Hemodilution during cardiopulmonary bypass: optimal hematocrit for safe outcome

Studies have implicated hemodilution during cardiopulmonary bypass (CPB) as an independent risk factor for perioperative morbidity and mortality, however, it is plausible that the variability in results so far quoted are species-specific or blood product covariate dependent. Nevertheless, obvious debate regarding the optimal degree of hemodilution during CPB with regard to patients' outcome still prevails in the modern cardiac surgery era. We agree from the reported arguments that the range of absolute differences in the perioperative hematocrit (HCT) seem more reasonable to use than individual values yet we present a new avatar of evidence in this letter regarding the optimal HCT to be used during normo/hypothermic CPB.