van der Spoel, J.I., Oudemans-van Straaten, H.M., Kuiper, M.A., van Roon, E.N., Zandstra, D.F., & van der Voort, P.H. (2007). Laxation of critically ill patients with lactulose or polyethylene glycol: A two-center randomized, double-blind, placebo-controlled trial. Critical Care Medicine, 35, 2726–2731.

To determine whether lactulose or polyethylene glycol (PEG) effectively promotes bowel function in critically ill patients, and to identify whether one is superior to the other.

On day 3 in critical care, consenting patients who had no bowel movements were randomized to one of three arms: lactulose, PEG 3350, or placebo. The lactulose solution was 13 gm of lactulose in 100 ml of sterile water. The PEG 3350 solution was 13.125 gm of PEG 3350 in 100 ml of sterile water. Finally, the placebo was 100 ml of sterile water. Each patient was medicated with the study liquid every eight hours via a nasogastric tube and was to receive 11 doses of treatment medication.

• The study reported on a sample of 308 critically ill intensive care unit (ICU) patients who did not have cancer.
• Mean patient age was 35.3 years (SD = 16.5) in the PEG group, 65.5 years (SD = 15) in the lactulose group, and 68.8 years (SD = 13.8) in the placebo group.
• The sample comprised 118 women and 190 men.

Two ICUs in the Netherlands

This was a double-blind, placebo-controlled, randomized trial.

• Acute Physiology and Chronic Health Evaluation II (APACHE II) 
• Sepsis-related organ failure assessment score
• Daily abdominal x-ray in patients with severe abdominal tenderness, abdominal distention, or suspected ileus
• Medication assessment
• Stool record

• Lactulose and PEG were more effective than placebo (69% versus 74% versus 31%, p = 0.001).
• No difference was found in the effectiveness of lactulose versus PEG (p = 0.27).
• Lactulose reduced length of stay (LOS) in the ICU compared with PEG or placebo. In addition, patients with earlier bowel movements had shorter LOS.
• Morphine affected defecation, but PEG may be better in this patient group. Neither cisapride nor erythromycin appeared to affect defecation.
• Adverse drug events were acute intestinal pseudo-obstruction, perforated ulcer, acute abdomen, death, and sinus bradycardia.

Both lactulose and PEG promoted bowel movements equally. In patients receiving morphine, PEG had a more significant effect.

The study lacked a lead-in period or data on patients’ prior bowel function and history of constipation.

Bowel function is promoted with the use of either lactulose or PEG. Lactulose may reduce LOS, and PEG may be better for patients who also are receiving morphine, but additional study is needed.