Proximal RUMM block in dogs: preliminary results of cadaveric and clinical studies

Ultrasound-Guided Greater Ischiatic Notch Plane Block Combined with the Caudal Quadratus Lumborum Block (GIN-TONIC Block) in Dogs Undergoing Pelvic Limb Surgery: Preliminary Results

This study assessed the analgesic and motor effects of the GIN-TONIC block, a combination of the greater ischiatic notch plane block and the caudal lateral quadratus lumborum block, in 24 dogs undergoing pelvic limb surgery. Dogs were randomly divided into two equal groups: GA received acepromazine [(20 µg kg-1 intravenously (IV)] as premedication, and GD received dexmedetomidine (2 µg kg-1 IV). General anesthesia was maintained with isoflurane, and both groups received a GIN-TONIC block using 2% lidocaine. Nociception during surgery and postoperative pain [assessed using the Glasgow Composite Measure Pain Score (GCMPS-SF)] were assessed. Fentanyl (2 µg kg-1 IV) was administered if nociception was noted and morphine (0.5 mg kg-1 IV) was administered during recovery if the pain scores exceeded the predefined threshold. Motor function was assessed during the recovery period using descriptors previously reported. All dogs received analgesics at the 4 h mark before being discharged. Three and two dogs in GD and GA required fentanyl once. Postoperative pain scores remained ≤4/20 for all dogs except one. Dogs achieved non-ataxic ambulation within 38.9 ± 10.3 and 35.1 ± 11.1 min after extubation in GD and GA, respectively. This study highlighted the potential of the GIN-TONIC block as a feasible regional anesthesia method for delivering perioperative analgesia in dogs undergoing pelvic limb orthopedic surgery.

Perioperative analgesic efficacy of lumbar erector spinae plane block in dogs undergoing hemilaminectomy: a randomized blinded clinical trial

OBJECTIVE

To evaluate the perioperative analgesic effect of the unilateral lumbar erector spinae plane block (ESPBL) in dogs undergoing hemilaminectomy.

STUDY DESIGN

Randomized, blinded clinical study.

ANIMALS

A total of 30 client-owned dogs undergoing thoracolumbar or lumbar hemilaminectomy for intervertebral disc extrusion (IVDE).

METHODS

Dogs were randomly assigned to receive a unilateral ESPBL, performed either with 0.4 mL kg-1 ropivacaine 0.5% [group ROPI (n = 15)] or with saline solution [CNT group (n = 15)]. Dogs were premedicated intravenously (IV) with acepromazine 5 μg kg-1 and methadone 0.2 mg kg-1, general anaesthesia was induced by administering IV midazolam 0.2 mg kg-1 and propofol to effect and maintained with isoflurane. Fentanyl was administered as rescue analgesia. Bradycardia [heart rate (HR) < 60 beats minute-1] with hypotension was treated with atropine IV. The Short-Form of the Glasgow Composite Pain Scale was used pre- and postoperatively at 1, 2, 4, 8, 12, 16, 20 and 24 hours after extubation, and methadone 0.2 mg kg-1 was administered IV when pain score was ≥ 5/20. HR and end-tidal concentration of isoflurane (Fe'Iso) were compared between groups with anova combined with a Dunnet's post hoc test. Time to the first rescue methadone and total dose of fentanyl (FENtot, μg kg-1 hour-1) and methadone (METtot, mg kg-1) in the first 24 postoperative hours were compared using unpaired Student's t test. Postoperative pain scores were compared with the Mann-Whitney test and atropine administration with a Fisher's exact test; p < 0.05.

RESULTS

HR, Fe'Iso, FENtot, METtot and atropine administration were significantly lower in group ROPI compared to CNT. Postoperative analgesic effect was significantly longer, and pain scores were significantly lower in group ROPI for all time points.

CONCLUSIONS AND CLINICAL RELEVANCE

Unilateral ESPBL with ropivacaine reduced perioperative opioid consumption and the occurrence of bradycardia in dogs undergoing hemilaminectomy.

