Most CPAP and BiPAP machines record a lot more than whether you wore the mask. Every night, your device is quietly logging dozens of data points — breathing patterns, pressure changes, mask seal, and more. The trouble is, most of that data never leaves the machine unless you go looking for it.
This guide walks through how to get your data off the machine, what the main numbers actually mean, and how to use that information to have a more productive conversation with your sleep specialist.
Note
This article is for informational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. Always discuss your therapy data and any changes to your treatment with a qualified clinician.
What Does Your CPAP Machine Actually Record?
Modern CPAP and BiPAP machines record data at two levels: summary statistics (what most apps show you) and full night flow data (what reveals the complete picture).
Summary data — recorded every night
- Usage hours— how long you wore the device
- AHI— apnoeas and hypopnoeas per hour
- Leak rate— how much air is escaping around your mask
- Pressure— the pressure your machine delivered
Full flow data — recorded on SD card
- Breath-by-breath flow waveforms — the actual shape of each breath
- Flow limitation— partial airway narrowing that restricts airflow
- RERAs— effort-induced arousals that fragment sleep
- Snore index— detected snoring events
The summary AHI on your machine's screen or companion app is useful, but it's often incomplete. A low AHI doesn't always mean your therapy is well optimised — flow limitation and RERAs can persist even when the headline number looks fine. Full flow data is where the detail lives.
How to Export Your Data
The method varies by manufacturer. In all cases, your data is stored on a standard SD card or via USB — no account or cloud service is required to access it.
ResMed (AirSense 10, AirSense 11, S9 series)
ResMed machines store detailed flow data on a standard SD card (older machines) or internal memory accessible via SD slot.
- Power off the machine.
- Locate the SD card slot — typically on the side panel of AirSense 10/11 models, or under the humidifier chamber on S9 models.
- Remove the SD card and insert it into your computer using an SD card reader.
- The card will contain a folder structure with
.edfand other data files holding your full-resolution flow data.
ResMed's myAir app shows you a nightly summary score, but does not give access to raw flow data. For the full picture, the SD card is the route.
Supported by: OSCAR, AirwayLab, and other open tools.
Philips Respironics (DreamStation, DreamStation 2, System One)
Philips machines use an SD card on older DreamStation and System One units.
- Power off.
- Remove the SD card from the slot on the side of the device.
- Insert into your computer — the card contains
.001Encore data files (System One) or Encore Pro format files (DreamStation).
Note: The DreamStation 2 stores data internally and currently has limited third-party compatibility. Check the OSCAR compatibility list for up-to-date support status.
The DreamMapper app provides summary data but does not expose raw flow waveforms.
Fisher & Paykel (ICON, SleepStyle)
Fisher & Paykel machines generally use an SD card or USB export.
- On the ICON series, the SD card is accessible under a door on the device front or side.
- On SleepStyle units, some models export via a USB connection to the companion app.
- Data is stored in proprietary formats; support varies across analysis tools. OSCAR's compatibility page is the most current reference.
Raw CPAP data comes in proprietary formats that differ by manufacturer and device generation. Tools like OSCAR and AirwayLab handle the parsing — you just point the tool at the folder on your SD card.
What the Numbers Mean
Once you have your data open in an analysis tool, here's how to read the main signals. For a deeper dive, see our full guide on how to read your CPAP data.
AHI (Apnoea-Hypopnoea Index)
Your machine's headline number. It counts complete airway obstructions (apnoeas) and partial obstructions with a drop in airflow (hypopnoeas), expressed per hour of sleep. A lower AHI generally indicates fewer scored breathing interruptions. However, scoring thresholds and event detection logic vary between devices — so a machine-scored AHI and a lab-scored AHI can differ.
Leak Rate
Expressed in litres per minute. Most devices have a built-in intentional vent leak to allow CO₂ to escape — this is normal. What to watch for is unintentional leak: a sustained elevation above your device's leak baseline. Elevated leak can affect air delivery and is often addressable with mask fit adjustments.
Flow Limitation
Shown as a value between 0 and 1, or as a time-series graph. It represents how “flattened” the top of each breath is. A rounded breath peak indicates unobstructed flow; a flat-topped peak is associated with partial airway narrowing. This signal may help you understand whether residual obstruction is present even when AHI is low.
