The effect of acidified enteral feeds on gastric colonization in critically ill patients: Results of a multicenter randomized trial

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Abstract
To evaluate the effect of acidified enteral feeds on gastric colonization in critically ill patients compared with a standard feeding formula. Randomized, double-blind, multicenter trial. Eight mixed intensive care units at tertiary care hospitals. We recruited mechanically ventilated critically ill patients expected to remain ventilated for >48 hrs. We excluded patients with gastrointestinal bleeding, acidemia, and renal failure requiring dialysis. We enrolled 120 patients; 38% were female, age (mean +/- SD) was 57.6+/-19.3 yrs, and Acute Physiology and Chronic Health Evaluation II score (mean +/- SD) was 21.6+/-7.6. Vital High Nitrogen (Abbott Laboratories, Ross Products Division, Columbus, OH) was used as the standard feeding formula for the control group (pH = 6.5). Hydrochloric acid was added to Vital High Nitrogen to achieve a pH of 3.5 in the experimental group. The main outcome measure was gastric colonization. Secondary outcomes included gastric pH, pneumonia, and mortality. The mean gastric pH in patients receiving acid feeds was lower (pH = 3.3) compared with controls (pH = 4.6; p<.05). One patient (2%) on acid feeds was colonized in the stomach with pathogenic bacteria, compared with 20 patients (43%) in the control group (p<.001). There was no difference in the incidence of pneumonia (6.1% in the acid feeds group vs. 15% in the control group; p = .19). Overall, there were 15 deaths in the acid feeds group and seven in the control group (p = .10); four patients in the acid feeds group and three in the control group died during the study period (p not significant). Acidified enteral feeds preserve gastric acidity and substantially reduce gastric colonization in critically ill patients. Larger studies are needed to examine its effect on ventilator-associated pneumonia and mortality.