• S E McNulty, J Mannion, M Brennan, and H Schieren.
• Department of Anesthesiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107-5092, USA.
• J. Cardiothorac. Vasc. Anesth. 1998 Aug 1;12(4):402-7.

ObjectiveTo determine how hemoglobin (Hb), platelet, and serotonin concentrations change during cardiopulmonary bypass (CPB) in sequestered blood from the pulmonary artery compared with circulating systemic blood; and to determine the correlation between platelet and serotonin variability at the two sites and clinical outcome measurements related to hemodynamics and blood loss.DesignA prospective clinical study.SettingA university hospital.ParticipantsTwenty patients undergoing elective aortocoronary bypass.InterventionsMeasurements of Hb, platelet, and serotonin concentrations were performed before, during, and after CPB on paired blood samples from the pulmonary artery and the radial artery. Hemodynamic measurements were recorded before and after CPB and chest tube drainage was recorded postoperatively.Measurements And Main ResultsThe Hb, platelet, and serotonin concentrations were all significantly different between radial artery and pulmonary artery samples at the different measurement times (p < 0.001, analysis of variance [ANOVA] for repeated measures). Hb, platelet, and serotonin concentrations were all significantly increased in the pulmonary artery at the time of aortic cross-clamping compared with the corresponding radial artery blood samples (p < 0.0005, ANOVA). During the period of ischemic arrest, Hb was unchanged in the pulmonary artery and remained significantly increased compared with systemic blood (p < 0.0005, ANOVA). Serotonin concentrations in both systemic and sequestered pulmonary artery blood had significant correlation with cardiac index (CI), right ventricular ejection fraction (REF), and systemic vascular resistance index (SVRI; p < or = 0.006, least squares analysis). Postoperative chest tube drainage most closely correlated with the platelet counts measured in both the radial and pulmonary arteries at the start of CPB (p < 0.05, least squares analysis).ConclusionDuring CPB, there were significant differences in Hb, platelet, and serotonin concentrations in sequestered pulmonary artery blood compared with circulating systemic blood. The initial differences and subsequent changes were most likely attributable to decreased hemodilution and a different pattern of platelet activation in the pulmonary artery blood compared with the systemic blood. Despite the hematologic differences, serotonin concentration and platelet counts in the pulmonary artery blood had significant correlation to indices of cardiac function and postoperative chest tube drainage, respectively. Platelet and serotonin changes in sequestered pulmonary artery blood were also associated with some of the adverse consequences of CPB.

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