Which Combination of Local Anesthesia is Superior for Postoperative Pain After Carpal Tunnel Surgery?: A Prospective Randomized Study.

The Wide-Awake Local Anesthesia No Tourniquet (WALANT) technique has become popular for hand surgery in the past decade. It consists of injecting a local anesthetic and epinephrine into the surgical site. Lidocaine, a short-acting local anesthetic, is used in the classic description. Adding a long-acting local anesthetic, such as bupivacaine, has been suggested for long surgeries.

However, the use of bupivacaine in shorter-duration procedures could combine the advantages of ambulatory surgery without a tourniquet with long-acting analgesia, improving postoperative pain and reducing the consumption of analgesics.

Patients undergoing first-time open carpal tunnel release surgery will be randomized to receive bupivacaine or lidocaine. Randomization will be generated by computer using random block sizes of 2 or 4 with an allocation ratio of 1:1.

Postoperatively, patients will receive standard medical care. It consists of 50 mg of diclofenac to take when they feel pain (with a minimum interval of 8 hours). Patients will be instructed to complete a medication log for pain and analgesic consumption. A blinded investigator will contact them by phone at 24 hours and 48hs. At two weeks, they will be controlled by research staff for complications.

Eighty-two patients will be recruited, 41 per arm, assuming a 20% loss. The sample size was calculated using a 90% power and 5% significance level. The objective was to detect a minimum difference of 2 points on a numeric scale ranging from 0 to 10 with a standard deviation of 2.5 points.