EFFECTS OF ANESTHESIA AND SURGERY ON PLASMA ENDOTHELIN LEVELS

To investigate the clinical significance of endothelin (ET), a potent and long-acting vasoconstrictor peptide in anesthesia and surgery, we measured plasma ET-like immunoreactivity (ET-LI) levels by using radio immunoassay in patients undergoing various kinds of surgery under gene ral anesthesia. No significant changes in plasma ET-LI levels were obs erved in patients undergoing relatively minor surgery under general an esthesia with nitrous oxide and halothane (n=6, enflurane (n=6), or is oflurane (n=5). Although plasma ET-LI levels after surgery in patients undergoing total knee replacement(l2.4 +/- 0.9 [mean +/- SEM] pg/mL, n=7), hysterectomy (11.4 +/- 0.6 pg/mL, n=8) or cholecystectomy (14.8 +/- 1.2 pg/mL, n=9) were no different from those before surgery, plasm a ET-LI levels after surgery in patients undergoing gastrectomy (20.4 +/- 1.9 pg/mL, n=15), esophagectomy (24.7 +/- 2.5 pg/mL, n=12), hepate ctomy (27.5 +/- 3.4 pg/mL, n=12), or heart surgery (43.1 +/- 4.1 pg/mL , n=18) were higher than those before surgery (P < 0.05). Changes in p lasma ET-LI levels during surgery had positive correlations with the d uration of the operation (n=100, r=0.51, P < 0.01) and intraoperative blood loss (n=100, r=0.30, P < 0.01). In patients undergoing subtotal esophagectomy, the plasma ET-LI level did not increase during the init ial 2 h, but increased gradually during surgery, reached a peak within a few hours after surgery, and declined slowly thereafter. These resu lts demonstrate that the plasma ET level increases gradually during ma jor surgery, whereas it does not during anesthesia and minor surgery, and plasma ET level varies with blood loss and duration of operation.