Continuous ambulatory peritoneal dialysis

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Introduced by Popovich et al,1 in 1976, continuous ambulatory peritoneal dialysis (CAPD) has the potential for affecting the extent to which peritoneal dialysis is used as an alternative procedure for patients with end-stage renal disease requiring dialysis. The concept of CAPD focuses on a continuous internal, portable dialysis system allowing increased mobility for the patient, while at the same time incorporating a basic physicologic approach to dialysis (Fig. 1). Our initial experience with CAPD described herein has been most encouraging, warranting continued participation of the patient and additional long-term clinical studies.

Physiologic considerations

Previous reports have suggested that the optimal approach for removing uremic toxins (e.g., urea, creatinine, and phosphorus) could be best achieved through a slower, more prolonged dialysis with lower clearance rates, but longer actual dialysis time.2 With the implementation of CAPD, a dialysis system is available that utilizes a physiologic, prolonged dialysis capable of stabilizing serum chemistry values through multiple, daily exchanges of commercially prepared dialysis solutions. CAPD utilizes both the actual lower efficiency of peritoneal dialysis and the peritoneal membrane's considerable ability to clear large molecules with relatively low dialysis flow rates.3

Although longer dialysis dwell periods ranging from 3 to 8 hours are required, small molecular-weight substances such as urea (60 to 70 daltons), diffuse rapidly across the peritoneal membrane with equilibration during an early phase of the dwell cycle. Larger molecular-weight substances such as creatinine (114 daltons) and middle molecular weight substances such as inulin and vitamin B12 (500 to 5000 daltons) diffuse at . . .



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