comparison between midazolam co-induction and propofol predosing for the induction of anaesthesia in the elderly

ABSTRACT

Co-induction is the administration of a small dose of a sedative or anaesthetic agent prior to induction of anaesthesia, the aim being to reduce the dose of induction agent required. The aim of this study was to compare the efficacy, safety and cardiovascular stability of low dose midazolam co-induction and propofol pre-dosing using propofol for induction of anaesthesia in elderly patients. In a randomized, placebo-controlled trial, we enrolled 60 patients aged 60 years or more with ASA between I and III attending for opthalmic surgery. The patients were allocated randomly to one of three groups, to receive either midazolam 0.02 mg.kg[-1], propofol 0.25 mg.kg[-1], or normal saline 2 ml [placebo] 2 min prior to induction of anaesthesia using propofol 1% infusion at 5 ml/min. The propofol dose requirements for induction were recorded for two end-points [loss of verbal contact [LOVC] and insertion of an oropharyngeal airway]. cardiovascular parameters, respiratory rate and oxygen saturation were recorded at 1-min intervals for each patient until induction was complete. Intraocular pressure was recorded before and after induction. The time and the dose of propofol required to induce LOVC, jaw relaxation [JR] and insertion of Guedel oropharyngeal airway showed a statistically significant decrease in both the midazolam and the propofol groups, when compared to the saline group, [P<0.05]. There was a statistically significant decrease in the intraocular pressure after induction in the saline and the propofol groups, [P<0.05]. The haemodynamic parameters [bloodpressure [Systolic and diastolic] and heart rate] and the respiratory rate of patients in all groups showed a statistically significant decrease [P<0.05] from baseline reading however the comparison between the groups showed that decrease was non significant. The oxygen saturation of patients in all groups showed a significant increase from preoperative baseline reading [P<0.05]. Midazolam co-induction and propofol predosing reduce the dose of propofol [33.5%] and [10%] respectively and the time required for induction of anesthesia by propofol infusion in the elderly with no improvement of cardiovascular stability