Assessment of an ultrasound-guided technique for catheterization of the caudal thoracic paravertebral space in dog cadaversRoger Medina Serrra, Carolina Palacios Jimenez, Paolo Monticelli, Mark Plested, Jaime Viscasillas.
The objectives of this study are to describe an ultrasound-guided technique to place catheters in the caudal thoracic paravertebral (CTPV) space in canine cadavers and evaluate the distribution of a 50:50 contrast-dye solution administered through them. Eight thawed adult beagle cadavers (9.2 ± 2.0 kg body total weight) were used. Thirteen catheters were placed. In a first phase a volume of 0.3 mL kg-1 of the contrast-dye was administered in all cases. After the injections, computed tomography (CT) scans were carried out to assess the distribution of the contrast-dye. In a second phase, extra 0.2 mL kg-1 of the contrast-dye was administered through 8 catheters, followed by a second CT scan. Two cadavers were dissected to assess the distribution of the contrast-dye. The injection site varied between T8-9 and T12-13. The evaluation of the CT scans showed contrast-dye within the paravertebral space in 92% (12/13) of the injections. The distribution pattern observed in all the injections within the TPV space was linear and intercostal in all cases. The median (range) linear spread of the contrast was 7 (5-10) spinal nerves and involved 3 (2-8) intercostal spaces. The contrast-dye reached lumbar regions in a 42% of the injections (5/12). A larger spread of the contrast-dye was not observed after the administration of a second dose of the injectate. No signs of epidural, intrapleural/intrapulmonary, intravascular or intraabdominal spread were observed. The dissection of the two cadavers confirmed the spread of the contrast-dye along the sympathetic trunk and intercostal spaces. The administration of 0.3 mL kg-1 of the contrast-dye in the CTPV space resulted in a distribution compatible with the block of nerves responsible for the innervation of the majority of the abdominal viscera and cranial abdominal wall.
Key words: Dog; Caudal thoracic paravertebral catheter; Regional anaesthesia; Ultrasound guided.