Bicarbonate Addition to Lidocaine-Epinephrine in Surgery Under WALANT

Study context WALANT (Wide Awake Local Anesthesia No Tourniquet) is increasingly used for ambulatory hand and foot surgery, as it allows surgery without preoperative fasting and provides effective local anesthesia without a tourniquet, while promoting early functional recovery.

Sodium bicarbonate is commonly added to lidocaine-epinephrine solutions to reduce injection-related pain and prolong the duration of the anesthetic block. However, its clinical benefit remains uncertain and may increase preparation complexity.

Therefore, a robust methodological assessment of the impact of bicarbonate omission on early postoperative recovery is warranted in ambulatory WALANT surgery.

Primary objective To evaluate the effect of two WALANT local anesthesia protocols (lidocaine-epinephrine with or without bicarbonate addition) on early postoperative recovery at 24 hours after ambulatory hand and foot surgery.

Key secondary objectives A) Sensory block onset time. B) Intraoperative anesthetic block failure rate. C) Pain related to injection of the WALANT anesthetic solution. D) Intraoperative pain intensity. E) Patient satisfaction with perioperative care. F) Postoperative pain scores. G) Postoperative analgesic consumption, including opioids. H) Duration of the anesthetic block I) Postoperative adverse events.

Study design and conduct This prospective, single-center, randomized, double-blind, noninferiority trial will compare two 20 mL WALANT (Wide Awake Local Anesthesia No Tourniquet) solutions in patients scheduled for distal hand or foot ambulatory surgery.

The intervention group will receive lidocaine 5 mg/mL combined with epinephrine 0.005 mg/mL (18 mL of solution mixed with 2 mL of saline as placebo), whereas the control group will receive a similar solution including 8.4% bicarbonate (18 mL of solution mixed with 2 mL of bicarbonate). Both solutions will be administered by orthopedic surgeons prior to surgical incision.

Additional solution will be administered if sensory block is insufficient prior to incision.The maximum total lidocaine dose per patient will not exceed 800 mg in adults, in accordance with the approved labeling and standard clinical use of the drug.

Adults (≥18 years) eligible for ambulatory WALANT procedures (hand or selected foot surgeries) will be screened during the preoperative orthopedic consultation (pre-inclusion visit). All eligible patients will receive oral and written information, with at least one day between the pre-inclusion and inclusion visits to allow time for reflection and informed consent.

After written consent is obtained, patients will be randomized in a 1:1 ratio to the control group (with bicarbonate) or the intervention group (without bicarbonate). The surgical procedure under WALANT will be performed by orthopedic surgeon investigators.

Preoperative pain intensity (NRS), surgery-related anxiety (NRS), and the QuickDASH score will be recorded prior to the surgical procedure. Before hospital discharge, postoperative pain and patient satisfaction will be assessed. All patients will receive a standardized postoperative analgesic regimen.

Postoperative follow-up calls conducted by the clinical research associate will occur at 24 hours (NRS pain score, QoR-15 score, duration of the analgesic block, analgesic consumption, and adverse events) and at 48 hours (NRS pain score and adverse events). Study participation will end after the 48-hour follow-up call.

The estimated sample size is 150 patients, with 75 patients in each study arm. For the primary outcome, the noninferiority margin for the QoR-15 score is set at 6 points.