Ultrasound guidance to approach the femoral nerve in the iliopsoas muscle: a preliminary study in the dog.

OBJECTIVE: To describe the location of the femoral nerve within the iliopsoas muscle and determine the feasibility and potential complications of an ultrasound-guided block. STUDY DESIGN: Prospective experimental trial. ANIMALS: Sixteen adult dogs, median weight 14.3 (range 3-37) kg. METHODS: Phase I. Computed tomographic images of the iliopsoas muscle and femoral nerve were analyzed in two dogs. Phase II. The location of the femoral nerve within the iliopsoas muscle was determined via ultrasonography in 11 healthy anaesthetized dogs. Phase III. Peripheral nerve stimulation and ultrasound were combined to perform femoral nerve blocks in three dogs. RESULTS: Using computed tomography, the femoral nerve and its L4-L5 roots were identified within the iliopsoas muscle. The nerve itself was traced until it branched off into the quadriceps femoris muscle. Using ultrasonography, it was possible to observe the femoral nerve in nine dogs (82%). Starting at the dorsal third of the iliopsoas muscle, its path was traced in a caudo-ventro-lateral direction, emerging from the iliopsoas muscle shortly before passing through the muscular lacuna where it became very difficult to identify. An ultrasound-guided femoral nerve approach was carried out successfully in all three dogs. CONCLUSIONS: It is possible to approach the femoral nerve using combined ultrasound guidance and peripheral nerve stimulation to a closer proximal point than previously described. CLINICAL RELEVANCE: The ultrasound-guided approach of the femoral nerve within the iliopsoas muscle has the potential to become an additional approach.

Anatomical and experimental studies of brachial plexus, sciatic, and femoral nerve-location using peripheral nerve stimulation in the dog.

OBJECTIVE: To investigate the anatomy of the brachial plexus, sciatic, and femoral nerves for the use of a peripheral nerve-stimulator to perform nerve blocks in dogs. STUDY DESIGN: Prospective experimental trial. ANIMALS: Four canine cadavers and four healthy adult dogs weighing 23 +/- 2.5 kg. METHODS: Phase I: in four canine cadavers, an anatomical study was conducted to evaluate accurate needle-insertion techniques. Phase II: the utility of these techniques, and the value of electrostimulation, were evaluated in four anesthetized dogs in lateral recumbency (medetomidine, 5 microg kg(-1)/ketamine 5 mg kg(-1)) using an electrical stimulator and shielded needles. RESULTS: For the brachial plexus, the needle was inserted cranial to the acromion, medial to the subscapularis muscle, at an angle of approximately 20-30 degrees in relation to a plane vertical to the surface on which the animal was lying, oriented parallel to the long axis of the animal, in a ventro-caudal direction. For the sciatic nerve, the needle was inserted just cranial to the sacrotuberous ligament, through the gluteus superficialis muscle, at an angle of approximately 60 degrees in relation to the horizontal plane, in a ventro-cranial direction, and up to the level of the ischium. For the femoral nerve, the needle was inserted perpendicular to the skin, just cranial to the femoral artery, and directed a little caudally. Using a peripheral nerve-stimulator, all nerves were located, and muscle contractions were elicited at a current of 0.2-0.4 mA. No complications were observed during the procedures. CONCLUSION: Electrostimulation of peripheral nerves is useful in locating the branches of the brachial plexus as well as the sciatic and femoral nerves in dogs. CLINICAL RELEVANCE: Peripheral nerve stimulation increases the reliability of a nerve block when compared with blind needle-insertion.

Anatomical and experimental studies of brachial plexus, sciatic, and femoral nerve-location using peripheral nerve stimulation in the dog.

OBJECTIVE: To investigate the anatomy of the brachial plexus, sciatic, and femoral nerves for the use of a peripheral nerve-stimulator to perform nerve blocks in dogs. STUDY DESIGN: Prospective experimental trial. ANIMALS: Four canine cadavers and four healthy adult dogs weighing 23 +/- 2.5 kg. METHODS: Phase I: in four canine cadavers, an anatomical study was conducted to evaluate accurate needle-insertion techniques. Phase II: the utility of these techniques, and the value of electrostimulation, were evaluated in four anesthetized dogs in lateral recumbency (medetomidine, 5 microg kg(-1)/ketamine 5 mg kg(-1)) using an electrical stimulator and shielded needles. RESULTS: For the brachial plexus, the needle was inserted cranial to the acromion, medial to the subscapularis muscle, at an angle of approximately 20-30 degrees in relation to a plane vertical to the surface on which the animal was lying, oriented parallel to the long axis of the animal, in a ventro-caudal direction. For the sciatic nerve, the needle was inserted just cranial to the sacrotuberous ligament, through the gluteus superficialis muscle, at an angle of approximately 60 degrees in relation to the horizontal plane, in a ventro-cranial direction, and up to the level of the ischium. For the femoral nerve, the needle was inserted perpendicular to the skin, just cranial to the femoral artery, and directed a little caudally. Using a peripheral nerve-stimulator, all nerves were located, and muscle contractions were elicited at a current of 0.2-0.4 mA. No complications were observed during the procedures. CONCLUSION: Electrostimulation of peripheral nerves is useful in locating the branches of the brachial plexus as well as the sciatic and femoral nerves in dogs. CLINICAL RELEVANCE: Peripheral nerve stimulation increases the reliability of a nerve block when compared with blind needle-insertion.

Electrical nerve stimulation to facilitate placement of an indwelling catheter for repeated brachial plexus block in a traumatized dog.

A 10-year-old, 7 kg, male mixed breed dog was presented, following a dog fight, with open fractures of the radius and ulna and extensive skin and muscle lesions. Using electric nerve stimulation, an indwelling catheter was positioned in the axillary space and 2 mg kg(-1) bupivacaine was injected. Complete sensory and motor blocks were obtained allowing amputation distal to the non-traumatized tissue and debridement of the limb. The injection of bupivicaine was repeated 5 hours after the first bolus and a similar result was obtained in term of muscle relaxation and pain alleviation. Subsequent injections were not successful in providing the same effect, most likely as a result of catheter displacement and alternate means of analgesia were used.