Effect of acidified enteral feedings on gastric colonization in the critically ill patient

OBJECTIVE: To evaluate the effect of acidified enteral nutritional formulas (feedings) on gastric colonization and pH in critically ill patients. DESIGN: Randomized, double-blind trial of three groups: a) regular feedings into the stomach; b) regular feedings into the duodenum; and c) acidified feedings into the stomach. Nasogastric aspirates for gastric pH and microbiological determinations were obtained daily for a mean of 5 days after feeding began. SETTING: ICU at a tertiary care hospital. PATIENTS: Thirty-one patients indicated to receive enteral feedings before day 4 in the ICU were randomized. Seven patients had their feedings discontinued because of intolerance, accidental extubation, or tolerance of oral supplementation. One patient received the wrong feedings and was dropped from the study. A total of 23 patients finished the study. They were mostly trauma (n = 15) or neurosurgical (n = 6) patients. The average age was 40 yrs (range 15 to 71). INTERVENTIONS: An enteral formula with a pH of 6.5 was used as the control feeding. Hydrochloric acid was added to the control feeding to titrate the pH to 3.5 and this acidified enteral formula was given to the experimental group. All patients received continuous enteral feedings via an 8-Fr feeding tube. MAIN RESULTS: Seven of eight patients receiving the acidified feedings were sterile (no microbial growth) on receiving feedings compared with five of 15 of those patients receiving regular feedings (p = .027). For those patients initially colonized, four of four patients receiving acidified feedings immediately became sterile and remained so. Only two of ten patients receiving regular feedings remained sterile (p = .021). The mean gastric pH of the acidified group was 3.2 compared with the group receiving regular feedings into the stomach (pH = 4.7) and the group receiving regular feedings into the duodenum (pH = 3.8) (p < .01). There was no evidence of gastrointestinal bleeding in any patient. CONCLUSIONS: Acidified enteral feedings are effective in eliminating and preventing gastric colonization in critically ill patients. Further investigation is needed to assess its effect on nosocomial infection rates.