Topical negative pressure (TNP) for partial thickness burns

  • Review
  • Intervention

Authors

  • Jason Wasiak,

    Corresponding author
    1. Monash University, Alfred Hospital, Victorian Adult Burns Service and School of Public Health and Preventative Medicine, Melbourne, Victoria, Australia
    • Jason Wasiak, Victorian Adult Burns Service and School of Public Health and Preventative Medicine, Monash University, Alfred Hospital, Commercial Road, Prahran, Melbourne, Victoria, 3181, Australia. J.Wasiak@alfred.org.au. jwasiak1971@gmail.com.

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  • Heather Cleland

    1. The Alfred Hospital, Victorian Adult Burns Service, Melbourne, Victoria, Australia
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Abstract

Background

A burn wound is a complex and evolving injury, with both local and systemic consequences. Treatments include using a variety of dressings, but newer strategies such as topical negative pressure therapy (TNP) have been developed to try and promote the wound healing process and minimise burn wound progression. TNP uses a suction force to drain excess fluids.

Objectives

To assess the effectiveness of TNP for those people with partial thickness burns.

Search methods

For this update we searched the Cochrane Wounds Group Specialised Register (searched 1 September 2010), the Cochrane Central Register of Controlled Trials (CENTRAL)(The Cochrane Library 2010 Issue 3), Ovid MEDLINE (1950 to August Week 3 2010), Ovid EMBASE (1980 to 2010 Week 34) and EBSCO CINAHL (1982 to 27 August 2010).

Selection criteria

All randomised controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated the safety and effectiveness of TNP for partial thickness burns.

Data collection and analysis

Two authors using standardised forms extracted the data independently. We assessed each trial for internal validity, and resolved differences by discussion.

Main results

One RCT, which was an interim report, satisfied the inclusion criteria. We undertook a narrative synthesis of results, as the absence of data, poor reporting or both precluded us from carrying out any formal statistical analysis. The trial was at high risk of bias.

Authors' conclusions

There is a no evidence regarding the use of TNP for treating partial thickness burn wounds.

摘要

背景

局部負壓 (Topical negative pressure; TNP) 用於治療局部深層燒傷 (partial thickness burns)

燒傷的傷口是一種複雜且逐步演變的外傷,可能造成局部或系統性的後果,其治療包括使用各種敷料,不過有些更先進的方法如局部負壓療法已經被用於促進傷口的癒合,以及避免燒傷傷口在急性期惡化而影響到更深層的組織。局部負壓是以吸力來吸除過量的液體。

目標

評估TNP用於局部深層燒傷患者的效果。

搜尋策略

我們搜尋了Cochrane Wounds Group Specialised Register (搜尋時間為2007年4月), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 第2期,2007年), Ovid MEDLINE (1950 年到2007年4月第4周), Ovid EMBASE (1980年到2007年第18周) 以及Ovid CINAHL (1982年到2007年4月第4周).

選擇標準

所有評估TNP用於局部深層燒傷的安全性與效果之隨機對照試驗 (randomised controlled trials;RCTs) 和具有控制組的臨床試驗 (controlled clinical trials;CCTs) 。

資料收集與分析

由兩位作者獨立以標準化的格式摘錄資訊,每個試驗都評估其內在效度,遇有有分歧時則透過討論來解決。由於資料有所遺漏、報告不完整,這兩者使得作者無法進行任何正規的統計分析,因此最後採取綜合敘述的方式來報告結果。

主要結論

有1個RCT符合我們的選擇標準,而這個試驗在方法學上的品質不佳。

作者結論

有1個品質欠佳的RCT研究過TNP用於局部深層燒傷,其樣本數與檢力不足以判斷出TNP和傳統燒傷傷口敷料治療間是否有差異。

翻譯人

本摘要由成功大學附設醫院邱曉萱翻譯。

此翻譯計畫由臺灣國家衛生研究院 (National Health Research Institutes, Taiwan) 統籌。

總結

缺乏實證說明局部負壓療法對於治療局部深層燒傷的患者是否有效。局部負壓 (TNP) 療法是指在傷口上施加負壓,在這種情況下,壓力可用於幫助抽吸過量液體、降低感染率以及增加傷口部位的血流,接著提供傷口氧氣與營養,以加速傷口的痊癒。TNP的別名是真空抽吸器 (vacuumassisted closure;VAC) ,用於緊緊密合吸附在傷口表面。

Plain language summary

Topical negative pressure (TNP) for treating partial thickness burns

Topical negative pressure (TNP) therapy is the application of negative pressure across a wound to help the wound to heal. In this instance, the pressure is used to help the drainage of excess fluid, reduce infection rates and increase localised blood flow, thereby supplying the burn wound with oxygen and nutrition to promote the healing process. Alternative names for TNP include vacuum-assisted closure (VAC) and sealed surface wound suction. There is a lack of evidence about whether TNP therapy is effective in treating people with partial thickness burns.

