Getting the Most from Your ResMed AirSense 11 Data

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 (available for $5-10)

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 — You may need your maximum pressure setting increased.

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 having flow limitation events, adjusting EPR may help.

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 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.

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.

Upload your AirSense 11 data and get instant insights →