Establishing the quadratus lumborum block in goats

Ultrasound-guided quadratus lumborum block in sheep: A cadaveric study

This prospective anatomical study aimed to establish an ultrasound-guided technique to the quadratus lumborum (QL) plane in sheep cadavers. Thirteen cadavers, weighing less than 117 kg, were included. In phase 1, one cadaver underwent dissection and two cadavers underwent 3D computed tomographic reconstruction for anatomical evaluation of the thoracolumbar region. In phase 2, two cadavers were used to compare two ultrasound techniques to the QL plane: lateral to the QL muscle with a transversal approach (LQL) and transmuscular between QL and psoas muscles with a longitudinal approach (TQL). For LQL, the reference was the first lumbar transverse process, whereas for TQL, it was the intertransverse region between the first and second lumbar vertebrae. The needle was advanced in-plane towards the specific target for each technique and a total of four injections were performed using 0.4 ml kg-1 of a dye-lidocaine solution. In phase 3, 10 cadavers received bilateral LQL injections (n = 20). All cadavers were then dissected to evaluate spread of dye. In phase 2, following LQL injections, no dye was observed in undesired locations; however, the dye was noted in the retroperitoneal space (1/2) after TQL injections. In phase 3, the 13th thoracic, first, second, third lumbar nerves, and sympathetic trunk segments were stained in 80%, 95%, 100%, 45% and 35% of the injections, respectively. In conclusion, the LQL technique was feasible, allowing staining of the spinal nerves innervating the cranial abdomen in sheep cadavers. Further studies in live animals are warranted.

Ultrasound-Guided Dorsolateral Approach for Quadratus Lumborum Block in Rabbits (Oryctolagus cuniculus): A Prospective, Randomized, Blinded, Cadaveric Study Comparing Four Different Injectate Volumes

Ultrasound-guided (US-guided) loco-regional anesthesia can provide significant analgesia and anesthetic-sparing effects when used in rabbits. The aims of this study were to investigate the thoraco-lumbar anatomy of the rabbits, particularly the quadratus lumborum (QL) muscle, to design an appropriate US-guided quadratus lumborum block (QLB) specific for rabbits, and to define the most adequate volume of injectate required to consistently cover the ventral branches of T11 to L3 without affecting the pelvic limb innervation (L4, L5 and L6). Sixteen adult rabbit cadavers were included in the study. After randomization, four different volumes of injectate (0.1 mL/kg, 0.2 mL/kg, 0.3 mL/kg and 0.4 mL/kg) were tested, with these volumes additionally randomized to two sites of injection (right or left QL fascia). An ultrasound-guided QLB was performed with a solution of lidocaine, iodinated contrast and tissue dye (in a proportion of 3:1:1 volume, respectively), with subsequent computed tomography (CT) and anatomical dissection, to evaluate the spread of the injectate. In all but one case, the US-guided QLB performed with a dorsolateral approach using 0.3 mL/kg was adequate, while a dose of 0.4 mL/kg consistently reached the targeted nerves but also extended to L4 and caudally. This may suggest that an injectate volume of 0.3 mL/kg may be the most appropriate to produce adequate spread while not affecting pelvic limb innervation.

Evaluation of High-Volume Injections Using a Modified Dorsal Quadratus Lumborum Block Approach in Canine Cadavers

Simple Summary

The quadratus lumborum (QL) block is an ultrasound-guided locoregional anesthesia technique. Its objective is to promote both visceral and somatic analgesia for abdominal procedures. Previous spread studies carried out in canine cadavers demonstrated its viability in this species but failed in consistently reach the spinal nerves responsible for the cranial abdominal wall innervation. Therefore, we hypothesize that a modified QL block technique, based on the administration of a higher volume of solution (0.6 mL kg⁻¹) in a dorso-medial position compared to the interfascial injection point between the QL and psoas minor muscles, could enhance its cranial spread, and promote a consistent distribution spread through the ventral branches of the spinal nerves and sympathetic trunk. For this purpose, a solution of dye/contrast was ultrasound-guide injected into six canine cadavers. The results were assessed through computed tomography and dissection, showing that the proposed technique is viable, safe, and stained the median and caudal abdominal nerves and the sympathetic trunk up to T13 consistently. However, our modified technique of QL block did not increase the cranial distribution of dye/contrast to the thoracic spinal nerves, and may not provide adequate somatic analgesia of the cranial abdominal wall.

Abstract

The quadratus lumborum (QL) block targets the fascial plane surrounding the QL muscle providing abdominal somatic and visceral analgesia. The extension of its analgesic effects is a subject of research, as it could not cover areas of the cranial abdomen in dogs. This study assesses in eight thawed canine cadavers, the distribution of high-volume injections (0.6 mL kg⁻¹ of a mixture of methylene blue and iopromide) injected between the psoas minor muscle and the vertebral body of L1. Anatomical features of the area of interest were studied in two cadavers. In another six dogs, QL blocks were performed bilaterally under ultrasound-guidance. The distribution of contrast was evaluated by computed tomography (CT). Hypaxial abdominal muscles were dissected to visualize the dye spread (spinal nerves and sympathetic trunk) in 5 cadavers. The remaining cadaver was refrozen and cross-sectioned. CT studies showed a maximum distribution of contrast from T10 to L7. The methylene blue stained T13 (10%), L1 (100%), L2 (100%), L3 (100%), L4 (60%) and the sympathetic trunk T10 (10%), T11 (20%), T12 (30%), T13 (70%), L1 (80%), L2 (80%), L3 (60%) and L4 (30%). These findings may suggest that despite the high volume of injectate administered, this modified QL block could not produce somatic analgesia of the cranial abdomen, although it could provide visceral analgesia in dogs.

A novel ultrasound-guided lateral quadratus lumborum block in dogs: a comparative cadaveric study of two approaches

OBJECTIVE

To describe an ultrasound-guided lateral quadratus lumborum (LQL) block technique and the spread characteristics of lidocaine-dye injected in the LQL plane using a transversal (LQL-T) or a longitudinal (LQL-L) approach.

STUDY DESIGN

Experimental anatomic study.

ANIMALS

A total of eight canine cadavers.

METHODS

Bilateral ultrasound-guided injections in the fascial plane lateral to the quadratus lumborum muscle and medial to the thoracolumbar fascia (LQL plane) with the needle directed at the first lumbar (L1) transverse process were performed using lidocaine-dye (0.3 mL kg^-1). Anatomical dissection determined the dye distribution, sympathetic trunk staining and number of spinal nerves stained circumferentially >1 cm.

RESULTS

The LQL fascial plane was ultrasonographically recognized in all cadavers and filled with lidocaine-dye in all eight cadavers with the LQL-T approach and in six with LQL-L. The injectate spread ventral to the lumbar transverse processes, around the quadratus lumborum muscle and dorsal to the transversalis fascia, affecting the ventral branches of the spinal nerves and the sympathetic trunk. A median (range) of 4 (3-5) and 3 (0-4) ventral branches of the thoracolumbar nerves were dyed with LQL-T and LQL-L approaches, respectively (p = 0.04). The most cranial nerve stained was the twelfth thoracic (T12) with the LQL-T approach and T13 with LQL-L, and the most caudal was L3 with both approaches. The incidence of sympathetic trunk staining was significantly higher using LQL-T (six injections) compared with LQL-L (one injection; p = 0.04). Dye was not observed in the lumbar plexus, epidural space or abdominal cavity.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasound-guided LQL-T approach resulted in a more consistent spread toward the spinal nerves and sympathetic trunk compared with LQL-L approach. Further studies are necessary to assess the LQL block effectiveness and success rate in live dogs.