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.