The patented dual colour sliders on the Asmaplan Plus define the management colour zones set by the healthcare professional for the asthmatic to follow.

100% is the asthmatics best. They yellow zone will typically be set to start at 80% of the astmatics best while the red zone will typically start at 60%.

Variability of PEF of greater than 20% should aler the asthmatic to a possible asthma attack.