ResMed AirSense 11: Get More from Your Data

The ResMed AirSense 11 records detailed therapy data on its SD card every night, including breath-by-breath airflow, pressure delivered, leak rate, respiratory rate, tidal volume, snore index, flow limitation, and every apnea or hypopnea event with exact timestamps. The myAir app shows a simplified daily score. The SD card contains roughly 20x more detail, and reading it is what lets you see exactly when events happened, what triggered them, and whether your therapy is genuinely working or just looks good on the score.

If you are looking to buy one, the AirSense 11 is available at CPAP.com.

What Your AirSense 11 Records

The ResMed AirSense 11 is one of the most data-rich CPAP machines available. Every night, it records:

• Breath-by-breath airflow at 25 samples per second
• Mask pressure: what pressure is actually being delivered
• Therapy pressure: what the machine is targeting
• Leak rate: how well your mask is sealing
• Respiratory rate: breaths per minute
• Tidal volume: air volume per breath
• Minute ventilation: total air moved per minute
• Snore index: detected snoring events
• Flow limitation: subtle airway narrowing
• Every respiratory event: obstructive apneas, central apneas, hypopneas, and RERAs with exact timestamps and durations
• SpO2 and pulse (if an oximeter is connected)

All of this data is stored on the machine's SD card in a medical data format called EDF (European Data Format).

myAir Shows You About 5% of This Data

ResMed's myAir app deliberately simplifies your data into a single "score" out of 100 based on:

• Usage hours (did you wear it?)
• Mask seal (was your leak acceptable?)
• Events per hour (your AHI)
• Mask on/off (how many times you removed it?)
• myAir score weighting (proprietary formula)

That score hides important nuances. You can get a "perfect" 100 with an AHI of 4.9, which is technically normal but significantly higher than most well-treated patients achieve. You can't see when events occurred, what type they were, how your pressure varied, or how leak affected your therapy.

The detailed data on your SD card tells a much more complete story.

How to Access Your SD Card Data

Step 1: Locate the SD Card

On the AirSense 11, the SD card slot is on the left side of the machine (when facing it). You'll need to:

1. Turn off or unplug the machine
2. Open the small door/cover on the side
3. Push the SD card to release it (push-to-eject mechanism)

Step 2: Read the Card

Insert the SD card into your computer using:

• A built-in SD card reader (many laptops have one)
• A USB SD card reader (opens in new tab) (available for a few dollars)

Your computer should mount it like a regular drive.

Step 3: Understand the File Structure

Your SD card contains:

SD Card Root/
├── STR.edf          ← Daily summary database
├── Identification.json
├── DATALOG/
│   ├── 20260327/    ← One folder per date
│   │   ├── ..._BRP.edf  ← Breath data (high-res flow)
│   │   ├── ..._PLD.edf  ← Periodic data (pressure, leak, etc.)
│   │   ├── ..._EVE.edf  ← Respiratory events
│   │   ├── ..._CSL.edf  ← Cheyne-Stokes data
│   │   └── ..._SA2.edf  ← Oximetry data (if connected)
│   └── 20260328/
│       └── ...
└── SETTINGS/

Each night may have multiple session files if you removed the mask during the night (bathroom breaks, for example).

Step 4: Analyze the Data

The EDF files are binary. You can't open them in a text editor. You need an analysis tool:

CPAP Clarity reads these files directly in your web browser. Just drag and drop the SD card folder and get instant results. Try it free →

Key AirSense 11 Data Points to Watch

Pressure Behavior

The AirSense 11 in AutoSet mode adjusts pressure throughout the night. Watching the pressure curve tells you:

• Flat, low pressure: Your airway is stable. Good sign.
• Gradually increasing pressure: The machine is responding to increasing events (common as you enter deeper sleep stages).
• Frequent large swings: May indicate the machine is "chasing" events caused by leak or positional changes.
• Pressure near maximum: Discuss with your provider whether your maximum pressure setting needs adjustment.

