title: Blood transfusion: In the air tonight?
abstract: The use of prehospital blood transfusion (PBT) in air medical transport has become more widespread. However, the effect of PBT remains unknown. The aim of this study was to examine the impact of PBT on 24-hour and overall in-hospital mortality.
  
  
  
  This is a retrospective cohort study of all trauma patients carried by air medical transport from the scene to a Level I trauma center from 2007 to 2013. We excluded patients who died on the helipad or in the emergency department. Primary outcomes measured were 24-hour and overall in-hospital mortality. Multivariable logistic regressions using all available patient data or the propensity score (for receiving PBT)-matched patient data were performed to study the effect of PBT on these outcomes.
  
  
  
  Of the 5,581 patients included in the study, 231 (4%) received PBT. Multivariable regression analyses did not show evidence of PBT effect on 24-hour in-hospital mortality (odds ratio [OR], 1.22; 95% confidence interval [CI], 0.61-2.44) and on overall in-hospital mortality (OR, 1.20; 95% CI, 0.55-1.79). In addition, using 1:1 propensity score-matched data, the analysis did not show evidence of PBT effect on 24-hour in-hospital mortality (OR, 1.04; 95% CI, 0.54-1.98) and on overall in-hospital mortality (OR, 1.05; 95% CI, 0.56-1.96). Factors associated with increased 24-hour mortality were advanced age, penetrating injury, increased blood transfusion requirement in the first 24 hours, and decreased Glasgow Coma Scale (GCS) score (p < 0.05). These factors were also associated with overall mortality, in addition to increased Injury Severity Score (ISS) (p < 0.05).
  
  
  
  This is the largest study to date of trauma patients who received PBT and were transported from the scene by air medical transport. Our results show no effect of PBT on 24-hour and overall in-hospital mortality. Previous studies also suggest no benefit of PBT, which is counterintuitive to damage-control resuscitation. Prospective data on PBT are needed to assess risk, cost, and benefit.
  
  
  
  Therapeutic study, level III.
authors.affiliation: From the Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Miller
authors.forename: Liping
authors.initials: L
authors.lastname: Du
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Krzyzaniak
authors.forename: Oliver L
authors.initials: OL
authors.lastname: Gunter
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Nunez
mesh_terms: D000328:Adult; D017732:Air Ambulances; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D004632:Emergency Medical Services; D004638:Emergency Treatment / Q000379:methods*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D057216:Propensity Score; D012189:Retrospective Studies; D015996:Survival Rate; D013714:Tennessee / Q000453:epidemiology; D014193:Trauma Centers; D014947:Wounds and Injuries / Q000628:therapy*