Two-point ultrasound-guided transversus abdominis plane injection in canine cadavers - a pilot study.
OBJECTIVE
This study evaluated the spread of a two-point transversus abdominis plane (TAP) injection in canine cadavers. Compared with previous techniques, the two-point TAP injection was developed to increase the consistency of local anaesthetic spread to the nerve segments T11, T12, L1, L2 and L3.


STUDY DESIGN
Prospective experimental trial.


ANIMALS
Five fresh canine cadavers.


METHODS
Two-point TAP injections were performed under ultrasound guidance by a single trained individual in canine cadavers (15.7-43.0 kg). Each hemi-abdomen was infiltrated and evaluated independently for a total of 10 evaluations of the technique. The first injection was performed at the level of the costo-chondral junction of the thirteenth rib, and the second injection was performed cranial to the tuber coxae. Each injection comprised 0.3 mL kg-1 methylene blue solution (0.0015 mg mL-1). Ten minutes after the injections, abdominal wall dissection was performed, and any nerves stained for a minimum of 10 mm along their long axis were identified and recorded.


RESULTS
During all injections, separation of the internal oblique and transversus abdominis muscles was observed on ultrasound. On dissection, branches of T12, T13, L1, L2 and L3 were adequately stained in 30%, 100%, 100%, 90% and 90% of injections, respectively. No staining of branches of T11 occurred in any of the cadavers. In one hemi-abdomen, branches of L1 and L3, but not L2, were stained.


CONCLUSIONS AND CLINICAL RELEVANCE
This study indicates that the two-point TAP injection delivers consistent dye dispersion to adequately stain branches of T13, L1, L2 and L3, with no coverage of T11 and poor coverage of T12, in fresh canine cadavers. An in vivo study using local anaesthetic should be performed to evaluate the analgesic efficacy of this technique in mid to caudal abdominal surgeries.
['Johnson|Emma K|EK|', 'Bauquier|Sébastien H|SH|', 'Carter|Jennifer E|JE|', 'Whittem|Ted|T|', 'Beths|Thierry|T|']
D000009:Abdominal Muscles D000772:Anesthesia, Local D000818:Animals D002102:Cadaver D004285:Dogs D005260:Female D007273:Injections, Intramuscular D008297:Male D010865:Pilot Projects D011446:Prospective Studies D018084:Ultrasonography, Interventional
cadaver TAP ultrasound analgesia dogs pain