Department of Clinical Sciences and Services, The Royal Veterinary College, Hatfield, UK.
Department of Veterinary Medical Science, Largo Paolo Braccini, Grugliasco, Italy.
Open Vet J. 2021 Jan-Mar;11(1):27-35. doi: 10.4314/ovj.v11i1.5. Epub 2021 Jan 14.
Thoracic paravertebral block (TPVB) entails injecting a local anesthetic inside the thoracic paravertebral space (TPVS). Loss of resistance to air injection (air-LOR) was the first technique described in humans to locate the TPVS. To date, no study has investigated the spread of any substance after injection into the TPVS using the air-LOR technique nor has described the cranial and caudal limits of the space.
To identify the boundaries of the TPVS, to determine whether the air-LOR technique is reliable for the identification of the TPVS and to examine the relationship between the volume of injectate and its spread.
After a preliminary phase, the thorax of five cat and five dog cadavers was accessed and eviscerated. After TPVS probing, the polyurethane foam was injected, and the cranial and caudal borders were recorded after its maximum spread. Different volumes of a mixture of new methylene blue and ioversol were injected in the TPVS after its localization with a Tuohy needle and air-LOR technique in fourteen dog and six cat cadavers. Lateral radiographs of the vertebral column were used to document needle positioning, spread pattern and extension. The thorax of these subjects was then accessed and eviscerated to observe and record the spread of the mixture.
Injecting a dye into the TPVS, localized by an air-LOR technique, resulted in multi-segmental and often bilateral subpleural staining of paravertebral, intercostal, and dorsal mediastinal structures in dog and cat cadavers. The lateral radiographs most often showed a mixed cloud-like and linear spread pattern, which could be a predictor of the longitudinal spread of the dye. The foam injected into the TPVS at the cranial and the caudal level revealed anatomical communication with the cervical, axillar, and lumbar paravertebral regions.
TPVS localization by air-LOR technique and injection results in a longitudinal multi-segmental spread in dog and cat cadavers. The communication of the TPVS with the axillary and lumbar regions could be of clinical interest for the brachial plexus and the lumbar intercostal nerve blocks in a clinical setting.
胸椎旁阻滞（TPVB）需要将局部麻醉剂注入胸椎旁间隙（TPVS）内。在人体中，首次描述的用于定位 TPVS 的技术是向空气注射时出现阻力消失（air-LOR）。迄今为止，尚无研究使用 air-LOR 技术描述注入 TPVS 后任何物质的扩散情况，也没有描述该空间的颅侧和尾侧极限。
确定 TPVS 的边界，确定 air-LOR 技术是否可用于识别 TPVS，并检查注射量与其扩散之间的关系。
在初步阶段，对五具猫和五具狗的尸体进行了胸部解剖和内脏清除。在 TPVS 探查后，将聚氨酯泡沫注入其中，并在其最大扩散后记录颅侧和尾侧边界。在十四只狗和六只猫的尸体中，使用 Tuohy 针和 air-LOR 技术定位 TPVS 后，向其中注入新亚甲基蓝和 ioversol 的混合物，并记录不同体积的混合物的扩散模式和扩展情况。使用脊柱的侧位 X 射线片记录针的位置、扩散模式和延伸。然后对这些标本进行胸部解剖和内脏清除，以观察和记录混合物的扩散情况。
在狗和猫的尸体中，通过 air-LOR 技术定位的 TPVS 内注射染料后，会导致多节段且经常是双侧的胸膜下、肋间和背侧纵隔结构的染色。侧位 X 射线片最常显示出混合云状和线状的扩散模式，这可能是染料纵向扩散的预测因素。在颅侧和尾侧水平注入 TPVS 的泡沫显示与颈、腋窝和腰段的 TPVS 区域存在解剖学连通。
通过 air-LOR 技术定位 TPVS 并注射后，在狗和猫的尸体中会导致纵向多节段扩散。TPVS 与腋窝和腰段的连通在临床环境中可能对臂丛和腰肋间神经阻滞具有临床意义。
