Blood Pressure, Volume, and Sodium Control in an Automated Peritoneal Dialysis Population

Abstract

To examine the control of blood pressure and volume, and the role of sodium removal in a single, large, contemporary, automated peritoneal dialysis (APD) population where icodextrin is used liberally and there is a policy to avoid long duration glucose-based daytime dwells. Observational cross-sectional study. A university hospital. 56 APD patients, with a mean duration on peritoneal dialysis of 1.9 years; 50% were prescribed icodextrin. Blood pressure, extracellular water volume (ECW)-to-intracellular water volume (ICW) ratio, and total (peritoneal and urinary) sodium removal. Sodium Removal: Mean total sodium removal, while low at 102.9 +/- 64.6 mmol/day, showed a wide range, with 41% having a sodium removal of >120 mmol/day. Total sodium removal correlated with total body water, ECW, and ICW (p < 0.001, p < 0.001, p < 0.025, respectively), as well as with height and weight (p < 0.06, p < 0.01 respectively). On multivariate analysis, only ultrafiltration volume and urine volume were significantly associated with total sodium removal (r(2) = 0.67, p < 0.0001 for both). There was also a correlation between sodium removal and urea nitrogen appearance (r(2) = 0.31, p < 0.001), with urea nitrogen appearance in turn being closely correlated with ICW (p < 0.001). Volume Status: The ECW/ICW ratio was 0.88 +/- 0.17, which was not significantly different to that found in hemodialysis patients without clinical evidence of fluid overload, either predialysis (0.96 +/- 0.16) or postdialysis (0.92 +/- 0.16); p = 0.07 and 0.36 respectively. Blood Pressure: Mean +/- standard deviation systolic blood pressure (BP) was 111.9 +/- 18.2 mmHg and diastolic BP was 63.3 +/- 11.9 mmHg, with only 4 (7%) patients having a systolic BP > 140 mmHg and 1 (2%) having a diastolic BP > 80 mmHg. Median number of antihypertensives was 1 per day. Blood pressure control and ECW/ICW ratio were similar in those with sodium removal >120 mmol/day compared to those with sodium removal < or =120 mmol/day (p = 0.39 for SBP, p = 0.70 for diastolic BP, p = 0.24 for ECW/ICW). We have shown that good blood pressure and volume control is achievable in a large contemporary APD population with liberal use of icodextrin and avoidance of long daytime glucose-based dwells. Neither low nor high sodium removal was associated with more frequent hypertension or volume expansion.