Tracheal wash and bronchoalveolar lavage: sampling technique and fluid interpretation

摘要

Once respiratory disease is identified it is important to determine the cause, but many of the clinical signs of respiratory disease are common to multiple causes. Examining the cytological characteristics of the respiratory secretions can provide both an aetiology and, with repeated sampling, an indication of treatment response. Most horses with pulmonary disease, accumulate excess respiratory secretion in the tracheal pool, approximately 15 cm proximal to the carina. There are 2 methods for collecting tracheal aspirates. Percutaneous transtracheal aspiration offers the benefit of bypassing the upper respiratory tract, almost eliminating the risk of sample contamination by commensal microflora of the nasopharynx. Transtracheal aspiration is performed in the mid trachea, where the tracheal rings are palpable ventrally. The area is clipped, disinfected and then 2 ml of local anaesthetic is injected subcutaneously. Next a large bore (14 to 10 gauge) catheter is passed between 2 tracheal rings into the lumen of the trachea, the stylette removed and narrow sterile tubing passed down into the lumen. Twenty to 50 ml of sterile saline is then infused into the trachea and aspirated from the tracheal pool.