Oximetry / Sleep apnea pre-screening

Supported Oximeters

Requirements:
– Android 4.3+,BT LE

What is Sleep Apnea?

Obstructive sleep apnea (OSA) is a dangerous and underdiagnosed disease. It’s prevalence in general population is around 2 – 7% [2] (with pessimistic estimates up to 25% in men [3]) and more than 80% of the population is not diagnosed[1].

Sleep Apnea is a disorder in which breathing repeatedly stops for long periods during the night. 

This often results in daytime sleepiness, fatigue-related vehicle accidents and in the long run could cause metabolic syndrome, neurocognitive deficits, vigilance decline and erectile dysfunction[4]. Untreated OSA is linked to diabetes, hypertention or stroke. Most of all sleep apnea rises risk of early death by 46%. According to the National Commission on Sleep Disorders Research, approximately 38,000 deaths occur on an annual basis that relate to cardiovascular problems that in one way or another are connected to sleep apneaObstruction_ventilation_apnée_sommeil.svg

Why is it so underdiagnosed?

Up to 93% of women and 82% of men with sleep apnea are not diagnosed. Why is that?

It’s difficult to find out if you have sleep apnea, since you are sleeping at the time it presents itself. Most people who have apnea do not know about it. But they still suffer it’s devastating consequences.

The recommended method of diagnosing sleep apnea is polysomnography (PSG). The patient spends a night in a sleep laboratory, tied to EKG, EEG, EMG, Oximeter and other sensors. It is understandable that even when someone suspects they might have apnea, the idea of sleeping in a lab may turn them off from taking the required actions. PSG testing can also be pretty expensive (e.g. $4600 in Alaska Sleep Clinic).

Do I have Sleep Apnea?

According to American Academy of Sleep Medicine groups with higher risk of sleep apnea include overweight (BMI=25-29.9) and obese (BMI>30) people, people with larger neck sizes and middle-aged to older people. Also regular high snoring may be a warning sign of OSA.

Because of the high incidence (every 4th to 50th person) and insufficient diagnostics, we believe some form of pre-screening in home conditions would be extremely valuable to prevent the destructive consequences of the disease. Especially if you consider those consequences can be effectively prevented.

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Pulse Oximetry can recommend visiting a doctor based on your nightly breathing data

The golden standard for apnea screening is PSG, which measures the AHI (apnea-hypopnea) index. Several studies has shown large correlation between AHI and ODI/RDI (oxyhemoglobin desaturation index, oximeter-derived respiratory disturbance index).

Screenshot from 2016-05-20 11-23-23

ODI/RDI indexes can be effectively obtained from Pulse Oximetry at home.

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How to use Sleep as Android for Sleep Apnea pre-screening

Sleep as Android supports StressLocator pulse oximeters. Simply pair your StressLocator device, enable Settings – Wearables – Pulse Oximeter, put the device on your finger and start sleep tracking.

In the morning Sleep as Android determines your RDI with the related severity scoring. Score over RDI >15 per hour is considered as a significant warning sign and visiting a sleep lab is highly recommended.

The blue line shown in graph is SpO2 curve. Every significant dip in SpO2 is marked by a CPAP mask symbol. This indicates 1 breathing disturbance episode. Every “mask” contributes 1/(sleep length hours) to the RDI.

 

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CAUTION: The use of Sleep as Android does not contain or constitute, and should not be interpreted as, medical advice or opinion. We are not licensed medical professionals, and we are not in the business of providing medical advice. You should always consult a qualified and licensed medical professional prior to beginning or modifying your sleep or lifestyle habits. Your use of this App does not create a doctor-patient relationship between you and the provider.

Apnea alarm to wake you up (from version 20161006)

In Settings > Wearables, you can set up an Apnea alarm which will wake you up when you have an apnotic episode. This will prevent your blood oxygen volume from dropping to dangerous levels.
TODO: Document behaviour with smartwatch

Troubleshooting

The app can ONLY connect to the stress locator when it’s first paired with the phone (or removed and re-paired) and no other app has been used (e.g. StressLocator app).

References


  1. T. Young, L. Evans, L. Finn, and M. Palta, “Estimation of the clinically diagnosed proportion of sleep apnea syndrome in middle-aged men and women.,” Sleep, vol. 20, no. 9, pp. 705–6, Sep. 1997.
  2. T. Young, M. Palta, J. Dempsey, J. Skatrud, S. Weber, and S. Badr, “The occurrence of sleep-disordered breathing among middle-aged adults.,” N Engl J Med, vol. 328, no. 17, pp. 1230–5, Apr. 1993.
  3. N. Marshall, K. Wong, P. Liu, S. Cullen, M. Knuiman, and R. Grunstein, “Sleep apnea as an independent risk factor for all-cause mortality: the Busselton Health Study.,” Sleep, vol. 31, no. 8, pp. 1079–85, Aug. 2008.
  4. L.-W. Hang, H.-L. Wang, J.-H. Chen, J.-C. Hsu, H.-H. Lin, W.-S. Chung, and Y.-F. Chen, “Validation of overnight oximetry to diagnose patients with moderate to severe obstructive sleep apnea,” BMC Pulmonary Medicine, vol. 15, no. 1. Springer Science + Business Media, 20-Mar-2015 [Online]. Available: http://dx.doi.org/10.1186/s12890-015-0017-z
  5. Vazquez, J., Tsai, W., Flemons, W., Masuda, A., Brant, R., Hajduk, E., … Remmers, J. (2000).  Automated analysis of digital oximetry in the diagnosis of obstructive sleep apnoea. Thorax, 55(4), 302–307. http://doi.org/10.1136/thorax.55.4.302
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