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Contrôle ventilatoire à l'exercice et en hypoxie : mise en évidence d'une périodicité constitutionnelle

Abstract : Breathing instability is a well-known phenomenon in human. Until now, it was observed in healthy subjects at altitude et in patients suffering from chronic heart failure (CHF) or sleep apnea syndrome (SAS), central, obstructive or mixed, mostly during sleep. A retrospective spectral analysis of standard hypoxic exercise test evidenced a ventilatory instability when the control system is submitted to a double stress, physiological (moderate exercise) and environmental (hypoxia, from 2000 to 4800m simulated altitudes). Prospective analyses positively correlated magnitude of the ventilatory oscillations to cardiac output (Q̇c) and ventilation (V̇E), whereas their period is shortened with increasing V̇E and Q̇c. Unlike the one-minute period apneas in CHF and SAS patients, we observed a much shorter period at exercise in hypoxia, between 11 and 12 seconds. Subjects with a higher ventilatory response to hypoxia and a greater sensitivity to CO₂ showed a deeper breathing instability. Hyperoxia and hypercapnia have opposite effects : O₂ inhalation does not alter the system stability, hypercapnia enhances the oscillatory phenomenon. A pharmacological treatment by acetazolamide (ACZ) improves breathing stability, supporting a major role of peripheral chemoreceptors in the genesis of ventilatory oscillations. A mathematical model of ventilation control including, among numerous cardiorespiratory parameters, sensibilities to O₂ and CO₂, peripheral-central interactions, confirms the contribution of hypoxia level and the delay of blood convection between lungs and peripheral chemoreceptors in the oscillations period. It also highlights a potential role of dead space in the onset of breathing instability.
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Submitted on : Monday, December 17, 2018 - 5:55:07 PM
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  • HAL Id : tel-01958198, version 1



Eric Hermand. Contrôle ventilatoire à l'exercice et en hypoxie : mise en évidence d'une périodicité constitutionnelle. Physiologie [q-bio.TO]. Université Sorbonne Paris Cité, 2016. Français. ⟨NNT : 2016USPCD037⟩. ⟨tel-01958198⟩



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