Kinetics of continuous ambulatory peritoneal dialysis (CAPD) with four exchanges per day

Fourteen patients who had no signs of peritonitis were studied during CAPD. Different exchange time schedules were used alternating exchanges with 1.5% and 2.6% glucose solutions. Usually longer exchanges followed shorter ones and vice versa. Total exchange time varied from 2--10 hours. Maximal ultrafiltration volumes were observed after 3 hours with 1.5% and 5 hours wit 2.6% glucose solutions. For small molecular weight solutes (urea, creatinine, sodium, potassium, and phosphate) dialyzate to plasma concentration ratios tended to be lower with 2.6% glucose solutions during the shorter exchanges. Equilibrium between plasma and dialyzate was attained for all these solutes by 10 hours total exchange time. The concentration ratios for inulin were similar with both types of solution, and did not achieve equilibrium by 10 hours. Protein concentrations and losses were higher with 2.6% glucose solution. Total protein and immunoglobulin losses per 24 hours were markedly lower than those reported for intermittent peritoneal dialysis. White blood cell counts increased slightly up to 5 hours and then remained constant up to 10 hours. Mononuclear cell counts were consistently higher than those of granulocytes. The efficiency of dialysis was not markedly influenced by uneven distribution of total exchange time. If 1.5% and 2.6% glucose solutions were used for particular time schedules, slightly higher dialysis efficiency could be obtained by using hyperosmolar solutions for the longer exchanges. Ultrafiltration volumes, protein and immunoglobulin losses, cell counts in dialyzate, and clearance of inulin varied among individual patients. Protein losses correlated positively with serum protein concentration and the body surface area of the patient. Clearances of insulin also correlated with body surface area but ultrafiltration volumes did not.