuous data as medians rather than means. We will report these data separately where appropriate. We will calculate the weighted mean difference (WMD) and 95% confidence interval (CI) for continuous data.

Binary data 

We will analyse binary outcomes by calculating the risk ratio (RR), risk difference (RD), and the number needed to treat for an additional beneficial outcome (NNTB) (with 95% CIs), will be determined when RD is statistically significant.

Unit of analysis issues

For each included study we will describe the repeated observations on participants at selected time points (within one week of EBT and at the point of discharge). We will analyse follow-up data available at the point of discharge from the hospital. If cluster trials are identified, we will adjust for clustering by applying the intra-cluster correlation coefficient.

Dealing with missing data

We will contact the original authors of included studies that have missing data and request that they supply the unreported data (e.g. group means and SDs, details of dropouts, and details of interventions received by the control group). If a study reports outcomes only for participants completing the trial, or only for participants who followed the protocol, authors will be contacted and asked to provide additional information to facilitate an intention-to-treat analysis, and, in instances where this is not possible, we will perform a complete case analysis.

We will decide to use the 'trim and fill' methodology if in the course of review, we need to adjust for publication bias as shown by asymmetry of a forest plot. We will highlight the impact of the missing data on the findings of the review in the Discussion section.

Assessment of heterogeneity

We will identify statistical heterogeneity in each of the included study using the Chi2 test and I2 statistic. We will perform visual assessment of forest plots to identify obvious overlaps and outliers. We will agree on how to handle heterogeneity depending on the degree indicated by the I2 statistic. As a rough guide, I2 values of less than 25% will be treated as indicating no heterogeneity, values of 25% to 49% as indicative of low heterogeneity, values of 50% to 74% as indicative of moderate heterogeneity and values of 75% or above as indicative of high heterogeneity (Higgins 2003). When heterogeneity is significant, outliers will be investigated and we will attempt to explain the heterogeneity. When heterogeneity is significant and cannot be explained, we will use sub-group analysis and sensitivity analysis to resolve the discrepancy.

Assessment of reporting biases

We will examine each included study for within-study selective outcome reporting. Where protocols are available, these will be compared against the final published paper with outcomes. Where protocols are not available, the outcomes listed under the Methods section of the study will be compared with the actual reported outcomes.  A matrix will be constructed to display the reported outcomes for each study. Where reporting bias is suspected, we will contact the authors of the affected studies requesting clarification and, possibly, that they supply the necessary data.

Data synthesis

We will use the Mantel-Haenszel statistical method to analyse dichotomous data, particularly where included studies have low event rates or small study sizes. The weighted or standardised mean differences (WMD) will be used for the analysis of continuous data. Where different studies present the same outcomes in dichotomous and continuous forms, statistical methods will be adopted to re-express risk ratio as weighted means and vice versa. We will conduct meta-analyses for trials with similar characteristics. We will carry out an intention-to-treat analysis or carry out a complete case analysis where there is loss to follow-up. We will use the fixed-effect model and present all our results with 95% CI. We will calculate the NNTB, the number needed to treat for an additional harmful outcome (NNTH), WMD and 95% CIs for our continuous outcomes, and RR and RD with 95% CIs for our dichotomous outcomes.

Subgroup analysis and investigation of heterogeneity

In cases of inter-study variability, we will conduct subgroup analysis for each outcome of interest as follows:

  1. preterm (< 37 weeks gestation) versus term (≥ 37 weeks gestation);

  2. the type of anticoagulant in the blood transfused (comparison will be made between citrate and heparin);

  3. the volume of blood used (comparison will be made between single-volume EBT and double-volume EBT);

  4. timing of administration of calcium (comparison will be made between administration during EBT or administration immediately after EBT).

Sensitivity analysis

We will agree on eligibility criteria (age range of participants, comparator group, range of doses of intervention and the range of time points to be evaluated in the analysis), type of data to be analysed (dichotomous or continuous) and the method of data analysis to be adopted. We will conduct sensitivity analyses if disparities are encountered with respect to any of the eligibility criteria earlier agreed upon. We will input missing data with replacement values and assume all the participants with missing data had a poor outcome. We will contact the Cochrane Neonatal Group's statistician when this decision is to be taken. We will perform sensitivity analysis to assess how sensitive the findings are if we do assume that all those participants with missing data had a poor outcome. We will decide on the other aspects of sensitivity analysis during the review. We will use a 'Summary of Findings' table to report the findings of sensitivity analyses.    


We acknowledge the opportunities provided by our home institutions (Olabisi Onabanjo University, Sagamu Nigeria, the University of Lagos, Nigeria and the Nigerian branch of the South African Cochrane centre), to write this protocol.

What's new

26 March 2014AmendedAuthor affiliation updated.

Contributions of authors

TAO initiated and designed the review. FEAL contributed to the design of the review. Both authors made substantial intellectual contributions to the protocol.

Declarations of interest

Tinuade A Ogunlesi: nothing to declare
Foluso EA Lesi: nothing to declare

Sources of support

Internal sources

  • Eunice Kennedy Shriver National Institute of Child Health and Human Development National Institutes of Health, Department of Health and Human Services, USA.

    Editorial support of the Cochrane Neonatal Review Group has been funded with Federal funds from the Eunice Kennedy Shriver National Institute of Child Health and Human Development National Institutes of Health, Department of Health and Human Services, USA, under Contract No. HHSN275201100016C.

External sources

  • No sources of support supplied