Constipation in long-term ventilated patients: associated factors and impact on intensive care unit outcomes

To characterize the factors associated with delayed defecation in long-term ventilated patients and to examine the relationship between delayed defecation and logistic organ dysfunction scores, acquired bacterial infections, and mortality in the intensive care unit.

Prospective observational cohort study.

A 21-bed polyvalent intensive care unit in a university hospital.

A total of 609 adult patients admitted over a 41-month period who underwent mechanical ventilation for ≥ 6 days.

None.

Three hundred fifty-three patients (58%) passed stools ≥ 6 days after they were admitted to the intensive care unit ("late" defecation). Patients with early and late defecation had similar general characteristics when admitted to the intensive care unit and had similar logistic organ dysfunction scores on the first day of mechanical ventilation. Several variables were independently associated with a delay in defecation: a Pao2/Fio2 ratio of less than 150 mm Hg (adjusted hazard ratio 1.40; 95% confidence interval: 1.06-1.60; p = .0073), a systolic blood pressure between 70 and 89 mm Hg (adjusted hazard ratio 1.48; 95% confidence interval: 1.17-1.79; p = .002), and systolic blood pressure < 68 mm Hg (adjusted hazard ratio 1.29; 95% confidence interval: 1.01-1.60; p = .03). Logistic organ dysfunction scores were significantly higher on the fourth and ninth days of mechanical ventilation in patients with late defecation than in those with early defecation. The crude intensive care unit mortality rate was 18% in patients with early defecation and 30% in patients with late defecation (p < .001). Acquired bacterial infections at any site occurred in 34% of patients with early defecation and 66% of patients with late defecation (p < .001).

A Pao2/Fio2 ratio of < 150 mm Hg and systolic blood pressure of < 90 mm Hg during the first 5 days of mechanical ventilation were independently associated with a delay in defecation. Our results suggest that constipation is associated with adverse outcomes in long-term ventilated patients.