Femoral Versus Radial Invasive Arterial Pressure Monitoring in Cardiac Surgery Patients

Background: Acute circulatory failure, often presenting as arterial hypotension, is a major contributor to postoperative morbidity and mortality. Accurate blood pressure (BP) monitoring is essential for timely therapeutic intervention, particularly in patients undergoing major surgery. Among invasive BP measurement sites, the radial artery is commonly used due to its accessibility and ease of catheterization. However, physiologically, the radial artery may underestimate central arterial pressure compared to the femoral artery, especially in patients receiving vasopressors or in critical conditions. This discrepancy can lead to overtreatment with vasopressors and associated complications. Current literature on the accuracy of radial versus femoral BP monitoring is outdated and based solely on observational studies. There is a lack of high-quality randomized data to inform clinical guidelines. Hypothesis: Femoral arterial pressure monitoring, by offering more accurate hemodynamic data, reduces the need for vasopressor support, particularly norepinephrine, compared to radial artery monitoring. Primary Objective: To compare the effect of femoral versus radial invasive BP monitoring on the proportion of patients requiring norepinephrine from anesthetic induction to postoperative day 7 (D7) following elective cardiac surgery. Norepinephrine treatment is defined by continuous intravenous administration of norepinephrine for more than 1 minute. Secondary Objectives : To compare the following outcomes between the two strategies within the first 7 postoperative days: incidence of acute kidney injury (AKI) according to KDIGO criteria, incidence of cardiac complications (arrhythmias requiring treatment, myocardial injury (troponin \>99th percentile or \>20% rise from baseline), myocardial infarction, cardiogenic shock, cardiac arrest), vaso-inotropic score (VIS), duration of any vasopressor therapy (days), ICU and hospital length of stay (days), all-cause mortality at day 7 and day 30, total duration (hours/days) and maximal dose of norepineprhine therapy, intraoperative hypotension episodes (MAP\<65 mmHg \> 5 min), incidence of arterial catheter-related complications (hematoma, bleeding, infection, thrombosis, arterial occlusion, malfunction, dislodgement). Primary Endpoint: The proportion of patients receiving continuous intravenous norepinephrine from anesthesia induction to postoperative day 7. Secondary Endpoints: AKI occurrence or need for renal replacement therapy; cardiac complications: atrial/ventricular arrhythmias requirinf treatment, myocardial injury (troponin \>99th percentile or \>20% rise from baseline), myocardial infarction (biomarker elevation + ECG or echocardiographic abnormalities), cardiogenic shock, cardiac arrest; maximum VIS in the OR, ICU admission, and day 1; intraoperative hypotension episodes (MAP\<65 mmHg \> 5 min); total norepinephrine support duration (in hours); duration of any vasopressor therapy; arterial line complications: malfunction, dislodgement, hematoma, thrombosis, infection, bleeding, arterial occlusion; ICU and hospital length of stay (days); all-cause mortality at day 7 and day 30 Study Design: A prospective, multicenter (Besançon and Dijon University Hospitals), randomized, superiority, single-blind, intention-to-treat clinical trial in adults undergoing elective cardiac surgery. Patients are randomized to femoral or radial artery catheterization for continuous BP monitoring. Sample Size: Based on an expected norepinephrine use rate of 70%, a 15% absolute risk reduction, α = 0.05, and power = 90%, 162 patients per group are required. Accounting for 5% data loss, 340 patients will be enrolled. Study Arms: Radial group: invasive BP monitoring via radial artery catheterization Femoral group: invasive BP monitoring via femoral artery catheterization The arterial line is placed under ultrasound guidance in the operating room and maintained postoperatively in the ICU or critical care unit until no longer clinically indicated. Eligibility Criteria Inclusion: adults patients ≥18 years undergoing elective on-pump cardiac surgery with informed consent. Exclusion: emergency surgery, use of dual arterial lines, heart transplantation, mechanical circulatory support, contraindications to radial/femoral catheterization, legal or ethical inability to consent. Study Timeline Inclusion period: 36 months Patient follow-up: 7 days post-surgery Total study duration: 36 months Data Collection: Clinical data are collected by research staff using an electronic case report form (e-CRF) via CleanWeb™ software. Expected Impact: There are currently no guidelines specifying the optimal site for invasive BP monitoring. This study aims to provide robust evidence on whether femoral BP monitoring improves clinical outcomes, reduces vasopressor use, and minimizes adverse events. Positive findings could inform future practice guidelines and lead to broader investigations in other clinical settings.