Clinical meaning
Peritoneal dialysis (PD) uses the body's own peritoneal membrane (the lining of the abdominal cavity) as a natural filter to remove waste products and excess fluid from the blood. A special fluid called dialysate is infused through a catheter into the abdominal cavity (peritoneal space). Waste products and excess electrolytes cross from the blood vessels in the peritoneum into the dialysate by diffusion (moving from high to low concentration), and excess water is pulled out by osmosis (the dialysate contains dextrose which draws water across the membrane). After a dwell period (4-6 hours for CAPD or 1-2 hours for automated cycler), the used dialysate is drained out carrying waste and fluid. This process is repeated multiple times daily.
Exam relevance
Risk factors: - Peritonitis (most common and serious complication) - Poor hand hygiene or break in sterile technique - Exit site or tunnel infection - Constipation (can impair drainage) - Malnutrition (protein lost in dialysate) - Hernias (from increased intra-abdominal pressure) - Diabetes (higher infection risk, protein losses worsen glycemic control)