Ultrasound-guided lumbar plexus block in volunteers; a randomized controlled trial.

Background: The currently best-established ultrasound-guided lumbar plexus block (LPB) techniques use a paravertebral location of the probe, such as the lumbar ultrasound trident (LUT). However, paravertebral ultrasound scanning can provide inadequate sonographic visibility of the lumbar plexus in some patients. The ultrasound-guided shamrock LPB technique allows real-time sonographic viewing of the lumbar plexus, various anatomical landmarks, advancement of the needle, and spread of local anaesthetic injectate in most patients. We aimed to compare block procedure outcomes, effectiveness, and safety of the shamrock vs LUT. Methods: Twenty healthy men underwent ultrasound-guided shamrock and LUT LPBs (2% lidocaine­adrenaline 20 ml, with 1 ml diluted contrast added) in a blinded randomized crossover study. The primary outcome was block procedure time. Secondary outcomes were procedural discomfort, number of needle insertions, injectate spread assessed with magnetic resonance imaging, sensorimotor effects, and lidocaine pharmacokinetics. Results: The shamrock LPB procedure was faster than LUT (238 [sd 74] vs 334 [156] s; P=0.009), more comfortable {numeric rating scale 0­10: 3 [interquartile range (IQR) 2­4] vs 4 [3­6]; P=0.03}, and required fewer needle insertions (2 [IQR 1­3] vs 6 [2­12]; P=0.003). Perineural injectate spread seen with magnetic resonance imaging was similar between the groups and consistent with motor and sensory mapping. Zero/20 (0%) and 1/19 (5%) subjects had epidural spread after shamrock and LUT (P=1.00), respectively. The lidocaine pharmacokinetics were similar between the groups. Conclusions: Shamrock was faster, more comfortable, and equally effective compared with LUT. Clinical trial registration: NCT02255591

The suprasacral parallel shift vs lumbar plexus blockade with ultrasound guidance in healthy volunteers--a randomised controlled trial.

Surgical anaesthesia with haemodynamic stability and opioid-free analgesia in fragile patients can theoretically be provided with lumbosacral plexus blockade. We compared a novel ultrasound-guided suprasacral technique for blockade of the lumbar plexus and the lumbosacral trunk with ultrasound-guided blockade of the lumbar plexus. The objective was to investigate whether the suprasacral technique is equally effective for anaesthesia of the terminal lumbar plexus nerves compared with a lumbar plexus block, and more effective for anaesthesia of the lumbosacral trunk. Twenty volunteers were included in a randomised crossover trial comparing the new suprasacral with a lumbar plexus block. The primary outcome was sensory dermatome anaesthesia of L2-S1. Secondary outcomes were peri-neural analgesic spread estimated with magnetic resonance imaging, sensory blockade of dermatomes L2-S3, motor blockade, volunteer discomfort, arterial blood pressure change, block performance time, lidocaine pharmacokinetics and complications. Only one volunteer in the suprasacral group had sensory blockade of all dermatomes L2-S1. Epidural spread was verified by magnetic resonance imaging in seven of the 34 trials (two suprasacral and five lumbar plexus blocks). Success rates of the sensory and motor blockade were 88-100% for the major lumbar plexus nerves with the suprasacral technique, and 59-88% with the lumbar plexus block (p > 0.05). Success rate of motor blockade was 50% for the lumbosacral trunk with the suprasacral technique and zero with the lumbar plexus block (p < 0.05). Both techniques are effective for blockade of the terminal nerves of the lumbar plexus. The suprasacral parallel shift technique is 50% effective for blockade of the lumbosacral trunk.