title: Factors influencing oxygen store during denitrogenation in the healthy patient.
abstract: OBJECTIVE
  To define the various factors that influence the rate of effective preoxygenation.
  
  
  METHODS
  Prospective, randomized study.
  
  
  METHODS
  Procedure room in a teaching hospital.
  
  
  METHODS
  14 ASA physical status I volunteers who performed 4 sessions of breathing in random order. Of these volunteers, 7 performed two extra sessions using vital capacity breathing, which were also completed in random order.
  
  
  METHODS
  Using the circle system, volunteers breathed with a mouthpiece and nose-clip until expired nitrogen reached 5%, using either a fresh gas flow of 5 L/min or 10 L/min or a system flushed with O(2).
  
  
  METHODS
  End-expired levels of O(2), nitrogen, and CO(2) were recorded.
  
  
  RESULTS
  Minute ventilation, functional residual capacity, and age were significant factors for rate of denitrogenation. However, height and weight were not significant factors in predicting time to denitrogenation. At low flow rates, flushing with O(2) significantly decreased the time of denitrogenation. There appeared to be little clinical benefit of flushing with O(2) when a 10 L/min O(2) flow was used.
  
  
  CONCLUSIONS
  A high gas flow rate appears critical to achieving rapid preoxygenation.
authors.affiliation: VA North Texas Healthcare System, Dallas, TX 75216, USA. sam.sum-ping@utsouthwestern.edu
authors.forename: Sam John T
authors.initials: SJ
authors.lastname: Sum Ping
authors.forename: Laila F
authors.initials: LF
authors.lastname: Makary
authors.forename: Michael D
authors.initials: MD
authors.lastname: Van Hal
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism*; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism*; D010100:Oxygen / Q000008:administration & dosage / Q000378:metabolism*; D011446:Prospective Studies; D012143:Respiratory Physiological Phenomena; D014797:Vital Capacity / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D009584:Nitrogen; D010100:Oxygen