Background

Burn injury remains an important source of morbidity and mortality. Every year, approximately two million people are burned, up to 80,000 are hospitalised as a result of burns and more than 6500 people die from such injuries in the USA alone (Brigham 1996). A skin burn is damage to the skin caused by heat or other caustic materials such as chemicals. Heat causes the most immediate and obvious injury. Excessive heat causes rapid protein denaturation and cell damage, thereby making the initial event a complex and evolving injury, with both local and systemic consequences - the latter manifesting once the burn area is greater than 20% of the body surface area (BSA) (Sheridan 2002).

Locally, the burn wound tends to extend during the acute phase of the injury secondary to microvascular changes, profound activation of white cells and platelets, and the development of oedema. Many small vessels are directly coagulated by the application of heat, while others will thrombose late and develop tissue dehydration (Boykin 1980). The systemic response to burning is characterised by interstitial oedema in distant organs, which is a swelling of any organ or tissue due to the accumulation of excess lymph fluid, and is secondary to a combination of wound-released mediators and hypoproteinaemia (abnormally small amounts of total protein in the circulating blood plasma)(Demling 1979; Youn 1992).

Burn wounds are often classified by depth: superficial (1st degree burn), partial thickness (2nd degree burn) or full thickness (3rd degree burn). Often, the depth of injury is diagnosed by the anatomic thickness of the skin involved (i.e. the epidermis (outer thin layer), stratum corneum (outer most layer) and the dermis (deepest layer)) and based on either clinical observation, objective assessment, or both. Clinical evaluation often relies on burn wound appearance: blanching, capillary return, presence and degree of fixed capillary staining and evaluation of retained light touch and pinprick sensation. Objective assessment tools such as laser doppler flowmetry, laser doppler imaging or indocyanine green video angiography, may be used to measure blood flow into the tissue and therefore, depth of burn injury (Demling 2005).

First-degree or superficial burns are confined exclusively to the epidermis or outer surface and are not generally significant injuries, as they heal rapidly and spontaneously. Partial thickness burns involve varying amounts of the dermis, may progress to become deeper, and heal with variable amounts of scarring, dependent in part on the depth of the burn.

Superficial partial thickness burns extend through the epidermis into the papillary (superficial) layer of the dermis. These wounds become erythematous, which is a reddening of the skin, because the dermal tissue has become inflamed. When pressure is applied to the reddened area, the area will blanch and demonstrate a brisk or rapid capillary refill upon release of the pressure, a hallmark of the superficial partial thickness burn (Demling 2005; Johnson 2003). Thin walled, fluid filled blisters will develop within minutes of the injury. As these blisters break, the exposed nerve endings transmit the senses of superficial pain, light touch and temperature, making these wounds extremely painful. The wound will be moist because the characteristic waterproofing of the epidermis has been lost, allowing body fluid to leak on the wound surface. Due to the involvement of the dermal blood vessels in this type of injury, moderate oedema is usually present (Demling 2005; Johnson 2003).

Deep partial thickness burns extend downward into the reticular (deeper) layer of the dermis and present as mixed red or waxy white. Areas of redness will continue to blanch when pressure is applied, but capillary refill may be absent or may be sluggish when pressure is released. Blisters are usually absent; however, the exposed surface of the wound is wet or moist, similar to superficial partial thickness burns. Oedema is marked and sensation is altered in areas of a deep partial thickness burn (Demling 2005; Johnson 2003).

Since the biology of wound healing has become better understood, many strategies have been developed to try to manipulate this wound healing process (Banwell 1999), and to minimise burn wound progression by involving deeper tissue in the acute phase. These range from a variety of dressings such as polyurethane films and hydrocolloids (Wasiak 2005), and skin substitutes, to the use of more complex and experimental techniques such as hyperbaric oxygen therapy (Villanueva 2004), growth factors and cytokine biology (Atiyeh 2005).

One way of manipulating the wound environment with a view to promoting healing is to apply topical negative pressure (TNP) across the wound surface via a dressing (Ubbink 2008). This negative pressure can induce an interstitial gradient shift which can cause a reduction in oedema, and a secondary increase in dermal perfusion, thus aiding in the removal of blood or serous fluid (Banwell 2004). It is postulated that the ability of TNP to produce a mechanical stress or force that has a direct effect in cellular activity and, in particular, the development of new blood vessels, may also contribute to a decrease in burn wound progression. The maintenance of a moist environment which provides optimal conditions for epithelialisation and the prevention of tissue desiccation (Banwell 1999; Banwell 2004) is also potentially advantageous (Pham 2003).

