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

Abstract

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

Real-Time Ultrasound/MRI Fusion for Suprasacral Parallel Shift Approach to Lumbosacral Plexus Blockade and Analysis of Injectate Spread: An Exploratory Randomized Controlled Trial

“…This is in keeping with previous studies investigating plasma concentration of local anesthetics in regional anesthesia [9, 32, 35]. No dose-finding studies have been conducted for the SSPS technique, but the minimal effective anesthetic volume of 0.5% ropivacaine to accomplish a successful Shamrock lumbar plexus blockade in 95% of patients (ED 95 ) is 36.0 mL (95% CI 19.7 to 52.2) [36].…”

“…Few previous studies have compared ultrasonography and MRI of the lumbosacral anatomy [30] and analyzed injectate spread with MRI [9, 31, 32]. The sensory mapping demonstrated segmental anesthesia from L2 to S1 in accordance with the perineural spread analyzed by MRI.…”

“…Based on ultrasound/MRI visualization of the intertransverse ligament (posteriorly) and the lumbosacral ligament (anteriorly) marking out the osteofibrotic tunnel, the tip of the block needle was placed in the anticipated position for needle insertion caudad to the intercristal line. Using needle navigation, the position and angle of the insertion were adjusted until the anticipated intersection of the needle tip and the ultrasound beam coincided with the target compartment posterior to the psoas major muscle [8, 9] displayed on the MR image (Figure 1). Guided by real-time ultrasound/MRI fusion and needle navigation, the needle was advanced with an out-of-plane technique until a “loss of resistance” confirmed the visualized penetration through the lumbosacral ligament and the needle tip position anterior to the ligament on MRI.…”

“…This technique was performed in the lateral decubitus position and has been described in-depth previously [9]. The endpoint of injection was “loss of resistance” confirming the needle penetration of the lumbosacral ligament, sonographically visualized if possible.…”

“…All these nerves can be anesthetized with a single injection paravertebrally between the transverse process of the fifth lumbar (L5) vertebra and the cranial border of the sacral ala [7, 8]. However, the accuracy of targeting the nerves with an ultrasound guided injection may be impaired due to the deep location of the target nerves as well as the lumbosacral bony structures generating acoustic shadows impeding the visibility of the needle trajectory [9], especially in old, fragile, comorbid, or obese patients [10–13]. Consequently, the efficiency and safety of the blockade may be undesirably affected and epidural spread of the injectate [9] as well as vascular, neural, or muscular injury may occur.…”