Aspiration of stomach contents into the lungs is closely associated with the development of pneumonia in critically ill tube-fed patients. In a two-year study conducted in five ICUs, nurses collected tracheal specimens from 360 ventilated, tube-fed patients to evaluate the frequency and extent of aspiration. Secretions were collected from each patient over a four-day period. More than 30% of the approximately 5,800 specimens were positive for the presence of the gastric enzyme pepsin, indicating aspiration, and 89% of the patients had at least one pepsin-positive specimen. Half of the patients developed pneumonia by the fourth day of study, and the rate of pepsin-positive secretions was twice as high in those patients as in those without pneumonia.
The presence of pneumonia increased the length of time patients spent on the ventilator, in the ICU, and in the hospital. When the head of a patient's bed was elevated at an angle of less than 30[degrees], the risk of aspiration was higher. It was also higher in patients who had a low Glasgow Coma Scale score, vomiting, or evidence of gastroesophageal reflux.
Lead author Norma Metheny notes, "Nurses can play a big role in reducing aspiration risk and therefore the incidence of pneumonia. One way is to keep the head of bed elevated to at least 30[degrees] whenever feasible; another is to ensure that feeding tubes remain in their intended locations after feeding has been started. Still another way is to measure gastric residual volumes at regular intervals (preferably every four hours) to detect high values. Alerting the physician when gastric residual volumes are high can lead to the use of prokinetic agents to improve gastric emptying. To reduce aspiration risk in patients who can't tolerate gastric feedings, small bowel feedings are preferred."