[Response of vasoactive substance to blood pressure changes during hemodialysis in uremic patients]

Ultrafiltration during haemodialysis (HD) may be the cause of blood pressure (BP) decline due to reduction of blood volume. In some patients, however, BP does not decrease or even rises during HD. The aim of the study was to answer the question: do uraemic hypertensive patients, showing a decline of mean blood pressure (MAP) during HD session (group A) differ from those showing a stable MAP during HD session (group B) with respect to hormonal profile of aldosterone (ALD), vasopressin (AVP), atrial natriuretic peptide (ANP), endothelin-1,2 (ET-1,2), blood nitric oxide (NO) and plasma renin activity (PRA). A total of 39 haemodialysed, hypertensive patients (17 female, 22 men) were studied. 24 patients (group A) showed a MAP decline of 10 mm Hg or more, while 15 patients (group B) showed MAP changes of less than +/- 10 mm Hg during HD session. PRA, ALD, AVP, ANP, ET-1,2, NO concentration were assessed in blood samples withdrawn from the arterial blood line before HD and after 60, 120, 180 and 240 minutes of HD session. Plasma ET-1,2 and blood NO concentration were also assessed after 30 minutes of HD. BV was continuously monitored with a Crit-Line equipment, BP was measured before and every 30 minutes on HD. Before HD session both examined groups showed similar baseline plasma levels of ALD, AVP, ANP, ET-1,2, NO, PRA and MAP. A 4-hours HD induced a significant increase in plasma ALD and AVP concentrations and a significant decline in ANP level in both groups of patients. In group A, PRA and blood NO concentration increased significantly, while plasma ET-1,2, level did not change during HD. In group B, no significant changes in PRA and blood NO level were noticed, while plasma ET-1,2 rose markedly. In addition in group B, a significant positive correlation was found between MAP and plasma ET-1,2 level changes, but a significant negative correlation between MAP and blood NO level changes.

Patients with a decline of MAP over 10 mm Hg during HD differ from those with a stable MAP by a different response of plasma ET and blood NO to HD induced volume changes.