Lemon MJ, Wilson DV, Nelson LL, et al.
Introduction/Purpose: Intercostal thoracotomy is a common surgical procedure in veterinary referral practice and is associated with a high degree of post-operative pain. None of the analgesic strategies currently employed for this procedure is completely effective nor universally accepted. Both use of a nerve stimulator to guide needle placement and “blind” landmark-guided techniques carry a risk of significant complications caused by inaccurate needle placement. In people, standard of care is performance of an ultrasound-guided paravertebral nerve block. This study aimed to develop a technique for ultrasound-guided injection into the canine thoracic paravertebral space.
Methods: Ultrasound-guided paravertebral injection of a mixture of radiographic contrast material and methylene blue dye was performed in 10 canine cadavers. A cranial (T4-T5) and a caudal (T9-T10) injection was performed in each cadaver. Immediately following injection, thoracic computed tomography was performed to evalua te injection accuracy and dispersion . Dispersion was classified as cloud-like , intercostal, or a combination thereof. The location of the needle tip in relation to the intervertebral foramen , needle angle , and presence of contrast material in any unanticipated location (e.g. pleural , mediastinal, epidural) were recorded . Dissection of the paraspinal region was performed and the length of each intercostal nerve stained with methylene blue was recorded.