Plasma arginine vasopressin levels and arterial pressure during open heart surgery.

A study of plasma arginine vasopressin (AVP) levels and their relation to changes in arterial pressure was undertaken in 13 patients undergoing open heart surgery. Seven of the patients received high doses of intravenous morphine (1 or 2 mg/kg) as part of their anaesthetic, whereas the other six did not. Increases in the AVP levels during cardiopulmonary bypass (CPB) were significant in both groups, but were significantly greater in the patients not receiving morphine (median 86.