Background: Hypertension, which is often associated with hypervolaemia, is common in haemodialysis patients and is a known determinant of target organ damage. Interdialytic weight gain due to volume overload has also been associated with mortality in haemodialysis patients.
Methods: We therefore studied 27 chronic haemodialysis patients who underwent 48-h ambulatory blood pressure monitoring between two midweek dialysis sessions, and 2D and M-mode echocardiography for determination of left ventricular mass index.
Results: Left ventricular hypertrophy (left ventricular mass index in men > 131 g/m2, women > 100 g/m2) was present in 70% (19/27) patients despite a mean 48-h blood pressure of 132 +/- 19/81 +/- 15 mmHg. Mean interdialytic weight gain was 1.6 +/- 0.8 kg and was not related to left ventricular mass index. Two patterns of interdialytic blood pressure change were apparent: in group 1 (16 patients) 48-h blood pressure increased (+19 +/- 12/13 +/- 9 mmHg), whereas in group 2 (11 patients) blood pressure fell (-10 +/- 13/-8 +/- 10 mmHg P < 0.0001). In both groups the number of hypertensive patients (group 1, 10/16; group 2, 6/11), the 48-h blood pressure (132 +/- 20/80 +/- 15 vs 132 +/- 18/82 +/- 15 mmHg) and interdialytic weight gain (+1.9 +/- 0.7 vs +1.3 +/- 0.7 kg) were similar. There was also no correlation between interdialytic blood pressure change and weight gain in either group.
Conclusions: We conclude that interdialytic blood pressure changes cannot be directly related to interdialytic fluid gain, even in apparent volume-dependent hypertension, emphasizing the importance of additional factors in the control of blood pressure in end-stage renal disease.