There are a number of names to describe the treatment of a wound with TNP including: subatmospheric pressure, vacuum-sealing technique, sealed surface wound suction, vacuum assisted closure (VAC), negative pressure therapy or dressing, foam suction dressing, vacuum compression, vacuum pack technique, negative pressure dressing and foam suction dressing (Banwell 2004). For the purposes of this review all variations of this intervention will be referred to as TNP. The use of TNP in burn wound management has been described by a number of clinicians (Kamolz 2004; Schrank 2004), and TNP is also used to treat donor sites and skin grafts (Moisidis 2004). Given its wide variety use and application in other wound conditions such as ulcers, we plan to summarise the evidence to determine whether TNP is safe, effective and beneficial to those patient with partial thickness burns.

Objectives

To determine whether TNP promotes the healing of partial thickness burns in adults.

Methods

Criteria for considering studies for this review

Types of studies

We included all randomised controlled trials (RCTs) and controlled clinical trials (CCTs) that evaluated the effectiveness of TNP for partial thickness burns.

Types of participants

We included studies involving adults aged 18 years or over with a partial thickness burn, the severity of which could be determined by either clinical evaluation or objective assessment, or both. Clinical evaluation relied on burn wound appearance, blanching, capillary return, presence and degree of fixed capillary staining and evaluation of retained light touch and pinprick sensation. Objective assessment involved the measurement of tissue perfusion using measuring modalities such as laser doppler flowmetry, laser doppler imaging or indocyanine green (ICG) video angiography.

Types of interventions

Studies were eligible if they compared TNP with standard burn wound therapies. Studies involving any mode of delivery of TNP were eligible including commercially available devices (such as VAC Pump, KCI Texas, USA), wall suction or surgical drainage bottles, as well as negative pressure cycles that varied in degree, application (including continuous and/or intermittent pressure cycles) and duration.

Types of outcome measures

Studies were eligible for inclusion if they reported any of the following outcome measures:

Primary outcomes
  • time to complete healing;

  • rate of change in wound area;

  • proportion of wound completely healed within the trial period.

Secondary outcomes
  • incidence of wound infection;

  • adverse events;

  • measures of satisfaction or patient preference;

  • quality of life.

Search methods for identification of studies

Electronic searches

The search methods section of the original version and first update of this review can be found in Appendix 1 and Appendix 2 respectively

For this second update we modified the previous search string and searched the following electronic databases:

  • Cochrane Wounds Group Specialised Register (searched 1 September 2010)

  • The Cochrane Central Register of Controlled Trials (CENTRAL) - The Cochrane Library 2010 Issue 3

  • Ovid MEDLINE - 1950 to August Week 3 2010

  • Ovid MEDLINE - In-Process & Other Non-Indexed Citations August 30, 2010

  • Ovid EMBASE - 1980 to 2010 Week 34

  • EBSCO CINAHL - 1982 to 27 August 2010

The following search strategy was used in The Cochrane Central Register of Controlled Trials (CENTRAL):

#1 MeSH descriptor Negative-Pressure Wound Therapy explode all trees
#2 MeSH descriptor Suction explode all trees
#3 MeSH descriptor Vacuum explode all trees
#4 ("negative pressure" or negative-pressure or TNP):ti,ab,kw
#5 (sub-atmospheric or subatmospheric):ti,ab,kw
#6 ((seal* NEXT surface*) or (seal* NEXT aspirat*)):ti,ab,kw
#7 (wound NEAR/3 suction*):ti,ab,kw
#8 (wound NEAR/3 drainage):ti,ab,kw
#9 ((foam NEXT suction) or (suction NEXT dressing*)):ti,ab,kw
#10 ((vacuum NEXT therapy) or (vacuum NEXT dressing*) or (vacuum NEXT seal*) or (vacuum NEXT assist*) or (vacuum NEAR closure) or (vacuum NEXT compression) or (vacuum NEXT pack*) or (vacuum NEXT drainage) or VAC):ti,ab,kw
#11 ("vacuum assisted closure technique" or VAC):ti,ab,kw
#12 (#1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9 OR #10 OR #11)
#13 MeSH descriptor Burns explode all trees
#14 (burn or burns or burned):ti,ab,kw
#15 (#13 OR #14)
#16(#12 AND #15)

The search strategies for Ovid MEDLINE, Ovid EMBASE and Ovid CINAHL can be found in Appendix 3, Appendix 4 and Appendix 5 respectively. The Ovid MEDLINE search was combined with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximizing version (2008 revision); Ovid format (Lefebvre 2009). The EMBASE and CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN) (SIGN 2010). We applied no language restrictions.

