Objectives: The detection of glucose in tracheal secretions has been used as an indicator of aspiration in mechanically ventilated, tube-fed children. Pepsin detection may be a more specific indicator. We determined the frequency of pepsin and glucose detection in tracheal secretions of mechanically ventilated children and studied the relationships between tracheal secretion pepsin and glucose and clinical evidence of gastroesophageal reflux.
Design: Prospective observational study.
Setting: University teaching hospital.
Patients: A convenience sample of mechanically ventilated children.
Interventions: Tracheal secretions were collected at the time of routine endotracheal tube suctioning. Tracheal aspirate glucose concentrations were assessed by using glucose oxidase reagent strips. Tracheal aspirate pepsin was detected by laboratory immunoassay.
Measurements and main results: One hundred tracheal aspirates were collected from 37 children. Pepsin (>or=1 microg/mL) was detected in nine aspirates, and glucose (>or=20 mg/dL) was detected in 59 aspirates. Overall, five (13.5%) patients had at least one pepsin-positive aspirate, and 33 (89%) had at least one glucose-positive aspirate. Patients with at least one pepsin-positive aspirate were more likely to have clinical evidence of gastroesophageal reflux than patients with pepsin-negative aspirates (5 of 5 vs. 9 of 32, p <.01, Fisher's exact test). Tracheal aspirate glucose positivity was unrelated to the administration of tube feedings and gastroesophageal reflux. No relationship between pepsin and glucose positivity was observed.
Conclusions: Pepsin is detectable in tracheal secretions of mechanically ventilated children at risk for aspiration. Elevated glucose concentrations in tracheal secretions can occur by mechanisms other than aspiration of glucose-rich formula. Pepsin may be a more specific marker for aspiration than glucose.