Objective: To compare isoflurane with midazolam for prolonged sedation in ventilated patients.
Design: Randomised controlled study.
Setting: General intensive care unit in university teaching hospital.
Patients: Sixty patients aged 17-80 years who required mechanical ventilation for more than 24 h.
Interventions: Sedation with either 0.1-0.6% isoflurane in an air-oxygen mixture (30 patients) or a continuous infusion of midazolam 0.02-0.20 mg/kg/h (30 patients). Sedation was assessed initially and hourly thereafter on a six point scale. The trial sedative was stopped when the patient was ready for weaning from ventilatory support.
Measurements and results: Measurements were made of haemodynamic, respiratory and biochemical variables regularly during the period of sedation and for a week after stopping the sedative agent. There was no difference in any of the physiological or biochemical variables recorded between the two groups. Patients sedated with isoflurane recovered more rapidly and were weaned from mechanical ventilation sooner than those sedated with midazolam.
Conclusions: Isoflurane is a useful agent for prolonged sedation of ventilated patients and does not have any adverse effect on the cardiorespiratory system or on hepatic, renal or adrenal function.