Sodium Bicarbonate for the Treatment of Severe Metabolic Acidosis With Moderate or Severe Acute Kidney Injury in ICU

Severe metabolic acidemia in the critically ill (pH equal or less than 7.20; PaCO2 equal or less than 45mmHg and bicarbonate concentration equal or less than of 20 mmol/l) is associated with a 50% rate of day 28 mortality. Moderate to severe acute kidney injury is a frequent cause of metabolic acidemia in the critically ill. When both severe metabolic acidemia and moderate to severe acute kidney injury are observed, day 28 mortality is approximatively 55-60%. Severe acidemia has been shown to be a biomarker of severity but may also contribute by itself to outcome. Investigators recently performed a multiple center randomised clinical trial (BICARICU-1) that suggests that sodium bicarbonate infusion titrated to maintain the pH equal or more than 7.30 is associated with a higher survival rate (secondary endpoint) in patients presenting both severe metabolic acidemia and moderate to severe acute kidney injury patients. Whether sodium bicarbonate infusion may improve long term survival (Day 90, primary outcome) in these severe acute kidney injury patients is currently unknown.

Inclusion Criteria: * Aged from 18 years old * Admitted in the ICU where the BICARICU-2 trial takes place * Within 6h before enrolment, the patient MUST present on the same arterial blood gas (the last available before enrollment) the 3 following criteria: pH ≤ 7.20 ; Bicarbonatemia ≤ 20 mmol/l ; AND PaCO2 ≤ 45mmHg ; * Moderate to severe acute kidney injury ("Kidney Disease Improving Global Outcome", KDIGO group of 2 or 3) * Within 48h of ICU admission, a total SOFA ≥ 4 OR an arterial lactate concentration ≥ 2 mmol/l * Signed informed consent form. According to the French law, considering the severity of the illness, the fact that most of these patients would be unable to consent (sedation or potential delirium) and that their proxies might not be contactable at the time of inclusion, a deferred consent process for emergency situations will be enabled. When deferred consent will be used, written permission to pursue the research will be obtained from the patient or proxy as soon as possible. If this consent is not obtained, the patient's data will not be used and they will be withdrawn from the trial. * Subjects must be covered by public health insurance Exclusion Criteria: * Pure respiratory acidosis (defined by pH 7.20, PaCO2 \>50 mmHg, bicarbonatemia equal or greater than (PaCO2-40)/10 + 24), digestive or urinary tract proven loss of fluid (equal or greater than 1500ml/24h) with concomitant loss of sodium bicarbonate, chronic kidney insufficiency (creatinine clearance ≤ 10ml/min), proven tubular acidosis, ketoacidosis, exogenous acids poisoning (aspirin, methanol, ), PaCO2 \> 45 mmHg and spontaneous breathing, sodium bicarbonate infusion or renal replacement therapy within 24h prior to screening prior to screening or imminent in the next 6h. * Pregnant or breast feeding patient * Patient who is in a dependency or employment with the sponsor or the investigator * Patient who was enrolled in another study and who is in the exclusion period for any enrolment in the present study * Life expectancy less than 48h * Consent refusal from the patient or his/her next of kin and the impossibility to enrol using the emergency procedure * Patients protected by law (Art.L 1121-5, 1121-6, 1121-8 du Code de la santé publique) * Absence of a French Health Care Insurance coverage