5 Does the Storage Age of Blood Transfused to Burn Patients Matter?

Abstract

Patients with major burns require multiple red blood cell (RBC) transfusions. Blood banks store blood up to 42 days and issue the oldest blood 1st to avoid wasting blood. Longer storage leads to potentially unfavourable degenerative changes in a RBC unit but it is not known if this has any important effects when this blood is transfused to an immunosuppressed burn patient. The purpose of this study was to determine if the storage age of transfused blood affects outcomes in burn patients. Data on storage age of transfused RBCs was collected in a multi-center prospective randomized controlled trial involving 345 patients that compared a liberal and restrictive transfusion threshold. The mean storage age of all blood transfused to each patient (AgeRBC) and the proportion of “very-old” transfused units stored ≥ 35 days (Prop35) were the measures of blood storage age. Outcomes were severity of multiple organ dysfunction, time to wound healing, duration of ventilation (DurVent), and mortality. Multivariate regression analyses adjusting for patient age, sex, burn size, inhalation injury, admission APACHE score, and number of RBC units transfused was performed. Values are shown as median [25th,75th Q] unless otherwise noted. A total of 303 subjects received ≥ 1 RBC transfusion (age 42 [30, 55.5] years, TBSA burn 33% [26, 48.5], 23.1% female, 22.8% with inhalation injury, admission APACHE 18 [13, 24]). These subjects received 13 [6, 27] RBC units (mean 23.4 ± 31.2, range 1–219). Of the 6768 RBC transfusions available for analysis the overall storage age was 26 [17,42] days (mean 25.6 ± 10.2 days). The proportion of RBC units ≥ 35 days old was 24%. Only 225 RBC units (3.3%) were “very fresh” (≤ 8 days old). AgeRBC was not significantly related to the number of transfusions in each patient. Blood transfused in the operating room (30.5% of all transfusions) had a significantly lower Prop35 than blood given in the burn unit (p<0.0001). Severity of multiple organ dysfunction, time to wound healing, 30-day mortality, and in-hospital mortality were not significantly related to either AgeRBC or Prop35. However, DurVent (n=165 transfused while ventilated) was significantly related to the number of RBC transfusions as well as AgeRBC (p=0.02) and Prop35 (p=0.01). The storage age of blood transfused to patients with major burns does not appear to have any clinically meaningful effect on multiple organ dysfunction, time to wound healing, or survival. Although statistically significant, the relationships between DurVent and AgeRBC and Prop35 were weak and investigation in a larger sample would be needed to clarify any interaction between use of older blood and longer mechanical ventilation. Presently, transfusion of “fresher” or “younger”blood in burn patients is not warranted.