The growing problem of intradialytic hypertension.

Intradialytic hypertension is not a rare complication of dialysis, with a prevalence of 5-15% among hemodialysis patients, and it seems to be associated with adverse outcomes. This complex phenomenon is not well understood, and many uncertainties exist regarding its pathophysiologic mechanisms and appropriate treatment strategies. Mechanisms that might be involved in the pathogenesis of intradialytic hypertension include extracellular volume overload, increased cardiac output, changes in electrolyte levels (particularly sodium), activation of the renin-angiotensin-aldosterone system, overactivity of the sympathetic nervous system, and endothelial cell dysfunction. Most current treatment strategies are based only on expert opinion and not on the results of randomized clinical trials, as very little data on the therapy of intradialytic hypertension are available. The most important treatment is adequate sodium and water removal, but reducing sympathetic hyperactivity and reducing endothelin-1 levels should also be considered. Well-designed, randomized clinical trials are urgently needed to better understand the pathophysiologic mechanisms of this complex phenomenon and to improve its diagnosis, prognosis and treatment.