Bowel motions in critically ill patients: a pilot observational study.

BACKGROUND

Limited information exists on the factors affecting bowel motions and the physical characteristics of stools in mechanically ventilated patients in the intensive care environment. We hypothesised that most stools in critically ill patients are not formed and that both diarrhoea and non-defecation are common.

DESIGN, SETTING AND PATIENTS: Pilot prospective observational study of 44 patients in a tertiary intensive care unit who were mechanically ventilated for more than 24 hours.

METHODS

We collected data on the frequency and appearance (Bristol stool chart) of bowel motions, and administration of nutrition, narcotics, anti-emetics, prokinetics and laxatives.

RESULTS

Forty-four patients (31 male) with a mean age of 60.3 years were monitored for 274 ventilation days. There were 168 days (61.3%) with no defecation. During the 106 days (38.8%) with bowel motions, there were 101 days (36.9%) with loose stools and 33 days (12.0%) with at least one episode of diarrhoea. Formed stools were present on only 5 days (1.8%). No patients developed clinical or radiological evidence of constipation or pseudoobstruction. Treatment with lactulose (P = 0.009) and ondansetron (P = 0.02) was associated with a day with bowel motions, while use of morphine (P = 0.025) was associated with non-defecation. Lactulose treatment was the only factor associated with stool volume (P < 0.001). A higher rate of enteral nutrition was associated with looser stools (P < 0.001), while morphine was negatively associated with looser stools (P < 0.001).

CONCLUSIONS

Among patients receiving mechanical ventilation for more than 24 hours, lack of bowel motions (non-defecation) was the most common physiological state. However, diarrhoea was also relatively common, and formed stools were rare.