Understand your CPAP data
Your machine reports a dozen numbers every morning and explains none of them. This is what each one measures, what a normal value looks like, and what it should change about the conversation with your doctor. Written by a sleep technologist, not a marketing team.
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AHI
Apnea-Hypopnea Index
The average number of breathing events per hour of therapy. It is the single number most clinicians look at first.
Read the full definitionLeak
Mask leak rate
Air escaping around the mask or through the mouth. Past a threshold it stops your machine from detecting events reliably.
Read the full definitionCompliance
Compliance, or usage hours
How many hours per night you actually wear the mask. In Belgium it also decides whether your therapy stays reimbursed.
Read the full definitionYour settings
EPR
Expiratory Pressure Relief
A comfort setting that drops the pressure while you breathe out, by 1, 2 or 3 cmH2O.
Read the full definitionAPAP vs CPAP
Auto-adjusting versus fixed pressure
CPAP delivers one pressure all night. APAP moves within a range, following what your airway needs.
Read the full definitionReading the detail
Central apnea
Central apnea, reported as Clear Airway
A pause where your airway is open but no effort is made to breathe. It comes from the brain, not from the throat.
Read the full definitionFlow limitation
Inspiratory flow limitation
A partly narrowed airway that never closes enough to score as an event. It is the earliest visible sign of obstruction.
Read the full definition95th percentile pressure
95th percentile pressure
The pressure your machine stayed below for 95 percent of the night. The most honest single figure for what your therapy needs.
Read the full definitionSee these numbers on your own nights
Your ResMed SD card is read in your browser, and only the nights you choose to save go to your account, hosted in the European Union. Accounts are not open yet: leave your email to be among the first to get access.
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