Fentanyl sparing effect of ultrasound-guided proximal radial, ulnar, median, and musculocutaneous nerve (RUMM) block for radial and ulnar fracture repair in dogs: a retrospective case-control study

This study retrospectively evaluated the fentanyl-sparing effect of ultrasound-guided proximal radial, ulnar, median, and musculocutaneous nerve (RUMM) block for radial and ulnar fracture repair in dogs. Fentanyl was prepared for intraoperative analgesia in dogs, although proximal RUMM block was performed using 0.5% or 0.25% bupivacaine before surgery in the block group. Dogs without a nerve block were assigned to the control group. The fentanyl dose in the block group [0.8 (0-1.9) μg/kg/hr] [median (interquartile range)] was significantly lower than in the control group [8.4 (7.2-10) μg/kg/hr]. Surgery was performed without fentanyl in >50% of the dogs (5/7), using 0.5% bupivacaine. Ultrasound-guided proximal RUMM block can be useful as an intraoperative analgesic for radial and ulnar fracture repair in dogs.

Axillary ultrasound-guided approach for the brachial plexus in pig cadavers: A descriptive study

Effective multimodal analgesia techniques are required when pigs are used as models in orthopedic human research. Regional anesthesia is a widely used technique to provide perioperative analgesia in animals undergoing orthopedic surgery. The brachial plexus (BP) block is indicated to desensitize the forelimb in many species but has not been yet described in pigs. The main aims of this study were to develop an ultrasound-guided axillary approach for the BP and to evaluate injectate spread and nerve staining in pig cadavers. Eight fresh F1 cross breed German Large White and German Landrace male pig cadavers were enrolled. Two cadavers were used for anatomical dissection of the axillary space and to determine the disposition of the BP. Six cadavers were used to perform a bilateral axillary ultrasound-guided approach for the BP, and after injecting 0.3 ml/kg of a solution of 2% lidocaine and new methylene blue (L-NMB), these were dissected to determine injectate spread and nerve staining. Upon dissection, the BP was observed in all the cases surrounded by the axillary sheath and in close proximity to the axillary artery. Ultrasonographic scanning and guidance for the approach to the BP was feasible in all cadavers and upon dissection, all the nerves forming the BP were stained in all their quadrants and in all the cases. In conclusion, the injection of 0.3 ml/kg of L-NMB through an ultrasound-guided axillary approach to the BP was feasible and adequate to entirely stain the BP in all pig cadavers. Further clinical studies are required to evaluate the effectiveness of this technique in live animals.

Lateral ultrasound-guided axillary RUMM block in cats: a pilot cadaveric study

OBJECTIVES

This study aimed to describe the prominent landmarks for an in-plane ultrasound-guided lateral approach to an axillary RUMM block in cats and document the anatomical distribution of injected solution in cadavers.

METHODS

Eleven mixed breed, frozen-thawed cat cadavers were used. The ultrasound probe was placed on the lateral aspect of the forelimb. A spinal needle was used to inject either methylene blue 5 mg/ml or permanent tissue dye 1:10 within the focal clustering point of the radial (R), ulna (U), median (M) and musculocutaneous (Mc) nerves. The block was approached from either a cranial or caudal direction. Specimens were immediately dissected. A successful block was defined as ⩾20 mm of continuous stain on all nerves (R, U, M and Mc), a partial block as one or more nerves stained ⩾20 mm continuously and a negative block failed to stain any nerve ⩾20 mm.

RESULTS

The cranial approach stained the R 8/9, U 6/9, M 6/9 and Mc 8/9 nerves successfully, while the caudal approach stained the R 7/9, U 8/9, M 7/9 and Mc 5/9 nerves successfully. There were no statistical differences on staining rates between approaches or limbs used.

