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Abstract

Introduction: The purpose of this study was to analyze samples of oral and tracheal secretions to assess for pepsin and salivary amylase. Hypothesis: Intubated patients will have pepsin and salivary amylase in the sputum, indicating possible microaspiration. Salivary amylase will be higher in oral secretions. Methods: This descriptive study was conducted in the critical care units. Ten adult subjects, on mechanical ventilation (MV) via an oral endotracheal tube (ETT) were enrolled following informed consent from the legal proxy. Secretions were suctioned from the trachea using a closed suction device and collected in a sputum trap; 5 mL sterile saline without preservative was used to rinse secretions into the trap. A sample of oral secretions was collected at the same time using a soft, 9” suction catheter; no saline was added to the specimen. The procedure was repeated in 1 to 4 hours when ETT suction was indicated. Specimens were frozen at -20°C until analysis. Assays of total pepsin and salivary amylase were run. Results: The majority of subjects were men (n=8), with a subglottic suction ETT (n=7), on tube feedings (n=9) via small-bore tube (n=5) in the stomach (n=7). Median values: age, 59 years; duration of MV, 6.3 days; ETT cuff pressure 24 cm H2O; head of bed, 30°; oral secretion volume, 5.5 mL. Gagging was not observed during oral suction. Pepsin (mean ng/mL) was found in oral secretions of 7 subjects (35.7) and in sputum of 6 (14.1). Salivary amylase (mean mmol/min/mL) was present in oral secretions (354.7) of all subjects, and in the sputum of 8 subjects (2.4). No differences were found in the proportion of subjects with positive pepsin or amylase in the sputum, and feeding tube location or intubation with a subglottic suction ETT. Conclusions: This pilot study identified a high percentage of intubated patients who had pepsin and/or salivary amylase present in their sputum, likely indicating microaspiration of secretions around the ETT cuff. As expected, salivary amylase was highest in the oral secretions. Ongoing efforts to prevent microaspiration (maintaining ETT cuff pressure, elevating head of bed, and suctioning oral secretions) are important. Additional research related to salivary amylase is needed.