Intraoperative blood salvage for penetrating abdominal and thoracic trauma
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess the effect and cost of IBS for patients with abdominal or thoracic trauma.
Background
Description of the condition
Trauma is the leading cause of death in people under the age of 45 years (Soyuncu 2007). Chest trauma constitutes about 10% to15% of injury cases and is responsible for about 25% of trauma deaths (Ziegler 1994). A further 10% of deaths result from abdominal injury (Ong 1994; Soyuncu 2007), which may be blunt (84%) or penetrating (16%) (Rozycki 1993). Uncontrolled bleeding is a major cause of death after trauma, and there is a correlation between the transfusion of blood products and morbidity (Moore 1997; Bowley 2006). Approximately 40% of the 11 million units of blood transfused in the United States each year are used for the emergency resuscitation of patients (Schulman 2002). The demand for blood is increasing, but the population of eligible, willing and healthy donors is in decline (Bowley 2006).
Description of the intervention
Over the past 20 years, intraoperative autologous transfusions have been used as an alternative to giving patients blood products from other individuals because of the risk of transfusion‐related infections such as hepatitis and human immunodeficiency virus (HIV) (Freischlag 2004). The incidence of hepatitis B and hepatitis C per unit of blood is estimated at 1 in 220,000 and 1 in 1,600,000 respectively, while the risk for HIV transmission is 1 per 1,800,000 (Busch 2003). Many patients who, for religious reasons, will not accept banked blood or autologous donated banked blood, may accept the use of autotransfusion devices to restore their blood volume during an operation (Freischlag 2004). Intraoperative blood salvage (IBS) could benefit such patients.
How the intervention might work
In IBS, a patient's own blood is sucked out of the body (for example, if there is internal bleeding), filtered and then returned to the patient intravenously. IBS could be utilized in trauma surgery to provide lifesaving blood (Harasawa 2005). One study (Liu 2001) has shown that IBS is highly effective in reducing the need for transfusion.
Why it is important to do this review
A number of studies have evaluated IBS in various ways, but none have included a meta‐analysis of data from patients with abdominal or thoracic trauma. One such study found ithat IBS had no discernable effect on rates of postoperative infection or mortality (Bowley 2006). Another study recommended limiting IBS transfusion to less than 10 units to reduce the risk of coagulopathy (Horst 1992). When blood is contaminated by enteric contents or other matter, its transfusion is contraindicated (Napier 1997; Vanderlinde 2002). Red blood cells should be washed before reinfusion, but this process is expensive. One Cochrane Review suggested that cell salvage was efficacious in reducing the need for allogeneic red blood cell transfusion in adult elective surgery (Carless 2006), but it did not include patients with penetrating abdominal or thoracic trauma, and cost was not included as an outcome. Therefore, we intend to perform a meta‐analysis to assessthe effectiveness and cost of IBS for patients with abdominal or thoracic trauma.
Objectives
To assess the effect and cost of IBS for patients with abdominal or thoracic trauma.
Methods
Criteria for considering studies for this review
Types of studies
We will include all randomised controlled clinical trials, regardless of publication status or language.
Types of participants
Patients who have suffered abdominal or thoracic trauma.
Types of interventions
The index intervention of IBS will be compared with no IBS.
Types of outcome measures
Primary outcomes
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Mortality
Secondary outcomes
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The amount of allogeneic and/or autologous blood transfused
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Postoperative complications (thrombosis, infection, renal failure, non‐fatal myocardial infarction)
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Costs
Search methods for identification of studies
We will aim to identify all relevant trials. Searches will not be restricted by language, year of publication, or publication status.
Electronic searches
We will search the following electronic databases:
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The Cochrane Injuries Group Controlled Trials Register (to latest date);
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The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (to latest issue);
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MEDLINE (1950 to latest version);
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PubMed (to latest version);
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EMBASE (1980 to latest version);
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The Chinese Bio‐medical Database (CBM) (to latest version)
The following search strategy, designed for use in MEDLINE, will be used as the basis for all other searches and will be adapted, where necessary, for use in other electronic databases;
1. exp Blood Transfusion, Autologous/
2. exp Blood Loss, Surgical/
3. exp Blood Transfusion/
4. (autotransfusion* or auto transfusion*).ab,ti.
5. ((cell* or blood) adj5 (transfusion or salvage or save*)).ab,ti.
6. 1 or 2 or 3 or 4 or 5
7. exp Abdominal Injuries/
8. exp thoracic injuries/
9. exp Wounds, Penetrating/
10. (abdominal or abdomen or chest or thoracic or trunk).ab,ti.
11. 9 and 10
12. ((abdominal or abdomen or chest or thoracic or trunk) adj3 (trauma* or injur* or penetrat* or stab*)).ab,ti.
13. ((Splenic or spleen or stomach or gastric) adj3 (rupture* or burst*)).ab,ti.
14. ((heart or cardiac or aortic or aorta*) adj3 rupture*).ab,ti.
15. 7 or 8 or 11 or 12 or 13 or 14
16. 6 and 15
17. randomi?ed.ab.
18. randomized controlled trial.pt.
19. controlled clinical trial.pt.
20. placebo.ab.
21. clinical trials as topic.sh.
22. randomly.ab.
23. trial.ti.
24. or/17‐23
25. humans.sh.
26. 24 and 25
27. 16 and 26
Searching other resources
We will check the reference lists of all relevant reviews and trials. Authors of relevant trial reports will be contacted in order to identify additional published or unpublished data. We aim to contact experts in the field to help identify other ongoing and completed studies and grey literature. Conference proceedings will be searched for relevant abstracts.
