Design and development of a device to diagnose and treat obstructive sleep apnoea

Philpott, Joel

Design and development of a device to diagnose and treat obstructive sleep apnoea

Thesis / Dissertation

2024

Publisher

Univerity of Cape Town

Department

Department of Human Biology

Faculty

Faculty of Health Sciences

Abstract

Sleep apnoea is the repeated cessation of breathing during sleep and can result in impaired concentration, excessive unexplained sleepiness, and sleep fragmentation. Long-term effects of the condition can include hypertension, stroke and cardiovascular disease, diabetes and glucose intolerance, and obesity. Sleep apnoea is linked to a hazard ratio of 1.97, indicating that individuals with this condition face almost twice the risk of experiencing a stroke or death compared to those without sleep apnoea. It is estimated that 425 million adults between the ages of 30 and 69 have moderate to severe sleep apnoea. A study conducted in Wisconsin, America, found that 82% of men and 93% of women with moderate to severe sleep apnoea had not been diagnosed. This is likely to be even higher in low-middle-income countries like South Africa, where there is limited access to healthcare. Limited access to healthcare also affects sleep apnoea treatment. A study conducted in Latin America found that of the 880 patients diagnosed with sleep apnoea, only 55.7% started Positive Airway Pressure (PAP) therapy, as many of the study participants could not afford a basic level of treatment. This study describes the development of a device that could reduce the prevalence of undiagnosed sleep apnoea cases and improve access to treatment. The developed system makes use of standard breathing effort and pulse oximetry sensors as well as a flow sensor to provide the necessary information to conduct a home sleep test for the diagnosis of sleep apnoea, as required by the American Academy of Sleep Medicine (AASM). The diagnostic algorithm proposed by the AASM is also used to identify apnoea events and present this information to a clinician. The system also provides a basic level of Continuous Positive Airway Pressure (CPAP) treatment, the most common treatment modality used for patients with sleep apnoea. The system performance specifications are tested according to the EN ISO 80601-2-70 testing protocol for the mean static pressure, dynamic pressure accuracy, and maximum flow rate. The ISO standard does not dictate minimum performance requirements; however, the device meets most of the requirements dictated by the Association for Respiratory Technology and Physiology (ARTP), except the requirements for the dynamic pressure accuracy where the device exceeded the maximum pressure range by 1.69cmH2O. The study has demonstrated that a single device could be used to address the high prevalence of undiagnosed and untreated sleep apnoea and thereby prevent associated health risks. Using a single device for the diagnosis and treatment of the condition may also allow clinicians to monitor the efficacy of treatment and ensure that the correct pressure level of the CPAP treatment is being used. However, further development and testing would be required before the device can meet all of the minimum performance requirements. These developments include improving the pressure control and adding the ability for the device to connect to the internet.

Keywords

human biology

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