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Master Thesis

Effet de la charge hypoxique dans la prévalence des complications cardiovasculaires chez les patients apnéiques, détermination d’un seuil et rôle du système nerveux autonome

Abstract : Introduction: Obstructive sleep apnea (OSA) is a common condition causing intermittent nocturnal hypoxemia and sleep fragmentation. It is associated with cardiovascular (CV) complications, the pathophysiological mechanisms of which could involve dysfunction of the autonomic nervous system (ANS). The apnea-hypopnea index (AHI) is used to assess the severity of OSA. However, it was recently demonstrated that hypoxemia would be a better parameter to assess CV morbidity and mortality, in particular the hypoxic burden (HB) taking into account the duration, the frequency and the intensity of oxygen desaturations. However, no severity threshold has been established yet. The objectives of our study were to define a HB threshold from which an increase in the prevalence of CV complications is observed and using this threshold, to explore the role of ANS dysfunction as a pathophysiological link between hypoxemia and CV complications. Material and methods: a total of 117 patients with a moderate to severe OSA diagnosis were enrolled between January 2018 and December 2019 in the sleep center of Lyon. The occurrence of a CV complication was assessed within 10 years before OSA diagnosis. HB was calculated as the area between the line passing through the 90% SpO2 threshold and the curve of oximetry values below 90%. ROC curves were used to determine the cutoff value of HB with the best sensitivity (Se) and specificity (Sp) for predicting the prevalence of CV events. Heart rate variability (HRV) analysis based on polysomnograms’ ECG was used to measure ANS activity. Results: the optimal cut-off value for HB was 1163.5%.s (AUC = 0.712, p <0.001) with Se and Sp of 66.7% and 76.3%, respectively. When separating the patients according to this hypoxemia threshold, significant differences were found concerning several HRV indices. Significant correlations between HB and some markers of ANS activity were found, independently of AHI and arousal index. Conclusion: In patients with moderate to severe OSA, a HB greater than 1163.5%.s is associated with a higher prevalence of CV complications. The increase in ANS activity associated with nocturnal hypoxemia and not with sleep fragmentation suggests a proper effect of hypoxemia on autonomic activity. Our study confirms that AHI should not be the only parameter to assess the severity of OSA, particularly in terms of CV risk.
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Master Thesis
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https://dumas.ccsd.cnrs.fr/dumas-03463732
Contributor : Bibliothèque Universitaire de Médecine Nice Connect in order to contact the contributor
Submitted on : Thursday, December 2, 2021 - 4:07:46 PM
Last modification on : Saturday, April 2, 2022 - 3:15:44 AM

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2021NICEM076.pdf
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  • HAL Id : dumas-03463732, version 1

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Benjamin Faure. Effet de la charge hypoxique dans la prévalence des complications cardiovasculaires chez les patients apnéiques, détermination d’un seuil et rôle du système nerveux autonome. Médecine humaine et pathologie. 2021. ⟨dumas-03463732⟩

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