EFFECTS OF HYPERVOLEMIA ON INTERDIALYTIC HEMODYNAMICS AND BLOOD-PRESSURE CONTROL IN HEMODIALYSIS-PATIENTS

The influence of hypervolemia on hemodynamics and interdialytic blood pressure, as well as in relation to vascular compliance, was investiga ted in 10 hemodialysis patients who were not receiving vasoactive medi cation, All subjects were studied during a relative normovolemic inter dialytic period (from 1 kg below dry weight postdialytic until dry wei ght predialytic) and a hypervolemic interdialytic period (from 1 kg ab ove dry weight postdialytic until 3 kg above dry weight predialytic), Interdialytic blood pressure was measured with an ambulatory blood pre ssure monitor, Cardiac output was echographically measured and total p eripheral resistance calculated postdialytic, mid-interdialytic, and p redialytic, At the same time, a blood sample was drawn for analyzing v asoactive hormones, sodium, and hematocrit. In all patients, ideal dry weight was estimated by echography of the caval vein, Arterial and ve nous compliance were measured with an ultrasound vessel wall movement detector system and a strain-gauge plethysmograph, After fluid load, a n increase in intravascular volume, an increase in caval vein diameter and cardiac output, and a decrease in peripheral resistance was obser ved, No significant influence of a 3-L fluid load was found on interdi alytic blood pressure course (153 +/- 24 mm Hg/90 +/- 19 mm Hg in the hypervolemic period and 146 +/- 27 mm Hg/89 +/- 22 mm Hg in the normov olemic period). Sodium and osmolality were similar in the hypervolemic and normovolemic interdialytic periods, After fluid load, a decrease in arginine vasopressin and angiotensin II was observed, which probabl y contributed to the decreased systemic vascular resistance, Catechola mines were not influenced by fluid load, but increased during the inte rdialytic period, suggesting accumulation after dialysis, Three of the 10 patients had higher systolic but not diastolic blood pressures aft er fluid load (159 +/- 13 mm Hg/81 +/- 22 mm Hg in the hypervolemic pe riod and 135 +/- 16 mm Hg/81 +/- 22 mm Hg in the normovolemic period), No correlation could be found between arterial or venous compliance a nd blood pressure changes, We concluded that a 3-L interdialytic fluid load does not result in higher blood pressure in most hemodialysis pa tients. (C) 1997 by the National Kidney Foundation, Inc.