title: Passive leg raising performed before a spontaneous breathing trial predicts weaning-induced cardiac dysfunction.
abstract: OBJECTIVE
  Weaning-induced cardiac dysfunction is more likely to occur if the heart does not tolerate the changes in loading conditions induced by spontaneous breathing trial (SBT). We hypothesized that the presence of cardiac preload independence before an SBT is associated with weaning failure related to cardiac dysfunction.
  
  
  METHODS
  We included 30 patients after a first failed 1-h T-tube SBT who had a transpulmonary thermodilution already in place. Preload independence [no increase in the pulse contour analysis-derived cardiac index ≥10 % during passive leg raising (PLR)] was assessed before the second SBT. Failure of the SBT related to cardiac dysfunction was defined by an increase in pulmonary artery occlusion pressure above 18 mmHg at the end of the SBT associated with clinical intolerance.
  
  
  RESULTS
  Fifty-seven SBTs were analyzed. The SBT failed in 46 cases. Overall, 31 failed SBTs were associated with weaning-induced cardiac dysfunction. During PLR, the cardiac index did not change in cases of failed SBTs with cardiac dysfunction, whereas it significantly increased in the other cases: 4 % (interquartile range, IQR 0-5) vs. 12 % (IQR 11-15), respectively. If PLR did not increase the cardiac index by more than 10 % before the SBT, the occurrence of SBT failure related to cardiac dysfunction was predicted with a sensitivity of 97 % [95 % confidence interval (CI) 83-100], specificity of 81 % (95 % CI 61-93) and area under the receiver-operating characteristic curve of 0.88 (95 % CI 0.78-0.98).
  
  
  CONCLUSIONS
  Preload independence assessed by a negative PLR test performed before an SBT predicts weaning failure related to cardiac dysfunction.
authors.affiliation: EA4533, Université Paris-Sud, Le Kremlin-Bicêtre, France, martin.dres@psl.aphp.fr.
authors.forename: Martin
authors.initials: M
authors.lastname: Dres
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Teboul
authors.forename: Nadia
authors.initials: N
authors.lastname: Anguel
authors.forename: Laurent
authors.initials: L
authors.lastname: Guerin
authors.forename: Christian
authors.initials: C
authors.lastname: Richard
authors.forename: Xavier
authors.initials: X
authors.lastname: Monnet
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology*; D003971:Diastole / Q000502:physiology; D015633:Extravascular Lung Water; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007362:Intensive Care Units; D007866:Leg / Q000098:blood supply* / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D063305:Organ Dysfunction Scores; D011237:Predictive Value of Tests; D056152:Respiratory Rate / Q000502:physiology; D013815:Thermodilution; D015300:Ventilator Weaning