The objective of this study is to assess the feasibility of estimating the clearance of iohexol as an indirect measure of glomerular filtration rate in patients with unstable renal function in the intensive care unit through analysis of rich iohexol plasma kinetics.

Inclusion Criteria:

• Age ≥ 18 years
• Patient admitted to intensive care for less than 12 hours
• Acute circulatory failure
• Patient carrying an arterial catheter
• Informed consent obtained
• Affiliated to social security system

Exclusion Criteria:

• Administration of iohexol the week before intensive care admission
• Administration of iohexol expected within 24 hours of study entry
• Known history of cutaneous immediate or delayed allergic reaction to the injection of the product
• Indication for albumin transfusion within 24 hours of potential inclusion in the study
• Pregnancy or breastfeeding in progress
• Patient under guardianship or judicial protection known at the time of inclusion
• Withdrawal of consent
• Administration of iohexol outside the study within 24 hours after administration of iohexol in the context of the study
• Administration of intravenous albumin in the 24 hours following administration of iohexol in the context of the study