OVERVIEW

What is peritoneal dialysis?

Peritoneal dialysis is a common renal replacement therapy that uses the peritoneal cavity as an exchange space and the peritoneum as a semipermeable membrane to remove excess water and metabolic waste from the body through diffusion, convection, and ultrafiltration.

It is performed within the abdominal cavity without requiring extracorporeal circulation or blood contact, making it relatively safe and better at preserving residual kidney function.

What are the common treatment methods for peritoneal dialysis?

Currently, the main peritoneal dialysis modalities include: Continuous Ambulatory Peritoneal Dialysis (CAPD), Intermittent Peritoneal Dialysis (IPD), Nocturnal Intermittent Peritoneal Dialysis (NIPD), Continuous Cyclic Peritoneal Dialysis (CCPD), and Tidal Peritoneal Dialysis (TPD). When performed using an automated peritoneal dialysis machine, it is also called Automated Peritoneal Dialysis (APD).

What is peritonitis in peritoneal dialysis?

Peritonitis in peritoneal dialysis, also known as peritoneal dialysis-associated peritonitis, refers to acute infectious inflammation of the peritoneal cavity caused by pathogens entering due to contamination, gastrointestinal inflammation, catheter-related infections, or iatrogenic procedures during peritoneal dialysis.

Peritonitis is a common complication of peritoneal dialysis. It may be directly related to the dialysis procedure or secondary to non-dialysis-related intra-abdominal or systemic diseases. It is also a direct or primary cause of death in 16% of peritoneal dialysis patients.

Prompt antibiotic treatment can often restore normal conditions.

Is the incidence of peritonitis high in peritoneal dialysis?

The incidence of peritonitis varies significantly among different peritoneal dialysis centers. The 2016 International Society for Peritoneal Dialysis guidelines recommend that the overall peritonitis rate in each center should not exceed 0.5 episodes per patient per year.

What severe consequences may occur if peritonitis in peritoneal dialysis is not treated promptly?

Most peritoneal dialysis-associated peritonitis cases resolve with antibiotic treatment. However, peritonitis can still lead to serious consequences, such as septic shock.

Additionally, severe peritoneal infection or chronic inflammation is a major cause of ultrafiltration failure and the need to switch to long-term hemodialysis.

SYMPTOMS

What are the common manifestations of peritonitis in peritoneal dialysis?

• The most common symptoms of peritonitis in peritoneal dialysis patients are abdominal pain and cloudy peritoneal dialysis effluent. The onset of abdominal pain and the appearance of cloudy effluent may not occur simultaneously.

• Patients undergoing automated peritoneal dialysis usually have no history of cloudy effluent when peritonitis occurs.

• Other symptoms include fever, nausea, vomiting, and diarrhea.

• A small number of patients may experience hypotension.

CAUSES

What are the causes of peritonitis in peritoneal dialysis?

In peritoneal dialysis patients, peritonitis may be directly related to peritoneal dialysis (dialysis-associated) or secondary to non-dialysis-related intra-abdominal or systemic diseases (secondary). Most cases are dialysis-associated.

Studies show that less than 6% of peritonitis cases in peritoneal dialysis patients are due to non-dialysis-related factors.

• Dialysis-associated peritonitis: The cause may be pathogenic skin bacterial contamination during exchange (i.e., touch contamination) or exit-site/tunnel infection. The most common microorganisms are gram-positive, typically coagulase-negative staphylococci.

• Secondary peritonitis: The cause may be underlying gastrointestinal pathology or, rarely, hematogenous spread. Causes include cholecystitis, appendicitis, diverticular rupture, severe constipation, bowel perforation, intestinal ischemia, and incarcerated hernia.
  It may also result from hematogenous or transvaginal spread, though this is much rarer than the intra-abdominal causes mentioned above. It may occur after endoscopy or other invasive procedures. Common microorganisms are enteric (e.g., Bacteroides) or polymicrobial.

Compared with dialysis-associated peritonitis, secondary peritonitis generally has a worse prognosis.

DIAGNOSIS

What tests are needed to diagnose peritonitis in peritoneal dialysis?

