The natural history and effect of resuscitation ratio on coagulation after trauma: a prospective cohort study.

OBJECTIVE: To investigate the natural history of coagulation factor perturbation after injury and identify longitudinal differences in clotting factor repletion by red blood cell:fresh frozen plasma (RBC:FFP) transfusion ratio.
BACKGROUND: Hemostatic transfusion ratios of RBC to FFP approaching 1:1 are associated with a survival advantage in traumatic hemorrhage, even in patients with normal coagulation studies.
METHODS: Plasma was prospectively collected from 336 trauma patients during their intensive care unit stay for up to 72 hours from February, 2005, to October, 2011. Standard coagulation studies as well as pro- and anticoagulant clotting factors were measured. RBC:FFP transfusion ratios were calculated at 6 hours after arrival and dichotomized into "low ratio" (RBC:FFP ≤ 1.5:1) and "high ratio" (RBC:FFP > 1.5:1) groups.
RESULTS: Factor-level measurements from 193 nontransfused patients provide an early natural history of clotting factor-level changes after injury. In comparison, 143 transfused patients had more severe injury, prolonged prothrombin time and partial thromboplastin time (PTT), and lower levels of both pro- and anticoagulants up to 24 hours. PTT was prolonged up to 12 hours and only returned to admission baseline at 48 hours in "high ratio" patients versus correction by 6 hours in "low ratio" patients. Better repletion of factors V, VIII, and IX was seen longitudinally, and both unadjusted and injury-adjusted survival was significantly improved in "low ratio" versus "high ratio" groups.
CONCLUSIONS: Resuscitation with a "low ratio" of RBC:FFP leads to earlier correction of coagulopathy, and earlier and prolonged repletion of some but not all procoagulant factors. This prospective evidence suggests hemostatic resuscitation as an interim standard of care for transfusion in critically injured patients pending the results of ongoing randomized study.