Abstract

NM-296

Feasibility of Using Ultrasound verification for Laparoscopic-Assisted TAP Blocks in Children

Munshey F, Chao S, Taylor J, Ramamurthi R, Tsui B
Lucille Packard Children's Hospital Stanford, Stanford, CA, United states

Introduction
Transverse abdominis plane (TAP) blocks for laparoscopic surgery have been shown to reduce post-operative pain. Recently, laparoscopic guided TAP blocks (LTAP) for adult surgery have emerged as an alternative to ultrasound guided TAP blocks (UTAP). (1) LTAP performed by the surgeon, rely on a sensation of a needle pop through the internal oblique muscle into the TAP along with Doyle’s internal bulge sign on the laparoscope camera as a marker for correct local anesthetic (LA) placement. The study objective is to investigate the spread of LA injection with LTAP using pre/post ultrasound (U/S) images and correlating them with post-operative pain scores and time to first rescue pain medication.

Methods
Following research ethics board approval, we conducted a prospective feasibility study on pediatric patients having laparoscopic general surgery. Parental consent was obtained on the day of surgery. After pneumoperitoneum, a pre-TAP block U/S image using a sterile high frequency linear probe was captured, followed by the surgeon performing bilateral LTAPs with a 22-gauge 50mm Pajunk needle with 0.5ml/kg of 0.25% bupivacaine per side (max 10mls). Immediately after, another ultrasound image was captured in the exact location. Post-operatively, 24-hour pain scores and time to first pain medication were recorded. U/S spread of LA was interpreted as being completely, partially or absent from the TAP by a blinded Pediatric Anesthesiologist.

Results
Five patients were approached and four patients were successful recruited with 8 LTAPs. 50% of the cases (2/4) showed at least partial or complete injection of LA in the TAP. In the cases where LA was not seen in the TAP at all, there were high pain scores seen with need of post-operative rescue pain medication within 6 -7 hours after the LA injection (Table 1).

Discussion
This is the first study to use U/S to examine the spread of LA after the performance of a LTAP. In our 4 patients studied, we successfully demonstrated that images can be acquired immediately after performing the LTAP with good visualization of LA spread using standard volumes. The potential benefit of having this information is the hope that it may better predict post-operative pain control. Though this small sample size is not adequate to infer on clinical efficacy, it does however, prove the concept and confirm feasibility to conduct future randomized controlled trials comparing LTAP vs UTAP with their spread and its correlation with post-operative pain.

Conclusion
Use of U/S to verify spread of LA for a LTAP block was used successfully, however its correlation with clinical efficacy needs further investigation.

References
1. Ravichandran NT, Sistla SC, Kundra P, et al. Laparoscopic-assisted Transverse Abdominis Plane block versus Ultrasonogrpahy guided TAP block in Postlaparoscopic Cholecystectomy Pain Relief: A Randomized Control Trial. Surg Laparosc Endosc Percutan Tech. 2017 Aug;27(4):228-232.