Plasma vasopressin levels and urinary sodium excretion during cardiopulmonary bypass: Comparison of halothane and morphine anesthesia

Abstract

Marked elevations of plasma vasopressin (antidiuretic hormone, ADH) levels have been reported during cardiopulmonary bypass (CPB). This study was undertaken to determine the effects of different anesthetics on ADH level and the changes in urinary flow and electrolyte content during CPB. Twenty-one patients undergoing elective open cardiac surgery were studied in three groups: Group I—halothane anesthesia; Group II—morphine anesthesia, I mg. per kilogram; and Group III—morphine anesthesia, 2 mg. per kilogram. In Group I vasopressin levels rose during operation (9.9 ± 4 to 82.4 ± 23 pg. per milliliter, p < 0.01) and bypass (172.4 ± 23 pg. per milliliter, p < 0.001). During bypass, urine Na+ also rose (69 ± 15 to 127 ± 4 mEq. per liter, p < 0.01) and urine K+ declined (64 ± 12 to 31 ±9 mEq. per liter, p < 0.01). In Group II, vasopressin rose during the surgical procedure (8.5 ± 15 to 17.9 ± 7 pg. per milliliter, p < 0.05) and bypass (82.3 ± 30 pg. per milliliter, p < 0.001). During bypass urine Na+ rose (73 ± 37 to 93 ± 25 mEq. per liter, p ± 0.05) and urine K+ declined (96 ± 7 to 51 ± 16 mEq. per liter, p < 0.05). In Group III vasopressin was not significantly elevated until bypass (7.8 ± 3.6 to 50.1 ± 18 pg. per milliliter, p < 0.01). During bypass, urine K+ declined (73 ± 7 to 40 ± 7 mEq. per liter, p < 0.05). Urine flow rose during bypass in all three groups. The rise in vasopressin was greater in Group I than in Group II or III (p < 0.01) during CPB. The rise in urine Na+ in Group I was greater than that in Group III (p < 0.05) as was the decline in urine K+ (p < 0.05). These data demonstrate that vasopressin levels are not affected by halothane or morphine anesthesia and that the response to surgical stimulation can be attenuated by the depth of anesthesia. They also suggest that there is a stress response to CPB, resulting in high levels of vasopressin and a Na+ diuresis, that can also be attenuated by the depth of anesthesia.