Searching other resources

For the original review we contacted authors of relevant studies to request details of unpublished or ongoing investigations and checked citations of retrieved studies for further trials. We did not repeat this exercise for the updates.

Data collection and analysis

Selection of studies

Two review authors (JW and HC) independently scanned records retrieved by the searches to exclude obviously irrelevant studies, and to identify trials that met the inclusion criteria. JW and HC retrieved and independently reviewed full text articles for the purpose of applying inclusion criteria. In all instances, we resolved differences of opinion by discussion.

Data extraction and management

JW and HC independently extracted data from the studies using standardised forms. Data extracted included country of origin, health care setting, study design, baseline characteristics of participants by treatment group, inclusion/exclusion criteria, details of intervention and comparison, outcome measures and results. We contacted the author of one primary study (Molnar 2004) to provide information when we encountered missing or incomplete data. We resolved all differences by discussion among the review authors.

Assessment of risk of bias in included studies

For the original review we undertook a quality assessment considering the adequacy of the randomisation and allocation concealment process, whether intention to treat (ITT) was undertaken, the level of blinding and whether the follow up was complete. For this update we have applied The Cochrane Collaboration tool for assessing risk of bias (Higgins 2009) to evaluate the one included study (Molnar 2004). This tool addresses six specific domains; namely sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting and other issues (e.g. extreme baseline imbalance) (see Appendix 6 for the criteria on which risk of bias judgements were made). A risk of bias table was completed for the one eligible study. Two review authors independently assessed the study and any disagreements were resolved by discussion.

Data synthesis

We did not undertake statistical summaries due to lack of data in the included study.

If available, we would have expressed dichotomous data as relative risk (RR) with 95% confidence intervals (CI). We would have presented continuous data as mean difference (MD) and 95% CI. We had planned to use a fixed-effect model to pool data where there was no evidence of significant heterogeneity between studies, and a random effects model when such heterogeneity was present (DerSimonian 1986). We would test statistical heterogeneity using the chi-squared test with significance at P < 0.10, and a quantification of the degree of heterogeneity using the I2 statistic (Higgins 2005). We had planned subgroup analysis by calculation of RR or MD in each subgroup and examination of the 95% CI. Non-overlap in intervals would have been taken to indicate a statistically significant difference between subgroups; however, no subgroup analysis was appropriate with the data available.

Publication bias was not tested and no time to event data was reported.

Results

Description of studies

See: Characteristics of included studies; Characteristics of excluded studies.

In the updates for this review we retrieved 13 new references from the searches; we excluded 12 on the basis of the abstract alone, and examined and excluded the full copy of one paper (Moisidis 2004). We identified a total of 33 references in the original version of this review. Independent scrutiny of the titles and abstracts identified 10 potentially relevant articles. We assessed these articles in full text, with nine being excluded because they were either case reports, case series or narrative reviews (Adamkova 2005; Banwell 2004a; Haslik 2004; Molnar 2004a; Nugent 2005; Schintler 2005), animal studies (Morykwas 1999) or did not address primary outcome measures (Kamolz 2004; Schrank 2004) (see Characteristics of excluded studies). We included one study which formed the basis of this review (Molnar 2004).

We did not identify any published full reports of RCTs using the aforementioned search strategy. We did not find additional studies when we examined citations of retrieved studies. We identified one relevant RCT abstract and contacted the authors. The authors stated that the abstract results were preliminary data that would be publishable in the foreseeable future (personal communication with Molnar 2004).

Molnar 2004 used a commercially available device (VAC Pump, KCI Inc, Texas, United States) to apply the negative pressure. We did not find additional studies that used wall suction or surgical drainage bottles as well as negative pressure cycles that varied in degree, application (including continuous and/or intermittent pressure cycles) and duration.

In Molnar 2004, 23 patients (age range 20 to 70 years, mean age 46 years; total burn surface area (TBSA) range from 5 to 40%, mean 16%) with bilateral thermal hand burns treated less than 24 hours post injury were randomised to either TNP (125 mmHg pressure) applied for 48 hours or silver sulphadiazine (SSD). All patients served as their own control. The trial reported on data at day 30 of a 60-day study period. Outcome measures assessed included: rate of burn healing by use of a Sigma Scan (Systat Software Inc, California, United States), volume of hand as determined by fluid displacement, range of motion, grip and pinch strength. To date, this trial had been reported as interim results in abstract only. Results were given for 23 of an unknown total sample size population and some additional information was supplied through personal communication with the author.

