Comparative evaluation of isoflurane and desflurane for postoperative cognitive decline in elderly patients: A prospective observational pilot study.

Background: Approximately 16%-62% of patients undergoing non cardiac surgeries develop postoperative cognitive dysfunction. We compared the incidence of postoperative cognitive dysfunction in older adults aged 60-80 years who underwent open abdominal surgeries under general anaesthesia using isoflurane or desflurane and correlated it with the serum concentration of interleukin 1, interleukin 6, tumour necrosis factor alpha, amyloid β and S100 on postoperative day 3.

Method: Forty American Association of Anesthesiologists Physical Classification I or II patients were included after acquiring institutional ethics committee approval, registering in the Clinical Trials Registry - India, and informed written consent. They underwent open abdominal surgery under general anaesthesia and epidurals between 2017 and 2019. Patients with substance abuse or any disorder affecting cognition were excluded. Postoperative cognitive dysfunction was assessed by Stroop test, Wisconsin Card Sorting Test, Trail making test - B, Porteus Maze test, PGI memory scale, mini-mental state examination, and Bender Gestalt test the day before surgery and on the third postoperative day along with blood samples.

Results: Thirty-seven percent of the patients developed postoperative cognitive dysfunction. The risk was similar to isoflurane in comparison with desflurane (risk ratio: 0.65, 95% confidence interval: 0.30, 1.40). A significant percentage increase in reaction time for Porteus Maze test and Trail making test - B was noted with isoflurane (6.69 (4.20-8.94) and 8.01 (2.08-12.5), respectively) in comparison with desflurane group (13.01 (9.09-17.33), p = 0.003 and 11.62 (7.5-17.5), p = 0.017, respectively).

Conclusion: Isoflurane and desflurane had a similar impact on the elderly for developing postoperative cognitive dysfunction and no correlation with any of the biomarkers used in the study on postoperative day 3.