The Effect of Forearm Nerve Blocks on Pain-free Tourniquet Time Compared to Local Anesthetic for Awake Hand Surgery

With increasing caseloads in some healthcare systems, patients requiring hand surgery may wait over two weeks for time in the general operating room schedule. During this time, fractures may heal, or tendons may retract, leading to a need for more extensive and longer procedures such as osteotomies or tendon reconstruction. It also prolongs time away from work, as well as home for rural patients who must relocate while awaiting surgery in major centers. Previously, it has been shown that performing closed hand fracture fixation on awake patients in a clinic or procedure room setting leads to 60-100% increases in daily case volume compared to the main operating room (OR) (Gillis, Steve). Fixation of hand fractures in this setting has also been shown to cost over 2000$ less than in the OR, by reducing staffing requirements, equipment, and anesthesia costs (Steve).

Performing hand surgery in awake patients under local anesthesia has been shown by numerous studies to be a safe and effective. Wide-awake hand surgery is generally well-tolerated, has lower post-operative opioid requirements, and is often preferred by patients (Thompson). Furthermore, by preventing the need for general anesthesia, this technique allows hand surgery to be performed in patients who may otherwise not be operative candidates. During flexor tendon repair, awake surgery provides the unique advantage of being able to actively test the repair intraoperatively. In Canada, awake surgery under local anesthesia is commonly done for tendon repairs, carpal tunnel release, and percutaneous pinning of fractures without a tourniquet (Gillis, Steve, Peters). While tourniquet use improves visualization of the operative field, when only local anesthesia is used patients can typically tolerate the tourniquet for less than 20 minutes before pain begins.

However, for ORIFs, flexor tendon repairs, etc., the use of a tourniquet is ideal for exposure of the operative site. Current literature suggests that the maximum pain-free tourniquet time is roughly 20 minutes, which is less than the average length of ORIFs (Gillis) and flexor tendon repair. Intravenous regional anesthesia (IVRA), i.e. Bier blocks, are well-established means of providing anesthesia for hand surgeries requiring tourniquet use, and enable tourniquet times from 20 minutes to two hours (Dekoninck, Brown). While these blocks prevent the need for general anesthesia, they still require an anesthetist to perform and monitor the block. More recently, forearm tourniquets with IVRA have been shown to be non-inferior to traditional proximal arm tourniquets, with lower doses of post-operative opioids required (Dekoninck, Farbood). However, compared to local anesthesia, IVRA for procedures were tourniquets are preferred still increases costs, staffing requirements, and resource use as they often take place in the OR. However, local anesthetic infiltration by the treating surgeon may not provide sufficient pain relief for the amount of tourniquet time required to complete many hand surgeries. Therefore, although many methods of anesthesia for hand surgery exist, include local anesthetic infiltration and proximal nerve blocks, there is not yet one 'gold standard' approach.

Ultrasound guided peripheral nerve blocks at the forearm level have previously been shown to be a safe, effective method of providing regional anesthesia for minor hand procedures, that are tolerated well by patients (Winter). The technique can be quickly taught to even junior residents, and does not require any specialized equipment outside of the ultrasound probe (Winter). These blocks take roughly five minutes to perform, and anesthesia is achieved after an additional five minutes, shorter than typical times for blind forearm nerve blocks (Lovely).

The investigators hypothesize that the pain patients experience after 20 minutes of tourniquet application with local anesthetic infiltration is not due to direct pressure on the proximal arm, but rather distal digital ischemia pain. Previously, it has been shown that ultrasound-guided regional block of the median, radial, and ulnar nerves in the forearm is effective analgesia for awake hand surgery (Winter). Currently, there are no randomized studies investigating if forearm nerve blocks can prolong pain-free tourniquet time compared to local anesthesia infiltration, by blocking this ischemic pain in the distal arm. The investigator's aim is therefore to determine if forearm nerve blocks prolong pain-free tourniquet time compared to local anesthetic infiltration.