Detection of airway occlusion in simulated obstructive sleep apnea/hypopnea using ultrasound: An in vitro study

Abstract

Obstructive sleep apnea/hypopnea Syndrome (OSAHS) is the most common form of Sleep Disordered Breathing (SDB) and it is estimated to affect approximately 6% of US adult population. Various methods have been proposed for the development of inexpensive screening methods to detect SDB to reduce the need for costly nocturnal polysomnography (NPSG). By using the existing air in the airway as an ultrasonic contrast agent, we propose a method to examine the narrowing or occlusion of the airway associated with OSAHS events. We describe here an in vitro study that approximates the anatomical and acoustic characteristics of the airway and neck. In this experiment, we simulate the fully open airway as well as apnea and hypopnea events. These in vitro studies results show significant differences in the ultrasonic signals acquired from the open airway model versus those from the model depicting apnea and hypopnea events. Therefore, the findings provide a foundation for development of an ultrasound system to detect SDB in vivo.

Upper airway occlusion detection using a novel ultrasound technique

“…A group of tandem physiological measurements is taken during the study to test and validate the feasibility of the design. The data acquisition system used for the ultrasound experimental setup is described in [7][8]. The transmitters were simultaneously pulsed at 10 Pulse Repetition Frequency (PRF=10) using OmniScan ® iX UT (Olympus NDT, Quebec, Canada).…”

“…We have reported in [7] and [8] the results of in vitro and in vivo characterization of ultrasonic sensors for the detection of occlusion in an upper airway, and have presented preliminary results on temporal features extracted from the ultrasonic waves.…”

A multi-feature classification approach to detect sleep apnea in an ultrasonic upper airway occlusion detector system

“…The idea of using ultrasonic transducers to detect OSA was first introduced by Al-Abed, et al [6]. For this purpose, ultrasonic waves were transmitted across the airway during sleep and detected laterally across the neck.…”

“…This approach is attractive as it is safe, non-invasive, low cost and can ultimately be made to be portable. The characterization of the ultrasonic sensors for the purpose of OSA detection has been reported in [6,7] for in vitro and in vivo studies, respectively, where temporal features of the received signals were used for classification. As a complementary study, [8] introduced the use of spectral features of the ultrasonic signals to detect OSA.…”

“…Our novelty in comparison with [6,7,8] is the proposed feature selection and classification methods where multiple temporal, spectral and wavelet-based features are calculated using the ultrasound signals. Multiple SVM classifiers (one classifier for each channel) are then trained and used to detect apnea in the received signals.…”