Minimisation of Blood Pressure Variability and Postoperative Nausea and Vomiting

Background: Intraoperative hypotension is associated with postoperative nausea and vomiting (PONV). Even though the exact mechanism linking PONV and hypotension is still unclear, a reduced intestinal tissue perfusion might trigger nausea and vomiting. Still to date only limited data evaluating intraoperative blood pressure and the incidence of PONV after general anesthesia exits. Furthermore, the effect of intraoperative blood pressure variability on the incidence of PONV has not been investigated yet. Therefore, we will test our primary hypothesis that the incidence of PONV during the early (0-2h) postoperative period will be minimized by targeting intraoperative blood pressure variability to a SPB of 120±5mmHg by using a continuous vasopressor infusion in female patients undergoing elective minor to moderate risk non-cardiac surgery.

Methods: We will include 272 women between 18 and 50 years of age undergoing minor- to moderate-risk noncardiac surgery in this randomized, double-blinded clinical trial. Patients will randomly be assigned to intraoperative management of blood pressure with a SPB of 120±5mmHg (intervention group) or standard of care intraoperative blood pressure management (control group). Our primary outcome will be the incidence of PONV during the early (0-2h) postoperative period between the groups. Nausea will be assessed in 15-min intervals in the PACU for the first two postoperative hours on a 100mm visual analog scale. A PONV episode will be defined as the occurrence of nausea (VAS 50mm or greater) or vomiting.

Statistics: The primary outcome, the incidence of PONV during the early (0-2 hours) postoperative period will be compared between the intervention and control group using a Chi- Square-Test.

Level of originality: Data regarding the effects of intraoperative blood pressure on PONV are very limited and mainly available from retrospective analysis. So far, the effects of blood pressure variability on PONV have not been investigated yet. As PONV is still one of the most common complications after general anaesthesia leading to delayed discharge from PACU, patient discomfort and increased medical costs, it is important to search for additional methods to manage PONV. Our patient population, being at increased risk of PONV, could therefore profit from a more rapid postoperative recovery.