[Arterial hypotension in dialysis]

Arterial hypotension, defined as a systolic blood pressure < 100 mmHg, is the most frequent complication in dialysis patients. Four types of hypotension can be identified: chronic, per-dialytic, hypotensive shock and the hypotension due to an unexpected cause. The pathophysiology is relatively well known when the hypotension is secondary to a decrease in the intravascular volume provoked by a sustained ultrafiltration rate during the dialysis session. However, new mechanisms also appear to play an-important role, namely, the dysfunction of the autonomic nervous system and the plasmatic accumulation of vasoactive substances such as adrenomedullin, nitric oxide, and asymmetric dimethyl arginine. Hypotensive episodes can be responsible of acute vascular complications such as myocardial ischemia, ischemic cerebro-vascular accidents, venous thrombosis (retina vein), intestinal ischemia and the aggravation of lower member arteritis. In the long-term, pre-dialysis hypotension has been found associated with an increased mortality rate. The goal of this article is to review the pathophysiological mechanisms involved in the arterial hypotension of dialysis patients, its treatment and the potential preventive measures.