Pendelluft detection by acoustic interferometry through an endotracheal tube

A respiratory monitoring method, comprising, with an electronic controller:

• analyzing an audio signal triggered during inspiratory and expiratory phases of a patient receiving mechanical ventilation therapy from a mechanical ventilator, the audio signal being acoustically coupled into the airway of the patient, to determine resonant frequencies of the airway;
• determining a shift between a resonant frequency at the inspiratory phase and a resonant frequency at the expiratory phase;
• and
• if there is a diminishment of the shift between the resonant frequency at the inspiratory phase and the resonant frequency at the expiratory phase, outputting an indication of the presence of pendelluft inside of a lung of the patient.

A respiratory monitoring device comprising an electronic controller configured to:

• analyze an audio signal triggered during inspiratory and expiratory phases of a patient receiving mechanical ventilation therapy from a mechanical ventilator, the audio signal being acoustically coupled into the airway of the patient, to determine resonant frequencies of the airway;
• determine a shift between a resonant frequency at the inspiratory phase and a resonant frequency at the expiratory phase;
• detect a presence of pendelluft inside of a lung of the patient as a diminishment of the shift between the resonant frequency at the inspiratory phase and the resonant frequency at the expiratory phase;
• and
• output an indication of the presence of pendelluft.