[Activity of ondansetron on the systemic vascular resistance and venous capacitance during cardiopulmonary bypass].

OBJECTIVE

To study the effect of ondansetron administered during cardio-pulmonary bypass surgery, in terms of mean arterial pressure, systemic vascular resistance and venous system capacitance.

PATIENTS AND METHOD

Twenty patients scheduled for non coronary cardiac surgery were randomly assigned to 2 groups. The study group received 4 mg ondansetron during the bypass and the control group received the same volume of physiological saline solution. The following parameters were recorded during the 10 minutes following administration of either substance: mean arterial pressure, calculated systemic vascular resistance, and the venous reservoir volume at the beginning and end of the study period.

RESULTS

Increased mean arterial pressure and systemic vascular resistance were recorded in both groups from the time of injection, with the highest levels recorded at 10 minutes. There were no statistical differences between the 2 groups. No changes in venous system capacitance were observed in either group, as there were no significant changes in venous reservoir volume of the extracorporeal circulation pump.

CONCLUSIONS

Ondansetron at the dose used has no effect on arterial or venous vessels. The increased resistance recorded in both groups can be attributed to the release of catecholamines during non pulsatile extracorporeal circulation with a non pulsatile flow.