Pharmacologic Management of Constipation in the Critically Ill Patient

Asad E. Patanwala, Pharm.D.; Jacob Abarca, Pharm.D., M.S.; Yvonne Huckleberry, Pharm.D.; Brian L. Erstad, Pharm.D., FCCP


Pharmacotherapy. 2006;26(7):896-902. 

In This Article


Of the 95 patients whose medical records were reviewed, 50 satisfied the study inclusion criteria. Medical records were not available for 11 patients. Complete data could not be obtained for 17 patients. Three patients had diarrhea on admission, five were receiving total parenteral nutrition with nonfunctional gastrointestinal tracts, five had undergone colostomy, and four had undergone bowel surgery before or after admission.

         Of the 50 patients included in the study, 25 (50%) did not have a bowel movement during the first 96 hours of MICU admission. No difference was observed between the group who did and the group who did not have a bowel movement with respect to mean age or median length of MICU stay. However, mean weight was significantly greater in the group with no bowel movement (          Table 1          ). In addition, no difference was noted between the two groups with respect to sex, mechanical ventilation, oral nutrition, or enteral nutrition (          Table 2          ). The predominant admitting service was the MICU (38 patients), followed by the surgical service (nine) and the neurologic service (three).        

         Occurrence of a bowel movement was not associated with type of admitting service. Bivariate analysis of the relationship between occurrence of a bowel movement and specific laxatives or prokinetic agents showed that bisacodyl, milk of magnesia, lactulose, docusate, metoclopramide, and erythromycin were not significantly associated with a bowel movement (          Table 2          ). However, a difference was noted between the group that had a bowel movement (10 patients) and the group that did not (three) with respect to the use of senna (p=0.02). Significant differences were also found when laxatives were grouped by class (          Table 2          ).        

         In our logistic regression analysis, the use of a stimulant or osmotic laxative was significantly associated with occurrence of a bowel movement (odds ratio [OR] 26.6, 95% confidence interval [CI] 3.2–221.0, p = 0.002). Of these, the most frequently used laxative was senna (13 patients), followed by bisacodyl (eight), lactulose (five), and milk of magnesia (two). Opioid use, expressed as logarithmic intravenous morphine equivalents, was negatively associated with a bowel movement (OR 0.756, 95% CI 0.59–.97, p = 0.03). Disease severity, as determined by APACHE II score, was also negatively associated with a bowel movement (OR 0.84, 95% CI 0.70–0.99, p = 0.04). Vasopressor use was significantly associated with occurrence of a bowel movement (OR 11.1, 95% CI 1.10–111.72, p = 0.04). Patients requiring vasopressors were also more likely to receive laxatives. The other five variables previously described did not significantly influence occurrence of a bowel movement (          Table 3          ).        


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