Comments on “Continuous Pericapsular Nerve Group Block for Hip Surgery: A Case Series”

Abstract

To the Editor W e read with interest the recently published case series on continuous Pericapsular Nerve Group (cPENG) block by Singh et al. 1 We congratulate and thank the authors for sharing their clinical experience. We would like to address the following issues.We agree with the author for the use of continuous catheter technique over a single-shot PENG block to increase the duration of analgesia. Recent literature also supports the use of cPENG for hip fractures in adult (intertrochanteric, subtrochanteric, and neck of femur) and pediatric (transcervical fracture of the femur) patients to provide effective analgesia in the perioperative period. 2,3 The PENG block targets the articular branches of femoral, obturator, and accessory obturator nerves that innervate the anteromedial hip capsule. The pain generators before and after hip surgery are different. Before surgery, pain is due to the pathology in the hip joint, which irritates the richly innervated capsule and surrounding nociceptors. But after surgery, it is mainly confined to the surgical dissection area. PENG block is best for joint analgesia but may not cover all the innervations of surgical dissection area. Hence, an adjunctive block like lateral femoral cutaneous nerve (LFCN) block 4 or opioid analgesics for optimal analgesia may be needed postoperatively.The authors have used 20 mL of local anesthetic (LA) as an initial bolus before starting the infusion. Based on the clinical findings, a decrease in the initial bolus from 20 to 10 mL has also been suggested recently to avoid the unintended quadriceps weakness. 5 Low volume LA may be adequate to cover the anterior hip joint capsule effectively as demonstrated in a cadaveric dye study. 6 The spreading pattern of 10 mL methylene blue dye was less than that of 20 mL. Still, it effectively stained the bursal space between the iliopsoas and anterior hip joint capsule. The spread in the subpectineal plane toward the obturator nerve may be less with the decrease in the volume of LA. However, few authors have reported motor weakness and analgesia in the LFCN territory with higher volumes and superficial deposition of LA. 5 So, it is difficult to comment on the appropriate volume of LA for the PENG block without a dose-finding study.One should be cautious about the inadvertent injury to LFCN while inserting the needle and the possibility of intravascular cannulation following catheter placement. 2,5 The catheter-through-needle technique was found to be more comfortable than catheter-over-needle method while inserting the catheter below the psoas tendon. 2 Further anatomical and clinical studies are needed to assess the benefits and complication of the cPENG block.

In Response

“…In Response W e would like to express our thanks to Sonawane and Mistry 1 for their insights on our publication. 2 We agree that the continuous Pericapsular Nerve Group (PENG) block is best suited for analgesia around the hip joint.…”