Abstract: In an artificial ventilation system and a method for controlling the artificial ventilation system for obtaining an optimized artificial ventilation of a lung system of a patient, optimal artificial ventilation is obtained when the blood system of the patient is maximally oxygenated and, at the same time, the negative influence on the cardio-pulmonary system is minimized. The ventilation system has a gas delivery unit for delivering controllable inspiration pulses to a patient, a monitoring unit for measuring at least one parameter related to the function of the lung system, such as a blood gas analyser, and a control unit for determining an optimal peak inspiratory pressure and pressure amplitude for the inspiration pulse based on the measured blood gas parameter.