A manual input-output device in a breathing apparatus, such as an anesthesia system, has a manual input for adjusting at least one patient critical operating parameter of the breathing apparatus. The manual input-output device is programmable for a haptic feedback and has an operating member for the manual input and a manual output, a detecting unit that detects a movement of the operating member, and a haptic feedback unit that applies a mechanical output to the operating member depending on the movement detected. The manual input-output device can be used for adjusting an opening pressure level of an adjustable pressure limiting (APL) valve.