1. Will Peritoneal Dialysis Modality Make a Difference in Peritonitis? Reference: Piraino B, Sheth H. Peritonitis – Does peritoneal dialysis modality make a difference? Blood Purif. 2010;29:145–149.

2. Background Peritonitis has remained a major problem in peritoneal dialysis (PD). It is a significant risk factor causing death in many patients, according to a recent analysis. Efforts are required continuously to lessen the peritonitis rate. Reports have revealed peritonitis rate of 0.48 episodes/year at risk in 150 continuous cycling PD (CCPD) patients in 1986. This was the period where a higher rate of peritonitis was majorly seen.

3. Modality and Immune Status Mesothelial cells of the kidney are vital, as transformed cells results in peritoneal neoangiogenesis and fibrosis, with concomitant peritoneal dysfunction in a span of time. The degradation products of glucose are more important than glucose exposure, lactate exposure and low pH of standard dialysis fluid in causing apoptosis of mesothelial cells. According to studies on peritoneal macrophage function and effluent opsonic activity in patients on continuous ambulatory PD (CAPD) and CCPD, significant changes were observed with longer (15 h) dwell times compared to shorter dwell times (4 h). Along with this increase in peritoneal total white cell concentration by more than 2-fold with the longer dwell time, enhancement in the uptake of Staphylococcus aureus by peritoneal macrophage, increase in the ability of the macrophages to mount a respiratory burst was seen.

4. Modality and Immune Status The long dwell time lead to increased mean effluent IgG and also a 5-fold increase in the concentration of effluent white blood cells and peritoneal macrophages. Increased concentration of peritoneal macrophages was seen on the ‘dry day’ after automated PD (APD) when compared to CCPD at the end of the long dwell. Impaired cytokine response to lipopolysaccharides resulted due to night- time dialysis (6 exchanges of 2 liters of dialysis fluid over 10–12 h). Peritoneal macrophages with tidal PD (initial fill of 2 liters with two consequent exchanges of 50% tidal cycle over 3 h) vs. CCPD (2 liters fill and drain, 2 cycles over 3 h) with a crossover design was able to phagocytose Escherichia coli better, when compared to the macrophages from the CCPD prescription. These preliminary results advise that manipulation of peritoneal prescription using a cycler succeeds in better immune function and reduced peritonitis.

5. Comparison of CAPD and CCPD Peritonitis Rates A randomized control trial (RCT) comparing peritonitis in CAPD using the Y-set with 3–5 exchanges of 2 liters to CCPD using 4–5 nocturnal cycles and 1 daytime exchange of 2 liters was done with 41 patients in each arm. The peritonitis rates in CAPD and CCPD were 0.94 and 0.51 episodes/year. The two groups had similar exit functions and based on the prescription, the CCPD patients were likely doing 2 connections/day and 1 disconnect, while the CAPD patients were doing 3–5 connections and disconnections. Although this study had a study design like randomized, initiation into the study at the start of dialysis and careful data analysis, the results were convincing. An observational study was conducted, which included 213 patients with beginning CAPD (Y set) and 115 patients beginning APD.

6. The center had a facility for nasal screening protocol for S. aureus and also treated the carriage with intranasal mupirocin. The rates of peritonitis risk were 0.64 vs. 0.31 episodes/year in CAPD and APD, respectively, and had similar exit infections due to mupirocin protocol. The results showed that APD patients performed with fewer connections and disconnections (less risk for contamination) compared to the CAPD patients. In a second randomized trial of ADP and CAPD, subjects were initially recommended on CAPD for a month and then high-average transporters were included. A 6-month follow-up was suggested followed by APD. The peritonitis rates at risk in CAPD and APD groups were 0.31 vs. 0.17 episodes/year. Two randomized controlled trials were done with disconnect systems for CAPD and Luer lock connections for APD. The results showed important decrements in peritonitis rates on APD when compared to CAPD.

7. The results gathered from multiple centers on peritonitis rates in patients on APD, CAPD and the United States Renal Data System (USRDS) analysis for incident CAPD and CCPD patients showed a scarcity in data collection and hence, actual peritonitis rates were not obtained though analysis of the risk of first peritonitis episode was done after 9 months on PD. The types of connection for the CAPD and CCPD patients could not be known, there was no clarity on the number of patients who have had a dry day on APD. The first 3 months on PD were not incorporated and finally the most vital part is that peritonitis rates could not be calculated. Apart from these, prescription is not given always in the studies of peritonitis on CAPD and APD. The peritonitis rates may be lower on a dry day theoretically. A randomized controlled study on comparing peritonitis rates in patients started on APD with dry day vs. a wet day are yet to be done and are very much required.

8. Conclusion There is scarcity of data on peritonitis in CAPD vs. APD. Further studies should include the connectology used with not only CAPD, but also APD and prescriptions for the number of connections. This field should require more randomized control studies. Importance should be given to reduce peritonitis risk. Till date, the available data suggest that the use of APD with Luer lock connections vs. CAPD with a disconnect system results in a decrease of peritonitis risk.

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