Intermittent enteral feeding in mechanically ventilated patients. The effect on gastric pH and gastric cultures.

Objective: To evaluate the effect of intermittent (16 h/d) enteral feeding (IEF) on gastric pH and gastric microbial growth in mechanically ventilated patients.

Design: Prospective, case-controlled study.

Setting: Medical ICU and infectious disease research laboratory in a university hospital.

Patient Population: Thirteen mechanically ventilated patients receiving continuous enteral feeding (CEF).

Methods: Gastric pH and quantitative gastric cultures were obtained while patients received CEF. Each patient's feeding schedule was changed to IEF. Daily gastric pH and quantitative gastric cultures were obtained for 5 consecutive days.

Results: Gastric microbial growth was found in 85% (11/13) of patients receiving CEF. Implementation of IEF did not clear gastric microbial growth, as only one patient subsequently reverted to negative culture. Similar gastric microbial growth continued in 90% (10/11) of patients after institution of IEF. Gastric pH did not decrease with the administration of IEF (gastric pH with IEF, 3.8 +/- 0.6 vs 4.7 +/- 0.5 with CEF (not significant [NS]). The amount of microbial growth was also unchanged with IEF (total growth with IEF, 7.8 x 10(5) +/- 5.2 x 10(5) cfu/mL vs 8.7 x 10(5) +/- 4.6 x 10(5) cfu/mL with CEF) (NS). Thirty-eight percent (5/13) of patients developed new Gram-negative rod growth in gastric cultures while receiving IEF. Gram-negative rod isolates increased from 25% of total isolates (CEF) to 40% (IEF).

Conclusion: Our preliminary data suggest gastric pH was not lowered and existing microbial growth was not cleared in ventilated patients receiving IEF after previously receiving CEF. Further controlled study in a larger group of patients is necessary to determine whether IEF is of benefit in decreasing gastric colonization and nosocomial pneumonia.