Читать книгу Canine and Feline Respiratory Medicine - Lynelle Johnson R., Lynelle R. Johnson - Страница 48

FNA of the lung is a suitable technique for evaluating diffuse interstitial or alveolar disorders or peripheral mass lesions within the thorax. It can be performed as a blind technique or with ultrasound guidance. However, because it can be associated with pneumothorax or hemothorax, careful patient selection is advised to limit complications. In animals that are not severely tachypneic or hyperpneic, percutaneous FNA of the lung can be performed safely and with minimal sedation. A small region of the chest is shaved and minor surgical preparation is completed. A 23–27 gauge 0.75–1.5 in. needle attached to a 3 ml syringe filled with air is passed perpendicularly through the skin and subcutaneous tissue cranial to the border of the rib into the lung parenchyma. It is inserted back and forth gently and quickly; then the needle and syringe are removed together for preparation of cytologic specimens. The syringe is detached from the needle and filled with air, and contents of the needle hub are gently sprayed onto a slide or cover slip for cytologic examination and Gram staining, if possible. If aspiration with an empty syringe fails to dispel material onto the slide, the syringe can be filled with 0.5–1 ml of sterile saline, and the aspirated material is suspended in the saline for a cytospin preparation. Even when the sample appears to be of low cellularity, cytopathology is recommended to detect cellular atypia or inflammation.

Figure 2.24 Ultrasound guidance is used to obtain a lung biopsy using a Temno biopsy needle.

Percutaneous lung biopsy can be obtained with use of an ultrasound‐guided biopsy needle in the anesthetized patient. This is performed more commonly in dogs than in cats. A surgical preparation is performed, and a 16–18 gauge Temno™ biopsy needle (Merit Medical Systems, South Jordan, UT) is guided into the lesion to obtain a 2 cm core tissue sample for histopathology (Figure 2.24). After either aspiration or biopsy, the animal should be placed in lateral recumbency with the side of the aspiration facing downward for 15–30 minutes to promote the development of a clot or seal at the aspiration site. Typically, an ultrasound is performed after the procedure to screen for hemorrhage or pneumothorax. Visualization of the normal “glide” sign as the lung slides across the pleura rules out one of these complications. An increase in respiratory rate or effort or detection of absent lung sounds near the site of aspiration would indicate hemorrhage or pneumothorax and the need for intervention.