Risk of bias in included studies

A full study report has not been identified, therefore the risk of bias assessment for Molnar 2004 was based on the conference abstract alone which was an interim report (see Characteristics of included studies). The study is described as "prospective, randomized, controlled, blinded, multi-center and web-based". However, the exact method of sequence generation was not specified in the abstract; allocation concealment was also not reported. Due to the nature of TNP, it is unlikely that the patients or treatment provider could have been blinded to the intervention. Molnar 2004 reported that a blinded principal investigator was used to determine the area of the burn at strategic time points to determine rate of healing of the burn (personal communication with the author). Because the study was an interim report, judging risk of bias for 'incomplete outcome data' was not possible; no attrition was reported at this point in the trial. Burn wound progression and hand function were pre-specified as outcomes in the abstract, both of which were reported (see risk of bias Figure 1).

Figure 1.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Effects of interventions

Due to missing data, poor reporting or both, a formal statistical analysis was not possible. A series of outcome measures such as the reduction in hand oedema, the volume of fluid displaced, and grip and pinch strength were reported by Molnar 2004, although these were not considered by our review. As a result we focused on the following outcome measures:

Primary outcomes

Time to complete healing

No data reported for this outcome.

Rate of change in wound area

Molnar 2004 reported a significant difference in burn size at day three (P < 0.09) and day five (P < 0.04), but not at day 14. No data were presented beyond P values.

Proportion of wounds completely healed within the trial period

No data reported for this outcome.

Secondary outcomes

Incidence of wound infection

No data reported for this outcome.

Adverse events

Molnar 2004 reports there were no discernable complications with VAC treatment of the acute burn.

Measures of satisfaction or patient preference

No data reported for this outcome.

Quality of life measures

No data reported for this outcome.

Discussion

This systematic review summarises the best available evidence relating to safety and effectiveness of TNP in adults with partial thickness burns. After an extensive search of the literature, we found one RCT which was an interim report and at high risk of bias.

There is currently an absence of evidence regarding the use of TNP for burn wounds, despite the theoretical considerations that may support the concept. Our results highlighted the need for high level, good quality research into the safety and effectiveness of TNP in adults with partial thickness burns. The trial by Molnar 2004 was methodologically weak and poorly reported. There was no description of the randomisation process; the degree of comparability of the burn injury to both hands at baseline was not reported; other weaknesses include: the absence of reporting on clinically relevant outcomes such as rate of healing, time to complete healing, rate of change in wound area, and proportion of the wound completely healed within the trial period; lack of clarity regarding the definition and reduction of oedema formation; and the ongoing use of SSD as a comparator which is not only known to be toxic to regenerating epithelial cells (Wasiak 2005), but may place patients at increased risk of developing further complications such as neutropenia (a lack of white blood cells), erythema multiforme (a rash usually resulting from a drug reaction), crystals in the urine and methaemoglobinaemia - where more than 1% of the haemoglobin in the blood has been oxidised to the ferric state (Subrahmanyam 1998).

The small sample size and preliminary analysis of only 20 patients precludes the drawing of any conclusions regarding the nature or frequency of adverse events.

Currently, larger trials with more patient numbers are underway with KCI Medical, the manufacturer of the TNP device, V.A.C.®. They are sponsoring a number of clinical trials that are condition specific. The study by Molnar 2004 is one such example and as authors of this systematic review we look forward to the published results.

Authors' conclusions

Implications for practice

There are no high quality RCTs on TNP for partial thickness burn injury.

Implications for research

This systematic review highlights the need for good quality research into the safety and effectiveness of TNP in partial thickness burns. Suggestions adapted by Ubbink 2008 indicate that future research includes:

  1. The need for a well designed, adequately powered, multi-centre RCT to evaluate the contribution of TNP in the retardation of burn wound progression and healing.

  2. The need for an RCT in which the comparison dressing represents current standard practice for partial thickness burns based on the best available evidence.

  3. The need for an RCT evaluating the effects of TNP on healing times, cost, quality of life, pain and comfort and whether there is an optimum TNP regime for partial thickness burns.

  4. The need for an economic evaluation to determine if the costs of TNP therapy justify its potential benefits in those with burn injury.

Acknowledgements

The authors would like to thank Sally Bell-Syer for her ongoing support and commitment and acknowledge the Wounds Group Editors (Nicky Cullum, Andrea Nelson and Gill Worthy) and referees (Susanne Hempel, Tom Potokar and Durhane Wong-Rieger) for their comments on both the protocol and review. The first update of this review was copy edited by Helena Mullineaux and Nancy Owens.

Data and analyses

Download statistical data

This review has no analyses.

Appendices

Appendix 1. Search methods - Original version 2007

We searched the Cochrane Wounds Group Specialised Register (searched April 2007), the Cochrane Central Register of Controlled Trials (CENTRAL)(The Cochrane Library Issue 2, 2007), Ovid MEDLINE (1950 to April Week 4 2007), Ovid EMBASE (1980 to Week 18 2007) and Ovid CINAHL (1982 to April Week 4 2007).

