[The effect of stress ulcer prevention on the incidence of pneumonia in artificial respiration].

The role of stress ulcer prophylaxis in increasing the risk of pneumonia in ventilator patients was analyzed prospectively in 142 artificially ventilated patients at a medical and surgical intensive care unit (104 males, 38 females, mean time of ventilation 7.9 days, mean age 46.5 years). The pH of gastric aspirate and bacterial counts in gastric fluid and tracheal secretions were investigated daily. Identical isolates from gastric aspirates and tracheal secretions were typed by agglutination, bacteriocin, or phage typing. An average of 2.1 bacterial species were isolated in 80.5% of all gastric aspirates. Bacterial counts increased with rising gastric aspirate pH, which was especially true for Gram-negative and less so for Gram-positive organisms; colony counts of Candida sp. decreased slightly. In 31.6% of patients identical bacterial species were first isolated from gastric aspirates and 1 to 2 days later from tracheal secretions. Of these microbes that were first isolated from gastric aspirate and later from tracheal secretions, 50.3% were Gram-negative, 37.5% Gram-positive, and only 4.2% Candida sp. One-half of all bacterial aspirations occurred between the 2nd and 7th day of ventilation; 80% occurred within 11 days of ventilation. Only 20% of all migrations of Gram-positive organisms from stomach to respiratory tract lead to pneumonia, as compared with 60% of Gram-negatives. At a gastric pH below 3.4 the incidence of ventilation pneumonia was 40.6%; above pH 5.0 the incidence was 69.2% (P less than or equal to 0.05). As pH increased, the organism causing pneumonia was significantly more often isolated first from the gastric aspirate and 1 to 2 days later from the tracheal secretion of the same patient.