A System for Monitoring Breathing Activity Using an Ultrasonic Radar Detection with Low Power Consumption

Ali Al-Naji,Javaan Chahl,Sadik Kamel Gharghan,Ali J. Al-Askery

doi:10.3390/jsan8020032

Abstract

Continuous monitoring of breathing activity plays a major role in detecting and classifying a breathing abnormality. This work aims to facilitate detection of abnormal breathing syndromes, including tachypnea, bradypnea, central apnea, and irregular breathing by tracking of thorax movement resulting from respiratory rhythms based on ultrasonic radar detection. This paper proposes a non-contact, non-invasive, low cost, low power consumption, portable, and precise system for simultaneous monitoring of normal and abnormal breathing activity in real-time using an ultrasonic PING sensor and microcontroller PIC18F452. Moreover, the obtained abnormal breathing syndrome is reported to the concerned physician’s mobile telephone through a global system for mobile communication (GSM) modem to handle the case depending on the patient’s emergency condition. In addition, the power consumption of the proposed monitoring system is reduced via a duty cycle using an energy-efficient sleep/wake scheme. Experiments were conducted on 12 participants without any physical contact at different distances of 0.5, 1, 2, and 3 m and the breathing rates measured with the proposed system were then compared with those measured by a piezo respiratory belt transducer. The experimental results illustrate the feasibility of the proposed system to extract breathing rate and detect the related abnormal breathing syndromes with a high degree of agreement, strong correlation coefficient, and low error ratio. The results also showed that the total current consumption of the proposed monitoring system based on the sleep/wake scheme was 6.936 mA compared to 321.75 mA when the traditional operation was used instead. Consequently, this led to a 97.8% of power savings and extended the battery life time from 8 h to approximately 370 h. The proposed monitoring system could be used in both clinical and home settings.

Highlights

Abnormal breathing syndromes are disorders and alterations in the breathing system that interfere with normal breathing processes and may be fatal if not diagnosed correctly, such as tachypnea, bradypnea, and central apnea
The subject was seated in front of the ultrasonic PING sensor at a distance of approximately 1 m and he was first asked to breathe normally for 10 s and breathe quickly for 13 s and hold his breath for 13 s followed by slow breathing for 38 s and hold his breath again for 20 s followed by irregular breathing for 18 s and back to normal breathing
Based on Bland-Altman analysis, the degree of agreement can be observed by calculating the standard deviation (SD) of the differences between measurements obtained by the reference system and proposed monitoring system and determining a confidence interval (±1.96 SD) within 95% of the differences between measurements, which is estimated by the mean difference

Summary

Introduction

Abnormal breathing syndromes are disorders and alterations in the breathing system that interfere with normal breathing processes and may be fatal if not diagnosed correctly, such as tachypnea, bradypnea, and central apnea. These syndromes of breathing are frequently caused by underlying damage to the respiratory system itself, respiratory muscle weakness [1], chronic fatigue [2], metabolic disorders, intensive use of narcotic medications [1], and some aspects of anxiety and depression [3]. The high cost of consumables, estimated to be $300 to $400 US per month [13] and the limited availability of the equipment in developing countries renders these techniques unsuitable under many circumstances

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