The invention comprises a ventilation apparatus and method for operating a ventilator of a ventilator apparatus, wherein in the method at least one duration ratio factor is set in a computing system of the ventilator apparatus at least one minute volume, at least one functional dead space volume and at least one time constant are determined a respiration frequency is computed, based on a previously defined lung model, depending on said determined parameters, where said computed respiration frequency is optimized on at least one minimum of a delivered parameter, which is induced to a patient using said ventilator an inspiratory time and an expiratory time are determined based on said computed respiration frequency and said duration ratio factor at least one tidal volume based on said previously computed respiration frequency and said determined minute volume is computed and a delivered respiratory parameter of the ventilator is closed loop controlled.
