The role of intraoperative hypotension on the development of postoperative cognitive dysfunction: a systematic review

STUDY OBJECTIVE: To clarify whether intraoperative hypotension contributes to the development of postoperative cognitive dysfunction. DESIGN: A systematic review of prospective studies reporting on intraoperative hypotension and postoperative cognitive dysfunction in elective, non-cognitive impaired, adult surgical patients. PubMed, EMBASE and the Cochrane Library were searched up to the 1st of January 2021. SETTING: Studies had to use a clear definition of hypotension, although differing definitions were accepted. Neurocognitive tests to determine postoperative cognitive dysfunction had to be done pre- and postoperatively, with a minimum follow-up of seven days postoperatively. MEASUREMENTS: Risk of bias was assessed using the Cochrane Risk of Bias Tool 2.0 for randomized controlled trials and the Newcastle-Ottawa Scale for cohort studies. MAIN RESULTS: Out of 941 studies screened, five randomized controlled trials and four cohort studies were included for qualitative analysis. Extensive methodological differences between studies were present hindering proper quantitive analysis. No studies reported statistically significant differences in incidence of postoperative cognitive dysfunction in hypo- compared to normotensive patients. Five studies reported exact incidences of postoperative cognitive dysfunction. CONCLUSIONS: This systematic review showed no conclusive association between intraoperative hypotension and the development of postoperative cognitive dysfunction. Given the vast methodological differences of the included studies, the role of intraoperative hypotension in the development of postoperative cognitive dysfunction remains uncertain. Future research into the association between intraoperative hypotension and postoperative cognitive dysfunction should be conducted in a standardized manner.