A system for ventilating lungs of a subject is disclosed herein. The system includes a control unit configured to control operation of the system. The system also includes a machine ventilator circuit configured to assist the breathing functions of the subject, the machine ventilator circuit includes an inspiration delivery unit, and an expiration circuit. The system also includes a manual ventilation circuit comprising a manual bag guiding a gas from the manual bag wherein a gas flow is guided out from the manual bag to assist an inspiration phase, a gas flow is received to fill the manual bag during an expiration phase, and wherein the gas flow received to fill the manual bag during the expiration phase at least partially comprises the gas flow guided to assist the inspiration phase.