For MEDLINE the search strategy was combined with the optimum trial search strategy described in the Cochrane Reviewers' Handbook (Higgins 2005). The search strategy was adapted for EMBASE and CINAHL.

The following strategy was used to search CENTRAL:

#1 MeSH descriptor Suction explode all trees
#2 MeSH descriptor Vacuum explode all trees
#3 "negative pressure" or negative-pressure or TNP
#4 sub-atmospheric or subatmospheric
#5 (seal* NEXT surface*) or (seal* NEXT aspirat*)
#6 wound* NEAR suction
#7 wound* NEAR drainage
#8 (foam NEXT suction) or (suction NEXT dressing*)
#9 (vacuum NEXT therapy) or (vacuum NEXT dressing*) or (vacuum NEXT seal*) or (vacuum NEXT closure) or (vacuum NEXT compression) or (vacuum NEXT pack*) or (vacuum NEXT drainage) or (suction* NEXT drainage)
#10 (#1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9)
#11 MeSH descriptor Burns explode all trees
#12 (burn or burns or burned):ti,ab,kw
#13 (#11 OR #12)
#14 (#10 AND #13)

No language restrictions were applied.

Appendix 2. Search methods - first update 2008

For this first update we searched the following electronic databases:

  • Cochrane Wounds Group Specialised Register (Searched 11/12/08);

  • The Cochrane Central Register of Controlled Trials (CENTRAL) - The Cochrane Library, Issue 4, 2008;

  • Ovid MEDLINE - 1950 to November Week 3 2008;

  • Ovid EMBASE - 1980 to 2008 Week 49;

  • EBSCO CINAHL - 1982 to December Week 1 2008.

The following search strategy was used in The Cochrane Central Register of Controlled Trials (CENTRAL):
#1 MeSH descriptor Suction explode all trees
#2 MeSH descriptor Vacuum explode all trees
#3 "negative pressure" or negative-pressure or TNP
#4 sub-atmospheric or subatmospheric
#5 (seal* NEXT surface*) or (seal* NEXT aspirat*)
#6 wound* NEAR suction
#7 wound* NEAR drainage
#8 (foam NEXT suction) or (suction NEXT dressing*)
#9 (vacuum NEXT therapy) or (vacuum NEXT dressing*) or (vacuum NEXT seal*) or (vacuum NEXT closure) or (vacuum NEXT compression) or (vacuum NEXT pack*) or (vacuum NEXT drainage) or (suction* NEXT drainage)
#10 (#1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9)
#11 MeSH descriptor Burns explode all trees
#12 (burn or burns or burned):ti,ab,kw
#13 (#11 OR #12)
#14 (#10 AND #13)

The search strategies for Ovid MEDLINE, Ovid EMBASE and Ovid CINAHL can be found in Appendix 2, Appendix 3 and Appendix 4 respectively. The Ovid MEDLINE search was combined with the Cochrane Highly Sensitive Search Strategy for identifying randomised trials in MEDLINE: sensitivity- and precision-maximizing version (2008 revision); Ovid format (Lefebvre 2009). The EMBASE and CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN) (SIGN 2010). We applied no language restrictions.

Appendix 3. Ovid MEDLINE search strategy

1 exp Suction/
2 exp Vacuum/
3 (negative pressure or negative-pressure or TNP).mp.
4 (sub-atmospheric or subatmospheric).mp.
5 ((seal$ adj surface$) or (seal$ adj aspirat$)).mp.
6 (wound adj5 suction$).mp.
7 (wound adj5 drainage).mp.
8 ((foam adj suction) or (suction adj dressing$)).mp.
9 ((vacuum adj therapy) or (vacuum adj dressing$) or (vacuum adj seal$) or (vacuum adj closure) or (vacuum adj compression) or (vacuum adj pack$) or (vacuum adj drainage) or (suction$ adj drainage)).mp.
10 or/1-9
11 exp Burns/
12 (burn or burns or burned).ti,ab.
13 or/11-12

Appendix 4. Ovid EMBASE search strategy

1 exp suction drainage/
2 exp vacuum assisted closure/
3 (negative pressure or negative-pressure or TNP).mp.
4 (sub-atmospheric or subatmospheric).mp.
5 ((seal$ adj surface$) or (seal$ adj aspirat$)).mp.
6 (wound adj5 suction$).mp.
7 (wound adj5 drainage).mp.
8 ((foam adj suction) or (suction adj dressing$)).mp.
9 ((vacuum adj therapy) or (vacuum adj dressing$) or (vacuum adj seal$) or (vacuum adj closure) or (vacuum adj compression) or (vacuum adj pack$) or (vacuum adj drainage) or (suction$ adj drainage)).mp.
10 or/1-9
11 exp Burns/
12 (burn or burns or burned).ti,ab.
13 or/11-12
14 10 and 13

Appendix 5. EBSCO CINAHL search strategy

1 exp Suction/
2 exp Vacuum/
3 (negative pressure or negative-pressure or TNP).mp.
4 (sub-atmospheric or subatmospheric).mp.
5 ((seal$ adj surface$) or (seal$ adj aspirat$)).mp.
6 (wound adj5 suction$).mp.
7 (wound adj5 drainage).mp.
8 ((foam adj suction) or (suction adj dressing$)).mp.
9 ((vacuum adj therapy) or (vacuum adj dressing$) or (vacuum adj seal$) or (vacuum adj closure) or (vacuum adj compression) or (vacuum adj pack$) or (vacuum adj drainage) or (suction$ adj drainage)).mp.
10 or/1-9
11 exp Burns/
12 (burn or burns or burned).ti,ab.
13 or/11-12 (9111)
14 10 and 13

Appendix 6. Judgement criteria for risk of bias assessments

1.  Was the allocation sequence randomly generated?

Yes, low risk of bias

The investigators describe a random component in the sequence generation process such as: referring to a random number table; using a computer random number generator; coin tossing; shuffling cards or envelopes; throwing dice; drawing of lots.

No, high risk of bias

The investigators describe a non-random component in the sequence generation process. Usually, the description would involve some systematic, non-random approach, for example: sequence generated by odd or even date of birth; sequence generated by some rule based on date (or day) of admission; sequence generated by some rule based on hospital or clinic record number.

Unclear

Insufficient information about the sequence generation process to permit judgement of ‘Yes’ or ‘No’.

2.  Was the treatment allocation adequately concealed?

Yes, low risk of bias

Participants and investigators enrolling participants could not foresee assignment because one of the following, or an equivalent method, was used to conceal allocation: central allocation (including telephone, web-based and pharmacy-controlled randomisation); sequentially-numbered drug containers of identical appearance; sequentially-numbered, opaque, sealed envelopes.

No, high risk of bias

Participants or investigators enrolling participants could possibly foresee assignments and thus introduce selection bias, such as allocation based on: using an open random allocation schedule (e.g. a list of random numbers); assignment envelopes were used without appropriate safeguards (e.g. if envelopes were unsealed or non­opaque or not sequentially numbered); alternation or rotation; date of birth; case record number; any other explicitly unconcealed procedure.

Unclear

Insufficient information to permit judgement of ‘Yes’ or ‘No’. This is usually the case if the method of concealment is not described or not described in sufficient detail to allow a definite judgement, for example if the use of assignment envelopes is described, but it remains unclear whether envelopes were sequentially numbered, opaque and sealed.

3.  Blinding was knowledge of the allocated interventions adequately prevented during the study?

Yes, low risk of bias

Any one of the following:

  • No blinding, but the review authors judge that the outcome and the outcome measurement are not likely to be influenced by lack of blinding.

  • Blinding of participants and key study personnel ensured, and unlikely that the blinding could have been broken.

  • Either participants or some key study personnel were not blinded, but outcome assessment was blinded and the non-blinding of others unlikely to introduce bias.

No, high risk of bias

Any one of the following:

  • No blinding or incomplete blinding, and the outcome or outcome measurement is likely to be influenced by lack of blinding.

  • Blinding of key study participants and personnel attempted, but likely that the blinding could have been broken.

  • Either participants or some key study personnel were not blinded, and the non-blinding of others likely to introduce bias.

Unclear

Any one of the following:

  • Insufficient information to permit judgement of ‘Yes’ or ‘No’.

  • The study did not address this outcome.

 4.  Were incomplete outcome data adequately addressed?

Yes, low risk of bias

Any one of the following:

  • No missing outcome data.

  • Reasons for missing outcome data unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias).

  • Missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups.

  • For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk not enough to have a clinically relevant impact on the intervention effect estimate.

  • For continuous outcome data, plausible effect size (difference in means or standardised difference in means) among missing outcomes not enough to have a clinically relevant impact on observed effect size.

  • Missing data have been imputed using appropriate methods.

No, high risk of bias

Any one of the following:

  • Reason for missing outcome data likely to be related to true outcome, with either imbalance in numbers or reasons for missing data across intervention groups.

  • For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk enough to induce clinically relevant bias in intervention effect estimate.

  • For continuous outcome data, plausible effect size (difference in means or standardized difference in means) among missing outcomes enough to induce clinically relevant bias in observed effect size.

