Abstract
Sleep apnea is a common sleep-related disorder that significantly affects the population. It is characterized by repeated breathing interruption during sleep. Such events can induce hypoxia, which is a risk factor for multiple cardiovascular and cerebrovascular diseases. Polysomnography, the gold standard, is expensive, inaccessible, uncomfortable and an expert technician is needed to score sleep-related events. To address these limitations, many previous studies have proposed and implemented automatic scoring processes based on fewer sensors and machine learning classification algorithms. However, alternative device technologies developed for both home and hospital still have limited diagnostic accuracy for detecting apnea events even though many of the previous investigational algorithms are based on multiple physiological channel inputs. In this paper, we propose a new probabilistic algorithm based on (only) oronasal respiration signal for automated detection of apnea events during sleep. The proposed model leverages AASM recommendations for characterizing apnea events with respect to dynamic changes in the local respiratory airflow baseline. Unlike classical threshold-based classification models, we use a Gaussian mixture probability model for detecting sleep apnea based on the posterior probabilities of the respective events. Our results show significant improvement in the ability to detect sleep apnea events compared to a rule-based classifier that uses the same classification features and also compared to two previously published studies for automated apnea detection using the same respiratory flow signal. We use 96 sleep patients with different apnea severity levels as reflected by their Apnea-Hypopnea Index (AHI) levels. The performance was not only analyzed over obstructive sleep apnea (OSA) but also over other types of sleep apnea events including central and mixed sleep apnea (CSA, MSA). Also the performance was comprehensively analyzed and evaluated over patients with varying disease severity conditions, where it achieved an overall performance of TPR=88.5%, TNR=82.5%, and AUC=86.7%. The proposed approach contributes a new probabilistic framework for detecting sleep apnea events using a single airflow record with an improved capability to generalize over different apnea severity conditions
Highlights
Sleep apnea is a highly prevalent sleep disorder that can cause significant daytime sleepiness and result in many cardiovascular comorbidities [1,2,3,4]
Recognizing true positive rate (TPR)/positive predictive value (PPV) tradeoff, and that TPR and PPV are performance metrics of competing natures, it can be noticed that using a Gaussian Mixture Model (GMM)-based classifier, we can achieve a high TPR with a significantly improved PPV compared to the rule-based classifier
For automatic detection of apneic events, we considered classification based on a probabilistic view using a GMM-based modeling framework
Summary
Sleep apnea is a highly prevalent sleep disorder that can cause significant daytime sleepiness and result in many cardiovascular comorbidities [1,2,3,4]. It is characterized by repetitive significant airflow reductions during sleep causing recurrent hypoxia and sleep fragmentation [5,6,7]. Obstructive sleep apnea (OSA) is characterized by repetitive upper airway obstruction that limit airflow from going in to the lungs with the presence of continued respiratory effort. Central sleep apnea (CSA) is characterized by the loss of all respiratory effort during sleep due to a neurological disorder.
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