Cardiovascular effects of intravenous propofol administed at two infusion rates: a transthoracic echocardiographic study

We assessed the haemodynamic changes after a propofol infusion at two rates in low-risk unpremedicated patients (ASA I-II). To determine contractility changes and loading conditions, we measured the ejection fraction, end-systolic quotient and fractional shortening on transthoracic echocardiograms. We studied 40 patients undergoing peripheral neurosurgical procedures under general anaesthesia induced by propofol alone (total dose 2.5 mg.kg-1). Patients were randomly assigned to receive propofol at an infusion rate of 10 mg.s-1; or 2 mg.s-1. Haemodynamic data were recorded simultaneously immediately before propofol infusion, at the end of infusion, and 5 and 10 min after the infusion ended. The higher infusion rate induced a larger decrease in mean arterial pressure than the lower infusion rate (- 20% vs. - 10% from baseline, p = 0.01). In both groups, global and segmental ventricular function remained unchanged throughout the study. In both groups, there were markedly reduced end-systolic quotients--presumably related to diminished afterload, and in the higher infusion-rate group a significant reduction in fractional shortening--presumably related principally to diminished preload.