[Dynamics of the level of plasma vasopressin and its role in the regulation of water-electrolyte metabolism in patients following aortocoronary bypass].

Changes in plasma vasopressin, K+, Na levels, osmolality in blood and urine samples, as well as hemodynamic parameters, cardiac output and circulating blood volume including, have been assessed in 38 patients 3, 6, 18 and 48 hours after aortocoronary bypass surgery. It has been found that vasopressin blood level in the postoperative period is considerably (5-7 times) higher than physiological hormone level. The main reasons for vasopressin blood level increase are surgical stress, increase in blood plasma osmolality, hypokalemia, a drop of the arterial blood pressure and central venous pressure elevation. Despite a high vasopressin level and its pronounced impact on the renal excretory function, the first postoperative hours are marked by polyuria, mediated mainly by osmotic diuresis due to infusions of high amounts of osmotically active substances.