Rationale and design of the Colloids infusion for Optimal outcomes In Non-cardiac surgery (COIN) randomized controlled trial

Abstract Background Post-induction hypotension is a common complications in surgical patients under general anesthesia. Previous evidence indicated preoperative fluid bolus infusion might improve hemodynamic stability after anesthesia induction. But the reported results regarding the postoperative clinical outcomes remains controversary. Methods Colloids infusion for Optimal outcomes In Non-cardiac surgery (COIN) trial is a multicenter, double-blinded, parallel-group, randomized controlled trial being conducted in seven tertiary hospitals in China. The trial will enroll and randomize 2,020 adult participants scheduled to undergo noncardiac surgery under general anesthesia with tracheal intubation. Participants will receive either 5 ml/kg of 6% hydroxyethyl starch 130/0.4 electrolyte solution (colloid group) or balanced multiple electrolyte solution (crystalloid group) prior to anesthesia induction. The primary endpoint is the incidence of postoperative complications within 30 days after surgery, defined as Clavien-Dindo classification Grade I or higher (any deviation from the normal postoperative course, including those requiring pharmacological treatment). The primary analysis will be an unadjusted, modified intention-to-treat comparison between patients randomized to colloids group and crystalloids group using chi-square test. The first patient was enrolled on July 12, 2023, and the trial is expected to be completed in June 2025. Conclusion The study aims to provide evidence-based insights into reducing postoperative complications in non-cardiac surgery patients undergoing general anesthesia, by comparing the effects of preoperative colloid versus crystalloid solution infusion prior to anesthetic induction. Should the findings demonstrate that colloid solution infusion effectively reduces the 30-day postoperative complication rate, this protocol may contribute to an optimized perioperative management strategy and further promote the clinical adoption of standardized preoperative hemodynamic management. Trial registration This study was registered at ClinicalTrials.gov under the identifier NCT05728645 on July 9, 2023, prior to its initiation ( http://clinicaltrials.gov ).