Peritoneal Dialysis Pilot Study: Evaluating Polyethylene Glycol (PEG) for Constipation

Constipation is a common condition, which impacts one in four Canadians Maintaining regular bowel movements is important in the peritoneal dialysis (PD) population because constipation can negatively impact the quality of dialysate flow and can result in impaired dialysis adequacy. Unfortunately, treating constipation is challenging in PD patients because of the diet and fluid restrictions required in this population, as well as the need for constipating calcium based phosphate binders.

Constipation treatment can be administered orally or rectally. Although patients often prefer oral therapy, there are occasions when rectal therapy is preferred (ie. rectal suppositories and enemas). Oral laxatives include bulk, osmotic, stimulant, and lubricants.

In the Nova Scotia (NS) PD Program, patients are counseled to maintain a type 3-4 stool on the Bristol Stool Chart (BSC). An ideal stool is a type 4, which appears like a sausage or snake and is smooth and soft in consistency. To maintain a type 3-4 stool, current therapy includes senna 8.6-17.2 g twice daily with the addition of lactulose 30-60 mL twice daily, as needed. Rescue therapy in the Current Bowel Protocol is lactulose 30-60 mL every hour until bowel movement.

There is limited evidence to guide the ideal bowel regimen in PD patients. Reasons to consider PEG therapy include the evidence promoting PEG in the general population with constipation, the positive outcomes found in a small population of PD patients (Mimidis 2005), as well as positive feedback from other provinces who currently recommend PEG in PD patients. The investigators postulate the PEG protocol would be as effective and safe as the Current Bowel Protocol, and thus will evaluate PEG in the PD population, the investigators will conduct a prospective, interventional, randomized, open label, pilot study.

All patients with recent laxative use will be approached for inclusion. Patients will be randomly assigned to the Current Bowel Protocol (senna/lactulose) or the PEG Bowel Protocol (PEG/lactulose) for 8 weeks.

The primary objective is to compare the efficacy of the PEG Bowel Protocol in preventing constipation to the Current Bowel Protocol. We will review the safety of the regimens by monitoring for adverse events from all laxatives and explore the impact of constipation in patients who experience PD treatment failure.

Inclusion criteria

• All patients in the peritoneal dialysis program in Nova Scotia who are currently taking laxatives.

Exclusion criteria

• Allergy or intolerance to any of the study laxatives (PEG, senna, lactulose); cognitive impairment or inability to document symptoms; known or suspected gastrointestinal obstruction or ileus; known or planned pregnancy; no laxative use in the last 3 months.