Breathing sound analysis for estimation of airlow rate

Abstract

Apparatus for use detection of apnea includes a microphone mounted in the ear of the patient for detecting breathing sounds and a second external microphone together with an oximetric sensor. A transmitter at the patient compresses and transmits the signals to a remote location where there is provided a detector module for receiving and analyzing the signals to extract data relating to the breathing. The detector uses the entropy or range of the signal to generate an estimate of air flow while extracting extraneous snoring and heart sounds and to analyze the estimate of air flow using Otsu's threshold to detect periods of apnea and/or hypopnea. A display provides data of the detected apnea/hypopnea episodes and related information for a clinician.

Description

[0001]This invention relates to an apparatus for use in breathing sound analysis for estimation of airflow rate.[0002]This application is related to a co-pending Application filed on the same day as this application under Attorney Docket No. 84201-1402 and entitled BREATHING SOUND ANALYSIS FOR DETECTION OF SLEEP APNEA / HYPOPNEA EVENTS.BACKGROUND OF THE INVENTION[0003]Acoustical respiratory flow estimation has drawn much attention in recent years due to difficulties in airflow measurement. In clinical respiratory and / or swallowing assessment, flow is usually measured by spirometry devices, such as pneumotachograph, nasal cannulae connected to a pressure transducer, heated thermistor or anemometry. Airflow is also measured by indirect means, i.e., detection of chest and / or abdominal movements using respiratory inductance plethysmography (RIP), strain gauges, or magnetometers. The most reliable measurement of airflow is achieved by a mouth piece or facemask connected to a pneumotachogra...

AI Technical Summary

Benefits of technology

[0138]1. Localize heart sounds with the method mentioned above.

[0139]2. Calculate the range or entropy values for the segments void of heart sounds.

[0140]3. Apply spline interpolation to estimate the values of the entropy or range value in the segments including heart sounds. This technique effectively cancels the effect of heart sounds on the entropy or range values of the tracheal sound.

Problems solved by technology

Acoustical respiratory flow estimation has drawn much attention in recent years due to difficulties in airflow measurement.

However, this device cannot be used during the swallowing assessment.

Potentially, this method could be an inaccurate measure of airflow because the air leaks around the nasal cannulae.

However, application of these techniques has some disadvantages, especially when studying young children or patients with neurological impairments, where the study of swallowing is clinically important.

Although the application of nasal cannulae may seem a minor intrusion, it can produce agitation in children and patients with neurological impairment.

In addition, applying the RIP devices is difficult in children with neurological impairment as their poor postural control and physical deformities can make it challenging to ensure stable positioning.

Capturing respiratory sounds at different flow rates for calibration may not always be possible prior to assessment especially when assessing young children, patients with neurological impairments and / or patients in emergency conditions.

This constitutes a research paper postulating that sleep apnea can be detected by breathing sound analysis but providing no practical details for a system which may be used in practise.

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