Detection of periodic breathing during CPAP therapy

• US 9,931,483 B2
• Filed: 05/28/2014
• Issued: 04/03/2018
• Est. Priority Date: 05/28/2014
• Status: Active Grant

• Current Assignee: 3B Medical Incorporated
• Original Assignee: DeVilbiss Healthcare LLC
• Inventors: Knepper, Michael, Thomas, Robert Joseph, Martens, Wim
• Primary Examiner(s): Ho, (Jackie) Tan-Uyen T
• Assistant Examiner(s): Boecker, Joseph D
• Application Number:
  US14/288,792
• Publication Number:
  US 20150343161A1
• Time in Patent Office: 1,406 Days
• Field of Search: None
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7253 characterised by using transforms
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: G16H 20/40 relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture
• CPC Class Codes: G16H 40/63 for local operation

Abstract

An improvement to a breathing therapy machine to detect and rate occurrences of periodic breathing and to alter the therapy delivered to a user of the device based on the rating.

Claims

1. A breathing therapy device comprising:

a blower;

a processor;

a flow sensing element, for sensing total flow of air and

said processor configured to;

collect flow data from said flow sensing element;

analyze said flow data to detect patterns of periodic breathing in a user of said device;

rate the severity of said periodic breathing, wherein rating the severity of said periodic breathing comprises configuring said processor to;

calculate a power envelope of a normalized amplitude signal representing waxing and waning cycles of said patient flow data;

calculate a signal representing a zero crossing variance of said normalized amplitude signal; and

classify the severity of said periodic breathing using said power envelope of said normalized amplitude signal and said signal representing the zero crossing variance; and

alter therapy delivered to said user based on said rated severity of said periodic breathing.

2. The breathing therapy device of claim 1 wherein said normalized amplitude signal is

a ratio of a fast moving average and a slow moving average of a power envelope of a patient flow signal derived from said flow data.

3. The breathing therapy device of claim 2 wherein said power envelope of said patient flow signal and said power envelope of said normalized amplitude are calculated using Hilbert Transforms.

4. The breathing therapy device of claim 2 wherein in order to derive said patient flow signal from said flow data said processor is further configured to:

down sample said flow data received from said flow sensing element; and

apply a high pass filter to filter out a DC component of said flow data, representing bias flow.

5. The breathing therapy device of claim 4 wherein said high pass filter is a 2nd order Butterworth filter.

6. The breathing therapy device of claim 2 wherein, in order to rate the severity of said periodic breathing, said processor is further configured to:

define ranges for said power envelope of said normalized amplitude signal and for said signal representing the zero crossing variance of said normalized amplitude signal for each category of severity;

calculate said rating as a function of time based on a membership of said power envelope of said normalized amplitude signal and said signal representing the zero crossing variance of said normalized amplitude signal in each of said categories.

7. The breathing therapy device of claim 6 wherein said membership in said categories is calculated using a statistical analysis.

8. The breathing therapy device of claim 7 wherein said statistical analysis utilizes a minimum distance estimation algorithm.

9. The breathing therapy device of claim 2 wherein altering therapy delivered to said user includes ceasing an increase in pressure when apnea events are detected.

10. The breathing therapy device of claim 2 wherein altering therapy delivered to said user includes decreasing pressure when sustained periods of periodic breathing are detected.