The clinical relevance of hemoglobin, platelet, and serotonin changes in sequestered and circulating blood during cardiopulmonary bypass.

OBJECTIVE

To 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.

DESIGN

A prospective clinical study.

SETTING

A university hospital.

PARTICIPANTS

Twenty patients undergoing elective aortocoronary bypass.

INTERVENTIONS

Measurements 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 RESULTS

The 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).

CONCLUSION

During 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.