Pepsin A is expressed exclusively in the gastric mucosa, thus detection of pepsin A in the airway of patients is a specific marker of airway aspiration. The GI Clinical Lab at Nemours offers a sensitive, reliable Elisa test to detect gastric pepsin in tracheal and bronchial secretions.
To collect tracheal secretion, attach a Luki trap to a suction catheter, pass the catheter down the endotracheal tube, and apply suction to the catheter as the catheter is withdrawn. If the secretion is too thick to be withdrawn, instill saline (2 cc) to the tracheal tube prior to aspirating the secretion.
To collect bronchial secretion, use a standard collection protocol. Collect 1 to 2 cc of bronchial washing fluid in a plain specimen tube.
Please avoid over-diluting the secretion with a large amount of saline during the collection. A minimum of 0.5 cc of fluid is required to determine gastric pepsin, protein content and pH. The airway fluid should be transferred to a small, tightly-capped plastic tube and frozen immediately after collection. Keep the sample frozen and ship on dry ice.