Quadratus lumborum block (QLB)

Abstract

Background and Objectives: The quadratus lumborum block (QLB) is an abdominal truncal block, similar to transversus abdominis plane block (TAPB). However, the characteristics of QLB with regard to its duration and safety are notwell known. The primary aimof this study was to deter- mine the block duration and the cutaneous sensory block area.Our second- ary analysis included assessment of the chronological change in arterial local anesthetic concentrations after QLB. Methods: This study included 11 patients scheduled for laparoscopic ovarian surgery under general anesthesia. The patients received bilateral single-injection QLBs (20 mL of 0.375% ropivacaine per side). Arterial blood was sampled at 10, 20, 30, 45, 60, 90, and 120 minutes after ropivacaine administration. The resultswere retrospectively comparedwith the results of our previous study on lateral TAPB. Results: The median duration of analgesia after QLB exceeded 24 hours andwas significantly longer than the duration of lateral TAPB(P =0.003). Quadratus lumborum block affected the T7-T12 dermatomes, whereas TAPB affected T10-T12. Arterial ropivacaine levels after block peaked at comparable time in the QLB and lateral TAPB groups (Tmax:35 [SD, 13] vs 35[SD, 11]minutes; P = 0.93). Peak ropivacaine concen- trations were significantly lower in QLB than in lateral TAPB (Cmax: 1.0[SD, 0.5] vs 1.8[SD, 0.4]μg/mL; P = 0.0003). Conclusions: Quadratus lumborum block resulted in a widespread and long-lasting analgesic effect after laparoscopic ovarian surgery and resulted in lower peak arterial ropivacaine concentrations as comparedwith those of lateral TAPB after 150 mg ropivacaine injection.