Medical ventilator designed for the implementation of assisted ventilation during cardiopulmonary resuscitation of a patient, comprising: - a gas source, - a ventilatory circuit comprising an inspiratory branch supplied with gas via the gas source, and an expiratory branch, which are both connected to a junction piece, - a respiratory interface connected to the junction piece and in fluidic communication with the ventilatory circuit, - control means with microprocessor, - CO 2 measurement means (20, 21) configured to carry out successive measurements of CO 2 content in the gas flow and provide said CO 2 content measurements to the control means, said control means processing said CO 2 content measurements, and - display means controlled by said control means, and wherein: - the control means are also configured to: i) process at least some of the CO 2 content values so as to establish at least one diagnosis of the ventilatory status of the patient chosen from closure of the airways, thoracic distension and target ventilation, and ii) order display of said at least one ventilatory status diagnosis on the display means, - and the display means are configured to display said at least one ventilatory status diagnosis, and wherein: - the gas source comprises a motorized turbine controlled by the control means, and characterized in that: - the control means are also configured to: i) determine at least one recommendation of action to be taken by the medical personnel as a function of said at least one ventilatory status diagnosis, and ii) order display of said at least one recommendation of action to be taken on the display means, and - the display means are configured to display said at least one recommendation of action to be taken. - a gas source, - a ventilatory circuit comprising an inspiratory branch supplied with gas via the gas source, and an expiratory branch, which are both connected to a junction piece, - a respiratory interface connected to the junction piece and in fluidic communication with the ventilatory circuit, - control means with microprocessor, - CO 2 measurement means (20, 21) configured to carry out successive measurements of CO 2 content in the gas flow and provide said CO 2 content measurements to the control means, said control means processing said CO 2 content measurements, and - display means controlled by said control means, - the control means are also configured to: i) process at least some of the CO 2 content values so as to establish at least one diagnosis of the ventilatory status of the patient chosen from closure of the airways, thoracic distension and target ventilation, and ii) order display of said at least one ventilatory status diagnosis on the display means, i) process at least some of the CO 2 content values so as to establish at least one diagnosis of the ventilatory status of the patient chosen from closure of the airways, thoracic distension and target ventilation, and ii) order display of said at least one ventilatory status diagnosis on the display means, - and the display means are configured to display said at least one ventilatory status diagnosis, and wherein: - the gas source comprises a motorized turbine controlled by the control means, and characterized in that: - the control means are also configured to: i) determine at least one recommendation of action to be taken by the medical personnel as a function of said at least one ventilatory status diagnosis, and ii) order display of said at least one recommendation of action to be taken on the display means, and - the display means are configured to display said at least one recommendation of action to be taken. - the control means are also configured to: i) determine at least one recommendation of action to be taken by the medical personnel as a function of said at least one ventilatory status diagnosis, and ii) order display of said at least one recommendation of action to be taken on the display means, and i) determine at least one recommendation of action to be taken by the medical personnel as a function of said at least one ventilatory status diagnosis, and ii) order display of said at least one recommendation of action to be taken on the display means, and - the display means are configured to display said at least one recommendation of action to be taken.