genitourinary disorders
Peritoneal Dialysis
Access
Peritoneal dialysis requires intraperitoneal access, usually via a soft silicone rubber or porous polyurethane catheter. The catheter may be implanted in the operating room under direct visualization or at the bedside by blind insertion of a trocar or under visualization through a peritoneoscope. Most catheters incorporate a polyester fabric cuff that allows tissue ingrowth from the skin or preperitoneal fascia, ideally resulting in a watertight, bacteria-impervious seal and preventing introduction of organisms along the catheter tract. Allowing 10 to 14 days between catheter implantation and use improves healing and reduces the frequency of early pericatheter leakage of dialysate. Double-cuff catheters are better than single-cuff catheters. Also, a caudally directed exit site (the opening of the tunnel through which the catheter enters the peritoneal cavity) lowers the incidence of exit-site infections (eg, by collecting less water during showering). Once access is established, the patient undergoes a peritoneal equilibration test, in which dialysate drained after a 4-hour dwell time is analyzed and compared with serum to determine solute clearance rates. This procedure helps determine the patient’s peritoneal transport characteristics, the dose of dialysis required, and the most appropriate technique. In general, adequacy is defined as a weekly Kt/V≥1.7 (where K is theureaclearance in mL/min, t is dialysis time in minutes, and V is volume of distribution ofurea[which is about equal to total body water] in mL). 