Effect of phenylephrine versus ephedrine on the incidence of postoperative delirium in elderly patients undergoing non-cardiac and non-neurosurgical procedures: protocol for a multicentre, double-blind, randomized, controlled trial

This study aims to determine whether the intraoperative management of hypotension with ephedrine, compared with phenylephrine, reduces the incidence of postoperative delirium in elderly patients undergoing major non-cardiac, non-neurosurgical surgery.</p> <p>This multicentre, randomized, double-blind, controlled trial will enrol 1,084 elderly patients scheduled for elective non-cardiac and non-neurosurgical major surgeries under general anaesthesia at seven hospitals in China.

Participants will be randomized in a 1:1 ratio, stratified by study centre, to receive continuous intravenous infusion of either phenylephrine or ephedrine to maintain mean arterial pressure within 20% of the baseline value. The primary outcome is the incidence of postoperative delirium within 7 days after surgery. Secondary outcomes include severity of postoperative delirium, numeric rating scale pain scores at rest and during activity at 24, 48 and 72 h postoperatively, intensive care unit (ICU) admission rate and length of ICU stay, length of postoperative hospital stay, incidence of in-hospital major adverse cardiovascular and cerebrovascular events (myocardial infarction, arrhythmia, heart failure, and stroke), and 30-day all-cause mortality.</p> <p>We hypothesize that ephedrine, when used to maintain intraoperative blood pressure, is superior to phenylephrine in reducing postoperative delirium in elderly patients undergoing major non-cardiac, non-neurosurgical surgery.