Although peripheral nerve blocks have been a safe and effective way to provide analgesia for procedures in a variety of settings, using this type of anesthesia does have risks that should not be overlooked. The incidence of Local Anesthetics Systemic Toxicity (LAST) was reported to be 0.04/1000 to 1.8/1000 in a recent summary. LAST, a life-threatening and sometimes fatal condition, was reported to be related to patient characteristics (such as advanced age, low muscle mass, liver disease, cardiac disease, renal disease or diabetes), local anesthetic characteristics and practice settings.
Lumbar plexus blocks (LPBs) combined with sciatic nerve blocks (SNBs) for lower extremity surgery are becoming increasingly popular. Due to the depth of the lumbar plexus and sciatic nerves, LPBs and SNBs were advanced regional anesthesia techniques and may be more likely to lead to LAST. LPBs and SNBs are traditionally performed using surface anatomical landmarks and nerve stimulation guidance. Ultrasound could offer direct visualization of the nerve structures, needle pathway and local anesthetics (LAs) spread in real time and is thus widely used in peripheral nerve blocks. Accumulating published data suggests higher efficacy and safety of nerve blocks with ultrasound guidance (US),[3,4] specifically for interscalene, supraclavicular, infraclavicular, and axillary blocks. Michael et al. reported that the use of ultrasound reduced the risk of LAST throughout its continuum by 60 to 65% compared to without ultrasound. However, most studies have focused on upper extremity blocks. Due to the deep location of the lumbar plexus and sciatic nerves, whether the use of ultrasound in LPBs and SNBs would be beneficial in terms of efficacy and safety remains a matter of debate. Most relevant published studies have suggested that ultrasound guidance would shorten both the time required to perform the block and the onset time.[10–12] However, there are limited studies comparing the incidence of LAST for LPBs and SNBs with ultrasound and nerve stimulator.
We designed this study to determine whether ultrasound guidance deep nerve blocks would decrease the incidence of LAST compare with nerve stimulation guidance and to identify associated risk factors of LAST.
BMC Anesthesiol. 2019;19(103) © 2019 BioMed Central, Ltd.