Protocol for a double-blinded randomised controlled trial investigating the use of adjunct bicarbonate in carpal tunnel release: a single-centre study

INTRODUCTION: This study aims to compare the effectiveness of buffered and non-buffered long-acting local anaesthetics in pain relief during and after carpal tunnel release (CTR) surgery. Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome. Surgical treatment of CTS, CTR, is the most common hand surgical operation. CTR is usually performed under local anaesthesia, the application of which is often the most painful event during the procedure. One important aspect of patient satisfaction is adequate pain management during and after CTR. Long-acting local anaesthetics provide good postoperative pain control. Adjunct bicarbonate has been shown to reduce pain during injection of local anaesthetic and to prolong its analgesic effect. To date, no published randomised controlled trial has compared buffered to non-buffered long-acting local anaesthetic during CTR. METHODS AND ANALYSIS: The study will randomly assign 116 patients with CTS to receive buffered or non-buffered mixtures of lidocaine and bupivacaine with epinephrine before CTR. The primary outcome is overall pain experienced during the injection of local anaesthetic, assessed with the Visual Analogue Scale. The secondary outcomes are pain intensity from the injection and during CTR, use of painkillers and pain intensity every 4 hours until third postoperative night, symptom severity and functional status preoperatively and at 3 months after surgery, and patient-rated outcome measures at 3 months after surgery. ETHICS AND DISSEMINATION: This protocol was approved by the Research Ethics Committee of the Northern Savo Hospital District (2311/2021). The study will be performed according to the principles of good clinical practice and the Declaration of Helsinki. The results are expected to be presented in an international hand surgical conference and the manuscript to be sent to a hand surgery-orientated peer-reviewed journal during 2024. TRIAL REGISTRATION NUMBER: This study is registered to clinicaltrials.gov, study ID NCT05328180.