Method and apparatus for detection and diagnosis of airway obstruction degree

A method of determining the airway impedance or degree of airway obstruction of a patient comprising the steps of:

• supplying breathable gas to the patient's airways with an interface;
• applying a selected audio-frequency oscillation component to a pressure of the breathable gas;
• sampling pressure and flow of the breathable gas in the interface to obtain pressure and flow data characteristic of the patient's airway;
• converting the sampled pressure and flow data to the frequency domain;
• processing the converted pressure and flow data to eliminate data having indicia of unreliability;
• and
• obtaining a mathematical function of the processed pressure and flow data to determine an index of airway impedance or degree of airway obstruction.

A method of determining the airway impedance or degree of airway obstruction of a patient comprising the steps of:

• supplying breathable gas to the patient's airways with an interface;
• applying a selected audio frequency oscillation component of a selected frequency to the breathable gas;
• measuring pressure and flow of the breathable gas in the interface to obtain pressure and flow data characteristic of the patient's airway;
• converting the pressure and flow data to the frequency domain;
• discarding converted pressure and flow data that have indicia of inaccuracy;
• and
• dividing the pressure data by the corresponding flow data to obtain an airway impedance or degree of airway obstruction value;
• and
• obtaining a mean impedance or degree of airway obstruction from the airway impedance or degree of airway obstruction values.

An apparatus for determining the airway impedance or degree of airway obstruction of a patient comprising:

• an interface adapted to be coupled to the patient's airways to supply a breathable gas;
• means for applying a selected audio-frequency oscillation component to a pressure of the breathable gas;
• at least one sensor in the interface to measure pressure and flow of the breathable gas in the interface and obtain pressure and flow data characteristic of the patient's airway;
• and
• a processor coupled to the sensor to convert the pressure and flow data to the frequency domain and to obtain a mathematical function of the processed pressure and flow data to determine an index of airway impedance or degree of airway obstruction.