title: Urine sodium concentration to predict fluid responsiveness in oliguric ICU patients: a prospective multicenter observational study.
abstract: BACKGROUND
  Oliguria is one of the leading triggers of fluid loading in patients in the intensive care unit (ICU). The purpose of this study was to assess the predictive value of urine Na(+) (uNa(+)) and other routine urine biomarkers for cardiac fluid responsiveness in oliguric ICU patients.
  
  
  METHODS
  We conducted a prospective multicenter observational study in five university ICUs. Patients with urine output (UO) <0.5 ml/kg/h for 3 consecutive hours with a mean arterial pressure >65 mmHg received a fluid challenge. Cardiac fluid responsiveness was defined by an increase in stroke volume >15 % after fluid challenge. Urine and plasma biochemistry samples were examined before fluid challenge. We examined renal fluid responsiveness (defined as UO > 0.5 ml/kg/h for 3 consecutive hours) after fluid challenge as a secondary endpoint.
  
  
  RESULTS
  Fifty-four patients (age 51 ± 37 years, Simplified Acute Physiology Score II score 40 ± 20) were included. Most patients (72 %) were not cardiac responders (CRs), and 50 % were renal responders (RRs) to fluid challenge. Patient characteristics were similar between CRs and cardiac nonresponders. uNa(+) (37 ± 38 mmol/L vs 25 ± 75 mmol/L, p = 0.44) and fractional excretion of sodium (FENa(+)) (2.27 ± 2.5 % vs 2.15 ± 5.0 %, p = 0.94) were not statistically different between those who did and those who did not respond to the fluid challenge. Areas under the receiver operating characteristic (AUROC) curves were 0.51 (95 % CI 0.35-0.68) and 0.56 (95 % CI 0.39-0.73) for uNa(+) and FENa(+), respectively. Fractional excretion of urea had an AUROC curve of 0.70 (95 % CI 0.54-0.86, p = 0.03) for CRs. Baseline UO was higher in RRs than in renal nonresponders (1.07 ± 0.78 ml/kg/3 h vs 0.65 ± 0.53 ml/kg/3 h, p = 0.01). The AUROC curve for RRs was 0.65 (95 % CI 0.53-0.78) for uNa(+).
  
  
  CONCLUSIONS
  In the present study, most oliguric patients were not CRs and half were not renal responders to fluid challenge. Routine urinary biomarkers were not predictive of fluid responsiveness in oliguric normotensive ICU patients.
authors.affiliation: AP-HP, GH St-Louis-Lariboisière, Anesthésie, Réanimation et brûlés, Hôpital St-Louis, Assistance Publique-Hôpitaux de Paris, 1 rue Claude Vellefaux, 75010, Paris, France. matthieu.legrand@aphp.fr.|UMR INSERM 942, Institut National de la Santé et de la Recherche Médicale (INSERM), Lariboisière Hospital, Paris, France. matthieu.legrand@aphp.fr.|Université Paris Diderot, F-75475, Paris, France. matthieu.legrand@aphp.fr.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Legrand
authors.affiliation: AP-HP, GH St-Louis-Lariboisière, Anesthésie, Réanimation et brûlés, Hôpital St-Louis, Assistance Publique-Hôpitaux de Paris, 1 rue Claude Vellefaux, 75010, Paris, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Le Cam
authors.affiliation: Service de Réanimation Adultes et USC, CHU Estaing, Clermont-Ferrand, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Perbet
authors.affiliation: Service des Réanimations, Pôle Anesthésie Réanimation Douleur Urgence, CHU Nîmes, Place du Professeur Robert Debré, 30029, Nîmes Cedex 9, France.|EA 2992, Faculté de Médecine, Université Montpellier, Nîmes, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Roger
authors.affiliation: Service de Réanimation Médicale, Hôpital Nord, CHU Saint-Etienne, EA3065, Faculté de Médecine Jacques Lisfranc, Saint-Etienne, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Darmon
authors.affiliation: Département d'Anesthésie-Réanimation, CHU Nancy, Vandoeuvre-Lès-Nancy, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Guerci
authors.affiliation: AP-HP, GH St-Louis-Lariboisière, Anesthésie, Réanimation et brûlés, Hôpital St-Louis, Assistance Publique-Hôpitaux de Paris, 1 rue Claude Vellefaux, 75010, Paris, France.
authors.forename: Axelle
authors.initials: A
authors.lastname: Ferry
authors.affiliation: AP-HP, GH St-Louis-Lariboisière, Anesthésie, Réanimation et brûlés, Hôpital St-Louis, Assistance Publique-Hôpitaux de Paris, 1 rue Claude Vellefaux, 75010, Paris, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Maurel
authors.affiliation: AP-HP, GH St-Louis-Lariboisière, Anesthésie, Réanimation et brûlés, Hôpital St-Louis, Assistance Publique-Hôpitaux de Paris, 1 rue Claude Vellefaux, 75010, Paris, France.
authors.forename: Sabri
authors.initials: S
authors.lastname: Soussi
authors.affiliation: Service de Réanimation Adultes et USC, CHU Estaing, Clermont-Ferrand, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Constantin
authors.affiliation: AP-HP, GH St-Louis-Lariboisière, Anesthésie, Réanimation et brûlés, Hôpital St-Louis, Assistance Publique-Hôpitaux de Paris, 1 rue Claude Vellefaux, 75010, Paris, France.|UMR INSERM 942, Institut National de la Santé et de la Recherche Médicale (INSERM), Lariboisière Hospital, Paris, France.|Université Paris Diderot, F-75475, Paris, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Gayat
authors.affiliation: Service des Réanimations, Pôle Anesthésie Réanimation Douleur Urgence, CHU Nîmes, Place du Professeur Robert Debré, 30029, Nîmes Cedex 9, France.|EA 2992, Faculté de Médecine, Université Montpellier, Nîmes, France.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Lefrant
authors.affiliation: Service d'Anesthésie-Réanimation, Hôpital Nord, AP-HM, Aix-Marseille Université, Marseille, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Leone
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology; D005260:Female; D005440:Fluid Therapy / Q000401:mortality* / Q000451:nursing; D006801:Humans; D007362:Intensive Care Units; D007552:Isotonic Solutions / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009846:Oliguria / Q000175:diagnosis* / Q000628:therapy; D011446:Prospective Studies; D012964:Sodium / Q000652:urine*
chemical_list: D007552:Isotonic Solutions; D012964:Sodium
keywords: Acute kidney injury; Cardiac output; Fluid responsiveness; Natriuresis; Urine output