title: Transthoracic Echocardiography with Doppler Tissue Imaging predicts weaning failure from mechanical ventilation: evolution of the left ventricle relaxation rate during a spontaneous breathing trial is the key factor in weaning outcome.
abstract: BACKGROUND
  There is growing evidence to suggest that transthoracic echocardiography (TTE) should be used to identify the cardiac origin of respiratory weaning failure.
  
  
  OBJECTIVE
  first, to evaluate the ability of transthoracic echocardiography, with mitral Doppler inflow E velocity to annular tissue Doppler Ea wave velocity (E/Ea) ratio measurement, to predict weaning failure from mechanical ventilation in patients, including those with atrial fibrillation; and second, to determine whether the depressed left ejection fraction and/or diastolic dysfunction participate in weaning outcome.
  
  
  METHODS
  The sample included patients on mechanical ventilation for over 48 hours. A complete echocardiography was performed just before the spontaneous breathing trial (SBT) and 10 minutes after starting the SBT. Systolic dysfunction was defined by a left ventricle ejection fraction under 50% and relaxation impairment by a protodiastolic annulus mitral velocity Ea under or equal to 8 cm/second.
  
  
  RESULTS
  A total of 68 patients were included. Twenty failed the weaning process and the other 48 patients succeeded. Before the SBT, the E/Ea ratio was higher in the failed group than in the successful group. The E/Ea measured during the SBT was also higher in the failed group. The cut-off value, obtained from receiver operating characteristics (ROC) curve analysis, to predict weaning failure gave an E/Ea ratio during the SBT of 14.5 with a sensitivity of 75% and a specificity of 95.8%. The left ventricular ejection fraction did not differ between the two groups whereas Ea was lower in the failed group. Ea increased during SBT in the successful group while no change occurred in the failed group.
  
  
  CONCLUSIONS
  Measurement of the E/Ea ratio with TTE could predict weaning failure. Diastolic dysfunction with relaxation impairment is strongly associated with weaning failure. Moreover, the impossibility of enhancing the left ventricle relaxation rate during the SBT seems to be the key factor of weaning failure. In contrast, the systolic dysfunction was not associated with weaning outcome.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Moschietto
authors.forename: Denis
authors.initials: D
authors.lastname: Doyen
authors.forename: Ludovic
authors.initials: L
authors.lastname: Grech
authors.forename: Jean
authors.initials: J
authors.lastname: Dellamonica
authors.forename: Hervé
authors.initials: H
authors.lastname: Hyvernat
authors.forename: Gilles
authors.initials: G
authors.lastname: Bernardin
mesh_terms: D000368:Aged; D015150:Echocardiography, Doppler / Q000379:methods* / Q000639:trends; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods* / Q000639:trends; D015656:Respiratory Mechanics / Q000502:physiology*; D017211:Treatment Failure; D016896:Treatment Outcome; D015300:Ventilator Weaning / Q000379:methods* / Q000639:trends; D016277:Ventricular Function, Left / Q000502:physiology*