Apparatus with automatic respiration monitoring and display

• US 7,337,778 B2
• Filed: 04/20/2005
• Issued: 03/04/2008
• Est. Priority Date: 06/16/1999
• Status: Expired due to Term

• Current Assignee: ResMed Pty Ltd. (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Smith, Jeffrey Peter, Martin, Dion Charles Chewe
• Primary Examiner(s): DeMille; Danton D.
• Assistant Examiner(s): MATTER, KRISTEN CLARETTE
• Application Number:
  US11/110,244
• Publication Number:
  US 20050178384A1
• Time in Patent Office: 1,049 Days
• Field of Search: 128/204.18, 12820421-20423, 128/204.26, 128/204.29, 345440-4402
• US Class Current: 128/204.21
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient

Abstract

A respiratory device is provided with a display showing a respiration signal related to a breathing pattern of a patient. This signal is derived from the difference between a sensed signal indicative of the respiration and airflow generated by the device and a baseline signal. The parameter is adjusted so that the respiration signal is restricted to a predetermined dynamic range. A short term average of the respiration signal (taken over about 0.5 seconds) and a long term average of respiration signals (taken over about 12 seconds) are calculated based on the CPAP measure. These averages are used to monitor the dynamic change in the respiration signal. If a large variation in either average is detected, the baseline is set to a value selected to rapidly reduce the respiration signal to a lower offset.

Claims

1. A respiratory apparatus for delivering a flow of air to a patient suffering from sleep disordered breathing comprising:

a blower that generates a flow of pressurized air;

a patient interface adapted to deliver air from said blower to the patient;

a display receiving and displaying a respiration signal and having a predetermined display range; and

a control unit coupled to said patient interface and adapted to sense a breathing parameter, said control unit including a display adjusting circuit that operates on said breathing parameter to generate a respiration signal indicative of the breathing pattern of the patient;

said control unit further deriving short-term and long-term averages of said respiration signal, said display adjusting circuit operating to adjust a baseline of said respiration signal in accordance with at least one of said long-term and short-term averages to restrict said respiration signal to said predetermined display range; and

wherein said display adjusting circuit adjusts the displayed respiration signal in accordance with said long-term average in response to one set of conditions, and adjusts the displayed respiration signal in accordance with said short-term average in response to another set of conditions.

2. A respiratory apparatus for delivering a flow of air to a patient suffering from sleep disordered breathing comprising:

a blower that generates a flow of pressurized air in accordance with a control signal;

a patient interface adapted to deliver air from said blower to the patient;

a display having a predetermined display range for displaying a respiration signal indicative of the breathing of the patient; and

a control unit coupled to said patient interface for generating said control signal and being adapted to sense a parameter characteristic of the breathing of said patient and to generate said respiration signal;

said control unit further (a) determining long-term and short-term averages of said respiration signal, (b) comparing said long-term average to the baseline of said respiration signal and changing said baseline in accordance with said long-term average if the difference between said baseline and said long-term average is equal to or greater than a predetermined value; and

(c) if said difference is less than said predetermined value, then comparing said short-term average to said baseline and changing said baseline in accordance with said short-term average if the difference between said baseline and said short-term average is greater than a predetermined value.

3. The respiratory apparatus of claim 2 wherein said respiration signal is calculated by subtracting said baseline from an instantaneous representation of the breathing of said patient.

4. The respiratory apparatus of claim 3 wherein said long-term average is calculated over a period of about twelve seconds.

5. The respiratory apparatus of claim 3 wherein said short-term average is calculated over a period of about 0.5 seconds.

6. A method for presenting a derived signal indicative of a patient'"'"'s breathing on a display having a predetermined display range, the method comprising the steps of:

generating a signal representative of a parameter related to the breathing of the patient;

determining a short-term average of said generated signal and a long-term average of said generated signal;

determining a baseline of said generated signal;

comparing said baseline to said long-term average and if the difference between said baseline and said long-term average is equal to or greater than a predetermined value, then changing said baseline to said long-term average;

if the difference between said baseline and said long-term average is less than said predetermined value, then comparing said baseline to said short-term average and changing said baseline to said short-term average if the difference between said baseline and said short-term average is greater than a predetermined value; and

displaying on said display a derived signal as a function of said generated signal and said baseline.

7. The method of claim 6 wherein said derived signal is calculated by subtracting said baseline from said generated signal.

8. The method of claim 7 wherein said long-term average is calculated over a period of about twelve seconds.

9. The method of claim 7 wherein said short-term average is calculated over a period of about 0.5 seconds.