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

AIMS: 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.

DESIGN

Prospective, multicenter, randomized, open-label, parallel-group, non-inferiority trial.

METHODS

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.

DISCUSSION: 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.

IMPACT: 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.

TRIAL REGISTRATION: This study has been registered on Chinese Clinical Trial Registry (ChiCTR.org.cn) under the identifier ChiCTR2500101331 (Apr 23, 2025).