How to Read Your O2Ring Overnight Report
What mean SpO2, lowest reading, ODI, T90 and heart rate mean on an O2Ring overnight report, and what to check before you trust them.
After a night with the ring, ViHealth gives you a chart and a handful of numbers. Here's what each number counts and what to check before you trust it. SleepU and Checkme O2 Max use the same app, so this applies to them too.
One thing first: home oximetry is not a sleep study. A sleep study records airflow, breathing effort and brain activity as well as oxygen.
What is mean SpO2?
It's your average blood oxygen (SpO2) across the whole recording.
A night is thousands of readings, so a few dozen dips barely move the average. Two very different nights can share the same mean. Use it as a check on the recording. If it's far from your usual figure, look at the chart for a loose ring first.
What is the lowest reading?
It's the single lowest SpO2 value of the night, sometimes called the nadir.
It's one reading out of thousands, so one squashed finger can set it. Find it on the chart before you believe it.
- A real low sits at the bottom of a smooth curve down and back up.
- A sensor error is a sudden spike, often with motion next to it.
What is ODI?
It's the number of times per hour your oxygen dipped and recovered. Most reports count drops of 3% or more, and some count 4%, which gives a lower number for the same night. Only compare numbers that use the same threshold.
The ODI post covers the 5, 15 and 30 lines you'll see quoted and where they come from. The rules for a single dip are in what counts as an oxygen dip.
What is T90?
It's the share of the recording your SpO2 spent below 90%. Some reports show it in minutes.
ODI counts how often you dipped. T90 measures how long you stayed low. Read them together, and see what is T90 for the detail.
Altitude changes T90 for everyone. Don't compare a night in the mountains, or readings from a flight, with a night at home.
What do the heart rate numbers mean?
Your pulse comes from the same sensor at the same moment as your oxygen. Compare it with your own usual figure, not with anyone else's. There's more in overnight heart rate and CVHR.
What should you check before trusting a night?
- Check the recording first. Long gaps, a short night or lots of motion mean you're reading the fit of the ring. See why your O2Ring data has gaps.
- Don't act on one night. Here's how many nights to record before you compare.
- Change one thing at a time. Then compare like with like.
- Take the trend to your doctor. A few weeks with notes is more use than one screenshot. Here's how to share it.
See a doctor if you snore loudly, someone has heard you stop breathing or gasp, or you're exhausted during the day.
How do you see more than one night?
ViHealth shows one night at a time.
- To put two nights next to each other, use the free compare tool.
- To open one exported file without an account, use the session viewer.
- To bring your old nights across, read moving from ViHealth.
Using a different model? See SleepU tips or Checkme O2 Max tips.
Not a medical device. Does not diagnose, treat or prevent any condition. Discuss results and changes with a clinician.