Abstract
Background: Ultrasound-guidance might decrease the incidence of local anesthetics systemic toxicity(LAST) for many peripheral nerve blocks compared to nerve stimulation. However, it remained uncertain whether ultrasound-guidance would be superior to the nerve stimulation for deep nerve block in the lower extremity. This study was designed to investigate that deep nerve block with ultrasound-guidance would result in a lower rate of LAST comparing to that with nerve stimulator-guidance.
Methods: Three hundred patients who were for elective lower limb surgery and desiring lumbar plexus blocks(LPBs) and sciatic nerve blocks(SNBs) were enrolled in this study. Patients were randomly assigned to receive LPB and SNB with ultrasound-guidance (Group U), nerve stimulator-guidance (Group N) and dual-guidance (Group M). The primary outcome was the incidence of the LAST. The secondary outcomes were number of needle redirections, motor and sensory block onset and restoration times in the nerve distributions, and associated risk factors.
Results: There were 18 patients with the LAST, including 12 in group U, 4 in group N and 2 in group M. For multiple comparisons among the tree groups, we found that the incidence of LAST in group U(12%) was significantly higher than that in group N(4%)(P=0.037) and group M(2%)(P=0.006). The OR of LAST with HBV infection and female gender was 3.352(95% CI,1.233-9.108, P=0.013 ) and 9.488(95% CI,2.142-42.093, P=0.0004), respectively.
Conclusions: For patients undergoing LPBs and SNBs, use of ultrasound may increase the incidence of the LAST. HBV infection and female gender were risk factors for deep nerve block.
Trial registration: This study was approved by the human research review committee at the southwest hospital of third military medical university. The protocol was registered prospectively with Chinese Clinical Trial Registry (ChiCTR-IOR-16008099) on March 15th,2016.
Keywords: Ultrasound; nerve stimulation; nerve block; female; HBV; LAST