Association between intraoperative hypotension and postoperative nausea and vomiting: a retrospective cohort study.

Postoperative nausea and vomiting (PONV) occurs in up to 30% of patients and its pathophysiology and mechanisms have not been completely described. Hypotension and a decrease in cardiac output are suspected to induce nausea. The hypothesis that intraoperative hypotension might influence the incidence of PONV was investigated. The study was conducted as a retrospective large single center cohort study. The incidence of PONV was investigated until discharge from post anesthesia care unit (PACU). Surgical patients with general anesthesia during a 2-year period between 2018 and 2019 at a university hospital in Germany were included. Groups were defined based on the lowest documented mean arterial pressure (MAP) with group H50: MAP <50mmHg; group H60: MAP <60mmHg; group H70: MAP <70mmHg, and group H0: no MAP <70mmHg. Decreases of MAP in the different groups were related to PONV. Propensity-score matching was carried out to control for overlapping risk factors. In the 2-year period 18.674 patients fit the inclusion criteria. The overall incidence of PONV was 11%. Patients with hypotension had a significantly increased incidence of PONV (H0 vs. H50: 11.0% vs.17.4%, Risk Ratio (RR): 1.285 (99%CI: 1.102-1.498), The study demonstrates an association between intraoperative hypotension and early PONV. A more severe decrease of MAP had a pronounced effect.