The effect of 50% N2O on the general haemodynamics of patients with heart valve lesions

Abstract

The effect of 50% N2O on the general haemodynamics of patients with heart valve lesions was evaluated. The addition of N2O to oxygen before cardiopulmonary bypass was associated with a decrease in the cardiac output from 3,60 ± 0,23 to 3,04 ± 0,17 l.min-1/m2 (P<0,001) although the filling pressure of the left ventricle remained constant and right ventricle preload was increased from 8,18 ± 0.99 to 9,85 ± 1,14 mmHg (P<0,05). Because the systemic blood pressure fell after N2O was added, the decrease in cardiac output is interpreted as representing a decrease in myocardial contractility. The changes in the inverse relationship between arterial blood pressure and stroke volume also support the concept that N2O suppresses myocardial contractility