title: Is there an alternative to pre-flight hypoxic challenge testing in scoliotic patients?
abstract: BACKGROUND
  Hypoxic challenge testing (HCT) is not readily available in all hospitals. It has recently been shown that resting oximetry does not reliably predict the results of HCT in patients with extrapulmonary restrictive lung disease. We assessed other clinical tests to see if they might be used as an alternative screen for HCT.
  
  
  METHODS
  People with primary thoracic scoliosis were recruited. Resting SpO(2), arterial blood gases (ABG's), lung function and shuttle walking test (SWT) were measured. All subjects underwent HCT breathing an inhaled oxygen fraction of 15% for 20 min, or until SpO(2) fell below 85%, when ABG's were taken.
  
  
  RESULTS
  Fourteen people (5 male) with thoracic scoliosis, Cobb angle 93 (31) degrees , aged 65 (8.5) years, FEV(1) 0.86 (0.4) L, FVC 1.2 (0.4)L were studied. The resting SpO(2) was 96 (2) %, PaO(2) 9.2 (1) kPa and PaCO(2) 6.1 (0.4) kPa. HCT was positive in 11 subjects (PaO(2) <6.6 kPa). Eight of 11 HCT positive subjects had a resting SpO(2) > 95%. Positive correlation was found between SpO(2) at SWT termination and PaO(2) following HCT (r = 0.56, p = 0.02). Those with saturations of 92% or under at SWT termination had positive HCT.
  
  
  CONCLUSIONS
  Despite normal resting SpO(2) subjects with thoracic scoliosis may have positive HCT. Current recommendations for air travel do not accurately identify these people. Desaturation following a SWT may provide a useful screening tool, however a low threshold for performing HCT on people with thoracic scoliosis prior to air travel is warranted.
authors.affiliation: Respiratory Support and Sleep Centre, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK.
authors.forename: Debrata
authors.initials: D
authors.lastname: Bandyopadhyay
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Oscroft
authors.forename: John M
authors.initials: JM
authors.lastname: Shneerson
authors.forename: Ian E
authors.initials: IE
authors.lastname: Smith
mesh_terms: D000337:Aerospace Medicine / Q000379:methods; D000368:Aged; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D008297:Male; D010092:Oximetry / Q000379:methods*; D017410:Practice Guidelines as Topic; D012131:Respiratory Insufficiency / Q000503:physiopathology* / Q000628:therapy; D012600:Scoliosis / Q000503:physiopathology* / Q000628:therapy