Cerebral Oxygen Metabolism Before and After RBC Transfusion in Infants Following Major Surgical Procedures

Abstract

Objective: Although infants following major surgery frequently require RBC transfusions, there is still controversy concerning the best definition for requirement of transfusion in the individual patient. The aim of this study was to determine the impact of RBC transfusion on cerebral oxygen metabolism in noncardiac and cardiac postsurgical infants.

Design: Prospective observational cohort study.

Setting: Pediatric critical care unit of a tertiary referral center.

Patients: Fifty-eight infants (15 after pediatric surgery and 43 after cardiac surgery) with anemia requiring RBC transfusion were included.

Interventions: RBC transfusion.

Measurements and main results: We measured noninvasively regional cerebral oxygen saturation and microperfusion (relative cerebral blood flow) using tissue spectrometry and laser Doppler flowmetry before and after RBC transfusion. Cerebral fractional tissue oxygen extraction and approximated cerebral metabolic rate of oxygen were calculated. Fifty-eight RBC transfusions in 58 patients were monitored (15 after general surgery, 24 after cardiac surgery resulting in acyanotic biventricular physiology and 19 in functionally univentricular hearts including hypoplastic left heart following neonatal palliation). The posttransfusion hemoglobin concentrations increased significantly (9.7 g/dL vs 12.8 g/dL; 9.7 g/dL vs 13.8 g/dL; 13.1 g/dL vs 15.6 g/dL; p < 0.001, respectively). Posttransfusion cerebral oxygen saturation was significantly higher than pretransfusion (61% [51-78] vs 72% [59-89]; p < 0.001; 58% [35-77] vs 71% [57-88]; p < 0.001; 51% [37-61] vs 58% [42-73]; p = 0.007). Cerebral fractional tissue oxygen extraction decreased posttransfusion significantly 0.37 (0.16-0.47) and 0.27 (0.07-039), p = 0.002; 0.40 (0.2-0.62) vs 0.26 (0.11-0.57), p = 0.001; 0.42 (0.23-0.52) vs 0.32 (0.1-0.42), p = 0.017. Cerebral blood flow and approximated cerebral metabolic rate of oxygen showed no significant change during the observation period. The increase in cerebral oxygen saturation and the decrease in cerebral fractional tissue oxygen extraction were most pronounced in patients after cardiac surgery with a pretransfusion cerebral fractional tissue oxygen extraction greater than or equal to 0.4.

Conclusion: Following RBC transfusion, cerebral oxygen saturation increases and cerebral fractional tissue oxygen extraction decreases. The data suggest that cerebral oxygenation in postoperative infants with cerebral fractional tissue oxygen extraction greater than or equal to 0.4 may be at risk in instable hemodynamic or respiratory situations.