CPAP Machines & Devices

Your CPAP machine is a quiet medical recorder. Every night it logs how you breathed, how much air leaked from your mask, how hard your airway resisted, and exactly what pressure it delivered second by second. The catch is that the manufacturer app on your phone — myAir, the old DreamMapper, or your device's built-in screen — shows you only a sliver of that record. This pillar is the hub for understanding what each machine family actually stores, where it hides the rest, and how to get at the full picture.

Below you'll find guides for every major brand we support, plus the machine modes and comfort settings that shape what your data looks like. Wherever you see a number like AHI, leak rate, or pressure, remember the recurring theme: a single night is noise, but trends over weeks tell the real story.

How CPAP machines record data

Almost every modern CPAP, APAP, and bilevel machine writes detailed therapy data to a removable card or stick. ResMed and Philips use a standard SD card; Fisher & Paykel uses a proprietary InfoUSB stick. Most of that data is stored in EDF (European Data Format), a standard medical waveform format — which is why third-party tools can read it at all.

There are two broad layers of data:

• Summary data — nightly totals like usage hours, AHI (apnea-hypopnea index: events per hour of sleep), leak rate, and the pressures used. This is roughly what your phone app shows.
• Detailed and waveform data — breath-by-breath flow rate, individual flagged events (obstructive apnea, central apnea, hypopnea, RERA, flow limitation), and high-resolution pressure traces. This is what clinicians and OSCAR users actually dig into, and it almost never reaches the manufacturer app.

The big exception is the Philips DreamStation 2, which encrypts its SD-card data — more on that below. To learn the practical mechanics of getting the card out and copying files safely, start with How to Download CPAP Data from Your SD Card.

Before any of the brand specifics matter, it helps to know what the numbers mean. If you're new to reading therapy data, the companion pillar Reading Your CPAP Data and its plain-English starter, How to Read Your CPAP Data, explain AHI, leak rate, and pressure from scratch.

Machine modes: CPAP, APAP, BiPAP, and ASV

The "mode" your machine runs in determines both how it treats you and what data it produces. A fixed CPAP logs a flat pressure line; an auto-adjusting APAP logs a pressure that moves all night; a bilevel machine logs two pressures (inhale and exhale) plus the gap between them, called pressure support.

For a full walkthrough of each mode, which models use it, and the data each one produces, see APAP vs CPAP vs BiPAP: Machine Modes and the Data Each Produces. If your machine has started flagging central (clear-airway) events, it's worth understanding the difference between obstructive and central apnea before you read anything into it.

ResMed machines

ResMed is the most common home CPAP brand, and its machines store unusually rich detail on the SD card — far more than the myAir app reveals. myAir is ResMed-only, gives you a 0–100 score weighted heavily toward usage hours, never publishes its formula, and shows no event-type, leak, or flow-limitation detail. It can even hand you a score of 100 on a night your AHI was 4.9.

• ResMed AirSense 11 Data: What Your SD Card Holds (and myAir Hides) — the current-generation APAP, recording breath-by-breath EDF data the app never surfaces.
• ResMed AirSense 10 Data Guide: SD Card and Card-to-Cloud Explained — the world's most widely used home APAP, including where the slot is and how ResMed's Card-to-Cloud model works.
• ResMed AirCurve 10 & 11 (VAuto, ST, ASV): Reading Bilevel Data — bilevel and ASV machines that log IPAP, EPAP, and pressure support, the richest data of any home device.
• ResMed EPR, Ramp & Climate Control: Verify Your Comfort Settings — how your data proves whether your comfort features are actually being delivered.

One ResMed-specific detail to know: ResMed reports excess leak, and its commonly cited threshold is 24 L/min at the 95th percentile. (Philips, by contrast, reports total leak — a different baseline, so the numbers aren't interchangeable.) Large leak matters because it can invalidate or under-report your AHI: if too much air is escaping, the machine may simply miss events. That's a core reason to look at leak alongside AHI rather than trusting a single headline number.

Philips Respironics machines

Philips machines split sharply into "before" and "after" the DreamStation 2.

