Can regional cerebral oxygen saturation guide red blood cell transfusion in high risk cardiac surgery?

Abstract

Introduction: Cardiac surgery (CS) is associated with a significant use of blood products. The aim of this study was to evaluate the effect of red blood cells concentrates (RBC) transfusion on regional cerebral oxygen saturation (SrO₂) in patients undergoing CS with additive EuroSCORE I > 6.

Material and methods: This is a prospective descriptive study. Patients with additive EuroSCORE I > 6 undergoing CS with extracorporeal circulation were included in the study. The demographic values, perioperative complications, hospital/ICU length of stay (LOS), as well as the preinduction baseline SrO₂values, the lowest SrO₂ value during surgery, number of blood products transfused, hemoglobine (HB) and pre and postransfusional SrO2 values were recorded, and events of significant decrease in SrO₂ below 20% of basal value or decrease below 50%. We considered responders those who had an increase post-transfusion SrO₂ at least 20% of pre-transfusion value, an increase of standar deviation (7.9) or an increase up to basal SrO₂.

Results: Data from 57 patients were collected. The average additive EuroSCORE I was 7.4 (SD 2.6) and the EuroSCORE II was 6.1 (SD 7.4). 52% were male. 35.1% of patients received intraoperative transfusion of at least one unit of RBC. The overall mortality was 8.7% (N = 5). During surgery 29.8% of the overall sample presented a decrease of more than 20% of baseline SrO2 or a value lower than 50%. Patients with a significant decrease in SrO2 presented a higher rate of perioperative complications (P=0.04) and longer ICU-LOS 4.3 (SD 3.6) vs. 6.8 (SD 8.2) days (P=0.01) and hospital LOS 10.1 (SD 3.1) vs. 14.2 (SD 9.4) days (P=0.01). Pretransfusional HB was 7.4 (SD 0.8) mg/dl and postransfusional value was 8.4 (SD 0.8) (P =0.00). Pretransfusional SrO2 was 59 (SD 8.6) and increased non- significantly after RBC transfusion to 61.1 (SD 7.9) (P=0.1). Only 6 patients out of 21 could be considered responders. There were no significant differences in morbidity, mortality or LOS between responders and non-responders.

Discussion: In our population a non statistically significant increase in SrO2 was observed after RBC transfusion. When considering responders few patients were identified by SrO₂. In conclusion SrO₂ might not be reliable triger to decide transfusion.

Keywords: Cardiac surgery; Cerebral oxygen saturation; Cirugía cardiaca; Saturación regional de oxígeno; Transfusion red blood cell; Transfusión de concentrados hematíes.