title: [Diagnostic importance of the alveolar-arterial oxygen gradient].
abstract: BACKGROUND
  The alveolar-arterial (A-a) oxygen gradient is the difference between the partial pressure of oxygen in the alveoli and the partial pressure of arterial oxygen and can be elevated in the case of pulmonary disease.
  
  
  METHODS
  We describe a 41-year-old patient with pneumonia who presented with abdominal pain, in whom calculation of the A-a gradient could have led to earlier diagnosis.
  
  
  CONCLUSIONS
  The A-a oxygen gradient is mainly of diagnostic importance and the presented nomogram allows easy and quick interpretation. This might lead to a more frequent use of the A-a oxygen gradient in the future.
authors.affiliation: Universitair Medisch Centrum Groningen, afd. Spoedeisende Hulp, Groningen. marijeweinans@hotmail.com
authors.forename: Marije A E
authors.initials: MA
authors.lastname: Weinans
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Drost-de Klerck
authors.forename: Jan C
authors.initials: JC
authors.lastname: ter Maaten
mesh_terms: D000328:Adult; D001158:Arteries; D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D011014:Pneumonia / Q000097:blood* / Q000175:diagnosis* / Q000503:physiopathology; D011650:Pulmonary Alveoli / Q000502:physiology*; D011659:Pulmonary Gas Exchange
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen