Desflurane versus isoflurane in geriatric patients. A comparison of psychomotor and postoperative well-being following abdominal surgical procedures

Abstract

The new volatile anaesthetic agent desflurane has a significantly lower blood-gas partition coefficient (0.42) than isoflurane (1.4), suggesting excellent intraoperative control of anaesthesia and rapid emergence and recovery from anaesthesia. However, only limited experience is available in geriatric patients undergoing major abdominal surgery. After approval by the local ethics committee and with written informed consent, 52 patients (> or = 65 years old, ASA class II or III) scheduled for major abdominal surgery were randomised to receive either desflurane (DES) or isoflurane (ISO) for maintenance of anaesthesia. After oral premedication with midazolam 3.75-7.5 mg, anaesthesia was induced with etomidate 0.2-0.3 mg/kg and fentanyl 3 micrograms/kg. Vecuronium 0.1 mg/kg provided muscle relaxation for endotracheal intubation. All patients were mechanically ventilated to maintain normocapnia. For maintenance of anaesthesia, DES or ISO was administered in 60% N2O and additional boluses of fentanyl and vecuronium were given as required. At the end of surgery, the neuromuscular blockade was reversed with neostigmine 0.02 mg/kg and DES or ISO was discontinued at the end of skin closure. Episodes of bradycardia and tachycardia and hypo- and hypertension, the time from the end of anaesthesia to extubation, opening eyes, squeezing hand, stating name and birthdate and to discharge from the recovery room were recorded. Until 360 minutes after the end of anaesthesia, the recovery of psychomotor functions was measured by means of simple reaction time tests, critical flicker fusion test, labyrinth test, ball bearing test, short and long-term memory test and digit symbol substitution test. The patient's well-being was documented with scores for pain, sedation and postoperative nausea and vomiting. Demographic data in both groups was similar (Tab. 1). Anaesthesia was significantly prolonged in the ISO group. No significant differences between groups were found for MAC hours and the total dose of fentanyl and vecuronium administered (Tab. 3). Intraoperative haemodynamics were comparable between both groups (Tab. 4). No episodes of increases in heart rate or blood pressure associated with rapid increases in DES concentration were seen. Early emergence parameters were faster in the DES group (Tab. 5). When compared to ISO, the overall test performance and testing ability was superior following DES. Psychomotor tests showed significantly better results up to 240 minutes after the end of DES anaesthesia (Tab. 7, Fig. 4). Comparing the postoperative well-being, there were mild advantages for DES (Tab. 6, Fig. 1, 2, 3). However, time to discharge of geriatric patients from the recovery room was significantly shorter in the DES group (median 171 vs. 215 min., p < 0.05). Using a balanced anaesthesia technique, we found desflurane as suitable as isoflurane for geriatric patients. Additionally, due to the fast emergence from anaesthesia, an improved cooperativity was found. In the DES group overall better postoperative psychomotor performance resulted in a shortening of discharge times from the recovery room. Hence, desflurane anaesthesia may be advantageous in geriatric patients.