Data collection and analysis
Selection of studies
The Injuries Group's Trials Search Co‐ordinator will run the relevant search strategies in the appropriate databases. Two authors (Sun and Li) will inependently screen the titles and abstracts of the citations identified by the search to determine which papers meet the predetermined inclusion criteria. In cases of doubt or disagreement, the full article will be obtained for inspection. The full text of all potentially relevant studies will be obtained and independently assessed to determine whether they meet the inclusion criteria. In the event of a disagreement, a third author (Gao) will be consulted to resolve the issue.
Data extraction and management
Data will be extracted from the trial reports by two authors (Sun and Liu) using a predesigned data extraction form. In the event of a disagreement, a third author (Yang) will be consulted. Trial authors will be contacted for missing data, where appropriate.
Assessment of risk of bias in included studies
Three authors (Sun, Liu and Li) will independently assess the methodological quality of selected trials. In the event of a disagreement, a third author (Yang) will be consulted. The following quality items will be assessed: adequacy of the randomisation process, adequacy of allocation concealment, intention‐to‐treat (ITT) analysis, completeness of follow‐up and blinding of investigators, participants and outcome assessors.
For each included study, the following items will be assessed by the review authors and presented in the Risk of Bias table.
1. Adequacy of the randomisation process:
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A ‐ Adequate sequence generation is reported using random‐number tables, computer random‐number generator, coin tossing or shuffling.
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B ‐ Did not specify one of the adequate reported methods in (A) but mentioned randomisation method.
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C ‐ Other method of allocation that may not be random.
2. Adequacy of allocation concealment:
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A ‐ Adequate ‐ allocation concealment method described (such as central randomisation or serially numbered, opaque, sealed envelopes) that would not allow investigators or participants to know or influence the composition of the comparison groups before eligible participants were entered into the study.
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B ‐ Unclear ‐ trials which either did not report the allocation concealment approach, or reported an approach that was not clearly adequate.
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C ‐ Inadequate ‐ inadequately concealed trials in which the method of allocation is not concealed, such as alternation methods or unsealed envelopes, or studies in which there is any information indicating that the investigators or participants could influence the composition of the comparison groups.
3. Blinding:
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A ‐ Blinding of treatment providers: Yes/No/Not stated
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B ‐ Blinding of participants: Yes/No/Not stated
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C ‐ Blinding of outcome assessors: Yes/No/Not stated
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D ‐ Blinding of data analysts: Yes/No/Not stated
4. ITT analysis
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A ‐ Yes: Specifically reported by authors that an intention‐to‐treat (ITT) analysis was undertaken and this was confirmed on study assessment, or not stated but evident from study assessment that an ITT was undertaken.
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B ‐ Unclear: Described as an ITT analysis, but unable to confirm on study assessment or not reported and unable to confirm by study assessment.
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C ‐ No: Lack of ITT confirmed on study assessment (patients who were randomly assigned to a comparison group were not included in the analysis because they did not receive the study intervention, withdrew from the study or were not included because of protocol violation), regardless of whether an ITT analysis was reported or not.
5. Completeness of follow‐up:
Percentage of participants for whom data were complete at the defined study end‐point.
As there is evidence that the quality of allocation concealment particularly affects the results of trials, the adequacy of concealment of treatment allocation will be assessed using the criteria developed by Schulz 1995.
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A: Trials deemed to have taken adequate measures to conceal allocation (that is, central randomisation; serially numbered, opaque, sealed envelopes; or other description that contained a convincing concealment method).
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B: Trials in which the authors either did not report an allocation concealment approach or reported an approach that did not fall into one of the other categories.
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C: Trials in which concealment was inadequate (such as alternation, reference to case record numbers or dates of birth).
Trials will be considered to have adequate sequence generation if, for example, they report using a random‐number table or computer random‐number generator.
Dealing with missing data
Missing data and attrition rates will be assessed for each of the included studies, and the number of participants who are included in the final analysis will be reported as a proportion of all participants in the study. Reasons given for missing data will be provided in the narrative summary and the extent to which the results are altered by missing data will be ascertained. The extent to which studies have conformed to an ITT analysis will also be assessed.
Assessment of heterogeneity
We used the chi squared test to assess heterogeneity between trials and the I2 statistic to assess the extent of inconsistency. We used a fixed‐effect model for calculating summary estimates and their 95% confidence intervals (CI) unless there was significant heterogeneity, in which case results were calculated using a random‐effects model.
Assessment of reporting biases
Funnel plots will be drawn to investigate any relationship between effect size and study precision (closely related to sample size) (Egger 1997). Such a relationship could be due to publication or related biases, or due to systematic differences between small and large studies. If a relationship is identified, the clinical diversity of the studies will be further examined as a possible explanation and described in the text.
Data synthesis
We analyzed the data using Review Manager Version 5 . We expressed results for dichotomous outcomes as odds ratios (OR) with 95% CIs and continuous outcomes as weighted mean differences (WMD) or standardised mean differences (SMD).
Subgroup analysis and investigation of heterogeneity
The following subgroup analyses were conducted, where possible, to explore important clinical differences among trials that might alter the magnitude of the treatment effect.
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Injury type (abdominal/thoracic trauma)
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Injury severity
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Method used to wash the red blood cells
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The use of transfusion protocols
Each of these factors has been identified as being important because they may influence a person's inclination or opportunity to engage with, and benefit from, IBS.
Sensitivity analysis
To assess the robustness of conclusions, sensitivity analyses will be performed according to the adequacy of allocation concealment (adequate versus inadequate).
