Predictive factors for platelet number after cardiopulmonary bypass and postoperative blood loss.

We retrospectively searched for factors that can predict the circulating platelet count after cardiopulmonary bypass (CPB) and postoperative blood loss. Correlations between the circulating platelet count after CPB and several other perioperative variables were investigated in 42 patients who underwent cardiac surgery using the same type of oxygenator. Correlations between perioperative variables and 24 hour postoperative blood loss were also investigated. A multiple stepwise regression analysis showed that the preoperative platelet count, age, and intraoperative blood transfusion values were independent predictors of the circulating platelet count after CPB (R2 = 0.661, p < 0.0001). Gender, operation type, and priority (elective or urgent) were not associated with the platelet count after CPB or postoperative blood loss. Independent predictive factors for postoperative blood loss consisted of age and intraoperative blood loss (R2 = 0.231, p = 0.006). In addition to preoperative platelet count, age and amount of intraoperative blood transfusion are predictive factors for circulating platelet count after CPB. The association of postoperative blood loss with age and intraoperative blood loss may suggest friability of the tissues, including blood vessels, in elderly patients.