Differential effects of sevoflurane and propofol anesthesia on left ventricular-arterial coupling in dogs.

Abstract

General anesthetics interfere with arterial and ventricular mechanical properties, often altering left ventricular-arterial (LVA) coupling. We hypothesized that sevoflurane and propofol alter LVA coupling by different effects on arterial and ventricular properties. Experiments were conducted in six anesthetized open-chest dogs for the measurement of left ventricular pressure and aortic pressure and flow. Measurements were performed during anesthesia with 0.5, 1.0 and 1.5 minimum alveolar concentration sevoflurane and 12, 24 and 36 mg/kg/h propofol. LVA coupling was assessed as the ratio of ventricular end-systolic elastance (E(es), measuring ventricular contractility) to effective arterial elastance (E(a), measuring ventricular afterload). The steady component of afterload, arterial tone, was assessed by systemic vascular resistance and arterial pressure-flow curves. The pulsatile component of afterload was assessed by aortic impedance and compliance. Sevoflurane decreased aortic pressure and cardiac output more than propofol. Sevoflurane reduced arterial tone, increased arterial stiffness and did not affect wave reflections. It increased E(a), decreased E(es) and reduced LVA coupling. Propofol reduced arterial tone, did not affect arterial stiffness and decreased wave reflections. It did not affect E(a), E(es) or LVA coupling. Sevoflurane increased ventricular afterload and decreased ventricular performance, thereby altering LVA coupling. Propofol did not affect ventricular afterload or ventricular performance, thereby preserving LVA coupling. Thus, propofol preserves LVA coupling in dogs better, and might be a better choice for patients with compromised left ventricular function.