Effect of packed red blood cell transfusion on cerebral oxygenation and metabolism after subarachnoid hemorrhage

Abstract

Introduction: Anemia is frequently encountered in critically ill patients and adversely affects cerebral oxygen delivery and metabolic function. However, there is limited evidence to support the use of packed red blood cell (PRBC) transfusion to optimize brain homeostasis after subarachnoid hemorrhage. The objective of this study was to investigate the effect of PRBC transfusion on cerebral oxygenation and metabolism in patients with subarachnoid hemorrhage. Methods: Prospective observational study in a neurological ICU of a university hospital. Nineteen PRBC transfusions were studied in 15 consecutive patients with subarachnoid hemorrhage that underwent multimodality monitoring (intracranial pressure, brain tissue oxygen and cerebral microdialysis). Data were collected at baseline and during 12 hours after transfusion. The relationship between Hb change and lactate/pyruvate ratio (LPR) and brain tissue oxygen (PbtO2) was tested in univariate and multivariable analyses. Results: PRBC transfusion was administered on median post-bleed day 8. The average Hb concentration at baseline was 8.1 g/dl and increased by 2.2 g/dl after transfusion. After transfusion initiation, PbtO2 increased between hours 2 and 4 and this rise was maintained until hour 10. LPR {Figure presentred} did not change during the 12 hours of monitoring. Multivariable analysis demonstrated that, after adjusting for peripheral oxygen saturation, cerebral perfusion pressure and LPR, the change in Hb concentration was independently and positively associated with change in PbtO2 (adjusted b estimate = 1.39 (95% confidence interval 0.09 to 2.69); P = 0.036). No relationship between change in LPR and change in Hb was found. Conclusions: Transfusion of PRBC results in PbtO2 improvement without a clear effect on cerebral metabolism after subarachnoid hemorrhage.