Though simple and attractive, the role of hydration for the prophylaxis of contrast nephrotoxicity has not been definitively established. We prospectively evaluated the role of deliberate saline hydration in patients undergoing nonemergency cardiac catheterization. Patients (n = 53) were randomized on the day prior to scheduled catheterization to one of two groups – group 1 (n = 27) received normal saline for 24 h (at a rate of 1 ml/kg/h) beginning 12 h prior to scheduled catheterization, and group 2 (n = 26) were allowed unrestricted oral fluids. Serum creatinine measured 24 and 48 h postcardiac catheterization was compared to the pre-randomization baseline value. The mean baseline calculated creatinine clearance was 79.6 ± 31.9 ml/min and the mean baseline creatinine was 106 ± 28 µmol/l. An increase in serum creatinine by at least 44.2 µmol/l (0.5 mg/dl), within 48 h of contrast exposure, was considered to represent clinically significant acute renal insufficiency. Ten subjects (18.9%) developed acute renal insufficiency. The incidence of acute renal insufficiency was significantly lower in group 1 (1 out of 27) as compared to group 2 (9 out of 26; p = 0.005 for comparison between groups; relative risk 0.11, 95% confidence interval 0.015 to 0.79). Twenty-four hours after contrast exposure, the mean increase in creatinine was less in group 1 vs. group 2 (8 ± 11 vs. 20 ± 21 µmol/l, p = 0.02). The increase in creatinine was not significantly different in group 1 vs. group 2 48 h after contrast exposure (12 ± 21 vs. 29 ± 40 µmol/l, p = 0.17). Deliberate saline hydration decreases the incidence of contrast-related acute renal failure and the severity of contrast-induced renal dysfunction in patients undergoing non-emergency cardiac catheterization.

The results of our analysis suggest that such informative censoring is independent of treatment modality and that even after correcting for dropout caused by death or transfer to another modality, patients starting on PD have a lower rate of decline in GFR (that is, better preservation of GFR) than patients starting on HD.

Peritoneal clearance studies were performed in rats undergoing acute peritoneal dialysis. Some of these animals were then exposed to laparotomy and mechanical drying of the peritoneum. Peritoneal clearance studies were repeated at intervals up to 11 days. Another group of rats was placed on daily peritoneal dialysis and allowed to spontaneously develop peritonitis which was not treated. These rats underwent peritoneal transport studies at differing durations of infection. In all groups, animals were sacrificed at the time of the last transport studies for morphological assessment of the peritoneum by light microscopy, scanning electron microscopy, and transmission electron microscopy. The results showed similar decreases in drainage volume and increases in glucose absorption and protein losses with both infection and drying. Both types of injury resulted in extensive mesothelial structural changes. While drying caused mainly denudation of the mesothelial surface, infectious peritonitis was associated with separation of mesothelial cells, and the appearance of numerous white blood cells between and on mesothelial cells. Exposure to peritoneal dialysis alone had no obvious effects on anatomy. Although changes in the peritoneal microcirculation and deeper structures cannot be excluded as contributing to peritoneal transport alterations, the findings suggest that alterations of mesothelium might explain some of the changes in peritoneal transport properties under the conditions of these studies.

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The contribution of peritoneal cavity lymphatic absorption to ultrafiltration kinetics and solute clearances in continuous ambulatory peritoneal dialysis was evaluated in patients with normal (group 1) and high (group 2) peritoneal permeability X area during 4-h exchanges using 2 liters 2.5% dextrose dialysis solution with 30 g added albumin. Cumulative lymphatic drainage in all continuous ambulatory peritoneal dialysis (CAPD) patients averaged 358±47 ml per 4-h exchange and reduced cumulative net transcapillary ultrafiltration at the end of the exchange by 58±7.2%. The peak ultrafiltration volume was observed before osmotic equilibrium between serum and dialysate was reached and occurred when the net transcapillary ultrafiltration rate had decreased to equal the lymphatic absorption rate. Thereafter the lymphatic absorption rate exceeded the net transcapillary ultrafiltration rate, and intraperitoneal volume decreased. Extrapolated to 4 X 2 liters, 2.5% dextrose, 6-h exchanges per d, lymphatic drainage reduced potential daily net ultrafiltration by 83.2±10.2%, daily urea clearance by 16.9±1.9%, and daily creatinine clearance by 16.5±1.9%. Although lymphatic absorption did not differ between the two groups, lymphatic drainage caused a proportionately greater reduction in net ultrafiltration in group 2 (P < 0.025), because these patients had more rapid dialysate glucose absorption (P < 0.05) and less cumulative transcapillary ultrafiltration (P < 0.01). These findings indicate that cumulative lymphatic drainage significantly reduces net ultrafiltration and solute clearances in CAPD and that ultrafiltration failure in CAPD occurs when daily lymphatic absorption equals or exceeds daily transcapillary ultrafiltration. Reduction of lymphatic absorption may provide a means for future improvement in the efficiency of CAPD.

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Net ultrafiltration was measured directly during hypertonic peritoneal dialysis exchanges in rats. Simultaneously, lymphatic absorption was measured by monitoring the disappearance of albumin in the instilled dialysis solution from the peritoneal cavity. The albumin method for measuring lymphatic absorption was also tested in rats absorbing Lactated Ringer's solution from the peritoneal cavity where absorption rate could also be measured directly. The findings suggest the following: 1.) lymphatic absorption rate is similar with both hypertonic dialysis solutions and Lactated Ringer's solution; 2.) lymphatic absorption is substantial and net ultrafiltration is well below true transcapillary ultrafiltration; and 3.) in our model, lymphatic absorption occurs at a relatively constant rate over six hours of dwell time.