Effects of propofol on haemodynamics and on regional blood flows in dogs submitted or not to a volaemic expansion

Abstract

This study was designed to examine the effect of volume loading on haemodynamic responses and regional cardiac function in dogs subjected to two infusion rates of propofol. Instrumentation was established to measure aortic and left ventricular pressures, cardiac output and myocardial segmental lengths. Measurements were taken during two successive infusion rates of propofol: 0.2 (P0.2) and 0.4 (P0.4) mg kg⁻¹ min⁻¹. One group (VL+) (n=6) received volume loading (dextran 40, 10 mL kg⁻¹ h⁻¹), the other group (VL−) (n=6) received only basal perfusion (Ringer solution, 2 mL kg⁻¹.h⁻¹). Regional blood flows were measured by radio-labelled microspheres. P0.4 induced a decrease in cardiac output and in dP/dt_max. End-diastolic length decreased with propofol without any difference between groups. Regional contractility was not modified by propofol or by volume loading. P0.4 decreased endocardial and epicardial blood flow in the VL-group only. Renal, small intestine and large intestine blood flows decreased in both groups with P0.4. P0.2 did not alter regional blood flows significantly. It was concluded that in this model, propofol infusion at 0.4 mg kg⁻¹ min⁻¹ induced splanchnic, renal and myocardial hypoperfusion in animals not submitted to a mild fluid loading. Fluid loading allowed myocardial perfusion to be maintained but could not prevent a marked decrease in splanchnic and renal perfusion.