Respiratory assistance device comprising a gas circuit (2, 16) designed to transport a gas flow, in particular an air flow, comprising: - measurement means arranged to measure at least one parameter representative of the gas flow transported by said gas circuit (2, 16), in particular an inspiratory branch of said gas circuit (2, 16), and configured to convert said at least one parameter representative of said gas flow into at least one signal representative of said gas flow, - signal processing means capable of and designed to process said at least one signal representative of the gas flow provided by the measurement means, and to deduct from this, at least one item of information relating to the carrying out or the non-carrying out of a cardiac massage on a patient, - ventilatory mode memorisation means configured to memorise several ventilatory modes, comprising at least: i) one first ventilatory mode corresponding to a carrying out of a cardiac massage and ii) one second ventilatory mode corresponding to a non-carrying out or a stopping of a cardiac massage, and - ventilatory mode selection means making it possible to select and apply the first or the second memorised ventilatory mode, according to said at least one item of information provided by the signal processing means or by activation by a user of adjustment and selection means, characterised in that: a) the ventilatory mode memorisation means are configured to memorise: - a first ventilatory mode comprising values of first low pressure, of first high pressure, with PH1>PB1 and of first data frequency, and - a second ventilatory mode comprising values of second low pressure, of second high pressure, with PH2>PB2 and PH2≥PH1, and of second data frequency, with F2>F1, and b) the ventilatory mode selection means are designed to actuate a changeover of the first ventilatory mode to the second ventilatory mode, or conversely, so as to modify the high pressure (PH1, PH2) and the frequency (F1, F2) in response to a detection of at least one item of information relating to an absence of a stopping of thoracic contractions or, conversely, a presence of thoracic contractions, or an activation by the user of the adjustment and selection means. - measurement means arranged to measure at least one parameter representative of the gas flow transported by said gas circuit (2, 16), in particular an inspiratory branch of said gas circuit (2, 16), and configured to convert said at least one parameter representative of said gas flow into at least one signal representative of said gas flow, - signal processing means capable of and designed to process said at least one signal representative of the gas flow provided by the measurement means, and to deduct from this, at least one item of information relating to the carrying out or the non-carrying out of a cardiac massage on a patient, - ventilatory mode memorisation means configured to memorise several ventilatory modes, comprising at least: i) one first ventilatory mode corresponding to a carrying out of a cardiac massage and ii) one second ventilatory mode corresponding to a non-carrying out or a stopping of a cardiac massage, and i) one first ventilatory mode corresponding to a carrying out of a cardiac massage and ii) one second ventilatory mode corresponding to a non-carrying out or a stopping of a cardiac massage, and - ventilatory mode selection means making it possible to select and apply the first or the second memorised ventilatory mode, according to said at least one item of information provided by the signal processing means or by activation by a user of adjustment and selection means, characterised in that: a) the ventilatory mode memorisation means are configured to memorise: - a first ventilatory mode comprising values of first low pressure, of first high pressure, with PH1>PB1 and of first data frequency, and - a second ventilatory mode comprising values of second low pressure, of second high pressure, with PH2>PB2 and PH2≥PH1, and of second data frequency, with F2>F1, and b) the ventilatory mode selection means are designed to actuate a changeover of the first ventilatory mode to the second ventilatory mode, or conversely, so as to modify the high pressure (PH1, PH2) and the frequency (F1, F2) in response to a detection of at least one item of information relating to an absence of a stopping of thoracic contractions or, conversely, a presence of thoracic contractions, or an activation by the user of the adjustment and selection means. a) the ventilatory mode memorisation means are configured to memorise: - a first ventilatory mode comprising values of first low pressure, of first high pressure, with PH1>PB1 and of first data frequency, and - a second ventilatory mode comprising values of second low pressure, of second high pressure, with PH2>PB2 and PH2≥PH1, and of second data frequency, with F2>F1, and - a first ventilatory mode comprising values of first low pressure, of first high pressure, with PH1>PB1 and of first data frequency, and - a second ventilatory mode comprising values of second low pressure, of second high pressure, with PH2>PB2 and PH2≥PH1, and of second data frequency, with F2>F1, and b) the ventilatory mode selection means are designed to actuate a changeover of the first ventilatory mode to the second ventilatory mode, or conversely, so as to modify the high pressure (PH1, PH2) and the frequency (F1, F2) in response to a detection of at least one item of information relating to an absence of a stopping of thoracic contractions or, conversely, a presence of thoracic contractions, or an activation by the user of the adjustment and selection means.