Acute kidney injury (AKI) affects up to 30% of critically ill patients and is associated with increased rates of mortality. Up to 60% of patients with AKI will ultimately require renal replacement therapy (RRT). Intermittent hemodialysis (IHD) is one of the main methods of RRT worldwide. In IHD-bicar, dialysate is composed by electrolytes, including calcium, and bicarbonate. To avoid calcium carbonate precipitation, dialysate has to be supplemented with acids (citric acid, chloride acid or acetic acid). However, IHD-bicar may be associated with hemodynamic instability or respiratory intolerance, mainly related to the CO2 release in the circulation during IHD (HCO3- <--> CO2 + H2O). Some recent studies showed that acetate free biofiltration (AFB-K), a technique that does not require dialysate acidification, could be associated with better hemodynamic stability and to a lower amount of CO2 delivered to the patients. AFB-K may thus improve the hemodynamic and respiratory tolerance of intermittent RRT in critically ill patients.

In this prospective observational study, investigators aim to characterize the hemodynamic and respiratory tolerances of HDI-bicar and AFB-K in critically ill patients requiring RRT.

Inclusion Criteria:

• Patients ≥ 18 years old
• Invasive monitoring of blood pressure
• Non opposition to the research
• Admission to the intensive care unit
• Need of intermittent hemodialysis

Exclusion Criteria:

• Sodium bicarbonate infusion
• Pregnancy or breastfeeding
• Juridical protection

Patients with acute kidney injury