[Plasma levels of atriopeptin and hemodynamics during major vascular surgery: comparison between isoflurane and...

Atrial natriuretic factor (ANF) is a peptide hormone released from atrial cardiocytes in response to atrial stretch. It has potent and selective effects on vascular smooth muscle, fluid and electrolyte balance, and may interact with other vasoactive substances. The influence of anaesthesia and major vascular surgery on the release and circulation of ANF is unknown. Therefore the relationships between haemodynamic variables, volume expansion and plasma ANF were studied in patients undergoing resection of abdominal aortic aneurysm, randomly assigned to receive isoflurane or propofol+fentanyl anaesthesia. The end point of anaesthetic regimens was the stabilization of mean arterial pressure between +/- 33% from baseline. Haemodynamic parameters and plasma ANF levels were measured preoperatively, after intubation, following aortic cross-clamping, 24 and 48 hours postoperatively. Because of well-known large degree in interpatient pharmacodynamic variability, anaesthesia with propofol and fentanyl did not ensure, usually, the established end point in dose ranges that did not produce unacceptable morbidity. ANF plasma levels were elevated during surgery and in the immediate postoperative period in both groups. A significant correlation was found between ANF levels and mean right atrial pressure. We concluded that anaesthetic drugs do not affect ANF release. Volume expansion for prevention of declamping shock increased, ANF from basal values, during surgery. Inadequacy of postoperative analgesia or persisting atrial stretch could explain the finding of high plasma levels during the immediate postoperative period.