Tracheobronchial aspiration of gastric contents in critically ill tube-fed patients: frequency, outcomes, and risk factors

Abstract

Objectives: To describe the frequency of pepsin-positive tracheal secretions (a proxy for the aspiration of gastric contents), outcomes associated with aspiration (including a positive Clinical Pulmonary Infection Score [a proxy for pneumonia] and use of hospital resources), and risk factors associated with aspiration and pneumonia in a population of critically ill tube-fed patients.

Design: Prospective descriptive study conducted over a 2-yr period.

Setting: Five intensive care units in a university-affiliated medical center with level I trauma status.

Patients: Each of the 360 adult patients participated for 4 days. Among the inclusion criteria were mechanical ventilation and tube feedings. An exclusion criterion was physician-diagnosed pneumonia at the time of enrollment.

Intervention: None. MEASUREMENTS AND MAJOR RESULTS: Almost 6,000 tracheal secretions collected during routine suctioning were assayed for pepsin; of these, 31.3% were positive. At least one aspiration event was identified in 88.9% (n = 320) of the participants. The incidence of pneumonia (as determined by the Clinical Pulmonary Infection Score) increased from 24% on day 1 to 48% on day 4. Patients with pneumonia on day 4 had a significantly higher percentage of pepsin-positive tracheal secretions than did those without pneumonia (42.2% vs. 21.1%, respectively; p < .001). Length of stay in the intensive care unit and need for ventilator support were significantly greater for patients with pneumonia (p < .01). A low backrest elevation was a risk factor for aspiration (p = .024) and pneumonia (p = .018). Other risk factors for aspiration included vomiting (p = .007), gastric feedings (p = .009), a Glasgow Coma Scale score <9 (p = .021), and gastroesophageal reflux disease (p = .033). The most significant independent risk factors for pneumonia were aspiration (p < .001), use of paralytic agents (p = .002), and a high sedation level (p = .039).

Conclusions: Aspiration of gastric contents is common in critically ill tube-fed patients and is a major risk factor for pneumonia. Furthermore, it leads to greater use of hospital resources. Modifiable risk factors for aspiration need to be addressed.

Figure 1

Relationship between percentage of tracheobronchial aspirates containing pepsin and the occurrence of pneumonia by day 4 (extensions indicate 95% confidence intervals).

Figure 2

Incidence of pneumonia increased steadily with the accumulation of pepsin-positive tracheal secretions (PPTS [%], proxy for aspiration event). The mean number of pepsin-positive tracheal secretions per patient on day 1 was 1.62; at the end of day 2 the total accumulated number per patient was 3.21; and at the end of day 3 it was 4.84.)