title: Volume and Pressure Delivery During Pediatric High-Frequency Oscillatory Ventilation.
abstract: OBJECTIVE
  Identify variables independently associated with delivered tidal volume (VT) and measured mean airway pressure during high-frequency oscillatory ventilation across the range of pediatric endotracheal tube sizes.
  
  
  METHODS
  In vitro study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  An in vitro bench model of the intubated pediatric respiratory system during high-frequency oscillatory ventilation was used to obtain delivered VT and mean airway pressure (in the distal lung) for various endotracheal tube sizes. Measurements were taken at different combinations of ventilator set mean airway pressure (Paw), amplitude (ΔP), frequency, and test lung compliance. Multiple regression analysis was used to construct multivariable models predicting delivered VT and mean airway pressure.
  
  
  RESULTS
  Variables independently associated with higher delivered VT for all endotracheal tube sizes include higher ΔP (p < 0.001), lower frequency (p < 0.001), and higher test lung compliance (p < 0.001). A multiplicative interaction between frequency and ΔP magnifies the delivered VT when ΔP is high and frequency is low (p < 0.001). Delivered mean airway pressure becomes lower than set Paw as ΔP increases (p < 0.001) and frequency increases (p < 0.05). Ventilator set Paw is the largest determinant of delivered mean airway pressure; however, increasing ΔP resulted in a lower delivered mean airway pressure. For example, in a 4.0 mm ID endotracheal tube, increasing ΔP by 10 cm H2O resulted in an average decrease of delivered mean airway pressure by 4.5%.
  
  
  CONCLUSIONS
  This is the first study to quantify the interaction between ΔP and frequency in delivered VT and the effect of ΔP and frequency on delivered mean airway pressure. These results demonstrate the need to measure or estimate VT and delivered pressures during high-frequency oscillatory ventilation and may be useful in determining optimal strategies for lung protective ventilation during high-frequency oscillatory ventilation.
authors.affiliation: 1Department of Anesthesiology and Critical Care Medicine, Children's Hospital Los Angeles, Los Angeles, CA. 2Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA. 3Department of Pediatric Critical Care, Geisinger Medical Center, Janet Weis Children's Hospital, Danville, PA.
authors.forename: Ronald
authors.initials: R
authors.lastname: Wong
authors.forename: Timothy
authors.initials: T
authors.lastname: Deakers
authors.forename: Justin
authors.initials: J
authors.lastname: Hotz
authors.forename: Robinder G
authors.initials: RG
authors.lastname: Khemani
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Ross
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Newth
mesh_terms: D002648:Child; D006612:High-Frequency Ventilation / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D007442:Intubation, Intratracheal / Q000295:instrumentation; D016014:Linear Models; D008168:Lung / Q000502:physiology*; D008170:Lung Compliance; D008953:Models, Anatomic; D015999:Multivariate Analysis; D013990:Tidal Volume