Can the inflammation markers of patients with high peritoneal permeability on continuous ambulatory peritoneal dialysis be reduced on nocturnal intermittent peritoneal dialysis?

BACKGROUND: Patients with high peritoneal permeability have the greatest degree of inflammation on continuous ambulatory peritoneal dialysis (CAPD), which may be associated with their higher mortality. Nocturnal intermittent peritoneal dialysis (NIPD; "dry day") may decrease inflammation by reducing the contact between dialysate and peritoneum and/or providing better fluid overload control. Therefore, the aims of this study were to determine and compare serum and dialysate concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) of patients with high or high-average peritoneal transport on CAPD, changed to NIPD, and ultimately to continuous cyclic peritoneal dialysis (CCPD).

METHODS: Crossover clinical trial in 11 randomly selected patients. All subjects had been on CAPD and were changed to NIPD, and ultimately to CCPD (6.4 +/- 3.1 months after initiation of study). All patients used glucose-based dialysate. Evaluations of clinical and biochemical parameters, dialysis adequacy, and serum and dialysis inflammation markers were performed at baseline on CAPD, 7 - 14 days after changing to NIPD, 7 - 14 days after switching to CCPD, and after 1 year of follow-up. All patients used only 1.5% glucose dialysate during evaluation days. CRP was determined by nephelometry, and IL-6 and TNF-alpha by ELISA.

RESULTS: Seven patients were high transporters and 4 high average. Ultrafiltration increased (p < 0.05) when patients changed from CAPD [0.38 L (-0.3 - 1.1 L)] to NIPD [2.64 L (0.7 - 4.7 L)]; it then decreased on CCPD [0.88 L (0.4 - 1.3 L) and at the end of study [0.65 L (0.3 - 1.0 L)]. This better fluid overload control was accompanied by decreased weight and systolic and diastolic blood pressure when patients changed from CAPD (89 +/- 13 kg, 160 +/- 23 and 97 +/-9 mmHg, respectively) to NIPD (86 +/- 17 kg, 145 +/- 14 and 86 +/- 9 mmHg, respectively), and increased weight and systolic and diastolic blood pressure on CCPD (85 +/- 15 kg, 143 +/-23 and 88 +/- 14 mmHg, respectively) and at the end of follow-up (87 +/- 16 kg, 155 +/- 24 and 89 +/- 12 mmHg, respectively). Median serum CRP decreased (p = 0.03), from 3.8 (1.6 - 8.5) mg/L on CAPD to 1.0 (0.4 - 4.4) mg/L on NIPD, but increased on CCPD [1.8 (1.3 - 21) mg/L] and at the end of the study [3.2 (0.3 - 8.2) mg/L]. Dialysate CRP decreased nonsignificantly, from 0.10 (0 - 0.5) mg/L on CAPD to 0 (0 - 0.03) mg/L on NIPD, to 0.01 (0 - 0.08) mg/L on CCPD, and to 0 (0 - 0) mg/L at final evaluation. Serum TNF-alpha concentration decreased, from 0.14 (0.04 - 0.6) pg/mL on CAPD to 0.01 (0 - 0.08) pg/mL on NIPD, and then increased to 0.06 (0 - 0.4) pg/mL on CCPD and to 0.11 (0 - 0.2) pg/mL at the end of the study; whereas dialysate TNF-alpha decreased, from 0.08 (0.03 - 0.2) pg/mL on CAPD to 0.04 (0 - 0.2) pg/mL on NIPD, and to 0 (0 - 0) pg/mL and 0 (0 - 0.05) pg/mL on CCPD and final evaluation respectively. Serum IL-6 decreased (p = 0.07), from 2.5 (2.0 - 4.2) pg/mL on CAPD to 1.0 (0.7 - 2.0) pg/mL on NIPD, and to 1.0 (0.8 - 2.9) pg/mL on CCPD and 1.0 (0.5 - 9.8) pg/mL at the end of the study; whereas dialysate levels remained similar on CAPD [8.0 (3.7 - 13) pg/mL] and NIPD [7.8 (5.1 - 23) pg/mL], and increased on CCPD [11.2 (9.5 - 19) pg/mL] and at final evaluation [11.2 (8.3 - 15) pg/mL].

CONCLUSIONS: NIPD significantly decreased serum CRP and displayed a trend to decrease TNF-alpha and IL-6 serum concentrations compared with CAPD; whereas CCPD tended to reverse these effects. These results did not appear to be due to decreased local peritoneal inflammation, but they could be associated with better control of fluid overload on NIPD. Thus, NIPD, as Long as the residual renal function allows it, may be useful in reducing the systemic inflammation of patients with high peritoneal membrane permeability.