When enough is enough: impact of packed red blood cells in massive transfusion outcomes.

Massive transfusion protocol (MTP) with fresh-frozen plasma and packed red blood cells (PRBCs) in a 1:1 ratio is one of the most common resuscitative strategies used in patients with severe hemorrhage. There are no studies to date that examine the best postoperative hematocrit range as a marker for survival after MTP. We hypothesize a postoperative hematocrit dose-dependent survival benefit in patients receiving MTP. This was a 53-month retrospective analysis of patients with intra-abdominal injuries requiring surgery and transfusion of 10 units PRBCs or more at a single Level I trauma center. Groups were defined by postoperative hematocrit (less than 21, 21 to 29, 29.1 to 39, and 39 or more). Kaplan-Meier (KM) survival probability was calculated. One hundred fifty patients requiring operative abdominal explorations and 10 units PRBCs or more were identified. There were no significant differences in demographics between groups. When comparing postoperative hematocrit groups, relative to a hematocrit of less than 21 per cent in KM survival analysis, an overall survival advantage was only evident in patients transfused to hematocrits 29.1 to 39 per cent (P < 0.03; odds ratio [OR], 0.284; 95% confidence interval [CI], 0.089 to 0.914). This survival advantage was not seen in the other groups (21 to 29: OR, 0.352; 95% CI, 0.103 to 1.195 or 39% or greater: OR, 0.107; 95% CI, 0.010 to 1.121). This is the first study to examine the impact of postoperative hematocrit as an indicator of survival after MTP in the trauma patient. Transfusion to hematocrits between 29.1 and 39 per cent conveyed a survival benefit, whereas resuscitation to supraphysiologic hematocrits 39 per cent or greater conveyed no additional survival benefit. This study highlights the need for judicious PRBC administration during MTP and its potential impact on survival in patients with postoperative supraphysiologic hematocrits.