THE EFFECT OF INTERDIALYTIC WEIGHT-GAIN ON PREDIALYSIS BLOOD-PRESSURE

Interdialytic weight gain is believed to influence predialysis blood p ressure. Since interdialytic weight gains vary among treatments for in dividual patients, blood pressure and weight gain data could be examin ed to determine how weight variations correlate with differences in bl ood pressure. Therefore, the quantitative effect on prehemodialysis bl ood pressure of typical interdialytic weight gains was prospectively s tudied in 19 nondiabetic patients on chronic hemodialysis. Over a mean of 23.6 treatments (range 17-25), the slope of each patient's prehemo dialysis blood pressure versus excess weight (prehemodialysis weight m inus baseline dry weight) was determined. The mean slope of the prehem odialysis mean blood pressure/excess weight regression line was 1.2 mm Hg/lb excess weight. No significant correlation was found between ind ividual prehemodialysis blood pressure/excess weight slopes and patien t age (r = 0.20), months on dialysis (r = 0.33), dry weight (r = 0.05) , or mean excess weight (r = 0. 19). Slopes did not differ for 3-day v ersus 2-day interdialytic intervals, hypertension-treated versus untre ated patients, or men versus women. In 5 patients, individual prehemod ialysis mean blood pressure/excess weight slopes were significantly gr eater than 0, averaging 2.4 mm Hg/lb excess weight (vs. 0.8 mm Hg/lb i n the remaining patients). These 5 volume-responsive patients did not differ clinically from the 14 volume-resistant patients. The weight ga ins commonly observed in patients undergoing chronic hemodialysis have only a modest effect on prehemodialysis blood pressure in the majorit y of patients.