RERAs (Respiratory Effort-Related Arousals)
Effort-induced arousals — the airway doesn't completely close, but increased respiratory effort causes a brief awakening or lightening of sleep. They contribute to sleep fragmentation without necessarily being counted in AHI. Not all machines report RERAs directly; it depends on the device and algorithm.
Pressure
If you're on APAP (auto-adjusting), your nightly pressure graph shows how the machine responded to detected events. Consistent high-pressure clustering at certain times of night can suggest positional patterns worth discussing with your clinician.
Exploring Your Data with AirwayLab
AirwayLab is an open-source tool for visualising and exploring PAP therapy data. It runs entirely in your browser — your data never leaves your device, which matters when you're dealing with sensitive health information.
Load your SD card data directly and explore:
- Nightly trend charts for AHI, leak, pressure, and usage
- Full-resolution flow waveforms for any night
- Flow limitation and RERA trends over time
- Side-by-side comparison across nights and weeks
The source code is published under GPL-3.0, so the analysis is verifiable — you can see exactly how events are being scored. AirwayLab is free and always will be for core analysis features. A premium tier is available for those who want to support continued development.
AirwayLab is designed to complement, not replace, tools like OSCAR. Many users use both — OSCAR for deep clinical-format reporting, AirwayLab for day-to-day visual exploration. They read the same underlying data.
Having a Better Conversation with Your Clinician
Your data is most useful when you bring it into a clinical conversation. A few practical approaches:
Export a trend report before your appointment
Most analysis tools can export a PDF summary covering the past 30–90 days. Bring this to your follow-up — it gives your specialist context faster than relying on device remote-monitoring summaries alone.
Note specific nights that felt different
If you woke up feeling unrefreshed, pull up that night's data and look at pressure and leak graphs. Targeted observations are often more useful than averages.
Ask about flow limitation and RERAs, not just AHI
If your AHI is controlled but you still feel tired, your clinician may want to look at these secondary signals. Having the data makes that conversation concrete.
Be specific about mask issues
If your leak data shows spikes at consistent times, that's useful clinical information — it might indicate movement during the night that breaks the seal.
Always frame observations from home analysis tools as things to discuss, not conclusions. Your clinician has your full history and clinical context that a visualisation tool doesn't replicate.
Frequently Asked Questions
How do I get data off my CPAP machine?
Most machines use a standard SD card. Power off, remove the card, and insert it into your computer. Tools like OSCAR and AirwayLab can then read the data files directly.
What is the difference between AHI and flow limitation?
AHI counts discrete breathing events (apnoeas and hypopnoeas) per hour. Flow limitation measures partial airway narrowing that may not meet the threshold for a scored event. Both are visible in full flow data from your SD card.
Can I analyse my CPAP data without installing software?
Yes. AirwayLab runs entirely in your browser — no download or install needed. Open the upload page, drag in your SD card files, and your data loads immediately.
Does my CPAP data leave my device when using AirwayLab?
No. AirwayLab processes all data locally in your browser. Nothing is uploaded to a server. Optional features like AI insights require explicit consent before any data is sent.
Which CPAP machines does AirwayLab support?
AirwayLab currently supports ResMed AirSense 10, AirSense 11, and AirCurve devices via SD card. Support for additional manufacturers is planned.
Summary
Your CPAP machine is generating detailed data every night. Getting it off the device is straightforward — an SD card and a free tool is all it takes. Understanding what AHI, leak rate, flow limitation, and RERAs may tell you about your breathing patterns can help you engage more meaningfully with your therapy and your care team.
Tools like AirwayLab and OSCAR exist to make your data accessible — in your browser, on your terms, with open and verifiable analysis.
Medical disclaimer
AirwayLab is an open-core software tool for reviewing PAP therapy data. It is not a medical device and does not provide medical advice, diagnosis, or treatment recommendations. All analysis is informational — always discuss your breathing data and therapy with a qualified sleep specialist.
Explore Your Data Free — No Install Needed
Load your SD card into AirwayLab and see your AHI, flow limitation, RERAs, and breathing patterns in minutes. No installation, no account required, 100% private.