Forearm ultrasound-guided nerve blocks vs landmark-based wrist blocks for hand anesthesia in healthy volunteers

Abstract

Objective: Although ultrasound-guided regional nerve blocks have become more commonplace in the emergency department, there is no evidence to suggest that they are more effective than traditional landmark-based wrist blocks for hand anesthesia. We hypothesized that ultrasound-guided forearm nerve blocks would provide superior analgesia as compared with conventional landmark-based wrist blocks.

Methods: Eighteen paired nerve injections were performed by an experienced operator on 12 healthy volunteers. Each subject's right arm was assigned to receive either an ultrasound-guided forearm block with a saline placebo wrist block or a traditional landmark-based wrist block with a saline placebo ultrasound-guided forearm block. The subject's left arm then received the alternate approach. All blocks were performed with 3 mL of 1% lidocaine. We evaluated sensory block to pinprick. Secondary outcome variables included pain associated with injection, participant's subjective assessment of block effectiveness, and presence of any complications.

Results: At 15 minutes postinjection, 14 of 18 (78%; 95% confidence interval [CI], 59%-97%) ultrasound-guided forearm blocks were successful, as opposed to 10 of 18 (56%; 95% CI, 33%-79%) anatomic wrist blocks. The ultrasound-guided forearm blocks had a 22% (95% CI, 2%-42%; P=.032) higher rate of success than the wrist blocks. The ultrasound-guided forearm block was subjectively felt to be denser by 12 of 18 (67%) subjects (P=.0034)).

Conclusions: Ultrasound-guided forearm nerve blocks performed by an experienced operator result in more effective hand anesthesia than traditional anatomic landmark-based wrist blocks.