A respiratory treatment apparatus for cycling synchronized respiratory pressure treatment, the apparatus comprising: a patient interface to direct a breathable gas; a flow generator coupled with the patient interface to generate the breathable gas in inspiratory and expiratory pressure cycles through the patient interface; a flow sensor to provide a signal indicative of flow through the patient interface; a processor, coupled with the flow generator and the flow sensor, characterized in that the processor configured to control: cycling from an inspiratory pressure to an expiratory pressure over a first plurality of cycles, wherein an associated cycling time for the cycling from the inspiratory pressure to the expiratory pressure is based on first cycling criteria; determining values of second cycling criteria during the control of the first plurality of cycles; and cycling from an inspiratory pressure to an expiratory pressure over a second plurality of cycles subsequent to the first plurality of cycles, wherein an associated cycling time for the cycling from the inspiratory pressure to the expiratory pressure is based on the second cycling criteria, the second cycling criteria being different from the first cycling criteria and being initiated for operation subsequent to the first plurality of cycles, wherein the first cycling criteria comprise: comparing an instantaneous patient flow measure to a threshold, or comparing an instantaneous pressure to a pressure threshold, and wherein the second cycling criteria is based on determined respiratory mechanics, wherein the respiratory mechanics is based on data measured during the first plurality of cycles. a patient interface to direct a breathable gas; a flow generator coupled with the patient interface to generate the breathable gas in inspiratory and expiratory pressure cycles through the patient interface; a flow sensor to provide a signal indicative of flow through the patient interface; a processor, coupled with the flow generator and the flow sensor, characterized in that the processor configured to control: cycling from an inspiratory pressure to an expiratory pressure over a first plurality of cycles, wherein an associated cycling time for the cycling from the inspiratory pressure to the expiratory pressure is based on first cycling criteria; determining values of second cycling criteria during the control of the first plurality of cycles; and cycling from an inspiratory pressure to an expiratory pressure over a second plurality of cycles subsequent to the first plurality of cycles, wherein an associated cycling time for the cycling from the inspiratory pressure to the expiratory pressure is based on the second cycling criteria, the second cycling criteria being different from the first cycling criteria and being initiated for operation subsequent to the first plurality of cycles, wherein the first cycling criteria comprise: comparing an instantaneous patient flow measure to a threshold, or comparing an instantaneous pressure to a pressure threshold, and wherein the second cycling criteria is based on determined respiratory mechanics, wherein the respiratory mechanics is based on data measured during the first plurality of cycles. cycling from an inspiratory pressure to an expiratory pressure over a first plurality of cycles, wherein an associated cycling time for the cycling from the inspiratory pressure to the expiratory pressure is based on first cycling criteria; determining values of second cycling criteria during the control of the first plurality of cycles; and cycling from an inspiratory pressure to an expiratory pressure over a second plurality of cycles subsequent to the first plurality of cycles, wherein an associated cycling time for the cycling from the inspiratory pressure to the expiratory pressure is based on the second cycling criteria, the second cycling criteria being different from the first cycling criteria and being initiated for operation subsequent to the first plurality of cycles, wherein the first cycling criteria comprise: comparing an instantaneous patient flow measure to a threshold, or comparing an instantaneous pressure to a pressure threshold, and wherein the second cycling criteria is based on determined respiratory mechanics, wherein the respiratory mechanics is based on data measured during the first plurality of cycles.