• Philips DreamStation 1 & System One: SD Card Data and How to Read It — the original DreamStation and the older System One store unencrypted, readable data that OSCAR and other tools handle well.
• Philips DreamStation 2: Why Its Data Is Encrypted and Your Options — the DreamStation 2 encrypts its SD-card data, so OSCAR and most third-party tools cannot read it. This became a much bigger deal when Philips's DreamMapper app shut down in January 2026, leaving DS2 users with very few ways to see their own detailed data. SomniCharts does support DreamStation 2 data — one of the few tools that does.
• Philips Respironics Recall, Explained Neutrally — and Your Data — a factual overview of the 2021 foam recall, the silicone-foam replacement, and the separate DS2 safety notice.

On the recall: it's a sensitive topic, so we keep it precise. After the original polyurethane (PE-PUR) foam recall, Philips replaced the foam with a silicone-based material. An FDA inspection report and independent lab tests (the latter commissioned by Philips) later raised concerns that the silicone foam could emit volatile organic compounds, including formaldehyde. The FDA itself did not issue a finding that the foam releases these chemicals; after learning that a silicone-foam device sold outside the U.S. failed one VOC test, it requested additional independent testing and, while that testing was pending, advised patients to keep using their repaired or replacement devices. Philips maintains that detected levels stayed below applicable thresholds, though some independent experts dispute which thresholds apply. The neutral guide covers this in full.

Löwenstein prisma machines

Löwenstein is the under-served brand: high-quality German machines (the prisma SMART, 20A, CPAP, 30ST, and CR) whose data almost no consumer tool reads well. Most analysis software simply ignores them. SomniCharts is a notable exception — it imports Löwenstein prisma data and explains it in plain language. See Löwenstein Prisma CPAP Data: How to Read the Under-Served Brand.

Fisher & Paykel SleepStyle

The Fisher & Paykel SleepStyle is the odd one out: it uses an InfoUSB stick rather than an SD card, and OSCAR derives some of its metrics from the flow graph rather than reading them directly. We cover it as ecosystem education in Fisher & Paykel SleepStyle: InfoUSB Data and OSCAR Caveats. To be clear: SomniCharts does not currently import Fisher & Paykel data — our supported import set is ResMed, Philips Respironics (including the DreamStation 2), and Löwenstein prisma.

What the manufacturer apps don't show you

Here's the gap that ties this whole pillar together. The phone apps are built to keep you compliant, not to make you informed:

Neither app shows you the flow-rate waveform, flow limitation, or RERAs — the subtle signs that you may be working harder to breathe even when your AHI looks fine. For what counts as a healthy AHI in the first place, see What Is a Good AHI on CPAP?.

Reading and keeping your data across machines

Two practical concerns come up constantly:

1. Getting the data off the device. The mechanics differ by brand. How to Download CPAP Data from Your SD Card walks through ResMed, Philips, and Löwenstein, then points you to tools that read it without a desktop install.
2. Keeping history when you switch brands. myAir and DreamMapper don't follow you to a new machine, and they don't talk to each other. Switching CPAP Brands? Keep Your Data History Across Vendors explains how to maintain one continuous record across ResMed, Philips, and Löwenstein.

This is exactly where a multi-vendor, cloud-based analyzer earns its keep. SomniCharts imports ResMed, Philips Respironics (including DreamStation 2), and Löwenstein prisma data and explains it automatically in plain language — including the events and leak detail the manufacturer apps leave out — so your history stays in one place even when your hardware changes.

A note on therapy goals

Throughout these guides you'll see one benchmark repeated: a residual AHI below 5 events per hour is the widely used target for effective CPAP. The AASM defines an "optimal" titration as reducing AHI to fewer than 5, and below 5 is also the normal, non-apneic range. Some clinicians aim lower (for example, under 1–2) when it's comfortably achievable, but there's no formal guideline setting "below 2" as a standard, and your individual goal is set with your provider.

Likewise, if central (clear-airway) events climb after you start CPAP, that can be treatment-emergent central sleep apnea, which often resolves on its own within weeks to a few months of continued therapy. The right move is never to raise your own pressure to chase those events — higher pressure doesn't fix central apneas and can sometimes provoke them. Bring the trend to your clinician instead. You can read more in Central Apneas Showing Up on CPAP.

Use your data to ask better questions, spot trends, and have an informed conversation with your sleep team — that's what every guide in this hub is built to help you do.