Analgesia Nociception Index to Explore Autonomic Nervous System in Patients With Continuous Renal Replacement Therapy

Inclusion Criteria: * Continuous renal replacement therapy in intensive care unit * Initiation of net ultrafiltration according to the protocol of the department or to EARLYDRY study (NCT 05817539) (3 criteria required): * Fluid overload \> 5% or peripheral oedema * Noradrenaline equivalent \<0.5μg/kg/min * No peripheral hypoperfusion * Invasive blood pressure monitoring * Central venous line in superior vena cava territory * Regular sinus rhythm * Patient awake or Richmond Agitation and Sedation Scale \> -3 Exclusion Criteria: * Ongoing administration of inotropes * Ongoing administration of beta blockers * Current administration of alpha-2 agonists * History of dysautonomia * Pregnant or breast-feeding woman * Mechanical circulatory assistance * Opposition to participate * Adults under legal protection * Persons deprived of their liberty by judicial or administrative decision