title: [Correction to the airflow measurement in the presence of a leak between the trachea and endotracheal tube].
abstract: OBJECTIVE
  To estimate the leak between the endotracheal tube and the trachea in newborns in order to compensate for errors in airflow measurement and to monitor mechanical variables from pressure and flow signals.
  
  
  METHODS
  Assuming that the leak resistance (Rf) is constant during a respiratory cycle, the resistive properties of the endotracheal tube were evaluated. The method was validated in the intensive care unit with a mechanical test lung and assessed on recordings of three newborns during mechanical ventilation for RDS. We have used a least squares method for the estimation of positive end expiratory pressure (PEEP) on both newborns and simulated data.
  
  
  RESULTS
  Direct measurements of simulated leak resistances on the mechanical lung are in agreement with our estimation of leak resistances. In newborns, the success of flow correction is evidenced on end inspiratory pauses: corrected flow drops to zero while raw data show a constant nonzero flow. On the simulated lung, the PEEP underestimation with uncorrected flow ranges from 10 to 20 cm H20 while the corresponding, underestimation with corrected flow is less than 2 cm H2O. In newborns, the flow correction shifts the estimated PEEP from negative values (-0.3 +/- 1.3 cm H2O before correction) to positive values (3.6 +/- 0.7 cm H2O after correction) higher than the imposed PEEP (2 cm H2O).
  
  
  CONCLUSIONS
  The efficiency of this simple method has been demonstrated. It could be used successfully on adult patients, as there will not be flow correction in the absence of leaks.
authors.affiliation: Faculté de Médecine, Université J Fourier Grenoble I, France.
authors.forename: E
authors.initials: E
authors.lastname: Bijaoui
authors.forename: P Y
authors.initials: PY
authors.lastname: Carry
authors.forename: A
authors.initials: A
authors.lastname: Eberhard
authors.forename: P
authors.initials: P
authors.lastname: Andrini
authors.forename: J P
authors.initials: JP
authors.lastname: Perdrix
authors.forename: P
authors.initials: P
authors.lastname: Baconnier
mesh_terms: D006801:Humans; D007231:Infant, Newborn; D007442:Intubation, Intratracheal; D016018:Least-Squares Analysis; D011175:Positive-Pressure Respiration; D011312:Pressure
vernacular_title: La correction du débit en présence d'une fuite entre trachée et sonde endotrachéale.