Time v Preasure Rate (Autoset)

[Sparticus]

Does anyone know if there is a set time for the preasure to increase to a set level? If a Apnea occurred during a base preasure level of 4cm and needed to climb to 12cm to stop the apnea, how long would it take? Is an autoset ruled by a set figure ie. 1cm increments = 20 second of time or is there other variables to consider like age of machine etc. I dont believe that holding ones breath is accurate enough to measure.

Any ideas would be helpfull