EFFECTS OF COOLER TEMPERATURE DIALYSATE ON HEMODYNAMIC STABILITY IN PROBLEM DIALYSIS PATIENTS

Symptomatic hypotension is a common and disabling complication of hemo dialysis treatments. The incidence of symptomatic hypotensive episodes is particularly high in patients who have normal or low blood pressur e at the initiation of dialysis and in patients who have large interdi alytic weight gains. The aim of this study was to determine whether co oling the dialysate temperature from 37-degrees-C to 35-degrees-C impr oved tolerance to dialysis in a group of 12 of these ''problem'' patie nts. A double-blinded protocol was performed in six hypotension-prone and six large weight gainers who were subjected to two identical hemod ialyses except for the dialysate temperature of 37-degrees-C or 35-deg rees-C. Changes in biochemical parameters and weight were comparable d uring the two maneuvers. Recumbent blood pressure declined significant ly (P < 0.01) during 37-degrees-C dialysis but not 35-degrees-C dialys is; blood pressure was significantly lower at 1, 2, and 3 hours of 37- degrees-C dialysis compared to 35-degrees-C dialysis (P < 0.05). Furth er, both supine and upright blood pressure was significantly lower fol lowing 37-degrees-C dialysis (P < 0.02). This lower blood pressure was present in both subgroups of patients. All 18 episodes of symptomatic hypotension noted during the study occurred during 37-degrees-C dialy sis. A significantly greater increase in peripheral vascular resistanc e (calf blood flow was measured directly by venous occlusion plethysmo graphy) occurred upon exposure to the 35-degrees-C dialysate in both s ubgroups of patients (P < 0,01); supine and upright post-dialysis plas ma norepinephrine values were also significantly greater (P < 0.001) a fter 35-degrees dialysis. Thus, 35-degrees-C dialysate significantly i mproves the hemodynamic tolerance to hemodialysis in hypotension-prone and large weight gainer patient groups and also reduces the incidence of symptomatic hypotension. This improvement is partly the result of a greater increase in peripheral vascular resistance, possibly mediate d via the efferent sympathetic nervous system.