CPAP pressure: what the values mean

This page explains terms. It is not a guide to changing your therapy pressure and does not replace medical advice. If you have trouble with your therapy, talk to your doctor, sleep lab or provider.

The unit: cm H₂O

Pressure is stated in centimetres of water (cm H₂O); 1 cm H₂O is roughly 1 hPa. Devices such as the ResMed AirSense 10 operate technically in the range of 4 to 20 cm H₂O.

Fixed pressure or pressure range

• CPAP: the device works with one fixed pressure set by your doctor.
• Auto-CPAP(e.g. AirSense 10 AutoSet): your doctor sets a minimum and a maximum pressure; the device adjusts within this range.
• Bilevel/BiPAP: two pressure levels for inhalation and exhalation – see CPAP or BiPAP?

What you can adjust – and what you cannot

The AirSense 10 user guide makes a clear distinction:

• For users, in the “My Options” menu: ramp (off, 5–45 minutes or auto), humidity level, mask fit test, airplane mode.
• Only by your provider or doctor: therapy pressure, pressure range, therapy mode and functions such as EPR or SmartStart that are enabled for you.

The ramp is a comfort function: the device starts at a lower pressure and slowly increases it to the prescribed value. It does not change the therapy pressure itself.

When should you talk to your doctor?

For example if the pressure feels uncomfortable, if the mask leaks often, if your mouth or nose dries out a lot, or if you do not feel rested despite therapy. Whether and how the settings are changed is up to your doctor.

Technical check of the device

Whether a device generates the set pressure correctly can be measured. At Desstronic we check pressure and flow with a manometer and flow meter – on every used device and through our CPAP service. Tested devices are in our CPAP category.

Frequently asked questions

We do not replace medical advice. Only change therapy pressure and settings as prescribed by your doctor.