Effects of propofol or desflurane on post-operative spirometry in elderly after knee surgery: A double-blind randomised study

Background Intravenous or volatile agents reduce respiratory function, which can result in respiratory complications in geriatric patients. We hypothesised that there would be no differences in lung function between anaesthesia established using either drug. Methods Elderly patients were randomly assigned to receive either propofol with remifentanil (n=48) or desflurane (DES) with remifentanil (n=52) for knee surgery. Spirometry tests including forced expiratory volume in 1s (FEV₁), forced vital capacity (FVC), forced mid-expiratory flow (FEF25-75), and FEV₁/FVC ratio were performed preoperatively, and 30min, 60min, and 24h after awakening. Emergence time and post-operative pain scores were also measured. Results Time to emergence was significantly longer in the propofol than in the DES group (17.0 vs. 12.5min, P=0.04). Post-operative FEV₁ (1.6 or 1.4l, P=0.68 between groups) were significantly lower than preoperative values (2.1 or 2.0l, P=0.001 vs. post-operative values, respectively) in both groups. Reduced FEV₁ lasted for 24h after surgery (1.7 or 1.6l, P=0.001 vs. preoperative values, respectively). Post-operative FVC or FEF25-75 were lower than preoperative values. FEV₁/FVC ratio did not change during the study period in both groups. There was no difference in FEV₁, FVC, FEF25-75, FEV₁/FVC, and post-operative pain between the two anaesthetic techniques. Conclusions Although there is a delay in awakening when using propofol, the effects of propofol on post-operative spirometry parameters are similar to those of DES when anaesthesia duration is approximately 3h. Decreased respiratory parameters persisted up to 24h after anaesthesia, irrespective of the choice of anaesthetic.