13.22: Extracorporeal Removal of Drugs: Peritoneal Dialysis and Hemodialysis

Patients with end-stage renal disease (ESRD) or those experiencing drug overdose often require extracorporeal methods to eliminate accumulated drugs and metabolites. Hemoperfusion, hemofiltration, and dialysis are the primary techniques to rapidly remove harmful substances without disrupting the patient's fluid and electrolyte balance. For those with compromised renal function, dosage adjustments of concurrent medications may be necessary during extracorporeal drug removal.

Dialysis is a process where waste metabolites and drugs are removed from the body by diffusion into dialysis fluid. The two main types are peritoneal dialysis and hemodialysis. In both methods, blood or body fluid is equilibrated with dialysis fluid across a semipermeable membrane, allowing waste to diffuse into the dialysis fluid. The dialysate, balanced in electrolytes and osmotic pressure, typically contains water, dextrose, potassium, sodium, chloride, bicarbonate, acetate, and calcium.

Peritoneal dialysis employs the peritoneal membrane in the abdomen as a filter. This membrane, consisting of visceral and parietal components, provides a surface area of 1–2 m² for diffusion and is permeable to solutes with molecular weights up to 30 kDa. A small portion of the splanchnic blood flow interacts with the peritoneum for dialysis. The procedure involves surgically placing a catheter into the peritoneal cavity, where dialysis fluid is instilled and later drained. Continuous ambulatory peritoneal dialysis (CAPD) is a prevalent form of this technique, especially among diabetic patients, allowing self-treatment without a dialysis machine.

Hemodialysis uses a dialysis machine to filter blood through an artificial membrane. It requires vascular access, often achieved through an arteriovenous fistula or graft. Blood flows to the dialysis machine, where waste materials are removed by diffusion and ultrafiltration before the blood is returned to the body. Hemodialysis is more efficient than peritoneal dialysis for drug removal, making it preferred for rapid detoxification in overdose or poisoning cases. Treatment frequency ranges from once every two days to three times a week, with each session lasting 2–4 hours. Factors such as residual renal function, body weight, and muscle mass influence the duration of dialysis and drug dosing.

Patients with end-stage renal disease or a drug overdose may require extracorporeal removal of drugs and their metabolites.

The most common technique, dialysis, removes waste products and drugs via diffusion and filtration into the dialysis fluid with the dialyzer acting as an artificial kidney. Two common types include peritoneal dialysis and hemodialysis.

In peritoneal dialysis, the peritoneal membrane acts as a filter.

A catheter is placed in the abdominal wall, and dialysis fluid is pumped into the peritoneal cavity, which helps remove waste from the body’s fluid. Periodically, the dialysate is drained and replaced with fresh dialysate.

In contrast, during hemodialysis, blood passes through the dialysis machine, where an artificial membrane removes waste materials before reintroducing the blood into the body.

The dialysis frequency varies from once every two days to three times a week, with each treatment time varying in duration.

It is influenced by factors such as residual renal function and patient characteristics.

Peritoneal dialysis is performed at home, enabling self-treatment, whereas hemodialysis, typically performed in a dialysis center, is preferred in emergencies.