A description of a technique for ultrasound-guided lumbar plexus catheter in dogs: cadaveric study.

OBJECTIVE: To describe an ultrasound-guided approach for lumbar plexus catheter placement in dogs.

STUDY DESIGN: Prospective experimental cadaveric study.

ANIMALS: Eleven thawed canine cadavers (13 ± 2 kg).

MATERIAL AND METHODS: A technique to place a catheter in the psoas compartment at the level of the lumbar plexus under ultrasound guidance was described. Ultrasonographic landmarks for the placement of a lumbar plexus catheter were identified as the body of the sixth lumbar vertebrae, the psoas muscle and the femoral nerve. All catheters were placed by the principal investigator using epidural sets with an 18-G Tuohy needle. The procedure was carried out twice in each cadaver, with the aim of placing a catheter at the point of the left and right lumbar plexuses. A total volume of 0.4 mL kg(-1) of 1% methylene blue solution was injected into the psoas compartment after which the catheter was removed. After performing the injection in four cadavers, the technique was modified, altering the angle of needle placement and length of catheter insertion. Staining of the femoral and obturator nerves was assessed. Success was recorded if both nerves were stained over a length >1 cm. The spreading of the dye into the abdomen or to the nerve roots was also recorded.

RESULTS: The success rate after the first four cadavers was four out of eight, and dye was found in the abdomen of two of the cadavers. When the modified technique was used in the subsequent seven cadavers, the success rate was 12 out of 14, and no dye was found in the abdomens.

CONCLUSIONS AND CLINICAL RELEVANCE: This technique has shown a high percentage of success and low rate of complications. The only complication investigated in this study was the spread to the abdomen or epidural space. To establish safety, clinical studies will be needed.