The relationship among carbon dioxide pneumoperitoneum, vasopressin release, and hemodynamic changes

We assessed the role of vasopressin (VP) for the hemodynamic response to pn eumoperitoneum in pigs. Four groups of anesthetized pigs were investigated. Nine pigs were intraabdominally insufflated with CO2 and eight were intraa bdominally insufflated with argon; eight pigs received an IV injection of 1 mg/kg SR 49059, a VP antagonist, before CO2 insufflation; and six pigs rec eived SR 49059 alone. Hemodynamics, plasma concentrations of VP and vasoact ive hormones, and Pace, were measured. Data were analyzed by using analysis of variance, Student's t-test, and Mann-Whitney U-test. Five minutes after insufflation, changes in systemic vascular resistance (SVR) were significa ntly correlated with changes in VP (r = 0.72; P = 0.005) but not with chang es in epinephrine, norepinephrine, renin activity, or PaCO2. SVR increased during CO2 insufflation but not during argon insufflation or CO2 insufflati on with a preceding infusion of SR 49059. The SR 49059 injection itself res ulted in increases in heart rate and cardiac output and decreases in blood pressure and SVR. We conclude that, during CO2 pneumoperitoneum in pigs, ab sorbed CO2 initiates a pathophysiological process that stimulates VP releas e. Hence, VP most likely plays a key role in the hemodynamic response to a CO2-induced pneumoperitoneum. Implications: Intraabdominal insufflation of CO2 is associated with hemodynamic and hormonal changes. Investigating CO2 and argon-insufflated pigs and using a vasopressin antagonist, we found tha t CO2 insufflation released vasopressin, which, in turn, induced hemodynami c perturbances.