The correlation of intraoperative hypotension and postoperative cognitive impairment: a meta-analysis of randomized controlled trials

Background There is no consensus on whether intraoperative hypotension is associated with postoperative cognitive impairment. Hence, we performed a meta-analysis to evaluate the correlation of intraoperative hypotension and the incidence of postoperative delirium (POD) or postoperative cognitive dysfunction (POCD).Methods We searched PubMed, Embase, and Cochrane library databases to find randomized controlled trials (RCTs) in which reported the relationship of intraoperative hypotension and POD or POCD. The retrieval time is up to January 2020, without language restrictions. Quality assessment of the eligible studies was conducted by two researchers independently using the Cochrane evaluation system.Results Five RCTs were included. For the incidence of POD, there are two studies with 99 participants in the low-blood pressure (LP) group and 94 participants in the high-blood pressure (HP) group. For the incidence of POCD, there are four studies with 360 participants in the LP group and 341 participants in the HP group, with a study contains both POD and POCD. No significant difference between the LP and the HP group was observed in the incidence of POD (RR = 3.30, 95% CI 0.80 to 13.54, P = 0.10), or POCD (RR = 1.26, 95% CI 0.76 to 2.08, P = 0.37). Furthermore, it also demonstrated that intraoperative hypotension prolonged the length of ICU stay, but did not increased the mortality, the length of hospital stay, and mechanical ventilation (MV) time.Conclusions There is no significant correlation between intraoperative hypotension and the incidence of POD or POCD.