Heterogeneity of the cardiovascular response to hemofiltration

Twenty-one stable maintenance hemodialysis patients were studied in a crossover format with hemofiltration to determine whether the lower incidence of symptomatic hypotension noted with hemofiltration could be correlated with changes in baroreflex function as tested using the cold pressor test and amyl nitrite inhalation study. Baroreflex function remained abnormal and unchanged in all patients in the face of a reduced incidence of symptomatic hypotension. Subdivision of the patients into frequent (greater than 1 episode/treatment) and infrequent (less than 1 episode/treatment) reactors during the hemodialysis control period resulted in the infrequent reactors, showing a significant increase in episodes of symptomatic hypotension/hemofiltration treatment where a significant reduction was noted with the frequent reactors. No clear correlation could be made between the incidence of symptomatic hypotension and the pre- to post-treatment change in body temperature. The presence of pretreatment hypertension, another previously identified correlate of symptomatic hypotension with hemodialysis, also could not be corroborated. Further, changes from baseline predialysis values in mean arterial pressure noted with hemofiltration could not be correlated with a changed incidence of symptomatic hypotension. We conclude that previously identified correlates of symptomatic hypotension noted in the hemodialysis setting may be dissociated during treatment with hemofiltration and that there is a heterogeneous patient response to this treatment. These data suggest that there are additional, as yet undetermined, pathophysiologic events that underly the symptomatic hypotension of artificial kidney treatment.