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

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.

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.

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)).

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