A Modified Approach Below the Lateral Arcuate Ligament to Facilitate the Subcostal Anterior Quadratus Lumborum Block

PURPOSE: The subcostal quadratus lumborum (QL) block was used in postoperative analgesia for abdominal surgery. However, it is difficult to precisely put the needle tip into the target fascia compartment. In the current study, we proposed a modified approach to facilitate the subcostal QL block. PATIENTS AND METHODS: Twenty-four patients scheduled for laparoscopic renal surgery were enrolled. The modified QL block was placed preoperatively. The transducer was placed just laterally to the tip of L1 transverse process to perform the parasagittal scan. The needle was inserted in-plane and advanced toward the target compartment between the QL muscle and the anterior thoracolumbar fascia and just below the lateral arcuate ligament. The 20 mL of 0.5% ropivacaine was injected slowly if the saline spread cranially via the posterior pathway of lateral arcuate ligament was observed on the sonogram. Then, the paramedian transverse scanning at the level of T12-L1 was performed to observe the injectate diffusion. The dermatomal coverage of sensory block was tested at 5 min and 10 min after LA injections. The complications associated with the block were recorded. RESULTS: Twenty-three (95.8%) patients received the successful block. All patients achieved the sensory block dermatomes of T9–T12 and T6–L1, at 5 and 10 minutes after injection, respectively. The mean numbers of block dermatomes were 5.6±1.8 at 5 min and 6.5±2.2 at 10 min after injection. Two out of twenty-three (8.7%) patients achieved coverage as cephalad as T5 at 10 min after injections. The lunar-shaped spread of LA along the diaphragm into the T12 paravertebral space was observed in every patient. No complications occurred. CONCLUSION: The modified subcostal QL block has the advantages of clear sonoanatomy, rapid onset time, and consistent dermatomal coverage and provides a new choice for postoperative analgesia of abdominal surgery. TRIAL REGISTRATION: Chinese Clinical Trial Registry: ChiCTR2000029210.