Plasma vasopressin levels during and after cardiopulmonary bypass in man

The effect of cardiopulmonary bypass (CPB) using high dose fentanyl anaesthesia on the concentrations of plasma arginine vasopressin (pAVP), serum electrolytes and osmolality was studied in 12 patients by repeated sampling up to 4th postoperative day. These values were also followed in another 20 patients for the first postoperative day. Fentanyl abolished the pAVP response often seen in major operations but not that produced by CBP. The pAVP concentration 4.8 +/- 0.8 pg/ml immediately after sternotomy increased to 27.2 +/- 1.5 pg/ml (P less than 0.001) after 5-10 minutes on CPB. By the 4th postoperative day the pAVP levels had reached normal values. The main reason for the elevated pAVP concentrations seems to be the onset of CPB, which provokes a fall in mean arterial pressure leading to pAVP release.