Automated control for detection of flow limitation
A respiratory flow limitation detection device, which can include an airway pressure treatment generator, determines a flow limitation measure 506 based one or more shape indices for detecting partial obstruction and a measure of a patient's ventilation or respiratory duty cycle. The shape indices may be based on function(s) that ascertain the likelihood of the presence of M-shaped breathing patterns and/or chair-shaped breathing patterns. The measure of ventilation may be based on analysis of current and prior tidal volumes to detect a less than normal patient ventilation. The duty cycle measure may be a ratio of current and prior measures of inspiratory time to respiratory cycle time to detect an increase in the patient's inspiratory cycle time relative to the respiratory cycle time. A pressure setting based on the flow limitation may then be used to adjust the treatment pressure to ameliorate the patient's detected flow limitation condition.
1. A method of a controller for determining a treatment setting in a respiratory treatment device, comprising:
receiving, by the controller, data representing a measure of respiratory flow obtained by a sensor;
from the data representing the measure of respiratory flow, determining a shape index representing a degree of partial obstruction;
from the data representing the measure of respiratory flow, determining a ventilation measure representing a degree of change in ventilation between a current breath and recent breath history, the degree of change in ventilation being a ratio of ventilation of the current breath to ventilation of the recent breath history;
determining a flow limitation measure based on the degree of partial obstruction and the degree of change in ventilation; and
calculating an adjustment amount to a treatment setting, the adjustment amount being a multiplication of the flow limitation measure,
wherein the controller operates the respiratory treatment device to control a treatment with the treatment setting.
2. The method of claim 1 wherein the shape index is determined from a number of breaths in a range from 1 to 3 breaths.
3. The method of claim 1 wherein the shape index is an M-shape breath index.
4. The method of claim 1 wherein the controller applies the treatment setting to set an auto-titrating respiratory treatment device.
5. The method of claim 1 wherein the treatment setting is a flow control setting.
6. The method of claim 1 wherein the treatment setting is a treatment pressure.
7. The method of claim 1 wherein the flow limitation measure is a fuzzy logic flow limitation measure derived from a fuzzy logic algorithm.
8. An apparatus for respiratory treatment comprising:
a sensor to determine a measure of respiratory flow;
a processor configured to:
(a) determine from the measure of respiratory flow a shape index representing a degree of partial obstruction,
(b) determine from the measure of respiratory flow a ventilation measure representing a degree of change in ventilation between a current breath and recent breath history, the degree of change in ventilation being a ratio of ventilation of the current breath to ventilation of the recent breath history;
(c) determine a flow limitation measure based on the degree of partial obstruction and the degree of change in ventilation; and
(d) calculate an adjustment amount to a treatment setting, the adjustment amount being a multiplication of the flow limitation measure; and
a flow generator configured to provide respiratory treatment, wherein the processor is configured to control generation of the treatment with the treatment setting.
9. The apparatus of claim 8 wherein the shape index is determined by the processor from a number of breaths in a range from 1 to 3 breaths.
10. The apparatus of claim 8 wherein the shape index is an M-shape index.
11. The apparatus of claim 8 wherein the apparatus comprises an auto-titrating respiratory treatment device.
12. The apparatus of claim 8 wherein the treatment setting is a flow control setting.
13. The apparatus of claim 12 wherein the apparatus comprises an auto-titrating respiratory treatment device.
14. The apparatus of claim 8 wherein the treatment setting is a treatment pressure.
15. The apparatus of claim 14 wherein the apparatus comprises an auto-titrating respiratory treatment device.
16. The apparatus of claim 8 wherein the flow limitation measure is a fuzzy logic flow limitation measure derived from a fuzzy logic algorithm.
17. An apparatus for respiratory treatment comprising:
means for determining a measure of respiratory flow;
means for determining a shape index representing a degree of partial obstruction from the measure of respiratory flow;
means for determining a ventilation measure representing a degree of change in ventilation between a current breath and recent breath history from the measure of respiratory flow, the degree of change in ventilation being a ratio of ventilation of the current breath to ventilation of the recent breath history;
means for determining a flow limitation measure based on the degree of partial obstruction and the degree of change in ventilation;
means for calculating an adjustment amount to a treatment setting, the adjustment amount being a multiplication of the flow limitation measure; and
means for generating and providing a respiratory treatment to a patient in response to the treatment setting adjustment amount, wherein the apparatus comprises an auto-titrating respiratory treatment device.
18. The apparatus of claim 17 wherein the flow limitation measure is a fuzzy logic flow limitation measure derived from a fuzzy logic algorithm.