Background: The couplings between cerebral oxygenation (rSO2), on-pump hematocrit and circuit prime are explored in this study.
Methods: Thirty-eight consecutive patients undergoing coronary revascularization with cardiopulmonary bypass (CPB) were matched on preoperative hematocrit < 40% and > 40% (n = 16). Similarly, six blood prime patients were matched with six crystalloid prime patients. Hematocrit and rSO2 levels were then compared on CPB.
Results: The preoperative hematocrit > 40% group retained higher levels on pump run (p < 0.01) and significantly higher rSO2 prior to CPB (64.8 +/- 9.6 versus 73.2 +/- 7.3), and on and off CPB (61.1 +/- 8.8 versus 67.4 +/- 6.4). Blood priming increased absolute rSO2 (2.3 +/- 6.3 versus -10.9 +/- 5.9) and % rSO2 (4.7 +/- 11.8 versus -14.2 +/- 7.4%) in the low hematocrit group.
Conclusion: Blood primes are instrumental in high-risk and low preoperative hematocrit patients in preventing cerebral oxygen desaturation during initiation and maintenance of CPB.