26.2: Peritoneal Dialysis II: Peritoneal Dialysis Systems and Complications

Peritoneal dialysis (PD) is a medical process that removes waste products and excess fluid from the body using the peritoneal membrane as a natural filter.

Peritoneal Dialysis Methods

Several methods can be used for peritoneal dialysis, including Acute Intermittent Peritoneal Dialysis, Continuous Ambulatory Peritoneal Dialysis, and Automated Peritoneal Dialysis, also known as Continuous Cyclic Peritoneal Dialysis.

Acute Intermittent Peritoneal Dialysis (AIPD) is used for patients with uremic symptoms, including fluid overload, acidosis, hyperkalemia, nausea, vomiting, fatigue, and altered mental status. Although AIPD is less efficient than hemodialysis (HD) at removing solutes and fluids, it causes more gradual fluid shifts, which makes it preferable for hemodynamically unstable patients. AIPD is commonly employed in urgent situations, such as when late-stage chronic kidney disease (CKD) patients require immediate dialysis. The treatment can be manual or automated, with exchange times ranging from 30 minutes to 2 hours, depending on the specific protocol.

Automated Peritoneal Dialysis involves four exchanges of 2 to 3 liters of dialysate into the peritoneal cavity each day, typically at regular intervals, for example, every 4 to 6 hours). Each exchange has a dwell time of about 4 hours, during which waste and excess electrolytes are removed. It offers continuous dialysis, providing more stable electrolyte and fluid levels than intermittent PD or HD. After each dwell period, the dialysate is drained and replaced, allowing ongoing waste removal throughout the day.

Automated Peritoneal Dialysis (APD) is the most common form of PD and is performed using a computerized cycler. This method allows patients to undergo dialysis overnight while they sleep. The machine performs four or more exchanges per night, each lasting 1 to 2 hours. Although convenient, nighttime dialysis alone may not provide sufficient solute and fluid clearance for all patients. As a result, 1 or 2 additional manual daytime exchanges might be necessary for specific individuals.

Complications of Peritoneal Dialysis

PD complications range from minor to severe if left untreated.

• Peritonitis is often caused by contamination during exchanges. Staphylococcus epidermidis and Staphylococcus aureus are the most common pathogens, but gram-negative bacteria like Escherichia coli and Pseudomonas aeruginosa can also be responsible. Prompt antibiotic treatment is critical to avoid serious outcomes.
• Bleeding in the effluent may occur after catheter insertion and usually resolves independently. Persistent or new bleeding may indicate intraperitoneal hemorrhage and requires immediate evaluation.
• Hernias can result from increased intra-abdominal pressure due to the dialysate, with a higher risk in older men and women who have had multiple pregnancies.
• Dialysate pressure can cause lower back pain and pulmonary issues like atelectasis or pneumonia. Atelectasis may be caused by fluid overload or reduced lung expansion, especially with high dialysate volumes. Pleuroperitoneal communication can cause pleural effusions, contributing to respiratory symptoms. Regular exercise, orthopedic support, and proper positioning can help manage these complications.
• Protein loss occurs due to the permeability of the peritoneal membrane and may increase during peritonitis. Gradual protein loss over time can lead to malnutrition. Dietary adjustments, like increased protein intake, are usually sufficient, but alternative dialysis methods may be needed in severe cases.