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Beyond AHI, Apnealytics tracks the other numbers that describe a night of therapy. Here’s what each one means.
These metrics are for tracking and coaching, not diagnosis. Prescribed settings come from your clinician — use Apnealytics to see how therapy is going over time, and make prescription changes with your provider, not on a hunch.

Usage & adherence

Usage is simply how long you wore the mask each night. The common adherence benchmark — used by many insurers, DOT medicals, and clinics — is the 4-hour / 70% rule: using the machine at least 4 hours a night on at least 70% of nights, often measured over a rolling 30-day window.
Partial nights still count toward the 70% — even a nap-length session helps. The Reports page produces a compliance summary you can save for your provider.

Leak

Leak is air escaping the mask, measured in L/min. Apnealytics tracks the 95th-percentile leak per night (the level your leak stayed below for most of the night). High leak matters for two reasons: it disrupts therapy, and it makes AHI and pressure readings unreliable — so it’s usually the first thing to fix. Quick wins: re-seat the mask lying down, try a different cushion size, replace a worn cushion, and for mouth leak on a nasal mask add a chin strap or switch to full-face.

Pressure, EPR & ramp

Pressure is measured in cmH₂O. Auto machines vary it through the night; the 95th-percentile pressure (P95) summarizes how hard your machine was working most of the time. Apnealytics also shows the median so you can see the typical vs. the busy end of the night.
EPR drops the pressure slightly when you exhale, so breathing out feels less like pushing against the machine. It’s a comfort setting, typically 1–3 cmH₂O.
Ramp starts at a low, easy pressure and gradually rises to your therapy pressure over a set time, so you can fall asleep before it reaches full strength.

Event composition

The same AHI can be made of very different events. Apnealytics shows the split between obstructive, central, hypopnea, and unclassified events so you can see what’s driving a night. The sub-indices are covered in Understanding AHI.

Oximetry — SpO₂, ODI & T90

If you add a recording pulse oximeter (such as a Wellue O2Ring or CMS50) or sync blood-oxygen from Apple Health / Health Connect, Apnealytics charts your overnight oxygen on the Vitals page and overlays it on the per-night waveform.
The percentage of your blood’s oxygen-carrying capacity in use. Healthy overnight values usually sit in the mid-to-high 90s. Apnealytics charts your nightly average alongside the nightly low.
How often your oxygen dropped by a meaningful amount per hour (desaturations). Where AHI counts breathing events, ODI counts their effect on your oxygen — so the two together tell you more than either alone.
How much of the night your oxygen spent below about 90%. Brief dips are normal; frequent or sustained time below 90% is what matters.
SpO₂ tells you what AHI can’t: AHI counts events, oximetry shows their impact on your body. An oxygen dip with no matching flow change is more likely a sensor artifact than a real apnea.

Waveforms

The per-night view stacks flow rate, pressure, leak, and (if you have oximetry) SpO₂ and pulse on a shared timeline. Line them up vertically: a real event usually shows across several strips at once — a flow drop that recovers with a big “catch-up” breath, a matching pressure response, and, a beat later, an SpO₂ dip.
Always read the leak strip first. A high-leak stretch makes every other number on that night unreliable.
Waveforms load that night’s detailed files on demand, so the first time you open an older night it may take a moment to fetch and render in your browser.