title: A comparison of the tissue oxygenation achieved using different oxygen delivery devices and flow rates.
abstract: BACKGROUND
  High-concentration normobaric oxygen (O₂) administration is the first-aid priority in treating divers with suspected decompression illness. The best O₂ delivery device and flow rate are yet to be determined.
  
  
  OBJECTIVE
  To determine whether administering O₂ with a non-rebreather mask (NRB) at a flow rate of 10 or 15 L·min ⁻¹ or with a demand valve with oronasal mask significantly affects the tissue partial pressure of O₂ (PtcO₂) in healthy volunteer scuba divers.
  
  
  METHODS
  Fifteen certified scuba divers had PtcO₂ measured at six positions on the arm and leg. Measurements were taken with subjects lying supine whilst breathing O₂ from a NRB at 10 or 15·L·min⁻¹, a demand valve with an adult Tru-Fit oronasal mask and, as a reference standard, an oxygen 'head hood'. End-tidal carbon dioxide was also measured.
  
  
  RESULTS
  While none of the emergency delivery devices performed as well as the head hood, limb tissue oxygenation was greatest when O₂ was delivered via the NRB at 15 L·min⁻¹. There were no clinically significant differences in end-tidal carbon dioxide regardless of the delivery device or flow rate.
  
  
  CONCLUSIONS
  Based on transcutaneous oximetry values, of the commonly available emergency O₂ delivery devices, the NRB at 15 L·min ⁻¹ is the device and flow rate that deliver the most O₂ to body tissues and, therefore, should be considered as a first-line pre-hospital treatment in divers with suspected decompression illness.
authors.affiliation: College of Marine and Environmental Sciences, James Cook University, Townsville, Emergency Department, The Townsville Hospital Townsville, Queensland, Australia 4814, E-mail: denise.blake@health.qld.gov.au.
authors.forename: Denise F
authors.initials: DF
authors.lastname: Blake
authors.affiliation: Emergency Department, The Townsville Hospital, Townsville, Queensland, Australia.
authors.forename: Philip
authors.initials: P
authors.lastname: Naidoo
authors.affiliation: Mount Isa Centre for Rural and Remote Health, James Cook University, Townsville.
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Brown
authors.affiliation: Hyperbaric Medicine Unit, The Townsville Hospital, Townsville.
authors.forename: Derelle
authors.initials: D
authors.lastname: Young
authors.affiliation: Divers Alert Network Asia-Pacific, Melbourne, Victoria, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Lippmann
mesh_terms: D000328:Adult; D001132:Arm; D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation / Q000379:methods; D002245:Carbon Dioxide / Q000378:metabolism; D004242:Diving; D004630:Emergencies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007866:Leg; D008297:Male; D008397:Masks; D010101:Oxygen Consumption; D010102:Oxygen Inhalation Therapy / Q000295:instrumentation* / Q000379:methods; D012016:Reference Values; D013990:Tidal Volume
chemical_list: D002245:Carbon Dioxide
keywords: DAN (Divers Alert Network); Scuba diving; decompression illness; equipment; first aid; medical kits; oxygen; transcutaneous oximetry