title: The walking-induced transient hack concept is valid & relies on a transient early-exercise hypoxemia.
abstract: BACKGROUND
  Decreased arterial oxygen pressure obtained at peak exercise is strong evidence of walking-induced hypoxemia, assuming that the lower pressure occurs just before exercise is stopped. Using empirical predefined models and transcutaneous oximetry, we have shown that some patients reporting exercise intolerance show a minimal value at the onset of walking and a post-exercise overshoot. These changes are referred to as transcutaneous "walking-induced transient hacks".
  
  
  METHODS
  In 245 patients, walking-induced transcutaneous oxygen pressure changes in the chest were analyzed using observer-independent clustering techniques. Clustering classes were compared to the profile types previously proposed with the cross-correlation technique. The classifications of patients according to both approaches were compared using kappa statistics. In 10 patients showing a hack on transcutaneous oximetry, we analyzed the results of direct iterative arterial sampling recorded during a new walking treadmill test.
  
  
  RESULTS
  Clustering analysis resulted in 4 classes that closely fit the 4 most frequently proposed empirical models (cross-correlation coefficients: 0.93 to 0.97). The kappa between the two classifications was 0.865. In 10 patients showing transcutaneous hacks, the minimal direct arterial oxygen pressure value occurred at exercise onset, and these patients exhibited a recovery overshoot reaching a maximum at two minutes of recovery, confirming the walking-induced transient hypoxemia.
  
  
  CONCLUSIONS
  In patients reporting exercise intolerance, transcutaneous oximetry could help to detect walking-induced transient hypoxemia, while peak-exercise arterial oximetry might be normal.
authors: L'Université Nantes Angers Le Mans, Centre Hospitalier Universitaire d'Angers, Laboratory for Vascular Investigations, Angers, France.
authors: Antoine
authors: A
authors: Bruneau
authors: Mathieu
authors: M
authors: Feuilloy
authors: Corinne
authors: C
authors: Dussaussoy
authors: Frédéric
authors: F
authors: Gagnadoux
authors: Georges
authors: G
authors: Leftheriotis
authors: Pierre
authors: P
authors: Abraham
mesh_terms: D000368:Aged; D062186:Arterial Pressure; D001785:Blood Gas Monitoring, Transcutaneous; D016000:Cluster Analysis; D005080:Exercise Test / Q000009:adverse effects; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010100:Oxygen / Q000097:blood*; D016138:Walking
chemical_list: D010100:Oxygen
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