A comparison between propofol and ketamine for anaesthesia in the elderly. Haemodynamic effects during induction and maintenance.

The haemodynamic effects of propofol and ketamine were studied in two groups of eight randomly allocated elderly patients (mean age 85.8 years) anaesthetised for hip replacement. Group 1 patients patients received propofol 1 mg/kg by intravenous bolus for induction and 0.1 mg/kg/minute by continuous infusion for maintenance. Group 2 patients received ketamine 1.5 mg/kg by intravenous bolus as induction dose and 50 micrograms/kg/minute by continuous infusion for maintenance. All patients breathed spontaneously via a facemask at FIO2 1.0. Haemodynamic status was established before induction and at 1, 3, 5, 10 and 15 minutes after induction. Arterial pressure and cardiac output decreased slightly in group 1 but heart rate, right atrial pressure and pulmonary arterial pressure remained unchanged. Myocardial oxygen consumption showed a significant decrease of 27%. There was a significant increase in blood pressure and pulmonary capillary wedge pressure (by 97%) in group 2. Cardiac output and systemic vascular resistance remained unchanged whereas myocardial oxygen consumption showed a very significant increase of 100%.