Introduction: The presence of an endotracheal tube (ETT) increases the risk for microaspiration of secretions around the ETT. Biomarkers of pepsin and salivary amylase may be used to identify microaspiration in intubated patients because of their naturally occurring presence in the stomach or oral cavity and non-occurrence in the respiratory tract. Microaspiration may be difficult to detect until pulmonary complications, such as lung injury or infection, occur. This study assessed the presence of pepsin and salivary amylase in oral and tracheal secretions of ventilated adults. Method(s): This is a secondary analysis of data collected from 11 critically ill, adult patients on mechanical ventilation (MV) enrolled in a study to identify cues for ETT suctioning. Two paired samples of oral and tracheal secretions were suctioned when clinically indicated. Tracheal secretions were suctioned with a closed system, and oral secretions were obtained with an oropharyngeal catheter. Specimens were analyzed for total pepsin, pepsin A, pepsin C, and salivary amylase according to established assays. Results: Of 11 subjects, the majority were men (n=8), on enteral feedings (n=9) via a feeding tube placed in the stomach (n=7), and intubated with a continuous subglottic suction ETT (n=8). Median values: age, 62 years; duration of MV, 5.5 days; ETT cuff pressure 24 cm H2O; head of bed, 30degrees]. Pepsin was in measured in both oral (30.5 ng/mL; n=8) and tracheal secretions (11.1 ng/mL; n=7); Similar findings were noted for pepsin A (oral 14.7 ng/mL, n=7; sputum 7.4 ng/mL, n=6) and pepsin C (oral 14.7, n=7; tracheal 7.4, n=6). Salivary amylase (mean micro]mol/min/mL) was present in all oral secretions (359.8) and in the sputum of 6 subjects (1.8). Discussion & Conclusions: The majority of intubated patients on MV had both pepsin and salivary amylase in their sputum, likely due to microaspiration of secretions.; This finding suggests greater efforts are needed to reduce patients' risk. Ongoing strategies to prevent gastric reflux are important such as head of bed elevation and monitoring residuals. Presence of salivary amylase within tracheal secretions may indicate a need for more frequent oropharyngeal suctioning as part of routine care of intubated patients. Analysis shows no variations of the presence of pepsin or salivary amylase in relation to feeding tube placement or type of ETT. Generalizability is limited by the small sample size.


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Thesis Completion





Sole, Mary Lou


Bachelor of Science in Nursing (B.S.N.)


College of Nursing

Degree Program



Dissertations, Academic -- Nursing;Nursing -- Dissertations, Academic







Access Status

Open Access

Length of Campus-only Access


Document Type

Honors in the Major Thesis

Included in

Nursing Commons