Inspiratory airway pressure system with admittance determining apparatus and method

A method of determining the airway patency of a patient, the patient exhibiting a breath cycle having inhalation and exhalation phases, said method comprising:

• using sensing means for repeatedly sensing a plurality of substantially simultaneous patient respiration flows and pressures during a patient inhalation phase and for producing signals representative thereof;
• using signal processing means for receiving said signals and responding thereto for determining a set of patient admittances from said flows and pressures and storing admittance data representative of said admittance set in a memory device, and using said signal processing means for determining said admittances as the dividend of flow divided by pressure;
• comparing in said signal processing means said admittance data with predetermined admittance templates stored in said memory device;
• and
• determining in said signal processing means the closest match of said admittance templates with said admittance data, said closest match being representative of patient airway patency during said phase.

An apparatus for determining the airway patency of a patient comprising:

• means for repeatedly sensing a plurality of substantially simultaneous patient respiration flows and pressures and for producing signals representative thereof;
• signal processing means for receiving said signals and responsive thereto for determining a set of respiratory admittances from said flows and pressure, said signal processing means including means for determining each of said admittances as the dividend of flow divided by pressure;
• and
• memory means for storing a plurality of airway admittance templates representative of a plurality of predetermined airway admittances correlated with airway patency,
• said signal processing means including means for determining which of said templates presents the closest matching admittance to said admittance set, the airway patency correlated with said matching admittance being representative of the patient's airway patency.