Analgesic efficacy of ultrasound-guided regional anesthesia: a meta-analysis.

STUDY OBJECTIVE To determine if the use of ultrasound guidance (vs non-ultrasound techniques) improves the success rate of nerve blocks. DESIGN Meta-analysis of randomized controlled trials (RCTs) in the published literature. SETTING University medical center. MEASUREMENTS 16 RCTs of patients undergoing elective surgical procedures were studied. Patients underwent ultrasound-guided or non-ultrasound techniques (nerve stimulation, surface landmark) for peripheral nerve blocks. Success rates were measured. MAIN RESULTS Ultrasound guidance (vs all non-ultrasound techniques) was associated with a significant increase in the success rate of nerve blocks [relative risk (RR) = 1.11 (95% confidence interval [CI]: 1.06 to 1.17, P < 0.0001]). When compared with nerve stimulator techniques only, ultrasound guidance was still associated with an increase in the success rate (RR = 1.11 [95% CI: 1.05 to 1.17, P = 0.0001]). For specific blocks, ultrasound guidance (vs all non-ultrasound) was associated with a significant increase in successful brachial plexus (all) nerve blocks (RR = 1.11 [95% CI: 1.05 to 1.20, P = 0.0001]), sciatic popliteal nerve block (RR = 1.22 [95% CI: 1.08 to 1.39, P = 0.002]) and brachial plexus axillary nerve block (RR = 1.13 [95% CI: 1.00 to 1.26, P = 0.05]) but not brachial plexus infraclavicular nerve block (RR = 1.25 [95% CI: 0.88 to 1.76, P = 0.22]). CONCLUSIONS Ultrasound-guided peripheral nerve block is associated with an increased overall success rate when compared with nerve stimulation or other methods. Ultrasound-guided techniques also increase the success rate of some specific blocks.