The effect of desflurane versus propofol anesthesia on postoperative delirium in elderly obese patients undergoing total knee replacement: A randomized, controlled, double-blinded clinical trial

The goal of this study was to investigate the incidence of delirium, wake-up times and early post-operative cognitive decline in one hundred obese elderly patients undergoing total knee arthroplasty. Prospective randomized trial. Operating room, postoperative recovery area, hospital wards. 100 obese patients (ASA II and III) undergoing primary total knee replacement under general anesthesia with a femoral nerve block catheter. Patients were prospectively randomized to maintenance anesthesia with either propofol or desflurane. The primary endpoint assessed by a blinded investigator was delirium as measured by the Confusion Assessment Method. Secondary endpoints were wake-up times and a battery of six different tests of cognitive function. Four of the 100 patients that gave informed consent withdrew from the study. Of the remaining 96 patients, 6 patients did not complete full CAM testing. Preoperative pain scores, durations of surgery and anesthesia, and amount of intraoperative fentanyl were not different between groups. One patient in the propofol group developed delirium compared to zero in desflurane. One patient in desflurane group developed a confused state not characterized as delirium. Fifty percent of the patients exhibited a 20% decrease in the results of at least one cognitive test on the first 2 days after surgery, with no difference between groups. There were no differences in the time to emergence from anesthesia, incidence of postoperative nausea and vomiting, and length of postanesthesia care unit (PACU) stay between the two groups. In conclusion we found a low incidence of delirium but significant cognitive decline in the first 48 h after surgery. In this relatively small sample size of a hundred patients there was no difference in the incidence of postoperative delirium, early cognitive outcomes, or wake up times between the desflurane or propofol group.