The haemodynamic effects of Propofol in combination with ephedrine during induction of general anaesthesia

Abstract

ABSTRACT Introduction: the propofol is an hypnotic agent which during the anesthetic induction can lead to hypotension. Objective: evaluate the ephedrine´s efficacy in preventing the arterial hypotension caused by the association between propofol and remifentanil as anesthetic inductors. Patients and Methods: thirty patients with age between 18 and 50 years, ASA state PI e PII, were randomly divided in three groups according to the solution in use. Group I (n = 10) propofol 1%; group II (n = 10) propofol 1% associated with ephedrine (0,5 mg.ml-1); Group III (n = 10) propofol 1% associated with ephedrine (1 mg.ml-1). The patients have been monitorized with non invasive blood pressure, continuous ECG in DII and pulse oxymeter. It has been administrated midazolam at the dose of 0,05mg.kg-1 intravenous 5 minutes before induction. After pre-oxygenation with FiO2 at 100%, it has been administrated remifentanil intravenous (0,5 mg.kg-1.min-1) by 90 seconds. Then, the patients received the propofol solution 1% (with/without ephedrine), in continuous infusion at rate of 180 ml.h-1 until the loss of the palpebral reflex followed by cisatracurium (0,15 mg.kg-1). Blood pressure, heart rate and oxygen saturation have been recorded in the moments: before induction, 1, 3, 5 and 10 minutes after propofol´s administration. Results: there were no statistically significant differences among groups in anthropometric data. The heart rate outline analyzed didn't show statistic significance between the groups. There has been reduction in the values founded at some moments between the groups I and II, however without clinical significance. In the arterial blood pressure (systolic and diastolic) data, there were reductions in the values at some moments compared to the initial time and between the groups, but they can't be classified as arterial hypotension. But, in group I, the ephedrine´s rescue dose administrated was larger comparing to the others groups (p < 0,05). Conclusion: there haven't been, in none of the groups, important clinical reduction of blood pressure and heart rate. However, in group I, more patients needed ephedrine´s rescue dose to correct hypotension (p < 0,05).