In major trauma patients who require blood transfusion, fresh frozen plasma (FFP) to packed red blood cell (RBC) ratios of up to 1:1 have been associated with reduced mortality in retrospective studies, which may be in part due to survival bias (some patients die before they can be given as much FFP as the survivors).
To eliminate this bias, Australian researchers reviewed 331 trauma patients receiving at least 5 units of red cells in the first 4 hours, with a median Injury Severity Score of 36. When deaths in the first 24 hours were excluded, FFP:RBC ratio had no association with mortality. They conclude that prospective randomised controlled trials are needed.
Fresh frozen plasma (FFP) use during massive blood transfusion in trauma resuscitation
Injury. 2010 Jan;41(1):35-9