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The walking-induced transient hack concept is valid & relies on a transient early-exercise hypoxemia.

Bruneau A, Feuilloy M, Dussaussoy C, Gagnadoux F, Leftheriotis G, Abraham P - PLoS ONE (2013)

Bottom Line: 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.Clustering analysis resulted in 4 classes that closely fit the 4 most frequently proposed empirical models (cross-correlation coefficients: 0.93 to 0.97).

View Article: PubMed Central - PubMed

Affiliation: L'Université Nantes Angers Le Mans, Centre Hospitalier Universitaire d'Angers, Laboratory for Vascular Investigations, Angers, France.

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.

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Related in: MedlinePlus

Preprocessing results.(a) The upper graph shows the original transcutaneous pO2 signal. The lower graph shows the preprocessed transcutaneous pO2 signal before clustering (second step) and the periods where the waveform is cut. (b) The upper graph shows the waveform of a cluster after the first step of the clustering. The lower graph shows the preprocessed waveform.
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pone-0062651-g001: Preprocessing results.(a) The upper graph shows the original transcutaneous pO2 signal. The lower graph shows the preprocessed transcutaneous pO2 signal before clustering (second step) and the periods where the waveform is cut. (b) The upper graph shows the waveform of a cluster after the first step of the clustering. The lower graph shows the preprocessed waveform.

Mentions: For the present study, each sample (Transcutaneous pO2 chest measurement) was characterized by a waveform (figure 1a, upper graph). Because walking duration was different among subjects, to improve the clustering analysis as a first step, we performed preprocessing (figure 1a, lower graph): each waveform was resampled by the linear interpolation technique to obtain 100 samples for each duration (rest, exercise and recovery). Finally, each waveform was denoised by a simple moving average with a window size of 25 data points (figure 1, lower graph).


The walking-induced transient hack concept is valid & relies on a transient early-exercise hypoxemia.

Bruneau A, Feuilloy M, Dussaussoy C, Gagnadoux F, Leftheriotis G, Abraham P - PLoS ONE (2013)

Preprocessing results.(a) The upper graph shows the original transcutaneous pO2 signal. The lower graph shows the preprocessed transcutaneous pO2 signal before clustering (second step) and the periods where the waveform is cut. (b) The upper graph shows the waveform of a cluster after the first step of the clustering. The lower graph shows the preprocessed waveform.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3643941&req=5

pone-0062651-g001: Preprocessing results.(a) The upper graph shows the original transcutaneous pO2 signal. The lower graph shows the preprocessed transcutaneous pO2 signal before clustering (second step) and the periods where the waveform is cut. (b) The upper graph shows the waveform of a cluster after the first step of the clustering. The lower graph shows the preprocessed waveform.
Mentions: For the present study, each sample (Transcutaneous pO2 chest measurement) was characterized by a waveform (figure 1a, upper graph). Because walking duration was different among subjects, to improve the clustering analysis as a first step, we performed preprocessing (figure 1a, lower graph): each waveform was resampled by the linear interpolation technique to obtain 100 samples for each duration (rest, exercise and recovery). Finally, each waveform was denoised by a simple moving average with a window size of 25 data points (figure 1, lower graph).

Bottom Line: 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.Clustering analysis resulted in 4 classes that closely fit the 4 most frequently proposed empirical models (cross-correlation coefficients: 0.93 to 0.97).

View Article: PubMed Central - PubMed

Affiliation: L'Université Nantes Angers Le Mans, Centre Hospitalier Universitaire d'Angers, Laboratory for Vascular Investigations, Angers, France.

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.

Show MeSH
Related in: MedlinePlus