title: New generation neonatal high frequency ventilators: effect of oscillatory frequency and working principles on performance.
abstract: BACKGROUND
  Several new generation neonatal ventilators that incorporate conventional as well as high frequency ventilation (HFOV) have appeared on the market. Most of them offer the possibility to use HFOV in a volume-targeted mode, despite absence of any preclinical data. With a bench test, we evaluated the performances of 4 new neonatal HFOV devices and compared them to the SensorMedics HFOV device.
  
  
  METHODS
  Expiratory tidal volumes (V(T)) were measured for various ventilator settings and lung characteristics (ie, modifications of compliance and resistance of the system), to mimic several clinical conditions of pre-term and term infants.
  
  
  RESULTS
  Increasing the frequency proportionally decreased the V(T) for all the ventilators, although the magnitude of the decrease was highly variable between ventilators. At 15 Hz and a pressure amplitude of 60 cm H2O, the delivered V(T) ranged from 3.5 to 5.9 mL between devices while simulating pre-term infant conditions and from 2.6 to 6.3 mL while simulating term infant conditions. Activating the volume-targeted mode in the 3 machines that offer this mode allowed the V(T) to remain constant over the range of frequencies and with changes of lung mechanical properties, for pre-term infant settings only while targeting a V(T) of 1 mL.
  
  
  CONCLUSIONS
  These new generation neonatal ventilators were able to deliver adequate V(T) under pre-term infant, but not term infant respiratory system conditions. The clinical relevance of these findings will need to be determined by further studies.
authors.affiliation: Neonatal and Pediatric Intensive Care Unit, University Hospital of Geneva, Switzerland.
authors.forename: Serge
authors.initials: S
authors.lastname: Grazioli
authors.affiliation: Neonatal and Pediatric Intensive Care Unit, University Hospital of Geneva, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Karam
authors.affiliation: Neonatal and Pediatric Intensive Care Unit, University Hospital of Geneva, Switzerland. peter.rimensberger@hcuge.ch.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Rimensberger
mesh_terms: D004867:Equipment Design; D006612:High-Frequency Ventilation / Q000295:instrumentation*; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal / Q000600:supply & distribution*; D011312:Pressure; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology / Q000628:therapy*; D015656:Respiratory Mechanics; D013673:Technology Assessment, Biomedical; D013990:Tidal Volume / Q000502:physiology*; D012122:Ventilators, Mechanical / Q000592:standards*
keywords: high frequency ventilation; neonatal intensive care; respiratory mechanics; volume-targeted ventilation