ODI-3 (Oxygen Desaturation Index, 3%)
The number of times per hour blood oxygen drops by 3% or more from a 2-minute rolling baseline. Each drop indicates a breathing disruption that affected oxygen levels.
What Is ODI-3 (Oxygen Desaturation Index, 3%)?
The Oxygen Desaturation Index at 3% threshold (ODI-3) counts the number of times per hour that blood oxygen (SpO2) drops by 3% or more from a 2-minute rolling baseline. Each drop represents a desaturation event, indicating a breathing disruption that was significant enough to reduce oxygen delivery to the blood.
ODI-3 is a sensitive measure of respiratory events because even partial airway obstruction that does not meet hypopnea criteria can cause measurable oxygen drops. A person with a low AHI but elevated ODI-3 may have breathing disruptions that are being missed by traditional scoring.
The 3% threshold captures a broader range of desaturation events than ODI-4 (which requires a 4% drop). This makes ODI-3 more sensitive to subtle breathing disruptions but also means it picks up some events that may be clinically less significant. AirwayLab also computes ODI-4 for comparison, as well as coupled events (where a desaturation occurs alongside a heart rate surge within 30 seconds).
Normal Ranges
How AirwayLab Measures This
The Oximetry Pipeline computes ODI-3 from Viatom/Checkme O2 Max CSV data. It maintains a 2-minute rolling baseline of SpO2 values and counts each drop of 3% or more as a desaturation event. Requires compatible pulse oximetry data uploaded alongside SD card data.
Try it with your dataFrequently Asked Questions
Do I need a pulse oximeter for AirwayLab?
No. Pulse oximetry data is optional. All four analysis engines work with SD card data alone. The oximetry pipeline activates only when you upload a Viatom/Checkme O2 Max CSV alongside your SD card data. It adds desaturation tracking, heart rate surge detection, and coupled event analysis.
What is the difference between ODI-3 and ODI-4?
ODI-3 counts oxygen drops of 3% or more per hour. ODI-4 counts drops of 4% or more. ODI-3 is more sensitive and will always be equal to or higher than ODI-4. ODI-4 uses a stricter threshold, capturing only more significant desaturations.
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Medical Disclaimer
AirwayLab is not a medical device and is not FDA-cleared or CE-marked. It is provided for educational and informational purposes only. The analysis results should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult qualified healthcare providers regarding your sleep therapy and any changes to PAP settings.