Comparison of xenon with propofol for supplementary general anaesthesia for knee replacement: a randomized study.

BACKGROUND Xenon anaesthesia is associated with rapid recovery and may also offer protection against neuronal damage. The aim of this study was to compare xenon with propofol for supplementary general anaesthesia in patients undergoing knee replacement in spinal anaesthesia. METHODS In total, 39 patients aged 60 or over were randomized to xenon 50-70% or propofol 3-5 mg kg(-1) h(-1). Vital signs and emergence time were recorded and cognitive function was assessed before operation, at discharge between the third and the fifth day and at 3 months using four neuropsychological tests. RESULTS Propofol supplementation was necessary in six xenon patients (29%) because of detectable movement of the upper body. Emergence time was significantly shorter with xenon (260 s for xenon and 590 s for propofol, P=0.001). There was no significant difference between the groups in blood pressure, heart rate, ventilatory frequency or end-tidal carbon dioxide concentration. No difference could be detected in cognitive function, which may be attributed to insufficient sample-size rather than the absence of a true difference. CONCLUSIONS Xenon was well tolerated for supplementary general anaesthesia in elderly spontaneously breathing patients but supplementation may be necessary. Compared with propofol, emergence was faster with xenon. A larger sample-size is needed if cognitive function is to be addressed.