A Two-Point Ultrasound-Guided Injection Technique for the Transversus Thoracis Plane Block: A Canine Cadaveric Study

Abstract

The transversus thoracis plane (TTP) block desensitizes the intercostal nerves that run through this plane, providing analgesia to the ventral thoracic wall. Two canine cadavers were used to assess the feasibility of the transverse approach for the TTP (t-TTP) under ultrasound guidance to inject a solution at the third and sixth intercostal spaces. Eight cadavers were used to compare the spread and number of intercostal nerves that were stained when a low volume (LV) 0.5 mL kg−1 or a high volume (HV) 1 mL kg−1 of a dye-lidocaine solution was injected into the same hemithorax, injecting the volume equally at these intercostal spaces using the transverse approach. Fisher’s exact test and Wilcoxon signed-rank test were used to contrast the spread of the different volume solutions. The injectate spread along the TTP after all injections, dying a median number (range) of 3 (2–5) and 6 (5–6) nerves with LV and HV, respectively (p = 0.011). The two-point injection of HV, using the t-TTP approach, is a feasible technique that provides a consistent staining from T2 to T7 intercostal nerves. The injection of HV instead of LV increases the spread and enhances the number of stained intercostal nerves.

Thoracic transversus plane block as part of a multimodal analgesia plan in a cat undergoing sternotomy

“…Regarding injection technique, previous recent studies described a transversal approach introducing the spinal needle in a ventro‐medial‐to‐dorso‐lateral direction using an in‐plane technique with one‐point 18 or two‐point injection 32 at the level of the fifth intercostal space or the third and sixth intercostal spaces, respectively.…”

Ultrasound‐guided parasternal block in a cat undergoing median sternotomy for pulmonary lobectomy

“…In veterinary medicine, two different approaches for US‐guided blocks have been described in dogs 6–8 to provide analgesia during median sternotomy. These techniques consist of injecting local anaesthetic (LA) in the vicinity of the distal portion of the intercostal nerves, between the internal intercostal muscle and the transversus thoracis muscle, either via a parasagittal approach 6 or via a transversal approach 7,8 . The authors stated that the main advantage seems to be related to a better ventilatory profile in the postoperative period, in comparison with traditional multiple intercostal blocks, as the muscles affected by these approaches do not play a significant role in ventilation.…”

“…These techniques consist of injecting local anaesthetic (LA) in the vicinity of the distal portion of the intercostal nerves, between the internal intercostal muscle and the transversus thoracis muscle, either via a parasagittal approach 6 or via a transversal approach. 7,8 The authors stated that the main advantage seems to be related to a better ventilatory profile in the postoperative period, in comparison with traditional multiple intercostal blocks, as the muscles affected by these approaches do not play a significant role in ventilation. In addition, time needed to perform these blocks should be shorter than bilateral intercostal blocks and, as they are performed with the patient in dorsal recumbency, changing the position is not necessary.…”

“…Locoregional anaesthesia has proved to be superior to systemic opioids in terms of analgesic effect and reduction of complications 5 . Over the last few years, two different approaches for US‐guided blocks have been described to provide analgesia during sternotomy in dogs 6–8 . Very recently, US‐guided transversus thoracis plane block has been reported in a cat with promising results 9 .…”

“…5 Over the last few years, two different approaches for US-guided blocks have been described to provide analgesia during sternotomy in dogs. [6][7][8] Very recently, US-guided transversus thoracis plane block has been reported in a cat with promising results. 9 This case report aims at confirming the usefulness of the US-guided parasternal block in a cat undergoing median sternotomy.…”