Hemodynamic stability during hemodialysis: A role for vasopressin?

Despite technological advances, intradialytic hypotension remains a serious complication for hemodialysis patients. A measure to prevent intradialytic hypotension is the biofeedback system Hemocontrol. The mechanism behind the improved hemodynamic stability with Hemocontrol dialysis is not fully elucidated. The results from this thesis suggest that the hormone vasopressin may play a role. Despite decreases in blood pressure and blood volume, vasopressin levels did not increase during conventional hemodialysis, presumably due to clearance of vasopressin by hemodialysis. Hemocontrol dialysis resulted in slightly but significantly higher intradialytic plasma vasopressin levels and was associated with better hemodynamic stability during treatment compared to conventional hemodialysis. Less nitric oxide production, enhanced sympathetic activity or a higher plasma refill rate did not seem to explain the improved hemodynamic stability with Hemocontrol dialysis. Besides vasopressin, we also studied copeptin. Copeptin and vasopressin are derived from the same prohormone. Copeptin is frequently used as surrogate marker for vasopressin although the effect of renal function and hemodialysis on the copeptin/vasopressin ratio is not thoroughly studied. We found that the copeptin/vasopressin ratio remained constant in patients with chronic kidney disease (CKD) with an eGFR >28 ml/min/1.73m2. In contrast, in patients with an eGFR ≤28 ml/min/1.73m2, copeptin levels were higher relative to vasopressin levels. Furthermore, vasopressin was cleared by hemodialysis to a greater extent than copeptin. Thus, copeptin did not accurately reflect the vasopressin concentration in patients with CKD stages 4, 5 and 5D. For hemodialysis patients experiencing intradialytic hypotension, vasopressin might be a promising drug to maintain intradialytic hemodynamic stability and deserves further attention.