Detection of ventilation sufficiency

Patent metadata

Field	Value
Publication number	US-10342939-B2
Application number	US-201214006772-A
Country	US
Kind code	B2
Filing date	Mar 15, 2012
Priority date	Mar 23, 2011
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

Automated methods provide a ventilation sufficiency assessment to evaluate patient respiration. In some embodiments, a ventilation histogram maybe determined from a measure of patient respiratory flow. Based on the histogram or associated ventilation data, hypoventilation or hyperventilation occurrences may be detected. For example, a kurtosis index and/or skewness index may be calculated with the data associated with the ventilation histogram and may be evaluated as an indication of hypoventilation or hyperventilation. An assessment of the number of peaks and other features of the ventilation histogram, such as in the case of a bimodal ventilation histogram, may be implemented to detect an occurrence of ventilation insufficiency or sufficiency. The detection methodologies may be implemented by a specific purpose computer, a detection device that measures a respiratory airflow or a respiratory treatment apparatus that provides a respiratory treatment regime based on the detected ventilation sufficiency.

First claim

The invention claimed is:

1. A method for controlling a processor to assess sufficiency of ventilation from a measured flow of breathable gas, the method comprising:
measuring, by way of a sensor, a flow of breathable gas representative of patient respiration;
deriving measures of ventilation from the measure of flow;
determining, with a processor, a histogram including the measures of ventilation, wherein the measures are volumes of breathable gas measured over a time interval; and
evaluating the histogram in the processor and, based on the evaluation, outputting an indication of occurrence of hypoventilation.

2. The method of claim 1 further comprising displaying a graph of the histogram on a visual display device.

3. The method of claim 1 wherein the histogram represents a frequency distribution of ventilation values taken over the course of a treatment session, each ventilation value comprising a measure of volume over a time interval, the time interval being shorter than the time of the treatment session.

4. The method of claim 3 wherein the time interval is on an order of a minute and the time of the treatment session is on an order of hours.

5. The method of claim 1 further comprising:
processing, in the processor, data associated with the histogram to calculate a skewness index;
comparing the skewness index to a threshold; and
indicating hypoventilation based on the comparison.

6. The method of claim 1 further comprising:
processing, in the processor, data associated with the histogram to detect a number of peaks of the histogram; and
indicating a presence or absence of hypoventilation based on the number of detected peaks.

7. The method of claim 1 further comprising:
processing, in the processor, data associated with the histogram to determine a kurtosis index;
comparing the kurtosis index to a threshold; and
indicating a presence or absence of hypoventilation based on the comparison.

8. The method of claim 1 further comprising controlling, with the processor, measuring of the flow of breathable gas, wherein the sensor is a flow sensor.

9. The method of claim 1 further comprising processing data representing the histogram to generate a hypoventilation indicator, the indicator representing an occurrence of an event of hypoventilation.

10. The method of claim 9 wherein the hypoventilation indicator comprises a probability value.

11. The method of claim 9 wherein the processing comprises a detection of peaks of the histogram.

12. The method of claim 11 wherein the processing comprises calculating a distance between peaks of the histogram and transforming the distance into a probability space.

13. The method of claim 11 wherein the processing comprises calculating a gradient between peaks of the histogram.

14. The method of claim 13 wherein the processing comprises calculating an area with respect to the gradient and transforming the area into a probability space.

15. The method of claim 9 wherein the processing comprises calculating a set of features of the histogram and generating the indicator based on an evaluation of the set of features.

16. The method of claim 15 wherein the set of features comprises two or more of the following features: a gradient between two largest peaks, a gradient between a largest peak and a center point, a gradient between a second largest peak and a center point, an area between two largest peaks, an area between a largest peak and a center point, an area between a second largest peak and a center point, a shape feature, kurtosis value and skewness value.

17. The method of claim 1 further comprising determining a measure of leak and distinguishing measures of ventilation for the histogram based on the measure of leak.

18. The method of claim 1 further comprising determining a measure of ventilation stability and distinguishing measures of ventilation for the histogram based on the measure of stability.

19. The method of claim 18 wherein the determining the measure of ventilation stability comprises any of one or more of a detection of an awake period, an apnea event, a periodic breathing event and an arousal event.

20. The method of claim 1 further comprising processing data representing the histogram to generate a hyperventilation indicator, the indicator representing an occurrence of an event of hyperventilation.

21. The method of claim 1 wherein the method further comprises, based on the evaluating, changing an operational parameter of a respiratory treatment apparatus assisting the patient's respiration.

22. A method for controlling a processor to assess sufficiency of ventilation from a measured flow of breathable gas, the method comprising:
measuring, by way of a sensor, a flow of breathable gas representative of patient respiration;
deriving measures of ventilation from the measure of flow;
determining, with a processor, a histogram including the measures of ventilation, wherein the measures are volumes of breathable gas measured over a time interval; and
evaluating the histogram in the processor and, based on the evaluation, outputting an indication of occurrence of hyperventilation,
wherein the method comprises:
processing, in the processor, data associated with the histogram to calculate a skewness index;
comparing the skewness index to a threshold, and
indicating hyperventilation based on the comparison.

23. A ventilation assessment apparatus comprising:
a flow sensor configured to measure a flow of breathable gas, and
a controller having at least one processor to access data representing a measured flow of breathable gas attributable to patient respiration obtained from the flow sensor, the controller being further configured to (a) control measuring of the flow of breathable gas with the flow sensor, (b) derive measures of ventilation from the measure of flow, (c) determine a histogram of the measures of ventilation, wherein the measures are volumes of breathable gas measured over a time interval and (d) evaluate the histogram in the processor and, based on the evaluation, output an indication of occurrence of hypoventilation.

24. The apparatus of claim 23 wherein the controller is further configured to display a graph of the histogram on a visual display device.

25. The apparatus of claim 23 wherein the histogram represents a frequency distribution of ventilation values taken over the course of a treatment session, each ventilation value comprising a measure of volume over a time interval, the time interval being shorter than the time of the treatment session.

26. The apparatus of claim 25 wherein the time interval is on an order of a minute and the time of the treatment session is on an order of hours.

27. The apparatus of claim 23 wherein the controller is further configured to:
process data associated with the histogram to calculate a skewness index;
compare the skewness index to a threshold; and
indicate an occurrence of hypoventilation based on the comparison.

28. The apparatus of claim 23 wherein the controller is further configured to:
process data associated with the histogram to detect a number of peaks of the histogram; and
indicate a presence or absence of hypoventilation based on the number of detected peaks.

29. The apparatus of claim 23 wherein the controller is further configured to:
process data associated

Assignees

• Armitstead Jeffrey Peter
• Ramanan Dinesh
• ResMed Pty Ltd

Inventors

• Armitstead Jeffrey Peter
• Ramanan Dinesh

Classifications

• A61B5/7264

  Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems · CPC title

• A61M2205/15

  Detection of leaks · CPC title

• A61M2016/0027

  pressure meter · CPC title

• A61M16/0057

  Pumps therefor · CPC title

• A61M2205/18

  with alarm · CPC title