Does plasma transfusion portend pulmonary dysfunction? A tale of two ratios.

BACKGROUND: An unresolved concern regarding resuscitation in the setting of massive hemorrhage is potential lung injury from the transfusion of relatively more plasma-rich components. However, the association between plasma-to-packed red blood cell (PRBC) ratio and subsequent pulmonary dysfunction remains unclear. The purpose of this study was to evaluate the impact of plasma/PRBC on PaO2-to-FIO2 (P/F) ratio in the setting of massive transfusion (MT).

METHODS: During a 5.5-year period, prospective data were collected on trauma patients who underwent MT, defined as 10 or more units of PRBC transfusion by completion of hemorrhage control. Deaths within 48 hours of arrival were excluded. Acute lung injury (ALI) and adult respiratory distress syndrome (ARDS) were defined as P/F ratio of less than 300 and less than 200 at 48 hours, respectively. Stepwise multiple regression analysis was performed to determine variables significantly associated with P/F ratio.

RESULTS: A total of 199 patients met inclusion criteria; 159 (80%) developed ALI, and 105 (53%) developed ARDS. ALI and ARDS were both associated with subsequent mortality: ARDS at 24% versus no ARDS at 10% (p < 0.05) and ALI at 21% versus no ALI at 2.5% (p < 0.05). Paradoxically, patients with P/F ratio of 300 or greater were found to have received more plasma (5.6 U vs. 4.3 U, p < 0.05) and higher plasma-to-PRBC ratio (1:2 vs. 1:3, p < 0.05) at completion of hemorrhage control. Stepwise multiple regression analysis, however, identified age (p < 0.001) and chest Abbreviated Injury Scale (AIS) score (p = 0.04), but not plasma/PRBC (p = 0.10), to be independent determinants of P/F ratio at 48 hours.

CONCLUSION: In this cohort of MT patients who survived beyond the first 48 hours, pulmonary dysfunction developed in the majority and was associated with a 10-fold higher risk of subsequent death. However, plasma-to-RBC ratio achieved during hemorrhage control had neither a positive nor a negative impact on subsequent P/F ratio. In fact, only unalterable patient factors including age and severity of thoracic injury were associated with subsequent P/F ratio.

LEVEL OF EVIDENCE: Prognostic study, level III.