Diarrhea in tube-fed patients: feeding formula not necessarily the cause

This study of diarrhea in tube-fed patients was undertaken to determine the proportion of cases in which feeding formula is not responsible for the diarrhea, the causes other than the feeding formula, and the diagnostic approach to diarrhea in tube-fed patients.

Inpatients at the Truman Memorial Veterans Hospital who received nasoenteric feeding during the time period from October 1986 through May 1988 were eligible for this study. Of 123 patients who received nasoenteric feeding, 32 patients had documented diarrhea (greater than 500 mL per day for at least two consecutive days) and were enrolled. Three of these patients received hypertonic feeding formula, whereas the remaining 29 received isotonic feeding formula. Prospective determinations of the causes of diarrhea were performed. Laboratory tests included fecal leukocytes, stool osmolality, stool electrolytes, and Clostridium difficile toxin assay. Diarrhea was considered osmotic if the stool osmotic gap was greater than 100 mmol/L. Clinical management involved reducing or stopping the feeding formula, stopping suspected medications, or administering appropriate antibiotics.

There were 32 episodes of diarrhea in tube-fed patients during the study period. A single cause could be specified in 29 cases. The tube feeding formula was responsible for diarrhea in only 21% of these cases. Medications were directly responsible in 61% and C. difficile in 17% of cases. Stool osmotic gap correctly distinguished osmotic from non-osmotic diarrhea in all cases.

When diarrhea develops in properly tube-fed patients, the feeding formula is usually not responsible for the diarrhea. Patients receiving nasoenteric tube feeding are frequently placed on liquid forms of medications. Many medicinal elixirs contain sorbitol, which is often the cause of diarrhea in tube-fed patients. Review of the medications and determination of the stool osmotic gap are the initial diagnostic steps of highest yield.