Ultrasound-guided lumbar plexus block using a transverse scan through the lumbar intertransverse space: a prospective case series.

Abstract

A paramedian transverse scan (PMTS) can be used to delineate the anatomy relevant for ultrasound-guided lumbar plexus block (LPB) through the lumbar intertransverse space. This case series evaluated the feasibility of using the PMTS to guide LPBs for anesthesia. After research ethics committee approval and written informed consent, 15 American Society of Anesthesiologists physical status 1 to III patients with body mass index of less than 35 kg/m scheduled for lower-extremity surgery received an ultrasound-guided LPB and a sciatic nerve block for anesthesia. The blocks were performed using the PMTS and in-plane needle insertion. Localization of the lumbar plexus was confirmed by obtaining quadriceps muscle twitch. Successful blocks were defined as adequate anesthesia for lower-extremity surgery in the sensory territory of the lumbar plexus. The articular process and psoas muscle were visualized on ultrasound in all 15 patients (mean age, 46.3 ± 20.4 years; body mass index, 22.2 ± 2.4 kg/m), but the lumbar plexus was identified in two-thirds of the patients. Blocks were successfully performed in 14 (93%) of the 15 patients. Poor visibility in 1 patient (7%) precluded the use of ultrasound guidance. The needle was visualized in the psoas muscle in 14 patients (93%), whereas proper needle location was confirmed in all patients by nerve stimulation. Needle to lumbar plexus contact was delineated on ultrasound in 8 (53%) and 14 patients (93%), before and after injection of local anesthetic, respectively. Adequate anesthesia was accomplished in all patients within 30 minutes of injection. Ultrasound-guided LPBs can be reliably accomplished using the PMTS.