Vasopressin responses during transurethral resection of the prostate.

The serum vasopressin (S-AVP) concentration, serum sodium concentration and osmolality, central venous pressure and fluid balance were measured during 10-min periods in 32 patients undergoing transurethral resection of the prostate. Concentration of S-AVP was unaffected by uncomplicated resection; irrigant absorption resulted in immediate increase in S-AVP concentration, but this increase could not explain the hypertension that occurred in some patients with absorption; a sudden decrease in the systolic arterial pressure was followed by a marked increase in S-AVP concentration; and extensive blood loss did not stimulate release of AVP, provided there was no associated arterial hypotension.