The two types of peritoneal dialysis differ mainly in the schedule of exchanges. In continuous ambulatory peritoneal dialysis (CAPD), the patient empties a fresh bag of dialysis solution into the abdomen. After
4 to 6 hours of dwell time, the patient returns the solution containing wastes to the bag. The patient then repeats the cycle with a fresh bag of solution. CAPD does not require a machine; the process uses gravity to fill and empty the abdomen. A typical prescription for CAPD requires three or four exchanges during the day and one long—usually 8 to 10 hours—overnight dwell time as the patient sleeps. The dialysis solution used for the overnight dwell time may have a higher con centration of dextrose so that it removes wastes and fluid for a longer time.