Sleep Apnea Diagnosis

Sleep Apnea Diagnosis2021-08-20T19:05:49+00:00
Clinical Need

Over 100 million people suffer from sleep apnea. The most common type of sleep apnea is obstructive sleep apnea (OSA), which occurs during sleep when breathing is blocked by the collapse of the relaxed tongue and/or fatty tissues at the throat.  Obstructive hypopnea is caused by the partial obstruction of the airway.  Central sleep apnea (CSA) occurs when the brain fails to activate muscles to breathe during sleep.  Mixed apnea is the combination of obstructive and central apnea.  Sleep apnea causes insufficient lung ventilation and sleep fragmentation.

Untreated sleep apnea increases the risk of hypertension, cardiovascular disease, stroke, and diabetes. It contributes to daytime sleepiness and increases risk of motor vehicle accidents. Frost & Sullivan estimated 29.4 million undiagnosed OSA in the U.S. adult population with economic cost nearly $150 billion in 2015. This is the fourth largest cost, after cancer, diabetes, and coronary heart disease.

Current Practices

Accurate and timely diagnosis of sleep apnea is crucial for effective treatment.  Current gold standard is polysomnography (PSG) in the sleep laboratory, which measures EEG, EOG, EMG, oronasal airflow, nasal pressure, respiratory effort, SpO2, body position, and snoring sound. The sleep study is scored manually to produce study outcomes such as the apnea-hypopnea index (AHI) – the average number of apnea and hypopnea events per hour of sleep.  This labor-intensive diagnosis requiring an overnight hospitalization makes in-lab sleep study expensive and inconvenient.  Some patients have trouble falling asleep due to discomfort from many attached sensors and the first-night effect.

Home sleep test (HST) is a cost-effective alternative to diagnose patients with moderate to severe sleep apnea. Limited signals are measured in HST to estimate the AHI: nasal pressure, SpO2, respiratory effort, and snoring. Though more HSTs are prescribed than PSG now, the reduced measurements often fail to accurately stratify the severity of the breathing disorder.


BiLab provides a method to quantify how much air fills the lungs in every breath. Using a multi-channel impedance plethysmography technology, tidal volume and minute ventilation signals are acquired to quantify apnea and hypopnea. These signals can be integrated with a PSG system for sleep apnea diagnosis.