Method and apparatus for optimizing the continuous positive airway pressure for treating obstructive sleep apnea

• US 6,299,581 B1
• Filed: 05/10/1996
• Issued: 10/09/2001
• Est. Priority Date: 05/07/1992
• Status: Expired due to Term

• Current Assignee: Puritan Bennett Corp. (Medtronic Plc), New York University
• Original Assignee: Puritan Bennett Corp. (Medtronic Plc), New York University
• Inventors: Norman, Robert G., Rapoport, David M., Gruenke, Roger A.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US08/644,371
• Time in Patent Office: 1,978 Days
• Field of Search: 128/671, 128/716, 128/721, 128/204.23, 128/206.13, 128/204.21, 128/725, 128/204.26, 600/484, 600/502, 600/529, 600/574, 600/534, 600/538
• US Class Current: 600/484
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/6803 Head-worn items, e.g. helmets, masks, headphones or goggles
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• 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 16/0677 Gas-saving devices therefor
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/04 Heartbeat characteristics, e.g. ECG, blood pressure modulation
• CPC Class Codes: A61M 2230/08 Other bio-electrical signals
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/62 Posture
• CPC Class Codes: A61M 39/228 with a tubular diaphragm constrictable by radial fluid force
• 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
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

In the treatment of obstructive sleep apnea, a method and apparatus are disclosed for optimizing the controlled positive pressure to minimize the flow of air from a flow generator while still ensuring that flow limitation in the patient'"'"'s airway does not occur. In particular, the invention relates to a breathing device and method of use to adjust a controlled positive pressure to the airway of a patient by detecting flow limitation from analysis of an inspiratory flow waveform. Once the presence of flow limitation has been analyzed, the system determines an action to take for adjustment of the controlled positive pressure. The pressure setting is raised, lowered or maintained depending on whether flow limitation has been detected and on the previous actions taken by the system. The preferred breathing apparatus consists of a flow generator, a flow sensor, an analog to digital converter, a microprocessor, and a pressure controller, a patient supply hose, a nasal fitting, and, optionally, a pressure transducer. Using the method of the present invention, the microprocessor adjusts the air pressure in the patient supply hose when flow limitation is detected in the airway of the patient.

Claims

1. A method for detecting flow limitation in an airway of a patient breathing air in an unassisted manner, comprising the steps of:

positioning a nasal fitting so as to be in fluid communication with such airway of said patient, to detect nasal flow in a quantitative manner;

generating with a sensor in fluid communication with said nasal fitting a first set of data values representative of an inspiratory flow of ambient air at negative pressures to the patient;

generating with a micro processor a plurality of indices, each independently descriptive of a waveform of the inspiratory flow at negative pressures in order to determine whether the first set of data values indicate a flow limitation in the patient and generating a second set of data values based on such indices representative of a flow limitation; and

storing in a computer memory the first set of data values generated by said flow sensor and the second set of data values generated by said microprocessor.

2. The method of claim 1 wherein said patient is in a physical position, further comprising the steps of:

generating with a position sensor a third set of data values representative of the physical position of the patient; and

storing in said computer memory the third set of data values.

3. The method of claim 1 wherein blood circulating within said patient has an oxyhemoglobin saturation level, further comprising the steps of:

generating with an oximeter a fourth set of data values representative of the oxyhemoglobin saturation level of the blood of the patient; and

storing in said computer memory the fourth set of data values.

4. The method of claim 1, further comprising the steps of:

generating with said flow sensor a fifth set of data values representative of an expiratory flow of ambient air from the patient; and

storing in said computer memory the fifth set of data values.

5. The method of claim 1, further comprising the steps of:

correlating with said microprocessing the stored sets of data values with a sinusoidal contour;

analyzing the stored sets of data values for flatness;

analyzing the stored sets of data values for respiratory effort; and

analyzing the stored sets of data values for relative flow magnitude.