  • ‘As-treated’ analysis done with substantial departure of the intervention received from that assigned at randomisation.

  • Potentially inappropriate application of simple imputation.

 Unclear

Any one of the following:

  • Insufficient reporting of attrition/exclusions to permit judgement of ‘Yes’ or ‘No’ (e.g. number randomized not stated, no reasons for missing data provided).

  • The study did not address this outcome.

5.  Are reports of the study free of suggestion of selective outcome reporting?

Yes, low risk of bias

Any of the following:

  • The study protocol is available and all of the study’s pre-specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre-specified way.

  • The study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre-specified (convincing text of this nature may be uncommon)

No, high risk of bias

Any one of the following:

  • Not all of the study’s pre-specified primary outcomes have been reported.

  • One or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g. subscales) that were not pre-specified.

  • One or more reported primary outcomes were not pre-specified (unless clear justification for their reporting is provided, such as an unexpected adverse effect).

  • One or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta-analysis.

  • The study report fails to include results for a key outcome that would be expected to have been reported for such a study.

Unclear

Insufficient information to permit judgement of ‘Yes’ or ‘No’. It is likely that the majority of studies will fall into this category.

 6.  Other sources of potential bias:

Yes, low risk of bias

The study appears to be free of other sources of bias.

No, high risk of bias

There is at least one important risk of bias. For example, the study:

  • Had a potential source of bias related to the specific study design used; or

  • Stopped early due to some data-dependent process (including a formal-stopping rule); or

  • Had extreme baseline imbalance; or

  • Has been claimed to have been fraudulent; or

  • Had some other problem.

Unclear

There may be a risk of bias, but there is either:

  • Insufficient information to assess whether an important risk of bias exists; or

  • Insufficient rationale or evidence that an identified problem will introduce bias.

What's new

DateEventDescription
2 September 2010New search has been performedNew search, no new studies identified, risk of bias assessment added, conclusions remain unchanged.

History

Protocol first published: Issue 4, 2006
Review first published: Issue 3, 2007

DateEventDescription
15 January 2009New search has been performedNew searches, no new studies included, conclusions remain unchanged
8 August 2008AmendedConverted to new review format.
27 April 2007New citation required and conclusions have changedSubstantive amendment

Contributions of authors

Jason Wasiak: literature searching, study selection, drafting of protocol, review development, drafting written submission of original review. Agreeing content of review updates.
Heather Cleland: drafting of protocol, review development, study selection drafting written submission of original review.

Contributions of editorial base

Nicky Cullum: edited the review, advised on methodology, interpretation and review content. Approved the final review and review update prior to submission.
Sally Bell-Syer: coordinated the editorial process. Advised on methodology, interpretation and content. Edited the review and the updated review, checked the search results for the update and actioned the feedback from the copy editors.
Ruth Foxlee: designed the search strategy, ran the searches and edited the search methods section for the updates.

Declarations of interest

None known.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Molnar 2004

  1. a

    TBSA: total burn surface area

MethodsRCT: "the study design was prospective, randomized, controlled, blinded, multi-center and web-based"
Participants23 patients (age range 20 to 70 years, mean 46 years; TBSA ranged from 5% to 40%, mean TBSA 16%) with bilateral hand burns treated within 24 hours of burn injury
InterventionsTNP (125 mmHg pressure) applied for 48 hours or silver sulfadiazine (SSD)
OutcomesRate of burn healing, volume of hand as determined by fluid displacement, range of motion, grip and pinch strength
NotesConference abstract only available; interim report on first 23 patients recruited
Risk of bias
ItemAuthors' judgementDescription
Adequate sequence generation?UnclearNot specified, although participants were reported as "randomized" to either the treatment or control group
Allocation concealment?UnclearNot reported
Blinding?
participants
NoNot possible due to nature of intervention
Blinding?
personnel delivering intervention
NoNot possible due to nature of intervention
Blinding?
outcome assessors
YesBlinding of principal investigator used to determine rate of burn healing (personal communication withy study author, information not available in abstract)
Incomplete outcome data addressed?
All outcomes
UnclearInterim report only; no attrition reported at this point in trial
Free of selective reporting?YesAll pre-specified outcomes presented in interim report
Free of other bias?YesNo other concerns

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Adamkova 2005Not a randomised controlled trial
Banwell 2004aNot a randomised controlled trial
Haslik 2004Not a randomised controlled trial
Kamolz 2004Did not address a pre-specified primary outcome measure
Moisidis 2004No separate data on burns
Molnar 2004aNot a randomised controlled trial
Morykwas 1999Animal study
Nugent 2005Not a randomised controlled trial
Schintler 2005Not a randomised controlled trial
Schrank 2004Did not address a pre-specified primary outcome measure

Ancillary