title: Efficiency of oxygen administration: sequential gas delivery versus "flow into a cone" methods.
abstract: OBJECTIVE
  Fio2 values of a new oxygen mask that exploits efficiencies afforded by sequential gas delivery (SGD) were compared to those of a nonrebreathing mask (NRM) and a Venturi oxygen mask.
  
  
  METHODS
  Prospective, single-blinded, randomized study.
  
  
  METHODS
  Laboratory study.
  
  
  METHODS
  Eight healthy male volunteers.
  
  
  METHODS
  Volunteers breathed through each of the masks at various minute ventilations (VE). Oxygen flows were 2, 4, and 8 L/min to the SGD mask but only 8 L/min to the other masks.
  
  
  RESULTS
  Net FIO2 was calculated from end-tidal fractional concentrations of oxygen and CO2 with the alveolar gas equation. Only the SGD mask at an oxygen flow of 8 L/min consistently provided both FIO2>0.95 (at resting VE) and higher FIO2 than the other masks at all VE. The SGD mask delivered FIO2 comparable to other masks at only a fraction of the oxygen flow and was characterized by a consistent relation between FIO2 and oxygen flow for a given VE.
  
  
  CONCLUSIONS
  We conclude that SGD can be exploited to provide FIO2>0.95 with oxygen flows as low as 8 L/min, as well as accurate and efficient dosing of oxygen even in the presence of hyperpnea.
authors.affiliation: University Health Network, Toronto General Hospital, University of Toronto, Canada.
authors.forename: Marat
authors.initials: M
authors.lastname: Slessarev
authors.forename: Ron
authors.initials: R
authors.lastname: Somogyi
authors.forename: David
authors.initials: D
authors.lastname: Preiss
authors.forename: Alex
authors.initials: A
authors.lastname: Vesely
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasano
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Fisher
mesh_terms: D000704:Analysis of Variance; D004867:Equipment Design; D006801:Humans; D008297:Male; D008397:Masks; D010102:Oxygen Inhalation Therapy / Q000295:instrumentation* / Q000379:methods; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D016037:Single-Blind Method