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 1 s (FEV1 ), forced vital capacity (FVC), forced mid-expiratory flow (FEF25-75), and FEV1 /FVC ratio were performed preoperatively, and 30 min, 60 min, and 24 h 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. 12.5 min, P = 0.04). Post-operative FEV1 (1.6 or 1.4 l, P = 0.68 between groups) were significantly lower than preoperative values (2.1 or 2.0 l, P = 0.001 vs. post-operative values, respectively) in both groups. Reduced FEV1 lasted for 24 h after surgery (1.7 or 1.6 l, 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 3 h. Decreased respiratory parameters persisted up to 24 h after anaesthesia, irrespective of the choice of anaesthetic.