Transtracheal aspiration in the horse: a photo essay.

The research article provides a pictorial guide on how to perform a transtracheal aspiration, a technique used to obtain samples from the horse’s respiratory tract for analysis.

Introduction

• The procedure known as transtracheal aspiration is a veterinary process to obtain samples from the equine respiratory tract. These can then be used for culture and cytologic examination, enabling diagnosis of various diseases.

Preparation for the Procedure

• The ventral midcervical region is prepared surgically over a 15-cm long length. This region is located at the center of the neck, on the underside.
• A small area is selected and infiltrated subcutaneously (under the skin) with 2-3 ml of lidocaine, providing local anesthesia.
• A small cut or ‘stab’ incision is made in the skin at this site.

Conducting the Aspiration

• A trocar, a surgical instrument with a sharply pointed end, along with a cannula, a thin tube to draw fluids, is introduced through the incision and the annular ligament, into the trachea (windpipe).
• Following the insertion, the trocar is removed, leaving the cannula in place.
• An 8-French (Fr) polypropylene catheter is then fed down the trachea through the cannula to a depth of around 35-40 cm.
• The catheter is connected to a 30 ml syringe, holding 20 ml of sterile saline, by a 3-way stopcock, a type of valve.
• The saline is rapidly injected into the trachea, and after the horse coughs, which ensures even distribution of saline, a sample (directly representative of the tracheal environment) of about 3 to 4 ml is drawn as the catheter is slowly withdrawn.

Post-procedure Actions and Possible Complications

• Once the sample is obtained, the cannula and catheter are removed from the horse’s trachea through the incision made earlier.
• The incised area is then treated with an antibacterial ointment, covered with gauze sponges, and tightly bound with elastic tape to prevent infection.
• Even though complications from this procedure are rare, they can include subcutaneous emphysema (leakage of air into the soft tissue under the skin), infection, pneumomediastinum (air leak into the mediastinum, the central compartment of the thoracic cavity), and damage to the cartilage rings (the structural components of the trachea).