IBP-DISTAL protocol: distal vs radial access for invasive BP in critical care

To determine whether distal radial artery (dTRA) cannulation is non-inferior to conventional radial artery (TRA) cannulation for first-pass success and subsequent safety and accuracy of invasive blood pressure monitoring in awake, critically ill adults. Prospective, multicenter, randomized, open-label, parallel-group, non-inferiority trial. The study will be conducted in three tertiary hospitals in northwestern China. Eligible patients (≥ 18 years old) requiring invasive arterial pressure monitoring, with palpable distal and proximal radial pulses and a negative modified Allen test, will be centrally randomized (1:1; stratified by previous ipsilateral intervention) to dTRA or TRA. Both groups will undergo blind puncture with a uniform 20 G catheter-over-needle system; ultrasound is reserved for rescue. Pre-procedure ultrasound maps vessel diameter, intima-media thickness and flow velocity. Primary endpoint: one-time success rate of catheterization. Secondary endpoints: total cannulation time, crossover rate, 24 h and 30-day radial artery occlusion (RAO) by Doppler, local complications (EASY hematoma grade), BARC major bleeding (types 2, 3, 5), accidental dislodgment, pain (VAS 0–10), functional score (Barthel Index), and major adverse cardiovascular/cerebrovascular events during ICU stay. Target enrollment 204 (102 per arm) gives 85% power to demonstrate non-inferiority at one-sided α = 0.025, allowing 20% failure rate. All ultrasound assessments are performed by technicians blinded to allocation. This nurse-led protocol reflects real-world Chinese practice (blind puncture, no ultrasound routine) while standardizing compression (≥ 5 min) and post-procedural care across centers. Results will clarify whether dTRA offers shorter hemostasis time, lower RAO and better comfort without compromising hemodynamic monitoring fidelity. If non-inferiority is confirmed, dTRA could become the preferred default access for invasive blood pressure monitoring in critical care, preserving future radial conduit and improving patient experience. This study has been registered on Chinese Clinical Trial Registry (ChiCTR.org.cn) under the identifier ChiCTR2500101331 (Apr 23, 2025).