RESUMEN
Esmolol a short acting beta[1]-receptor antagonist is known to reduce the cardiac output [CO]. Preinduction CO is a significant predictor for propofol dose required for induction of anesthesia. This study was designed to determine the effect of esmolol dose on propofol required for induction of anesthesia. Eighty patients were randomly allocated to placebo group I [saline] and esmolol groups Il, Ill, IV received esmolol bolus doses 0.5, 1 and 1.5 mg/kg respectively followed by i.v. infusion of 250 micro g/kg/min. After 5 minutes anesthesia was induced by propofol 10 mg/mI at 10 ml/min by infusion pump, the primary end point used was the propofol dose/kg at loss of response to command and duration of induction were recorded. CO, BP [Blood Pressure], HR [Heart Rate] and SpO[2]% saturation were monitored non-invasively. CO was measured before and after esmolol injection [at preinduction time]. Esmolol doses 0.5, 1 and 1.5 mg/kg. followed by esmolol infusion significantly reduced CO by 12%, 14.6% and 18.9% and reduced propofol dose required for induction of anesthesia by 15.3%, 23.38% and 3.6% from placebo group respectively. in addition the duration of induction was reduced significantly in group II, Ill and IV by 12.5%, 22.5% and 32.1% from placebo [group I] respectively in the same order. Esmolol dose reduced propofol induction dose and duration of induction of anesthesia in an inversely proportional manner possibly due to the effect of esmolol dose on preinduction cardiac output [CO]