Performance comparison of improvised prehospital blood warming techniques and a commercial blood warmer.
BACKGROUND
Prehospital transfusion of packed red blood cells (PRBC) may be life saving for hypovolaemic trauma patients. PRBCs should preferably be warmed prior to administration but practical prehospital devices have only recently become available. The effectiveness of purpose designed prehospital warmers compared with previously used improvised methods of warming has not previously been described.


METHODS
Expired units of PRBCs were randomly assigned to a warming method in a bench study. Warming methods were exposure to body heat of an investigator, leaving the blood in direct sunlight on a dark material, wrapping the giving set around gel heat pads or a commercial fluid warmer (Belmont Buddy Lite). Methods were compared with control units that were run through the fluid circuit with no active warming strategy.


RESULTS
The mean temperature was similar for all methods on removal from the fridge (4.5°C). The mean temperatures (degrees centigrade) for all methods were higher than the control group at the end of the circuit (all P≤0.001). For each method the mean (95% CI) temperature at the end of the circuit was; body heat 17.2 (16.4-18.0), exposure to sunlight 20.2 (19.4-21.0), gel heat pads 18.8 (18.0-19.6), Buddy Lite 35.2 (34.5-36.0) and control group 14.7 (13.9-15.5).


CONCLUSIONS
All of the warming methods significantly warmed the blood but only the Buddy Lite reliably warmed the blood to a near normal physiological level. Improvised warming methods therefore cannot be recommended.
CareFlight, NSW, Australia.
James
J
Milligan
CareFlight, NSW, Australia; Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
Anna
A
Lee
The Heart Centre for Children, The Children's Hospital at Westmead, NSW, Australia.
Martin
M
Gill
CareFlight, NSW, Australia; The Children's Hospital at Westmead, NSW, Australia.
Andrew
A
Weatherall
CareFlight, NSW, Australia.
Chloe
C
Tetlow
CareFlight, NSW, Australia. Electronic address: alang@careflight.org.
Alan A
AA
Garner
D001803:Blood Transfusion / Q000295:instrumentation*; D001831:Body Temperature; D004632:Emergency Medical Services; D019983:Guideline Adherence; D006361:Heating / Q000295:instrumentation*; D006400:Hematocrit; D006358:Hot Temperature; D006801:Humans; D020896:Hypovolemia / Q000628:therapy; D008872:Microwaves; D011897:Random Allocation; D015203:Reproducibility of Results; D017694:Rewarming / Q000295:instrumentation*; D014947:Wounds and Injuries / Q000628:therapy
Prehospital; Transfusion; Trauma; Warming