Inspiratory airway pressure system using constant pressure and measuring flow signals to determine airway patency

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 patient respiration flows being maintained under substantially constant pressure during a patient inhalation phase and for producing flow signals representative thereof;
• using signal processing means for receiving said flow signals and responding thereto for determining a set of patient airway patency values from said flow signals in view of said pressure of breathable gas delivered by said means for supplying and storing patient airway patency data representative of said set of patient airway patency values in a memory device, and using said signal processing means for determining said patient airway patency values from said flow signals;
• comparing in said signal processing means said patient airway patency data with predetermined airway patency templates stored in said memory device;
• and
• determining in said signal processing means the closest match of said airway patency templates with said patient airway patency data, said closest match being representative of patient airway patency during said phase.

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

• means for repeatedly sensing a plurality of patient respiration flows being maintained under substantially constant pressure and for producing flow signals representative thereof;
• signal processing means for receiving said flow signals and for determining a set of patient airway patency values from said flow signals in view of said pressure being maintained substantially constant;
• and
• memory means for storing a plurality of airway patency templates representative of a plurality of predetermined airway patency data arrays,
• said signal processing means including means for determining which of said airway patency templates presents the closest matching airway patency to said set of patient airway patency values, the matching airway patency template being representative of the patient's airway patency.

An apparatus for the treatment of obstructive sleep apnea in a patient having an airway, the apparatus comprising:

• a source of breathable gas;
• means for maintaining an inspiratory gas flow from said source to a patient airway, and for maintaining a relatively constant pressure at the airway;
• means for generating inspiratory flow signals representative of the inspiratory gas flow to the airway in view of said pressure being maintained relatively constant;
• means for comparing the inspiratory flow signals to a template of flow values representative of an obstruction in the airway;
• and
• means for adjusting the pressure at the airway, wherein the pressure is increased when comparing the inspiratory flow signals to the template of flow values indicates patient airway obstruction, and wherein the pressure is decreased when comparing the inspiratory flow signals to the template of flow values does not indicate patient airway obstruction.

A method for controlling the positive airway pressure to a patient, the method comprising the steps of:

• generating inspiratory flow signals representative of the inspiratory airflow to a patient when the change in airway pressure is sensed to be approximately zero;
• comparing the inspiratory flow signals to a template of flow values representative of patient airflow obstruction in view of the change in said pressure being sensed to be approximately zero;
• increasing the airway pressure when the comparison of the inspiratory flow signals to the template of flow values indicates patient airway obstruction;
• and
• decreasing the airway pressure when the comparison of the inspiratory flow signals to the template of flow values does not indicate patient airway obstruction.

A method of determining the airway patency of a patient, the patient exhibiting a breath cycle having an inhalation phase of substantially constant airway pressure, the method comprising:

• sensing a plurality of patient respiration flows during a patient inhalation phase;
• generating flow signals representative of the patient respiration flows when the change in airway pressure is sensed to be about zero;
• determining patient airway patency values from said flow signals;
• comparing the patient airway patency values with predetermined patient airway patency templates in view of the change in said pressure being sensed to be about zero;
• and
• determining the template having the best fit with the patient airway patency values, wherein the template having the best fit is representative of patient airway patency during the patient inhalation phase.