Peritoneal effluent should be sent for cell count and differential count, Gram stain, and culture. For febrile patients, complete blood count and blood cultures should also be tested. If there is purulent drainage at the exit site, a culture of the purulent drainage should also be performed:

• Peritoneal fluid cell count and differential count: The primary laboratory finding for bacterial peritonitis is an elevated white blood cell count in the peritoneal effluent, usually exceeding 100 cells/mm³. In contrast, PD patients without peritonitis typically have a white blood cell count below 8 cells/mm³.

• Gram stain and culture: Peritoneal effluent cultures are positive in 80%–95% of peritonitis cases.

• Exit-site culture: Any purulent drainage from the exit site should be cultured, as isolation of the same microorganism from both the exit site and peritoneal effluent suggests that the exit-site infection may be the cause of peritonitis.

• Blood culture and complete blood count: For patients with fever or signs of sepsis, blood cultures and complete blood count testing can help determine the possibility of systemic infection.

What precautions should be taken when collecting peritoneal dialysis fluid samples?

• For continuous ambulatory peritoneal dialysis (CAPD), peritoneal fluid samples can be collected after 4–6 hours of dwell time.

• For automated peritoneal dialysis (APD) patients, 1L of dialysis fluid is typically infused and allowed to dwell for at least 2 hours before drainage. The effluent is then inspected for turbidity and sent for cell count, differential count, and culture.

• For patients suspected of peritonitis due to abdominal pain but without peritoneal dialysis fluid in the abdominal cavity, 1L of dialysis fluid can be infused and allowed to dwell for at least 1–2 hours before collection for testing.

How is peritonitis diagnosed in peritoneal dialysis?

Peritonitis should be suspected if a peritoneal dialysis patient presents with abdominal pain or cloudy effluent. Patients with cloudy effluent should be presumed to have peritonitis, even in the absence of other historical or physical examination findings. These patients should receive empirical treatment until the diagnosis is confirmed or ruled out.

Definitive diagnosis: Peritonitis is diagnosed if two or more of the following criteria are met:

• Clinical features consistent with peritonitis (abdominal pain or cloudy effluent).

• Peritoneal effluent white blood cell count >100 cells/mm³ or >0.1×10⁹/L after at least 2 hours of dwell time, with neutrophils accounting for >50%.

• Positive effluent culture.

TREATMENT

How should peritonitis in peritoneal dialysis be treated?

The treatment of peritonitis in peritoneal dialysis requires empirical therapy based on the patient's condition or antibiotic treatment selected according to the patient's test results.

• For initial empirical treatment, first-generation cephalosporins + broad-spectrum Gram-negative antibiotics or vancomycin + broad-spectrum Gram-negative antibiotics are often used.

• Regarding the specific route of administration, antibiotics can be administered intraperitoneally, either continuously (adding medication during each peritoneal dialysis exchange) or intermittently (adding medication only once daily or every few days during one peritoneal dialysis exchange).
  For intermittent administration, the peritoneal dialysis solution containing antibiotics should remain in the abdomen for at least 6 hours.

• When the dialysis solution appears cloudy, heparin is usually added to help dissolve and prevent the formation of fibrin clots.

• In cases of recurrent peritonitis, refractory peritonitis, refractory catheter infection (exit and tunnel infection), fungal or mycobacterial peritonitis, or peritonitis related to intra-abdominal lesions, catheter removal is necessary.

• Other treatments for recurrent or relapsing peritonitis may include fibrinolytic drugs and peritoneal lavage.

• Generally, peritoneal dialysis does not need to be discontinued for more than 2 days in cases of peritonitis. For refractory cases, discontinuation of peritoneal dialysis for more than 2 days may be required.

DIET & LIFESTYLE

What should patients with peritonitis pay attention to in their daily life during peritoneal dialysis?

• Maintain aseptic techniques and environmental hygiene during routine peritoneal dialysis procedures.

• Adjust diet to prevent constipation or diarrhea, improve nutritional status, and enhance immune function.

PREVENTION

How to Prevent Peritonitis in Peritoneal Dialysis?

• Prophylactic antibiotics may be administered before invasive procedures such as dental work, and peritoneal dialysis fluid should be drained before any abdominal or pelvic procedures.

• Treat hypokalemia.

• Prevent and treat exit-site infections of the dialysis catheter and pelvic inflammation early.

• Early treatment of pre-existing abdominal-related conditions are also measures to reduce the occurrence of peritonitis.