The effect of acidified enteral feeds on gastric colonization in critically ill patients: results of a multicenter randomized trial. Canadian Critical Care Trials Group

Crit Care Med. 1999 Nov;27(11):2399-406. doi: 10.1097/00003246-199911000-00013.


Objective: To evaluate the effect of acidified enteral feeds on gastric colonization in critically ill patients compared with a standard feeding formula.

Design: Randomized, double-blind, multicenter trial.

Setting: Eight mixed intensive care units at tertiary care hospitals.

Patients: 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.

Interventions: 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.

Measurements and main results: 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).

Conclusions: 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.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria / growth & development*
  • Bacteria / isolation & purification
  • Critical Care / methods*
  • Critical Illness / therapy
  • Cross Infection / epidemiology
  • Cross Infection / microbiology
  • Cross Infection / prevention & control*
  • Double-Blind Method
  • Enteral Nutrition*
  • Female
  • Gastric Acid / metabolism
  • Gastric Mucosa / metabolism
  • Humans
  • Hydrogen-Ion Concentration
  • Incidence
  • Intensive Care Units
  • Male
  • Middle Aged
  • Pneumonia, Bacterial / epidemiology
  • Pneumonia, Bacterial / microbiology
  • Pneumonia, Bacterial / prevention & control*
  • Respiration, Artificial*
  • Stomach / microbiology*