AcuPebble to Remotely Monitor Patients With OSA on CPAP Therapy

Obstructive sleep apnoea (OSA) affects almost one billion people globally and can lead to numerous health consequences including ischaemic heart disease, hypertension, stroke and arrhythmias. It also has a profound impact on patient's quality of life and has a high economic burden on society. Continuous positive airway pressure (CPAP) therapy is globally accepted gold-standard treatment, virtually eliminating OSA (by normalising the apnoea-hypopnoea index (AHI)), thus improving quality of life, decreasing sleepiness and reducing medical sequelae. A high residual AHI may still be present despite adequate CPAP usage in some patients. This patient population will suffer with on-going / worsening somnolence, sleep apnoea symptoms and potentially increased cardiovascular risk, which will no doubt reduce their adherence thus increasing their residual AHI, perpetuating a viscous cycle.

Currently CPAP machines can store airflow and pressure data, displaying residual events and compliance indices. However, algorithms between devices vary and there are no standards on how to use the data, and there is mixed data surrounding residual event accuracy. A review by the American Thoracic Society concluded that while CPAP usage can be reliably determined from tracking systems, residual events (residual AHI) and mask leak data are not easy to interpret and differ depending on manufactures. Some studies have found that this is especially the case in relation to detecting hypopnoeic events. Therefore, a more accurate and simple system is needed to accurately determine usage and residual events, that is: standardised, reliable and independent of machine manufacturer. Overnight oximetry is used by some Trusts as a surrogate marker of residual events. However, studies that have validated overnight oximetry against polysomnography (gold standard) have found the specificity and sensitivity decrease with decreasing severity of disease. Therefore this is not a practical or reliable way to monitor patients remotely.

Therefore we aim to assess whether we can accurately measure the residual AHI with a simple, accurate, novel wearable device in patients undergoing CPAP therapy. This will enable us to accurately assess treatment effect and highlight patients who require more intensive / change in their therapy.

AcuPebble SA100 is a CE marked novel wearable device developed by Acurable Ltd which has already been validated as an automated diagnostic tool for OSA with a high positive (96%) and high negative (995) predictive value when compared to a gold standard sleep study. This is currently in clinical use. We intend to assess whether AcuPebble SA100 can also be used to accurately detect the residual AHI in patients with OSA on CPAP therapy.

Patients in this study will be asked to wear both AcuPebble SA100 and a gold standard multi-channel sleep study simultaneously, alongside using CPAP therapy for two consecutive nights. We will then compare the residual AHI from AcuPebble SA100 with gold standard, as well as comparing the accuracy of the CPAP machine AHI with gold standard. This will also enable us to detect whether AcuPebble SA100 is more accurate that the CPAP machine.

We will also assess the usability of AcuPebble SA100 in this population.