title: Ventilator-induced overdistension in children: dynamic versus low-flow inflation volume-pressure curves.
abstract: We applied to 20 paralyzed ventilated children (0.15 to 14.3 yr, six with acute respiratory distress syndrome [ARDS]) the low-flow inflation (LFI) technique providing quasi-static volume-pressure (V-P) curves and compared the assessment of overdistension (OD) on dynamic and LFI (reference) inspiratory V-P curves. Dynamic curves were obtained at the airway opening during regular constant flow ventilation (Servo 300). Then LFI curves were obtained. Two analyses were performed: First, the nonlinear coefficient c of a second order polynomial equation (SOPE) fitted to dynamic data obtained during constant flow was compared with the c of SOPE fitted to LFI curve (within tidal volume [VT]). Second, the dynamic C20/C (ratio of compliance of the last 20% of the curve (C20) to total compliance [C]) was compared with the determination of the upper inflection point (UIP) on the LFI curve. OD was defined as a negative value of c, a C20/C < 0.80, an UIP included within the VT range for that child during regular ventilation. Using LFI V-P curves as reference, SOPE offered a better detection of OD than dynamic C20/C or the determination of the UIP by graphical means. Indeed the first analysis showed a substantial agreement (kappa 0.75) between dynamic c and LFI c detection of OD whereas the second analysis showed a poor agreement (kappa 0.22) between C20/ C and LFI detection of the UIP. In conclusion, quasi-static V-P curves can easily be obtained in children with the LFI technique. SOPE offers a good detection of OD on dynamic and LFI V-P curves but the C20/C index seems to be an inadequate measure of OD.
authors.affiliation: Service de Réanimation Pédiatrique, Centre Hospitalier et Universitaire de Lille, Lille, France.
authors.forename: V
authors.initials: V
authors.lastname: Nève
authors.forename: E D
authors.initials: ED
authors.lastname: de la Roque
authors.forename: F
authors.initials: F
authors.lastname: Leclerc
authors.forename: S
authors.initials: S
authors.lastname: Leteurtre
authors.forename: A
authors.initials: A
authors.lastname: Dorkenoo
authors.forename: A
authors.initials: A
authors.lastname: Sadik
authors.forename: R
authors.initials: R
authors.lastname: Cremer
authors.forename: R
authors.initials: R
authors.lastname: Logier
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008449:Maximal Expiratory Flow-Volume Curves; D012121:Respiration, Artificial / Q000379:methods