title: Does inferior vena cava respiratory variability predict fluid responsiveness in spontaneously breathing patients?
abstract: BACKGROUND
  We have almost no information concerning the value of inferior vena cava (IVC) respiratory variations in spontaneously breathing ICU patients (SBP) to predict fluid responsiveness.
  
  
  METHODS
  SBP with clinical fluid need were included prospectively in the study. Echocardiography and Doppler ultrasound were used to record the aortic velocity-time integral (VTI), stroke volume (SV), cardiac output (CO) and IVC collapsibility index (cIVC) ((maximum diameter (IVCmax)- minimum diameter (IVCmin))/ IVCmax) at baseline, after a passive leg-raising maneuver (PLR) and after 500 ml of saline infusion.
  
  
  RESULTS
  Fifty-nine patients (30 males and 29 females; 57 ± 18 years-old) were included in the study. Of these, 29 (49 %) were considered to be responders (≥10 % increase in CO after fluid infusion). There were no significant differences between responders and nonresponders at baseline, except for a higher aortic VTI in nonresponders (16 cm vs. 19 cm, p = 0.03). Responders had a lower baseline IVCmin than nonresponders (11 ± 5 mm vs. 14 ± 5 mm, p = 0.04) and more marked IVC variations (cIVC: 35 ± 16 vs. 27 ± 10 %, p = 0.04). Prediction of fluid-responsiveness using cIVC and IVCmax was low (area under the curve for cIVC at baseline 0.62 ± 0.07; 95 %, CI 0.49-0.74 and for IVCmax at baseline 0.62 ± 0.07; 95 % CI 0.49-0.75). In contrast, IVC respiratory variations >42 % in SBP demonstrated a high specificity (97 %) and a positive predictive value (90 %) to predict an increase in CO after fluid infusion.
  
  
  CONCLUSIONS
  In SBP with suspected hypovolemia, vena cava size and respiratory variability do not predict fluid responsiveness. In contrast, a cIVC >42 % may predict an increase in CO after fluid infusion.
authors.affiliation: Intensive Care Unit, Department of Nephrology, Amiens University Medical Center, 80054, Cedex 1, Amiens, France. airapetian.norair@chu-amiens.fr.|Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. airapetian.norair@chu-amiens.fr.
authors.forename: Norair
authors.initials: N
authors.lastname: Airapetian
authors.affiliation: Intensive Care Unit, Department of Nephrology, Amiens University Medical Center, 80054, Cedex 1, Amiens, France. maizel.julien@chu-amiens.fr.|INSERM U-1088, Jules Verne University of Picardie, Amiens, France. maizel.julien@chu-amiens.fr.
authors.forename: Julien
authors.initials: J
authors.lastname: Maizel
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. alyamani.ola@chu-amiens.fr.
authors.forename: Ola
authors.initials: O
authors.lastname: Alyamani
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. mahjoub.yazine@chu-amiens.fr.|INSERM U-1088, Jules Verne University of Picardie, Amiens, France. mahjoub.yazine@chu-amiens.fr.
authors.forename: Yazine
authors.initials: Y
authors.lastname: Mahjoub
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. lorne.emmanuel@chu-amiens.fr.|INSERM U-1088, Jules Verne University of Picardie, Amiens, France. lorne.emmanuel@chu-amiens.fr.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lorne
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. levrard.melanie@chu-amiens.fr.
authors.forename: Melanie
authors.initials: M
authors.lastname: Levrard
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. ammenouche.nacim@chu-amiens.fr.
authors.forename: Nacim
authors.initials: N
authors.lastname: Ammenouche
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. seydi.aziz@chu-amiens.fr.
authors.forename: Aziz
authors.initials: A
authors.lastname: Seydi
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. tinturier.francois@chu-amiens.fr.
authors.forename: François
authors.initials: F
authors.lastname: Tinturier
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. lobjoie.eric@chu-amiens.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Lobjoie
authors.affiliation: Department of Anesthesiology and Intensive Care, Amiens University Medical Center, Amiens, France. dupont.herve@chu-amiens.fr.|INSERM U-1088, Jules Verne University of Picardie, Amiens, France. dupont.herve@chu-amiens.fr.
authors.forename: Hervé
authors.initials: H
authors.lastname: Dupont
authors.affiliation: Intensive Care Unit, Department of Nephrology, Amiens University Medical Center, 80054, Cedex 1, Amiens, France. slama.michel@chu-amiens.fr.|INSERM U-1088, Jules Verne University of Picardie, Amiens, France. slama.michel@chu-amiens.fr.
authors.forename: Michel
authors.initials: M
authors.lastname: Slama
mesh_terms: D000328:Adult; D000368:Aged; D002302:Cardiac Output / Q000502:physiology*; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D006801:Humans; D057446:Hydrodynamics; D020896:Hypovolemia / Q000097:blood* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012119:Respiration; D012143:Respiratory Physiological Phenomena; D014463:Ultrasonography; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging / Q000502:physiology* / Q000503:physiopathology