Comparing severity diagnosis of sleep disordered breathing in a small Respiratory Physiology Department: Konica-Minolta 300i Oximeter (level IV) vs. Nox-T3 (level III)

Abstract

Until this year, the Respiratory Physiology Department at Stepping Hill Hospital used a level IV device to diagnose sleep apnoea, the Konica-Minolta 300i Oximeter, which can only measure heart rate (HR) and oxygen saturation (SpO2). Sleep apnoea severity was determined using the oxygen desaturation index (ODI) following AASM guidelines. We compared diagnostic outcomes of tests performed using the Konica-Minolta oximeter and ResMed’s Nox-T3.

The study sample was 179 (male = 56%) limited polysomnography studies (LPSG) performed on the Nox-T3, which was then compared to 201 (male = 48%) overnight oximetry tests (ONO) performed on the Konica-Minolta. Preliminary results appear to show a negative correlation with regard to sleep apnoea severity when comparing the 2 devices. LPSG diagnosed with better accuracy sleep disordered breathing than ONO. If ONO alone is offered as a diagnostic tool there is a risk of underdiagnosis and patients might miss on treatment which will adversely affect their quality of life and health outcomes.

There are few studies in the literature comparing level III and level IV monitors, most studies compare to level I (polysomnography) as this is deemed the gold standard. However, in non-tertiary hospitals, access is often restricted to this equipment. Despite level IV studies being still widely used and accepted as a diagnosis tool in many non-tertiary centres our department's experience showed that level III studies were more accurate and equally accessible at diagnosing sleep disordered breathing when compared with a level IV device.