Salem MM
Hypertension in the hemodialysis population: A survey of 649 patients

Am J Kidney Dis (Sep) 26:461-468 1995

This is a descriptive study of blood pressures in 649 mostly (89%) black patients in dialysis units in Mississippi. Patients were classified as hypertensive if they were taking anti-hypertensive meds or if mean predialysis MAP was greater than 114 mm Hg. Isolated systolic hypertension was defined as presystolic greater than 160 with a prediastolic BP less than 90. Patients were judged to be volume responsive if MAP decreased by more than 5% during dialysis.

About 72% of the total population was hypertensive according to this definition. Of the hypertensives, about 80% were being treated, and 20% were not. BP was lower in patients more than 65 years of age. Hypertension was "volume responsive" in 65% of cases, BP increased during dialysis in 9%, and BP was largely unchanged in the remainder of patients. MAP fell by 10% in untreated hypertensives, but only by 7% in patients receiving one or more drugs. Predialysis BP was similar in patients whose etiology of ESRD was hypertension, glomerulonephritis, diabetes, and PCKD. Of the 40% hypertensives receiving monotherapy, 22% were on CCBs, 10% on vasodilators, 10% on sympatholytics, and 5% on ACE-inhibitors. Pre-MAP was similar in these groups, and the ACE-group had similar interdialytic weight gains to the others (other data have suggested that ACE inhibitor administration to thirsty patients with high renin levels mitigates thirst).

Comment: In the analyses, treated hypertensive patients were mixed in with untreated patients, thus, a chicken vs. egg question comes up with a number of the findings. In the abstract, the author implies that anti- hypertensives may not be effective, as BP was only 3 mm less in treated hypertensives than in untreated hypertensives. This is a flawed argument, as patient selection may play an important role (i.e., if the treated patients had not been treated, their BP may have been much higher, with the presently untreated cohort representing a mildly affected subgroup). A further point made is, that since the BP fell by only 7% in treated hypertensives vs. 10% in treated hypertensives, volume is not an important component to the hypertension. The author also found, in agreement with Luik et al (Contrib Nephrol 106:90-93, 1994), that BP gain did not correlate with interdialytic weight gain. Yet, 65% of patients were volume responsive by the author's own definition, and the adequacy of ultrafiltration is difficult to assess in dialysis patients. Futhermore, volume overload per se may predispose to LVH independently of the level of blood pressure. This study does serve to focus attention on the gravity of the problem of high BP in dialysis patients. (Daugirdas)

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CRF by organ system : Cardiovascular/Hypertension
H: Special problems : Dialysis patients