Efficacy of Ultrasound-guided Peripheral Nerve Block Versus Forearm Bier's Block in Patients Undergoing Carpal Tunnel Release: A Randomized Controlled Trial

Introduction:

In Belgium, several ways of anesthesia are used to perform hand surgery, being general anesthesia, intravenous regional anesthesia as well as locoregional anesthesia. Locoregional anesthesia and intravenous regional anesthesia are often performed since patients can be discharged from the hospital more rapidly. A forearm intravenous regional anesthesia (IVRA; mini-Bier's block) is an effective and safe technique to perform hand surgery, especially since the dose of the used anesthetic is reduced compared to a regular upper arm Bier's block, leading to a reduced risk of local anesthetic toxicity. An ultrasound-guided distal peripheral nerve block is often used for hand surgery, in which the nervus medianus and the nervus ulnaris can be affected locally. Research showed that this technique is associated with a reduced surgical procedure time when compared to intravenous regional anesthesia (1). In the Jessa Hospital, a carpal tunnel release is often performed using the forearm intravenous regional anesthesia. However, to date, the analeptic effectivity of the forearm intravenous regional anesthesia has not been compared to the distal peripheral nerve block.

Outcome measures:

The primary aim of this study is to compare the analgesic effectivity of the forearm intravenous regional anesthesia versus the ultrasound-guided distal peripheral nerve block. Our hypothesis is that the latter technique is superior. A blinded surgeon will determine the analgesic effectivity of these techniques (graded as "complete" or "incomplete") and divide the effectivity in 4 grades. Grade 1 and grade 2 are considered "complete" blockade, while grade 3 and grade 4 are considered "incomplete" blockade. Grade 1: complete motor and sensory blockade, grade 2: partial motor blockade but no pain or deep pressure sensitivity, grade 3: partial motor blockade with mild pain requiring rescue local or opioid analgesia, grade 4: incomplete motor- and sensory blockade requiring sedation/conversion to general anesthesia). Secondary study outcomes are patient's pre-, intra-, and post-operative pain scores at several time points, measured via an 11-point Numeric Rating Scale (NRS) in which number 0 means "no pain at all", number 5 means "moderate pain" and number 10 means "worst possible pain". General patient satisfaction as well as satisfaction of the surgeon regarding the used technique will be measured via a 7-point Likert Scale, in which number 1 means "extremely dissatisfied" and number 7 means "extremely satisfied". Furthermore, the time spend in the operating room, the time of surgical procedure and the use of post-operative medication use will be recorded as well.

Design: