Wellue O2 Ring · OxySmart · O2Ring S · O2Ring 5103
See your overnight SpO2 next to your CPAP
CPAP Clarity reads your Wellue ViHealth CSV and computes AASM-style ODI at both 3 and 4 percent thresholds, mean and minimum SpO2, time below 88 percent, and motion-aware coverage. All of it lines up next to your CPAP AHI on the same night.
Can the O2 Ring screen for sleep apnea?
More legitimately than a smartwatch or a sleep-stage wearable, but still not as a substitute for a sleep study. Overnight pulse oximetry has decades of clinical validation as a screening tool specifically for sleep-disordered breathing. The Hang et al. 2015 BMC Pulmonary Medicine study reported around 87 to 90 percent sensitivity and 86 to 93 percent specificity for detecting moderate-to-severe OSA using ODI derived from overnight oximetry.
The mechanism is direct: an obstructive or central apnea blocks airflow, oxygen falls, and the pulse oximeter captures the dip. Snoring or partial obstruction without desaturation can slip through, and central sleep apnea with arousal but minimal desaturation can also be missed, so a clean ODI does not rule apnea out. A high ODI on a single clean night, on the other hand, is a meaningful signal.
If you are using the O2 Ring to screen yourself, pair the data with a validated questionnaire and a clinician conversation.
- STOP-BANG questionnaire: the most validated 8-question apnea screener.
- AHI and ODI: how the two metrics relate: useful for interpreting an ODI you measured at home.
- How to get tested for sleep apnea: the path from a high ODI to a clinical diagnosis.
What CPAP Clarity reads from your O2 Ring
CPAP Clarity computes the mean and median oxygen saturation across the full recording. The mean is what most clinicians cite when they ask about your overnight oxygen.
Oxygen Desaturation Index at the AASM-recommended 3% threshold. Counts SpO2 drops of 3 percent or more lasting at least 10 seconds, divided by recording hours (gap-corrected for motion).
ODI at the AASM-acceptable 4% threshold. Most CPAP clinics in the United States still use the 4% rule. CPAP Clarity reports both so you have the number your clinician asks for.
The single lowest oxygen value during the recording, with the motion artifact filtered out. Useful for catching brief severe dips that the average hides.
The total minutes your SpO2 sat below 88 percent (the CMS supplemental-oxygen threshold) and the percent of total recording time. A standard reporting line on clinical pulse oximetry studies.
Pulse oximeters drop and corrupt readings when you move. CPAP Clarity flags motion-saturated stretches and excludes them from ODI denominators rather than silently inflating events.
Per the AASM 2018 manual, baseline is the peak SpO2 in the prior 120 seconds of clean readings. The baseline is frozen during an in-progress desaturation so the dip is not diluted into its own reference.
Every O2 Ring night joins by calendar date to your CPAP session. The dashboard shows AHI, leak, and usage hours alongside ODI3, ODI4, mean SpO2, and minimum SpO2 for the same night.
How the O2 Ring compares to other ways to track overnight oxygen
| Feature | Wellue O2 Ring | Apple Watch | Home Sleep Study |
|---|---|---|---|
| Continuous overnight SpO2 | Yes: ~4 second cadence | Partial: Sampled, not continuous | Yes: Medical-grade continuous |
| ODI calculation | Yes: AASM 3% and 4% | No: Not surfaced in Health export | Yes: Gold standard |
| Minimum SpO2 + time below 88% | Yes: Both reported | No: Not in the export shape | Yes: Clinical reporting standard |
| Sleep stages | No: Not measured | Yes: Movement-based estimate | Yes: EEG, AASM scored |
| Airflow and respiratory effort | No: Not measured | No: Not measured | Yes: Essential for apnea typing |
| FDA cleared as a pulse oximeter | Yes: Viatom 510(k) for SpO2 | Yes: Series 6+ SpO2 sensor | Yes: Medical-grade equipment |
| FDA cleared to diagnose apnea | No: Not a diagnostic device | No: Notification feature only | Yes: Standard of care |
For overnight oxygen specifically, the O2 Ring is the closest consumer device to a clinical pulse oximeter. It does not provide airflow, respiratory effort, or sleep staging, so it cannot replace a sleep study. For tracking and follow-up, it is the most useful consumer signal a CPAP user can collect.
Which should you use?
you want overnight ODI and minimum SpO2 numbers your sleep physician will recognize. You already have a CPAP and want a second source of evidence on therapy effectiveness. You are screening yourself and want a real oximetry signal.
you already wear one daily. You value sleep stages alongside spot SpO2. You want Apple's sleep apnea notification feature on Series 9 and later. You do not need overnight ODI as a primary metric.
you suspect untreated sleep apnea and need a diagnosis. Home oximetry is flagging a problem and you want medical-grade confirmation. Your physician needs the full airflow and respiratory-effort picture for a treatment decision.
What an abnormal night might look like
Representative example. Numbers below are illustrative, not a real user's data.
In a representative concerning night, the O2 Ring CSV might score ODI3 of 18.4 events per hour and ODI4 of 9.2 events per hour, with mean SpO2 of 93 percent, minimum SpO2 of 81 percent, and 22 minutes spent below 88 percent across a 7 hour 18 minute recording. The CPAP side of the same night might show AHI 2.1, median leak 5 L/min, and a 6 hour 50 minute usage block.
In this illustrative scenario, the two streams tell different stories. The CPAP scored a quiet night by its own metric (AHI under 5), but the oxygen channel did not. ODI3 of 18.4 sits in the moderate range under the AASM tiering, the minimum SpO2 of 81 percent is below the threshold most clinicians flag, and the 22 minutes below 88 percent is the line CMS uses for supplemental oxygen consideration. That kind of CPAP-clean / oxygen-abnormal split usually points at residual flow limitation the CPAP is not scoring, central events that are blocking airflow without triggering an obstructive label, or REM-clustered events the AHI denominator dilutes.
None of those numbers prove anything on their own. A persistent multi-week pattern of high ODI on clean-AHI CPAP nights is the kind of signal worth bringing to a sleep physician. A single night with an oximeter cap that slipped is not. Look for the pattern across at least two weeks of recordings before drawing conclusions.
How to import your O2 Ring data
Record an overnight session on your ring
Wear the O2 Ring as you normally do. Keep the ring on for the full night so the recording covers the full window. The ring auto-starts when worn.
Export the night as a CSV from ViHealth
Open the ViHealth app on your phone, tap the night you want, then tap Share, then CSV. The app emails or AirDrops the file to your computer.
Drop the CSV onto CPAP Clarity
Open the Oxygen page at /oximeter and drop the CSV onto the import card. The whole parse runs in your browser. Nothing leaves your device.
Frequently Asked Questions
Can the Wellue O2 Ring screen for sleep apnea?
Overnight pulse oximetry has a long, validated history as a sleep apnea screening tool. A 2015 BMC Pulmonary Medicine study by Hang et al. reported about 87 to 90 percent sensitivity and 86 to 93 percent specificity for detecting moderate-to-severe OSA using ODI. The O2 Ring records the raw signal that ODI is calculated from. It is not a diagnostic device, and a clean ODI does not rule apnea out, but a high ODI is a meaningful signal to bring to a sleep physician along with a STOP-BANG score.
What is the difference between ODI 3% and ODI 4%?
Both numbers count oxygen desaturations per hour. The 3% rule counts every SpO2 drop of at least 3 percent that lasts at least 10 seconds; the 4% rule requires a 4 percent drop instead. The AASM recommends the 3% threshold; most US clinics still report the 4% value because Medicare's hypopnea definition uses 4%. CPAP Clarity computes both. Your number will look higher under the 3% rule because more events qualify.
Which Wellue model does CPAP Clarity support?
All four current shapes: the O2 Ring (6-column CSV from ViHealth), OxySmart (3-column fingertip clip CSV), O2Ring S (6-column with 12-hour AM/PM timestamps), and O2Ring 5103 (4-column with day-first European date format). The parser auto-detects the CSV shape from the header row. The math is identical across models; only the file format varies.
Why does my ViHealth ODI differ from CPAP Clarity's ODI?
ViHealth uses a fixed baseline window and does not subtract motion-saturated time from the denominator. CPAP Clarity follows the AASM 2018 manual: baseline is the peak SpO2 in the prior 120 seconds, the baseline freezes during an in-progress desaturation, and the denominator excludes motion gaps longer than 60 seconds. The two values usually agree within a couple of events per hour. CPAP Clarity's number matches what an OSCAR-style scoring of the same CSV produces.
Is my pulse oximetry data shared with anyone when I import it?
No. The CSV is parsed entirely in your browser. CPAP Clarity does not upload your SpO2 data to any server. Your readings are stored only in your browser's local IndexedDB, on the device you imported from. Clearing your browser data, or using the data hub at /data, removes them.
How is overnight ring pulse oximetry different from a sleep study?
A sleep study (in-lab polysomnography or a Type III home sleep test) uses a medical-grade pulse oximeter alongside airflow, respiratory effort, EEG, and EMG sensors. Sleep stages are clinically scored from EEG. The O2 Ring records only the oxygen and pulse channel. It is excellent at catching the desaturation pattern that goes with obstructive apnea, but it cannot stage your sleep or count specific apnea types. Use it as a screening or trend tool, not as a substitute for a study.
Primary Sources
- American Academy of Sleep Medicine, hypopnea scoring criteria update. Recommends 3% desaturation threshold; accepts 4% as alternative.aasm.org
- Hang et al., 2015. Validation of overnight oximetry to diagnose patients with moderate to severe obstructive sleep apnea.BMC Pulmonary Medicine
- American Academy of Sleep Medicine, 2018. Consumer Sleep Technology: An AASM Position Statement.Journal of Clinical Sleep Medicine
- Berry et al., 2012. Rules for Scoring Respiratory Events in Sleep: Update of the 2007 AASM Manual. The peer-reviewed paper behind the desaturation, hypopnea, and ODI scoring rules CPAP Clarity follows.Journal of Clinical Sleep Medicine
Related Reading
- Pulse Oximeter for CPAP: What the O2 Ring Adds: the full walkthrough of overnight oximetry alongside CPAP data.
- AHI and ODI: How the Two Metrics Relate: why a normal AHI can hide an abnormal ODI and vice versa.
- Oura Ring for Sleep Apnea: how the autonomic signals from Oura complement the oxygen signal from the O2 Ring.
- Apple Watch with CPAP: where Apple's SpO2 sits between sample-based wrist readings and continuous ring oximetry.