Intradialytic hypotension is a common complication of hemodialysis sessions in patients with chronic renal failure, with an estimated prevalence of 10 to 30%. This hypotensopn is classically defined by a decrease in systolic blood pressure greater than 30 mmHg associated with clinical signs (cramps, abdominal pain, unconsciousness, convulsions). Its repetition is correlated with cardiovascular events, neurological events and excess mortality. Several clinical factors have been proposed to predict the risk of intradialytic hypotension such as age, certain comorbidities (diabetes, ischemic heart disease...), dialysis modalities (hemodialysis), ultrafiltration, conductivity but also alterations of the autonomic nervous system (especially the sympathetic system).

In recent years, the study of vegetative functions has been facilitated by the use of SUDOSCAN® (Impeto, Paris, France) which is a simple, non-invasive tool that allows the study of Chlorine conductance directly reflecting the activity of small non-myelinated C fibers that innervate the sweat glands. SUDOSCAN® has shown good sensitivity and specificity in the diagnosis of vegetative damage in diabetic patients and also a good correlation with cardiac autonomic neuropathy. More recently, SUDOSCAN® has shown good sensitivity in the detection of neuropathies small fibers especially in diabetic patients. This sensitivity is comparable to QST-type quantitative tests and the correlation with cardiovascular dysautonomia tests is good. This test, simple and fast realization, does not require the active participation of the patient. There is a good correlation between the results of SUDOSCAN® and the reduction of intra-dermal fiber density at cutaneous biopsy.

Hemodialysis patients are at risk of peripheral neurological involvement not only because of an increasing incidence of diabetes (30-40%) but also because of the abnormal production and elimination of certain uremic toxins. Few studies exist on the anomalies of the vegetative system in hemodialysis. A recent publication has suggested a difference in nerve excitability depending on the type of hemodialysis suggesting nerve changes secondary to ionic changes. The identification of patients at risk of intradialytic hypotension during dialysis sessions could be useful for adapting hemodialysis protocols.

Patients will be classified into 2 groups according to the occurrence of intradialytic hypotension. Group 1 corresponds to patients with intradialytic hypotension and group 2 corresponds to patients without intradialytic hypotension.

Inclusion Criteria:

• Patient whose age ≥ 18 years
• Patient on hemodialysis for more than 6 months
• Patient affiliated with a health insurance plan
• Francophone patient
• Patient giving free, informed and express consent

Exclusion Criteria:

• Patient with lesions, wounds, amputations preventing the measurement of the chlorine conductance of the palms of the hands and feet
• Patient with a disability that prevents them from standing while measuring conductance / SUDOSCAN®
• Patient already included in an interventional research protocol
• Patient under tutorship or curatorship
• Patient deprived of liberty