Volume overload in patients treated with continuous ambulatory peritoneal dialysis associated with reduced circadian...

While a high blood pressure (BP) in patients receiving maintenance ambulatory peritoneal dialysis (CAPD) is associated with congestive heart failure and an increased mortality, the relevance of diurnal variations in BP is unknown.

In a prospective study, we enrolled 76 prevalent patients receiving stable CAPD (age 60.4 +/- 13.8 years; 37 males). BP was measured over 24 h using an automated device. We also performed routine clinical and biochemical measurements, as well as the Karnofsky index to evaluate physical activity. Volume status was assessed using bioimpedance analysis.

69 patients (with an average time on dialysis of 24.4 +/- 22.5 months) completed the study. Of these, 16 patients experienced a drop in BP >10% at night (dippers), while 53 patients did not (non-dippers). Comparing these two groups, dippers had significantly lower extracellular water (ECW) (13.8 +/- 2.1 vs. 15.9 +/- 3.3 l; p < 0.05), normalized extracellular water (nECW) (0.22 +/- 0.05 vs. 0.26 +/- 0.04 l/m; p < 0.05), and serum albumin (38.2 +/- 2.9 vs. 35.9 +/- 3.7 g/l; p < 0.05). Age, Karnofsky index, vintage, residual renal Kt/V and peritoneal Kt/V, total Kt/V, dose of antihypertensive drugs, mean systolic and diastolic BP did not significantly differ between these groups. Correlation analysis showed the coefficient of variation (CV) of BP positively correlated with E/T (r(2) = 0.292; p < 0.05), diabetic (r(2) = 0.267; p < 0.05), male (r(2) = 0.257; p < 0.05), nECW (r(2) = 0.278; p < 0.05) and ECW (r(2) = 0.249; p < 0.05) negatively correlated with albumin (r(2) = -0.280; p < 0.05). Furthermore, in a multivariate linear regression model, E/T, albumin and sex were independently associated with CV for BP.

We show that reduced BP variation is common in CAPD patients and associated with volume overload and hypoalbuminemia. Furthermore, the relationship between nutritional, inflammatory status and dipping needs further studies.