Haemodynamic Stability During Induction of General Anesthesia With Propofol and Remifentanil: A Randomized, Controlled, Double-blind Study Comparing Low vs High Propofol Doses.

Typically, one or more adjuvant medications are administered to supplement induction of general anesthesia. When combining anesthetic drugs, the hypnotic effects are often synergistic. Propofol is associated with hypotension and bradycardia and used together with remifentanil or sedative agents it may give synergistic or additive sedative and hemodynamic effects.

Claeys (1988) and Fairfield (1991) examined the cardiovascular effects of propofol 2-2.5 mg/kg induction dose and found significant reductions i SBP and SVR and small changes in CO, SV and HR. De Wit (2016) examined hemodynamic changes in different steady state propofol serum concentrations, and found a dose dependent SBP reduction, reduction in resistance of arterial and systemic circulation and a reduction in mean systemic filling pressures (MSFP) indicative of a reduction in "stressed volumes". The effective dose (ED) 95% for loss of consciousness for propofol was determined to 1.75 mg/kg when used alone, and 1.38 mg/kg when used together with remifentanil 0.25 microg/kg/min (total induction dose 1.75 microg/kg remifentanil) in a study by Koh et al. We want to examine the hemodynamic effects of giving a low (1.4 mg/kg) vs a high (2.4 mg/kg) propofol dose combined with a moderate remifentanil dose (about 1.5 microg/kg).