Ultrasound-guided continuous parasacral ischial plane block for diabetic foot ulcer healing: study protocol for a single-centre, prospective, randomised, open-label, blinded-endpoint controlled trial.

Introduction: Diabetic foot ulcers (DFU) represent a significant global health burden, drastically reducing quality of life and increasing amputation risk. Associated pain and peripheral vascular disease complicate management and healing. Continuous parasacral ischial plane block (CPIPB), a regional anaesthesia technique targeting the sacral plexus, has shown potential in preclinical studies and feasibility assessments to improve lower limb analgesia and perfusion by modulating sympathetic tone. This trial aims to evaluate the efficacy and safety of CPIPB combined with standard of care (SOC) compared to SOC alone for promoting the healing of chronic DFU. Methods and analysis: This study utilizes a single-centre, prospective, randomised, open-label, blinded-endpoint (PROBE) parallel-group design. A total of 78 participants aged 20-89 years with a DFU (University of Texas Classification 1A-2D) present for >4 weeks but <1 year, with an area between 1-20 cm², and adequate perfusion (ABI >0.7 or equivalent) will be recruited after a 2-week SOC run-in period (inclusion requires <30% wound area reduction). Participants will be randomised (1:1) using variable block randomisation to either: 1) CPIPB + SOC: ultrasound-guided catheter placement in the parasacral ischial plane for continuous infusion of 0.2% ropivacaine at 5 mL/h for 14 days, combined with SOC; or 2) SOC alone: including glycaemic control, appropriate debridement, and standard dressings. The primary outcome is the incidence of complete ulcer healing at 12 weeks. Secondary outcomes include time to complete healing, percentage change in ulcer area, proportion achieving ≥50% area reduction, ulcer recurrence, infection rates, pain scores (VAS), lower limb perfusion assessments (TcPO2, Peak Systolic Velocity), health-related quality of life (Wound-QoL), and safety events. Statistical analysis will primarily use the intention-to-treat principle, comparing groups using chi-square tests, t-tests/Mann-Whitney U tests, Kaplan-Meier analysis, and logistic/linear regression models adjusting for baseline covariates where appropriate. Discussion: This study aims to evaluate the effects of a 12-week treatment with CPIPB and SOC on patients with DFU. We hypothesize that, compared to SOC alone, CPIPB combined with SOC would significantly improve ulcer healing without provoking significant adverse reactions. These findings potentially pave the way for a safe and effective adjunctive therapy for DFU. Clinical trial registration: https://www.chictr.org.cn/, identifier ChiCTR2400083504.