Peritoneal dialysis (PD) is a type of dialysis that uses the peritoneum in a person's abdomen as the membrane through which fluid and dissolved substances are exchanged with the blood. It is used to remove excess fluid, correct electrolyte problems, and remove toxins in those with kidney failure. Peritoneal dialysis has better outcomes than hemodialysis during the first two years. Other benefits include greater flexibility and better tolerability in those with significant heart disease.
Side effects Complications may include infections within the abdomen, hernias, high blood sugar, bleeding in the abdomen, and blockage of the catheter. Peritoneal dialysis is not possible in those with significant prior abdominal surgery or inflammatory bowel disease. It requires some degree of technical skill to be done properly.
Mechanism
In peritoneal dialysis, a specific solution is introduced and then removed through a permanent tube in the lower abdomen. This may occur either at regular intervals throughout the day known as continuous ambulatory peritoneal dialysis (CAPD), or at night with the assistance of a machine known as automated peritoneal dialysis (APD), or continuous cycling peritoneal dialysis (CCPD). The solution is typically made of sodium chloride, bicarbonate, and an osmotic agent. Glucose is the most commonly used osmotic agent and different concentrations of glucose in the dialysis fluid affect the ultrafiltration. Icodextrin is a high molecular weight glucose polymer developed as an alternative osmotic agent with slower absorption from the peritoneal cavity, facilitating better ultrafiltration. It is recommended for long dwells in patients with difficulties achieving or maintaining euvolemia.
History and culture The solution used for peritoneal dialysis is on the World Health Organization's List of Essential Medicines. As of 2009, peritoneal dialysis was available in 12 of 53 African countries.
Medical uses Peritoneal dialysis is a method of renal replacement therapy for those needing maintenance therapy for late stage chronic kidney disease and is an alternative to the most common method hemodialysis.
Complications
PD-related peritonitis A common cause of peritonitis is touch contamination, e.g. insertion of catheter by un-sanitized hands, which potentially introduces bacteria to the abdomen; other causes include catheter complication, transplantation of bowel bacteria, and systemic infections. Most common type of PD-peritonitis infection (80%) are from bacterial sources. Infection rates are highly variable by region and within centers with estimated rates between 0.06–1.66 episodes per patient year. With recent technical advances peritonitis incidence has decreased over time. Antibiotics are needed if the source of infection is bacterial; there is no clear advantage for other frequently used treatments such as routine peritoneal lavage or use of urokinase. The use of preventative nasal mupirocin is of unclear effect with respect to peritonitis. Of the three types of connection and fluid exchange systems (standard, twin-bag and y-set; the latter two involving two bags and only one connection to the catheter, the y-set uses a single y-shaped connection between the bags involving emptying, flushing out then filling the peritoneum through the same connection) the twin-bag and y-set systems were found superior to conventional systems at preventing peritonitis. The fluid used for dialysis uses glucose as a primary osmotic agent. According to a 2020 review published in the American Journal of Nephrology, some studies suggest that the use of glucose increases the risk of peritonitis, possibly as a result of impaired host defenses, vascular disease, or damage to the peritoneal membrane. The acidity, high concentration and presence of lactate and products of the degradation of glucose in the solution (particularly the latter) may contribute to these health issues. Solutions that are neutral, use bicarbonate instead of lactate and have few glucose degradation products may offer more health benefits though this has not yet been studied. The mortality rate of peritoneal dialysis related peritonitis is estimated to be 3-10%, with approximately 50% of cases resulting in hospitalization. Peritoneal fluid studies with a white blood cell count greater than 100 per μL and greater than 50% neutrophils strongly suggest peritonitis, with a definitive diagnosis based on culture of microorganisms from the peritoneal fluid. In order to avoid delaying treatment, a cloudy fluid in the dialysate fluid can be assumed to be due to peritonitis unless an alternative cause is identified. Peritonitis in those undergoing PD is usually due to gram positive bacteria. Intraperitoneal antibiotics are preferred to intravenous as they have a greater effect at the area of infection, unless sepsis is present, in which case intravenous antibiotics are indicated. The peritoneal dialysis catheter may have to be removed if the infection does not resolve with antibiotics, and it is recommended that the PD catheter be removed in all cases of fungal peritonitis.
Volume shifts The volume of dialysate removed as well as patient's weight are monitored. If more than 500ml of fluid are retained or a liter of fluid is lost across three consecutive treatments, the patient's physician is generally notified. Excessive loss of fluid can result in hypovolemic shock or hypotension while excessive fluid retention can result in hypertension and edema. Also monitored is the color of the fluid removed: normally it is pink-tinged for the initial four cycles and clear or pale yellow afterward. The presence of pink or bloody effluent suggests bleeding inside the abdomen while feces indicates a perforated bowel and cloudy fluid suggests infection. The patient may also experience pain or discomfort if the dialysate is too acidic, too cold or introduced too quickly, while diffuse pain with cloudy discharge may indicate an infection. Severe pain in the rectum or perineum can be the result of an improperly placed catheter. The dwell can also increase pressure on the diaphragm causing impaired breathing, and constipation can interfere with the ability of fluid to flow through the catheter.
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