# US 12,214,125 B2 · Distinguishing between central and obstructive sleep apnea

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- Number: US 12,214,125 B2
- Document ID: US12214125B2
- Status: Granted
- Kind: B2
- Application number: 17/303,161
- Filed: 2021-05-21
- Published: 2021-11-04
- Granted: 2025-02-04
- Earliest claimed: 2013-04-17
- Assignees: Fisher & Paykel Healthcare Limited
- Applicants: Fisher & Paykel Healthcare Limited
- Inventors: David Robin Whiting; Amol Man Malla; Simei Gomes Wysoski
- Web page: https://patentgrep.com/patent/US12214125B2

## CPC

- A61M 16/0069: {the speed thereof being controlled by respiratory parameters, e.g. by inhalation}
- A61B 5/087: Measuring breath flow
- A61B 5/4818: {Sleep apnoea}
- A61B 5/4836: {Diagnosis combined with treatment in closed-loop systems or methods (A61B5/0036 takes precedence)}
- A61B 5/7267: {involving training the classification device}
- 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}
- A61M 2016/0027: {pressure meter}
- A61M 2016/003: {with a flowmeter}
- A61M 2016/0036: {in the breathing tube and used in both inspiratory and expiratory phase}
- A61M 2205/3303: Using a biosensor
- A61M 2205/3334: Measuring or controlling the flow rate
- A61M 2205/50: with microprocessors or computers
- A61M 2230/40: Respiratory characteristics
- G16H 50/70: for mining of medical data, e.g. analysing previous cases of other patients
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA

## Abstract

Apparatuses and methods for detecting sleep apnea and classifying the events as obstructive sleep apnea (OSA) and/or central sleep apnea (CSA) are disclosed herein. The apparatuses can include respiratory treatment devices that have an auto adjusting algorithm that is able to classify a sleep apnea as CSA or OSA so that an appropriate pressure can be applied to the patient depending on the type of sleep apnea detected. The apparatuses and methods can use characteristics of at least one breath preceding the apnea event in classifying the event.

## Claims

### Claim 1

A respiratory apparatus comprising:
a pressure or flow sensor for detecting a sensed breath, and
a control system configured to:
analyze one or more apnea features to make a determination whether a detected apnea event is obstructive sleep apnea or central sleep apnea,
wherein the one or more apnea features is derived from the sensed breath by calculating one or more statistical metrics of one or more breath features within one or more predefined breath-windows, each comprising a number of breaths preceding the detected apnea event.

### Claim 2 (depends on 1)

The respiratory apparatus of claim 1, wherein the one or more breath features are normalized by dividing the one or more breath features with a corresponding breath feature of a standard breath.

### Claim 3 (depends on 2)

The respiratory apparatus of claim 2, wherein the standard breath is a sinusoidal representation of average breath features derived from a local breath-window.

### Claim 4 (depends on 3)

The respiratory apparatus of claim 3, wherein the standard breath is derived by fitting two respective sinusoids to average inspiration and expiration measures of breaths in the local breath-window.

### Claim 5 (depends on 4)

The respiratory apparatus of claim 4, wherein the two respective sinusoids can be derived from one or more of: 1) mean of maximum flow, 2) mean duration of inspiration, 3) mean minimum flow, and 4) mean total breath duration over the local breath-window.

### Claim 6 (depends on 5)

The respiratory apparatus of claim 5, wherein the control system makes the determination by using a trained classifier.

### Claim 7 (depends on 6)

The respiratory apparatus of claim 6, wherein the trained classifier uses a simple logistics model.

### Claim 8 (depends on 6)

The respiratory apparatus of claim 6, wherein the trained classifier uses a logistics model.

### Claim 9 (depends on 6)

The respiratory apparatus of claim 6, wherein the trained classifier uses one or more of a neural network model, logistics model, multiple perception model or support vector machine.

### Claim 10 (depends on 6)

The respiratory apparatus of claim 6, wherein the control system classifies the detected apnea event by determining a probability distribution and comparing the probability distribution to a threshold value.

### Claim 11 (depends on 1)

The respiratory apparatus of claim 1 wherein the determination is made during the detected apnea event.

### Claim 12 (depends on 1)

The respiratory apparatus of claim 1, wherein the control system:
in response to the control system classifying the apnea event as an obstructive sleep apnea, increases a pressure provided by the apparatus; and
in response to the control system classifying the apnea event as a central sleep apnea, maintains or decreases the pressure provided by the apparatus.

### Claim 13

A method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea, the method comprising:
detecting a sensed breath using a pressure or flow sensor,
deriving one or more apnea features from the sensed breath by calculating one or more statistical metrics of one or more breath features within one or more predefined breath-windows, each comprising a number of breaths preceding the detected apnea event, and
analyzing the one or more apnea features to make a determination whether a detected apnea event is obstructive sleep apnea or central sleep apnea.

### Claim 14 (depends on 13)

The method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea of claim 13 further comprising:
in response to the control system classifying the apnea event as an obstructive sleep apnea, increasing a pressure output of a blower; and
in response to the control system classifying the apnea event as a central sleep apnea, maintaining or decreasing the pressure output of a blower.

### Claim 15 (depends on 13)

The method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea of claim 13 further comprising normalizing the one or more breath features by dividing the one or more breath features with a corresponding breath feature of a standard breath.

### Claim 16 (depends on 15)

The method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea of claim 15, wherein the standard breath is determined by a group of 1 to 12 pre-apnea breaths.

### Claim 17 (depends on 15)

The method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea of claim 15, wherein the standard breath is a sinusoidal representation of average breath features derived from a local breath-window.

### Claim 18 (depends on 17)

The method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea of claim 17, wherein the standard breath is derived by fitting two respective sinusoids to average inspiration and expiration measures of breaths in the local breath-window.

### Claim 19 (depends on 18)

The method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea of claim 18, wherein the two respective sinusoids can be derived from one or more of: 1) mean of maximum flow, 2) mean duration of inspiration, 3) mean minimum flow, and 4) mean total breath duration over the local breath-window.

### Claim 20 (depends on 19)

The method of determining if an apnea is an obstructive sleep apnea or a central sleep apnea of claim 19, wherein the control system makes the determination by using a trained classifier.