CONCLUSIONS AND RELEVANCE

The lateral approach to an axillary RUMM block is feasible in cats and may be a useful alternative to current approaches used for brachial and antebrachial desensitisation. Both cranial and caudal approaches produced similar results; however, further research in live animals will determine the clinical applicability.

Development of a lateral ultrasound-guided approach for the proximal radial, ulnar, median and musculocutaneous (RUMM) nerve block in cats

OBJECTIVE

To describe a lateral ultrasound (US)-guided approach to the radial, ulnar, median and musculocutaneous (RUMM) nerves through a single proximal in-plane insertion in cats and to determine whether one or two injection points are required to successfully stain all the target nerves.

STUDY DESIGN

Prospective study.

ANIMALS

A total of eight client-owned healthy cats and 12 cat cadavers.

METHODS

In live cats, the US anatomy of the brachium, the landmarks and the site for needle accesses were determined. Then, 12 thawed feline cadavers were used to assess the spread of dye solution and nerve staining following the US-guided proximal-lateral-humeral RUMM injection using one and two injection points. Each cadaver was injected with 0.15 mL kg^-1 of a 0.25% new methylene blue solution in either a single injection aimed for the radial nerve of one limb (G1) or via two sites delivering 0.1 mL kg^-1 and 0.05 mL kg^-1 aimed for the radial and musculocutaneous nerves of the opposite limb, respectively (G2). Upon dissection, staining of the target nerves around their circumference for length of >1 cm was considered successful.

RESULTS

Sonoanatomy was consistent with anatomy upon dissection and target nerves were identified in all cadavers. Staining was 100% successful for the radial, median and ulnar nerves in both groups, and 41.7% and 100% for the musculocutaneous nerve in G1 and G2, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

This novel lateral US-guided approach for the proximal RUMM nerve block allowed a good identification of the nerves and related structures, and it provided a consistent muscular structure through which the needle could be easily guided. An injection performed in two aliquots (within the caudal and cranial compartments of the neurovascular sheath) appeared to be necessary to successfully stain all the target nerves.

Locoregional Anesthesia of the Thoracic Limbs and Thorax in Small Animals

The incorporation of nerve stimulation and ultrasound guidance to veterinary regional anesthesia allows accurate performance of techniques to block the thoracic limb and the thorax. When performed correctly, regional anesthesia can either constitute an alternative to the use of opioids and other systemic analgesics, or have a significant opioid-sparing effect. This article provides an overview of some techniques described using objective methods of nerve location, which can be used to provide perioperative locoregional anesthesia and analgesia to the thoracic limb and thorax. The approaches described may be used to decrease the perioperative use of opioids in small animals.

Ultrasonographic study of a modified axillary approach to block the major branches of the brachial plexus in dogs

OBJECTIVE

To provide ultrasonographic mapping of the axillary region of dogs to facilitate identification of the major branches of the brachial plexus in relation to the axillary artery.

STUDY DESIGN

Prospective study.

ANIMALS

A total of two dog cadavers and 50 client-owned, healthy dogs weighing >15 kg.

METHODS

In Phase 1, anatomical dissections were performed to identify the relation of the major brachial plexus nerves to the axillary artery. In Phase 2, with the dogs in dorsal recumbency with thoracic limbs flexed naturally, the axillary space was scanned using a linear array probe oriented on the parasagittal plane until the axis transverse to nerves was found. Then, the transducer was rotated to a slight lateral angle approximately 30° to midline. The examination aimed to identify the axillary artery and the musculocutaneous, radial, median and ulnar nerves in addition to determining their position and distribution in four predefined sectors.

RESULTS

The musculocutaneous nerve was observed in all animals cranial to the axillary artery. The radial, ulnar and median nerves were distributed around the axillary artery, with >90% on the caudal aspect of the axillary artery (sectors 1 and 2).

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasonography identified the location of the brachial plexus nerves near the studied sectors, providing useful guidance for performing a brachial plexus nerve block.