SpO2 From a Paired Oximeter on Your ResMed

Most people think their CPAP and their oxygen data live in two separate places: the machine writes to its SD card, and a pulse oximeter writes to its own app. On some ResMed machines that is not quite true. If you connect a compatible pulse oximeter to the machine, the ResMed records its oxygen and pulse readings straight onto the same SD card as your therapy data, timestamped against your breathing. The AirSense 11 does it wirelessly over Bluetooth; the AirSense 10 and AirCurve do it through a wired adapter. It is a quiet feature that even a lot of sleep clinicians do not know exists.

CPAP Clarity now reads that data automatically. This article covers which machines do it, the oximeter you need, how to set it up, and what you see once the card is imported.

How a ResMed records oxygen from a connected oximeter

The ResMed AirSense 10, AirSense 11, and the AirCurve line can all take readings from an external pulse oximeter and log them locally, but the way you connect the oximeter is different depending on your machine.

The AirSense 11 does it over Bluetooth. It has a short-range radio, the same one that syncs your nightly summary to myAir, and it pairs wirelessly with a compatible Bluetooth oximeter worn on the wrist.

The AirSense 10 and the AirCurve 10 do it with a cable. ResMed sells an oximetry adapter module that plugs into the port below the SD card slot, and a finger sensor connects to that. There is no Bluetooth pairing on those machines.

Either way, once the oximeter is recording, the machine writes a second stream into each night's session folder on the SD card, alongside the flow, pressure, and event data it already stores. That stream is the oximeter's oxygen saturation (SpO2) and pulse rate, sampled once per second. Because the machine writes it with its own clock, the oxygen data lines up second for second with your therapy. There is no guessing at which oximeter reading matches which apnea.

This is different from importing a standalone ring like a Wellue O2Ring. With a ring, you record on the ring, export a file from the ring's app, and drop that file in separately. With a connected oximeter, there is no second export. The oxygen data is already on your CPAP card, so it comes in when you import the card.

What you need

The oximeter depends on your machine. On the AirSense 11, the wireless unit is the Nonin WristOx2 Model 3150 with Bluetooth Low Energy, a wrist-worn recording oximeter that pairs over Bluetooth. On the AirSense 10 and AirCurve 10, you use the ResMed oximetry adapter module plus a compatible Nonin finger sensor (the XPod), connected by cable rather than paired. Nonin is a long-established medical pulse oximetry company, and both are built for overnight recording.

Two things to know before you consider this route. First, these are prescription devices sold through medical suppliers, not over-the-counter gadgets, so you cannot simply add one to a cart. Second, they are expensive: the wireless Nonin 3150 runs generally around a thousand dollars new, with the manufacturer software an additional cost. That price buys genuine lab-grade accuracy, which is why some patients working through stubborn oxygen problems with their doctor choose it over a consumer ring.

For most people, a consumer recording ring is the more practical way to track overnight oxygen, and CPAP Clarity reads those too. See the pulse oximeter guide for the everyday option. The connected-oximeter path in this article is for people who already own, or are prescribed, one of these medical units.

How to set it up

The connection step depends on your machine, and the exact menu wording varies by firmware.

On the AirSense 11, put the machine into its Bluetooth pairing mode from the setup menu and pair the Nonin 3150 the way you would pair headphones. Once the two are paired, the machine remembers the oximeter. On the AirSense 10 or AirCurve 10, there is no pairing: plug the ResMed oximetry adapter module into the port below the SD card slot and connect the finger sensor to it.

Then wear the oximeter as you sleep with the machine running. It records, and the machine pulls the readings in and writes them to the SD card through the night. You do not need to touch the oximeter's own software for CPAP Clarity to read the data, because the readings you care about are already on the CPAP card.

Finally, import your SD card into CPAP Clarity the way you always do. Take the card out in the morning, drop the whole card folder onto the import area, and let it parse. The oxygen data rides in with the therapy data.

What CPAP Clarity shows

Once the card is imported, your oxygen shows up on the Oxygen page and in the dashboard, labeled so you know it was recorded by your CPAP rather than a separate device. Every night that carried oximeter readings gets the same analysis CPAP Clarity runs for any oximeter:

Minimum SpO2, the single lowest oxygen reading of the night, which catches brief severe dips that an average hides.
Mean and median SpO2, the numbers most clinicians ask about when they want your overall overnight oxygen.
Oxygen Desaturation Index (ODI) at both the 3 percent and 4 percent thresholds. The American Academy of Sleep Medicine recommends the 3 percent rule; many United States clinics still report the 4 percent value because Medicare's hypopnea definition uses 4 percent, so CPAP Clarity reports both.
Time below 88 percent, the total minutes your oxygen sat under the threshold that United States rules use when considering supplemental oxygen.
Pulse rate, averaged and at the 95th percentile.

