title: Changes in aortic blood flow induced by passive leg raising predict fluid responsiveness in critically ill patients.
abstract: BACKGROUND
  Esophageal Doppler provides a continuous and non-invasive estimate of descending aortic blood flow (ABF) and corrected left ventricular ejection time (LVETc). Considering passive leg raising (PLR) as a reversible volume expansion (VE), we compared the relative abilities of PLR-induced ABF variations, LVETc and respiratory pulsed pressure variations (DeltaPP) to predict fluid responsiveness.
  
  
  METHODS
  We studied 22 critically ill patients in acute circulatory failure in the supine position, during PLR, back to the supine position and after two consecutive VEs of 250 ml of saline. Responders were defined by an increase in ABF induced by 500 ml VE of more than 15%.
  
  
  RESULTS
  Ten patients were responders and 12 were non-responders. In responders, the increase in ABF induced by PLR was similar to that induced by a 250 ml VE (16% versus 20%; p = 0.15). A PLR-induced increase in ABF of more than 8% predicted fluid responsiveness with a sensitivity of 90% and a specificity of 83%. Corresponding positive and negative predictive values (PPV and NPV, respectively) were 82% and 91%, respectively. A DeltaPP threshold value of 12% predicted fluid responsiveness with a sensitivity of 70% and a specificity of 92%. Corresponding PPV and NPV were 87% and 78%, respectively. A LVETc of 245 ms or less predicted fluid responsiveness with a sensitivity of 70%, and a specificity of 67%. Corresponding PPV and NPV were 60% and 66%, respectively.
  
  
  CONCLUSIONS
  The PLR-induced increase in ABF and a DeltaPP of more than 12% offer similar predictive values in predicting fluid responsiveness. An isolated basal LVETc value is not a reliable criterion for predicting response to fluid loading.
authors.affiliation: Medical Intensive Care Unit, Cochin Hospital, APHP, Université Paris Descartes, 27, rue du Faubourg Saint Jacques, 75679 Paris Cedex 14, France. aurelie.l@club-internet.fr
authors.forename: A
authors.initials: A
authors.lastname: Lafanechère
authors.forename: F
authors.initials: F
authors.lastname: Pène
authors.forename: C
authors.initials: C
authors.lastname: Goulenok
authors.forename: A
authors.initials: A
authors.lastname: Delahaye
authors.forename: V
authors.initials: V
authors.lastname: Mallet
authors.forename: G
authors.initials: G
authors.lastname: Choukroun
authors.forename: J D
authors.initials: JD
authors.lastname: Chiche
authors.forename: J P
authors.initials: JP
authors.lastname: Mira
authors.forename: A
authors.initials: A
authors.lastname: Cariou
mesh_terms: D000368:Aged; D001013:Aorta, Thoracic / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D016638:Critical Illness / Q000453:epidemiology* / Q000628:therapy*; D005260:Female; D005440:Fluid Therapy; D006801:Humans; D007866:Leg / Q000098:blood supply* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016683:Supine Position / Q000502:physiology*