title: Extremely low flow tracheal gas insufflation of helium-oxygen mixture improves gas exchange in a rabbit model of piston-type high-frequency oscillatory ventilation.
abstract: OBJECTIVE
  The purpose of this study was to show the effects of the tracheal gas insufflation (TGI) technique on gas exchange using helium-oxygen mixtures during high-frequency oscillatory ventilation (HFOV). We hypothesized that a helium-oxygen mixture delivered into the trachea using the TGI technique (0.3 L/min) would enhance gas exchange during HFOV.
  
  
  METHODS
  Three rabbits were prepared and ventilated by HFOV with carrier 70% helium/oxygen or 70% nitrogen/oxygen gas mixture with TGI in a crossover study. Changing the gas mixture from nitrogen70% to helium70% and back was performed three times per animal with constant ventilation parameters.
  
  
  RESULTS
  Compared with the nitrogen-oxygen mixture, the helium-oxygen mixture of TGI reduced PaCO2 by 7.6 mmHg (p < 0.01) and improved PaO2 by 14 mmHg (p < 0.01). Amplitude during TGI was significantly lower with the helium-oxygen mixture than with the nitrogen-oxygen mixture (p < 0.01) and did not significantly affect mean airway pressure.
  
  
  CONCLUSIONS
  This study demonstrated that a helium-oxygen mixture delivered into the trachea using the TGI technique would enhance CO2 elimination and improve oxygenation during HFOV.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Baba
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Nakamura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Aikawa
authors.forename: Kenichi
authors.initials: K
authors.lastname: Koike
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D006371:Helium / Q000494:pharmacology*; D007327:Insufflation / Q000379:methods*; D010100:Oxygen / Q000494:pharmacology*; D011659:Pulmonary Gas Exchange / Q000187:drug effects*; D011817:Rabbits; D012121:Respiration, Artificial / Q000379:methods*; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide; D006371:Helium; D010100:Oxygen