Importance of arterial measurement sites for intraoperative hemodynamic management during major abdominal surgeries: The IPAMS randomized trial protocol

IntroductionReliable hemodynamic parameters are crucial to prevent perioperative hypotension, one of the most significant modifiable risk factors for postoperative morbidity and mortality. The current standard of care for intraoperative hemodynamic monitoring is achieved through an arterial radial catheter, but its reliability has been increasingly questioned due to the incidence of a phenomenon called the radial-to-central arterial pressure gradient. Studies have shown that this gradient occurs in one-third of cardiac surgery patients predominantly during moments of hemodynamic instability, when accurate blood pressure monitoring is critical. However, it remains unclear whether and how this phenomenon affects non-cardiac surgical populations. ObjectivesThe main objective is to study whether brachial arterial pressure monitoring reduces intraoperative vasopressor dosage compared to conventional radial monitoring. We hypothesized that patients undergoing major abdominal surgery with brachial arterial pressure monitoring will require lower time-weighted average of phenylephrine administration compared to those monitored with radial arterial pressure. Our secondary objectives are to systematically describe the incidence of radial-to-brachial pressure gradients and identify predictive factors associated with this phenomenon. Materials and methodsThis single center randomized clinical trial will enroll 200 adult patients between 18 and 90 years of age, undergoing major abdominal surgery. Besides standardized anesthesia management, all patients will receive radial and brachial blood pressure monitoring, but only one blinded catheter will guide intraoperative hemodynamic management. We will record radial and brachial arterial pressure curves, standard intraoperative data and post-operative complications. EthicsThis trial has been approved by the regional ethics committee (Comite dEthique de la Recherche du CIUSSS de lEst de lIle de Montreal) Trial registrationhttps://ClinicalTrials.gov (May 21st, 2025). Unique protocol ID: 2023-3299. Trial identification number: NCT06982001