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Abstract
A short cut review was carried out to establish whether prehospital blood transfusion in the trauma patient with active haemorrhage can reduce mortality. 11 directly relevant papers were found using the reported search strategy. Of these two presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. It is concluded that prehospital blood transfusion may reduce short-term mortality in these patients, but that the evidence level is low and further definitive randomised controlled trials are needed to prove benefit.
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Clinical scenario
A 30-year-old male involved in a high-speed motorcycle accident is attended to by a prehospital critical care team. On scene the patient is moribund and in a shocked state. As the reversible causes of shock are addressed you wonder if resuscitation with blood products rather than crystalloid would improve the patient's chances of survival. Major haemorrhage protocols are used in hospital and intuition would suggest potential benefit if these protocols were administered at the point of injury, in order to reduce the later incidence of coagulopathy.
Three-part question
In [prehospital patients with traumatic haemorrhage] is [a blood transfusion superior to care without transfusion] at [reducing mortality]?
Search strategy
A literature search of EMBASE, MEDLINE and CINAHL was conducted via NHS Evidence. UK Blood Services Transfusion Evidence Library, Google Scholar were also searched.
Medline and CINAHL: [(prehospital*.ti.ab OR pre-hospital*.ti.ab OR “HEMS.”ti.ab OR helicopter* adj2 emergenc*.ti.ab OR “air medic*”.ti.ab OR “emergency medic* service*.”ti.ab OR ground adj4 medic*) AND (exp WOUNDS AND INJURIES/OR h?emorrhag*.ti.ab OR trauma*.ti.ab) AND (exp BLOOD TRANSFUSION/OR “red blood cell*."ti.ab OR plasma adj2* transfuse*.ti.ab OR fresh frozen plasma.”ti.ab)] [LIMIT to English and Human].
EMBASE (date of searching 2 March): [(prehospital*.ti.ab OR pre-hospital*.ti.ab OR “HEMS.”ti.ab OR helicopter* adj2 emergenc*.ti.ab OR “air medic*”.ti.ab OR “emergency medic* service*.”ti.ab OR ground adj4 medic*) AND (exp INJURY/OR h?emorrhag*.ti.ab OR trauma*.ti.ab) AND (exp BLOOD TRANSFUSION/OR “red blood cell*."ti.ab OR plasma adj2* transfuse*.ti.ab OR fresh frozen plasma.”ti.ab)] [LIMIT to English and Human].
EMBASE; 265 papers, MEDLINE; 104 papers, CINAHL; 57 papers, UK Blood Services Transfusion Evidence Library; 121 papers, Google Scholar; 50 papers.
The Cochrane Library Issue 3 of 12 March 2016
MeSH descriptor: [Blood Transfusion] explode all trees AND prehospital ti, ab.kw=4 results
Outcome
After review of title and abstract 11 papers were found and reviewed in full. Seven were excluded after full text review due to the following: three poor quality, two wrong comparison group, one descriptive study and one unpublished study (table 1).
Relevant papers
Comments
All of the studies included are of a retrospective observational design and are therefore subject to selection bias and confounding. In addition, several are distinct ‘before and after’ comparisons, a methodology which has numerous flaws and limited ability to assess causation (Goodacre et al 2015).5 The dependence on evidence from observational studies is common in the setting of prehospital trauma care; the number of high-quality randomised control trials is small and design is challenging across regions with variable geography, medical response times, patient demographics and levels of medical response. In conclusion, all of the four papers suggest an early survival benefit (6–24 h), however there is limited evidence of a sustained reduction in mortality. These data are also level 4 evidence only and conclusions should therefore be regarded as hypothesis generating. The feasibility of delivering prehospital blood has been demonstrated in multiple cohort studies (Rehn et al 2015).6 It is the effectiveness, cost, resource implications and risk/benefit profile that remain in question. Several future studies are planned that may help address these questions (Reynolds et al 2015, Dretzke et al 2014, RePHIL).7–9
Clinical bottom line
There is a potential clinical benefit in prehospital blood transfusion. However, this has not been confirmed with high-level evidence and potential harms/costs remain unquantified. Further high-quality randomised control trials are needed, with stratified design accounting for injury type, scene times and prehospital response.