System for measuring respiratory function

• US 7,094,206 B2
• Filed: 09/09/2002
• Issued: 08/22/2006
• Est. Priority Date: 04/23/1999
• Status: Expired due to Fees

• Current Assignee: Trustees of Tufts College
• Original Assignee: Trustees of Tufts College
• Inventors: Hoffman, Andrew
• Primary Examiner(s): NASSER, ROBERT L
• Application Number:
  US10/237,552
• Publication Number:
  US 20030100843A1
• Time in Patent Office: 1,443 Days
• Field of Search: None
• US Class Current: 600/529
• CPC Class Codes: A61B 2503/40 Animals
• 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 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/0878 using temperature sensing means
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61D 99/00 Subject matter not provided for in other groups of this subclass
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

The present invention relates to a system for measuring respiratory function of living organisms. More particularly, signals indicative of the change in lung volume, defined as active and passive work, required to breathe and the airflow through the respiratory system of the living organism are obtained and processed as waveforms to provide a signal indicative of the respiratory restriction. The methods of the present invention measure clinical forms of airway obstruction, airway reactivity and lung volume and may be used to continuously or intermittently monitor patients with compromised respiratory function. In a preferred embodiment, a head-out, breath in respiratory plethysmograph system provides the signals indicative of change in lung volume as related to pressure changes in a chamber. Further, flowmetric variables are generated that provide a characterization of airway obstructions.

Claims

1. The method for diagnosing sleep apnea conditions of a living organism comprising the steps of:

obtaining a first input signal from a first sensor indicative of a change in lung volume during breathing by said living organism;

obtaining a second input signal from a second sensor indicative of airflow through the respiratory system of said living organism during the change in lung volume; and

processing said first input signal and said second input signal by analyzing phase and magnitude differences between the first input signal and the second input signal, and to calculate a third signal indicative of a respiration restriction condition that adversely effects sleep of said living organism.

2. The method according to claim 1, wherein the processing step comprises the step of comparing said first input signal to said second input signal.

3. The method according to claim 2, further comprising of obtaining the first input signal through use of at least one of respiratory induction plethysmography, a head out, breath-in plethysmograph, an impedance plethysmography, an optoelectric plethysmograph and a fiber optic respiration plethysmograph.

4. The method according to claim 1, further comprising determining the location of a respiratory restriction by analyzing whether phase and magnitude differences occur in one of an inspiratory portion of said first and second signals and an expiratory portion of said first and second signals.

5. The method according to claim 1, further comprising of obtaining the second input signal through use of one of a nasal cannula and a pneumotachographic measurement device.

6. The method according to claim 1, further comprising of obtaining the second input signal through use of an ultrasonic device.

7. The method according to claim 1, further comprising of obtaining the second input signal through use of one of a thermistor, and an acoustic sensor.

8. The method according to claim 1, further comprising of obtaining the second input signal through use of a breath-sound intensity device.

9. The method according to claim 1, further comprising the step of calibrating first input signal.

10. The method according to claim 1, wherein the first input signal is processed to provide a measure of functional residual capacity and specific airway resistance.