EPR (Expiratory Pressure Relief)

The AirSense 11 supports EPR levels 1-3, which reduces pressure when you breathe out for comfort. Your data shows the actual EPR pressure delivered. If you're seeing flow limitation events, discuss your EPR setting with your provider.

The STR.edf Summary File

This is a hidden gem. It contains a daily summary of every metric going back over a year. It includes AHI, leak percentiles, pressure percentiles, respiratory rate, tidal volume, and all machine settings for every day. This is where trend analysis gets powerful.

AirSense 11 Settings Your Data Reveals

Pulling the SD card lets you see settings that myAir keeps hidden. Three are worth checking on every import:

AutoSet vs. fixed CPAP mode. AutoSet is the default on most AirSense 11 prescriptions. The data shows whether the machine is genuinely adjusting (which is what AutoSet is for) or sitting near the minimum pressure most of the night (which can mean either your airway is stable or your prescribed range is set too low). For a deeper look at how pressure should behave through the night, see our CPAP pressure settings guide.

EPR level and mode. EPR (Expiratory Pressure Relief) drops the pressure during exhale by 1, 2, or 3 cmH2O. Your data shows the actual EPR pressure delivered breath by breath, so you can confirm the prescribed setting is what is reaching you. EPR Full Time is the most common setup; EPR Ramp Only turns the relief off after the ramp period ends.

Response setting (Soft / Standard). AutoSet has a responsiveness setting that controls how quickly the machine raises pressure when it detects an event. Standard is the default; Soft responds more slowly. You will not see "Response" as a labeled channel in the data, but you can infer it from how aggressively the pressure climbs after a cluster of events.

Common Patterns Your AirSense 11 Data Will Show

Once you can see the breath-by-breath chart, certain patterns repeat across nights:

REM-clustered events. Your throat muscles relax more during REM sleep, so apneas and hypopneas tend to bunch into ~90-minute cycles. APAP handles this automatically; fixed CPAP users sometimes see clusters that the single prescribed pressure was not titrated against.

Position-dependent events. Apneas often cluster when you roll onto your back. If you correlate the event timeline with your sleeping position (a journal entry or an Apple Watch / Oura overlay), you can see whether positional therapy alone might reduce your AHI.

Leak signatures. Mouth leaks at higher pressures look like a steady high-leak baseline that lasts hours. Mask-shift leaks look like brief leak spikes when you change position. Telling the two apart matters: the first is a mask-type or chin strap (opens in new tab) question; the second is a fit-and-headgear question. Our leak fix guide walks through both.

Central apnea cluster after starting CPAP. If your data shows a sudden rise in central apneas (CA) after a prescription change, that is the signature of treatment-emergent central sleep apnea. Worth mentioning to your provider.

AirSense 11 Supply Replacement: Let the Data Tell You When

The Medicare and ResMed replacement schedules are calendar-based ceilings, not personalized signals. Your data tells you when each consumable is actually starting to fail.

Filters affect motor noise + airflow restriction. A clogged filter shows up as gradually rising machine noise (subjective) and on AutoSet machines as wider pressure variability (the machine works harder to deliver the same prescribed pressure). Replacing monthly is the safe ceiling; replace sooner if you live somewhere dusty or have pets.

Water chamber affects humidity output + biofilm risk. Mineral buildup that does not dissolve with a vinegar soak is the signal. ResMed recommends every 6 months on the AirSense 11 HumidAir chamber; tap-water users typically need to replace sooner.

AirSense 11 supplies for data-driven replacement

Monthly Filter

AirSense 11 Disposable Filter (30-pack)

30-pack of disposable filters specific to the AirSense 11 (the AS10 pack is a different geometry). Monthly replacement gives almost three years per pack.

Compare on Amazon→

Humidifier Replacement

AirSense 11 Compatible Water Chamber

Replacement water chamber compatible with the AirSense 11, with a 20-pack of disposable filters included. Replace every 6 months, or sooner if mineral buildup will not dissolve with a vinegar soak.