Because the oxygen was recorded on the CPAP's own clock, it joins your therapy night exactly. On the dashboard you can see a night where the CPAP scored a low AHI while the oxygen still dipped, which is one of the most useful mismatches a CPAP user can spot. Our walkthrough on how AHI and ODI relate covers why a clean AHI can sit next to an abnormal ODI, and what usually explains it.

Why the numbers might differ from your oximeter's own app

The oxygen-drop numbers, ODI in particular, are computed the standard way from the recorded readings. Your Nonin software may report a slightly different drop count, because different tools apply the counting rules a little differently and because the Nonin's own software may work from a finer internal signal than the readings written to the CPAP card.

The oxygen levels themselves, your minimum, mean, and time below a threshold, are direct reads of what the machine recorded, and those we have checked sample for sample against OSCAR, the widely used open-source CPAP analyzer, so they match what the raw data holds. If your derived numbers look off next to your Nonin app, that is worth a closer look, and it is the kind of thing a screenshot from the app helps settle.

What this is and what it is not

A recording oximeter, paired or standalone, is a screening and tracking tool. It is not a sleep study and it is not a diagnosis. A sleep study measures airflow, respiratory effort, brain activity, and oxygen together, and a clinician scores it. A pulse oximeter measures only the oxygen and pulse channel.

That channel is genuinely useful. Overnight oximetry has a long validated history as a screening signal for sleep-disordered breathing, and a lab-grade device like the Nonin gives you that signal with hospital-level accuracy. But a clean oxygen night does not rule apnea out, and a bad one does not diagnose it. Persistent patterns across weeks, brought to a sleep physician, are what these numbers are for. If your oxygen readings concern you, the next step is a clinician, not a different gadget. Our guide on how to get tested for sleep apnea covers that path.

Everything CPAP Clarity does with this data happens in your browser. The oxygen readings, like your therapy data, are parsed on your own device and stored only there. Nothing about your recording is uploaded.

Common Questions

Which ResMed machines can record from a connected oximeter?

The AirSense 11 pairs one over Bluetooth. The AirSense 10 and AirCurve 10 use a wired oximetry adapter module instead. Either way the readings land on the SD card. Travel and summary-only machines that do not write detailed nightly session data to the card, such as the AirMini and the AirStart, do not carry this stream. CPAP Clarity's reading has been checked sample for sample against OSCAR on the AirSense 11 path. The AirSense 10 records oximetry through its wired adapter into the same kind of ResMed oximetry file, so it should read the same way, but we have not yet validated an AirSense 10 recording. If you have one, import your card and let us know how it looks.

Do I have to use the Nonin software at all?

No. For CPAP Clarity, you only need to import your CPAP SD card. The oxygen readings are already written to the card by the machine, so the Nonin's own program is optional. If you want to compare CPAP Clarity's drop counts against the device's, that is where the Nonin software or app is handy.

Which oximeter do I need?

It depends on your machine. The AirSense 11 pairs with the wrist-worn Nonin WristOx2 3150 BLE over Bluetooth. The AirSense 10 and AirCurve 10 use the ResMed oximetry adapter module with a Nonin finger sensor. Do not buy the wireless 3150 for an AirSense 10; it will not pair. If you do not have either, a consumer recording ring is the more affordable route to overnight oxygen, imported separately. See the pulse oximeter guide.

My CPAP already shows oxygen. Why import it here?

The machine records the readings, but it does not turn them into ODI, minimum SpO2, time below 88 percent, or a night-by-night trend you can read at a glance. That is what CPAP Clarity adds, alongside your AHI, leak, and usage for the same night.

Will this work on data I recorded before I found this site?

Yes, as long as the oxygen was on the card when you recorded those nights. Re-import your card and any nights that carried paired-oximeter readings will pick up the oxygen analysis.

Primary Sources

Nonin Medical. WristOx2 Model 3150 with Bluetooth Low Energy. A wrist-worn recording pulse oximeter with Bluetooth Low Energy for overnight SpO2 and pulse capture. nonin.com WristOx2 3150 BLE (opens in new tab)
American Academy of Sleep Medicine. AASM clarifies hypopnea scoring criteria. Recommends the 3 percent desaturation threshold and accepts 4 percent as an alternative. aasm.org (opens in new tab)
U.S. Food & Drug Administration. Pulse Oximeter Basics. Explains the difference between medical, over-the-counter, and general-wellness oximeters and what affects accuracy. fda.gov (opens in new tab)