title: Passive leg-raising and end-expiratory occlusion tests perform better than pulse pressure variation in patients with low respiratory system compliance.
abstract: OBJECTIVE
  We tested whether the poor ability of pulse pressure variation to predict fluid responsiveness in cases of acute respiratory distress syndrome was related to low lung compliance. We also tested whether the changes in cardiac index induced by passive leg-raising and by an end-expiratory occlusion test were better than pulse pressure variation at predicting fluid responsiveness in acute respiratory distress syndrome patients.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Medical intensive care unit.
  
  
  METHODS
  We included 54 patients with circulatory shock (63 ± 13 yrs; Simplified Acute Physiology Score II, 63 ± 24). Twenty-seven patients had acute respiratory distress syndrome (compliance of the respiratory system, 22 ± 3 mL/cm H2O). In nonacute respiratory distress syndrome patients, the compliance of the respiratory system was 45 ± 9 mL/cm H2O.
  
  
  RESULTS
  We measured the response of cardiac index (transpulmonary thermodilution) to fluid administration (500 mL saline). Before fluid administration, we recorded pulse pressure variation and the changes in pulse contour analysis-derived cardiac index induced by passive leg-raising and end-expiratory occlusion. Fluid increased cardiac index ≥ 15% (44% ± 39%) in 30 "responders." Pulse pressure variation was significantly correlated with compliance of the respiratory system (r = .58), but not with tidal volume. The higher the compliance of the respiratory system, the better the prediction of fluid responsiveness by pulse pressure variation. A compliance of the respiratory system of 30 mL/cm H2O was the best cut-off for discriminating patients regarding the ability of pulse pressure variation to predict fluid responsiveness. If compliance of the respiratory system was >30 mL/cm H2O, then the area under the receiver-operating characteristics curve for predicting fluid responsiveness was not different for pulse pressure variation and the passive leg-raising and end-expiratory occlusion tests (0.98 ± 0.03, 0.91 ± 0.06, and 0.97 ± 0.03, respectively). By contrast, if compliance of the respiratory system was ≤ 30 mL/cm H2O, then the area under the receiver-operating characteristics curve was significantly lower for pulse pressure variation than for the passive leg-raising and end-expiratory occlusion tests (0.69 ± 0.10, 0.94 ± 0.05, and 0.93 ± 0.05, respectively).
  
  
  CONCLUSIONS
  The ability of pulse pressure variation to predict fluid responsiveness was inversely related to compliance of the respiratory system. If compliance of the respiratory system was ≤ 30 mL/cm H2O, then pulse pressure variation became less accurate for predicting fluid responsiveness. However, the passive leg-raising and end-expiratory occlusion tests remained valuable in such cases.
authors.affiliation: AP-HP, Hôpital de Bicêtre, Service de Réanimation Médicale, Le Kremlin-Bicêtre, France. xavier.monnet@bct.aphp.fr
authors.forename: Xavier
authors.initials: X
authors.lastname: Monnet
authors.forename: Alexandre
authors.initials: A
authors.lastname: Bleibtreu
authors.forename: Alexis
authors.initials: A
authors.lastname: Ferré
authors.forename: Martin
authors.initials: M
authors.lastname: Dres
authors.forename: Rim
authors.initials: R
authors.lastname: Gharbi
authors.forename: Christian
authors.initials: C
authors.lastname: Richard
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Teboul
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output; D005260:Female; D005440:Fluid Therapy / Q000379:methods; D006801:Humans; D007866:Leg / Q000098:blood supply / Q000503:physiopathology; D008170:Lung Compliance; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011187:Posture / Q000502:physiology; D011446:Prospective Studies; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome