Evaluation of daily urinary urea excretion, to guide Renal Replacement Therapy weaning, in Intensive Care Units.

The objective is to show that remove the dialysis catheter, once daily urinary urea excretion is greater than 1.35 mmol/kg/d, would increase more than 3 days the number without dialysis catheters, and thus without dialysis, the first 28 days after insertion.

Daily urinary urea excretion = urea (mmol/L) x diuresis (L/d) / weight (kg).

Daily urinary excretion of urea may provide a safe and reproducible renal replacement therapy withdrawal criterion, according to a recent French study (citations). A rate greater than 1.35 mmol/kg/d would predict a weaning success of 97.1% at 1 week. This criterion is influenced by the use of diuretics, and is easily accessible and achievable. Daily urinary urea excretion is representative of the recovery of renal function. The French study establishing this new withdrawal criterion was monocentric and retrospective. However, we changed our practices as soon as we became aware of them.

French multicentric (Bordeaux University Hospital, Libourne, Pau and Bayonne Hospitals) study, before and after:

• Period before: patients who were dialysed in the intensive care units of Bordeaux, Libourne, Pau and Bayonne, from November 2013 to November 2015.
• Period after: patients selected prospectively in the 4 hospitals.

When diuresis > 100 ml/d, an urinary ionogram is realized daily. Measurement of urinary urea excretion every day. Ablation of the catheter as soon as daily urinary urinary excretion > 1.35 mmol/kg/d.

Measurement of daily urinary excretion the following 3 days.

Inclusion Criteria:

• All patients > 18 of age, who have a Renal Replacement Therapy, in intensive care unit,
• with a diuresis > 100 ml/d.

Exclusion Criteria:

• Patients still presenting "hard" criteria for RRT: metabolic acidosis with pH < 7.15 and PCO2 <50mmHg; acute pulmonary edema (> 5l 02 or 50% FiO2 for Sp02 > 95%) objectified by echocardiography; K> 5.5 mmol/l after treatment
• Renal transplantation
• Long-term chronic kidney injury or short-term dialysis project (arteriovenous fistula created).
• Acute Kidney Injury secondary to thrombotic microangiopathy
• Acute Kidney Injury secondary to an obstacle even if dialysed
• RRT started for toxic cause without IRA (lithium,...)

All patients > 18 years of age, admitted to intensive care unit, who have a RRT for AKI.