Compare on Amazon→

For the full cross-machine supply timeline, see our CPAP supply replacement schedule.

AirSense 11 vs. AirSense 10

The AS11 records largely the same data as the AS10, with a few differences:

Feature	AirSense 10	AirSense 11
Signal naming	"Mask Pres", "Leak"	"MaskPress.2s", "Leak.2s"
Connectivity	SD card + cellular	SD card + Bluetooth + cellular
Oximetry file	SAD.edf	SA2.edf
EPR options	Same	Same
Data resolution	Same	Same

The underlying data quality is essentially identical. The AS11 added Bluetooth connectivity and a slightly different file naming convention, but the therapy data itself is comparable. For a side-by-side decision guide on which generation to choose, see AirSense 11 vs AirSense 10.

Making the Most of Your Data

1. Check weekly, not daily. Night-to-night variation is normal. Weekly trends matter more.
2. Look at leak first. Most "bad nights" trace back to mask seal issues.
3. Track after changes. Changed your mask, pillow, or settings? Compare data before and after.
4. Bring data to appointments. Your sleep doctor will appreciate detailed reports instead of "I think I'm sleeping better."
5. Don't obsess. Data should inform, not stress you. An AHI of 3 vs. 2 isn't clinically meaningful; see what a good AHI looks like for the bands and what they mean.

For a deeper walkthrough of what each metric means, see how to read your CPAP data. Ready to get started? Our CPAP Clarity guide shows you how to go from SD card to insights in 60 seconds.

See what CPAP Clarity shows for AirSense 11 users →

Frequently Asked Questions

Does the AirSense 11 record more data than myAir shows? Yes, by a large margin. The myAir app shows a daily score, your usage hours, your AHI, leak status, and mask on/off events. The SD card carries the underlying breath-by-breath airflow + pressure + leak + flow-limitation + every event with timestamps + a full year of daily summaries in the STR.edf file. Reading the SD card is the only way to see when events happened, what triggered them, and how your therapy varied through the night.

Where is the SD card slot on the AirSense 11? On the left side of the machine when facing it, behind a small door. The slot uses a push-to-eject mechanism: push the card in once to release it. Power the machine off before removing the card.

Can I read AirSense 11 data on my phone instead of a computer? Yes. iOS 17+ Safari and Android Chrome both support folder picking from an SD card reader plugged into the phone. See our phone import + cloud storage guide for the step-by-step.

What file format does the AirSense 11 use? EDF (European Data Format), a standard medical-data format. The files are binary, not readable in a text editor. CPAP Clarity parses them directly in your browser; OSCAR (a free desktop app) also reads them.

What is in the STR.edf file? A daily summary database covering up to a year of past nights. Each row has AHI, leak percentiles, pressure percentiles, respiratory rate, tidal volume, and the machine settings active that day. This is where trend analysis gets powerful; one bad night is rarely the story.

How often should I import my AirSense 11 data? Weekly is enough for trend awareness; nightly is overkill for most users. Night-to-night variation in AHI is normal. Import after any change (new mask, new pillow, new pressure setting) so you can compare before and after, and import before every sleep doctor appointment.

Primary Sources

• Patil SP, Ayappa IA, Caples SM, Kimoff RJ, Patel SR, Harrod CG. Treatment of Adult Obstructive Sleep Apnea with Positive Airway Pressure: An American Academy of Sleep Medicine Clinical Practice Guideline. J Clin Sleep Med. 2019 Feb 15;15(2):335-343. The current AASM guideline on when CPAP, APAP, and BiPAP are appropriate for adults with OSA. PubMed 30736887 (opens in new tab)
• National Heart, Lung, and Blood Institute. CPAP (NHLBI patient education page). Plain-language overview of how CPAP works and the common side effects to expect. nhlbi.nih.gov CPAP (opens in new tab)