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Oximeters that work with Apnealytics
Your CPAP machine estimates how often your breathing was disturbed. A pulse oximeter records what happened to your oxygen. Apnealytics puts the two on the same timeline: a CPAP oximeter overlay that lays SpO₂ and pulse over the night's airflow, pressure and events, then summarises the desaturations as ODI₃, ODI₄ and T90. Oximetry overlays are part of the Pro plan.
Supported oximeters
If your oximeter exports a file with a timestamp, SpO₂ and pulse columns, it will import. If it exports only to a closed app with no file, it will not.
| Device | Import path | Status |
|---|---|---|
| Wellue O2Ring (and O2Ring variants) | CSV export from the Wellue app | Supported, Pro |
| Contec CMS50 family (CMS50D+, CMS50F, CMS50I and others) | CSV export from Contec's desktop software or app | Supported, Pro |
| ResMed oximetry (SAD.edf) | Read automatically from the SD card when a ResMed-compatible oximeter module was attached | Supported, Pro |
| Any oximeter that exports EDF or CSV | File import, with a column mapper for CSV | Supported, Pro |
How import works
Record the night with the oximeter running alongside your CPAP.
Export the session from the oximeter's app or desktop software as CSV (or EDF if offered).
In Apnealytics, open the night and choose Add oximetry, or drop the file on Import. The web portal and the iPhone and Android apps all accept oximeter files.
Apnealytics aligns the oximeter's clock with the machine's
If the clocks differ, you can nudge the offset by hand.
The overlay appears on the night, and ODI₃, ODI₄ and T90 are added to the night's summary.
What the overlay shows
SpO₂ and pulse on the same timeline as events
Scroll the night and watch whether a cluster of hypopneas on the event strip lines up with a dip in SpO₂ and a rise in pulse. If it does, the events had a cost. If it does not, the machine may have flagged events that were not deep enough to matter, or the oximeter may have missed them. Either is worth knowing.
Desaturation markers
Each drop of 3 percent or more from the preceding baseline is marked, and each drop of 4 percent or more is marked more strongly. You can click any marker to zoom the Pro waveform viewer to that moment.
Summary numbers
Average SpO₂, lowest SpO₂, average and highest pulse, ODI₃, ODI₄ and T90 for the night, and trends of each across 30 nights or any range.
ODI and T90, briefly
ODI₃ (oxygen desaturation index, 3 percent) is the number of times per hour SpO₂ dropped by at least 3 percent from its recent baseline. ODI₄ uses a 4 percent threshold and is stricter.
T90 is the share of the night, in minutes or percent, that SpO₂ spent below 90 percent.
ODI is not the same as AHI. AHI counts airflow events the machine detected; ODI counts oxygen drops the oximeter detected. They often move together but can diverge. Neither is a diagnosis. Read more in SpO₂ explained.
Pro note
Oximetry import and overlays are a Pro feature at $8.99 a month or $99.99 a year. Pro is per account, so every family login on the account gets it. The Free plan still syncs the daily SpO₂ average and low from Apple Health or Health Connect, which is a daily summary rather than a night-long trace. See pricing.
Choosing an oximeter
Any oximeter that exports a file works, so the choice comes down to comfort and battery. Ring-style devices like the O2Ring are the most comfortable for all-night wear. Finger-clip devices like the CMS50 family are cheaper and widely available, but a clip on the finger can come loose during sleep. Wrist units with a soft finger probe sit in between. Apnealytics does not sell oximeters or take referral payments.
Questions people ask
Which pulse oximeters work with Apnealytics?
The Wellue O2Ring, the Contec CMS50 family, ResMed's SAD.edf oximetry file, and any oximeter that exports EDF or CSV with timestamp, SpO₂ and pulse columns. Import is on the web portal and in the iPhone and Android apps. Oximetry overlays are a Pro feature.
What is the difference between ODI and AHI?
AHI is the number of apneas and hypopneas per hour that your CPAP machine detected from airflow. ODI is the number of oxygen desaturations per hour that your oximeter detected. They measure different things and can disagree. Seeing both on one timeline is the point of the overlay. Neither is a diagnosis.
Does Apnealytics read my Apple Watch SpO₂ as an overlay?
No. Apple Health provides daily SpO₂ summaries (average and low), not a continuous overnight trace, and Apnealytics shows those beside your therapy on every plan. For a night-long overlay you need a dedicated oximeter that exports a file. See Apple Watch and Apple Health.
How do I line up the oximeter with my CPAP data?
Apnealytics aligns the two by timestamp automatically. Oximeter clocks drift, so if the SpO₂ dips sit a minute or two off the events, drag the offset control on the night to correct it. Setting the oximeter's clock from your phone before each recording keeps drift small.
Is oximetry available on the Free plan?
Not the overlay. The Free plan includes the daily SpO₂ average and low from Apple Health or Health Connect. Night-long oximeter import, the overlay, ODI₃, ODI₄ and T90 are Pro features.
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