O2092: Quadratus Lumborum Blocks Reduce Post-operative Opioid Utilization After Laparoscopic Appendectomy: A Single Institution Review

Background: The quadratus lumborum (QL) block is a regional anesthetic technique which covers T7 to L1 dermatomes, making it an optimal choice for upper and lower abdominal procedures. QL blocks have been shown to reduce pain scores and post-operative rescue opioid analgesic use in adults undergoing laparoscopic pelvic surgeries. There is limited evidence to support utilization of QL blocks in the pediatric population. In this study, we assess the impact of QL blocks on pain scores and opioid utilization in patients undergoing laparoscopic appendectomy. We hypothesize that patients receiving preoperative QL blocks will have lower pain scores and decreased utilization of opioid analgesics.

Methods: A retrospective chart review was conducted for 2,179 pediatric patients undergoing laparoscopic appendectomy at two hospitals within a multi-hospital children’s health care system from 2017-2021. One of the hospitals routinely utilized preoperative QL blocks. We evaluated associations between block status (no block vs. QL block) and pain scores, proportion of patients requiring rescue opioid analgesia, and total morphine equivalent utilization both in PACU and in the 24-hour post-operative period. We also compared adjunct analgesic use including acetaminophen and NSAIDs (ketorolac or ibuprofen) between the groups. Subgroup analyses were conducted according to appendicitis category (uncomplicated vs. complicated).

Results: The QL block group had lower pain scores in the PACU (2.5 vs. 2.9, p=0.01) and post-operatively (2.3 vs. 2.8, p=0.003). Additionally, the proportion of patients requiring rescue opioid analgesia in the QL block group was reduced in the PACU (41.6% vs. 51.0%, p< 0.001) and in the first 24 hours post-operatively (12.1% vs. 28.4%, p< 0.001) compared to those without a block. Morphine equivalent utilization (mg/kg) was reduced in the PACU (0.062 vs. 0.101, p< 0.001), but not in the 24-hour post-operative period (0.054 vs. 0.071, p=0.33). Adjunct analgesic use was higher in the QL group for both acetaminophen (10.2% vs. 6.9%, p=0.01) and NSAIDs (33.0% vs. 18.3%, p< 0.001) in the PACU, but not in the 24-hour post-operative period. Similar trends were noted when patients were stratified into complicated versus uncomplicated appendicitis groups.

Conclusion: QL blocks represent a useful adjunct to multimodal perioperative pain regimens to reduce pain and limit opioid usage, as patients who received QL blocks reported lower pain scores and were less likely to receive rescue opioid analgesia. Our results also underscore the fact that consistent administration of acetaminophen and ibuprofen is a critical component of opioid stewardship. The observed reduction in morphine equivalents in the PACU which did not persist in the 24-hour post-operative period is not surprising since QL blocks are most effective for 6 to 8 hours. Further studies with protocolized opioid and non-opioid pain management regimens are needed to assess the efficacy of QL blocks in minimizing overall opioid utilization.