Method and apparatus for determining conditions of biological tissues

• US 20030120182A1
• Filed: 10/15/2002
• Published: 06/26/2003
• Est. Priority Date: 04/20/2000
• Status: Active Grant

• Current Assignee: Respiri (Israel) Ltd.
• Original Assignee: PulmoSonix Pty., Ltd. (Spenda Ltd.)
• Inventors: Ramsden, Clive Andrew, Berger, Philip John, Wilkinson, Malcolm Howard
• Granted Patent: US 7,347,824 B2
• Time in Patent Office: Days
• US Class Current: 600/587
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence

Abstract

The present invention relates to a method of determining characteristics of biological tissues in humans and animals. In particular, it relates to determining the characteristics of tissues such as the lungs and airways by introducing a sound to the tissue, and recording the sound. The invention further includes an apparatus capable of such measurement. In a first aspect of the present invention there is provided a method of determining characteristics of biological tissue in situ, including: introducing a sound to the tissue at first position; detecting the sound at another position spaced from the first position after it has travelled through the tissue; calculating the velocity and attenuation of sound that has travelled through the tissue from the first position to another position; and correlating the velocity and attenuation of the detected sound to characteristics of the biological tissue.

Claims

1. A method of determining characteristics of tissue of the respiratory system in situ, said method including:

introducing an audible sound to the tissue at first position;

detecting the sound at another position spaced from the first position after it has travelled through the tissue;

calculating the velocity and attenuation of sound that has travelled through the tissue from the first position to another position; and

correlating the velocity and attenuation of the detected sound to characteristics of the tissue of the respiratory system.

2. A method according to claim 1 wherein the characteristics include any one of make-up of tissue, volume, condition or position in the body.

3. A method according to claim 1 or 2 wherein the tissue of the respiratory system is selected from the group including lung tissue or tissues of the upper airway.

4. A method according to any one of claims 1 to 3 wherein the audible sound is produced with frequencies in the range of 20 Hz to 20 kHz

5. A method according to any one of claims 1 to 4 wherein the sound is produced at a sound pressure level between 1 and 100 Pascal.

6. A method according to any one of claims 1 to 5 wherein the sound is detected by a sound detector means including a microphone or a vibration detector having a frequency response that is flat in the acoustic region.

7. A method according to claim 6 wherein the frequency response that is flat in the acoustic region is between 20 HZ and 20 kHz.

8. A method according to anyone of claims 1 to 7 for determining a state of the upper airways in a respiratory tract in a patient in situ, said method including:

introducing an audible sound at first position in the upper airways;

detecting the sound after it has travelled through the upper airways at another position spaced from the first position;

calculating the velocity and attenuation of the sound travelled through the upper airways from the first position to another position; and

correlating the velocity and attenuation of the sound to the state of the upper airways.

9. A method according to claim 8 wherein the state of the upper airways is determined as an obstructed or open airway.

10. A method according to claim 8 or 9 wherein the state of the upper airways is determined to monitor obstructive sleep apnoea and wherein a change in the velocity and attenuation of the sound indicates a change in the state of the upper airway.

11. A method according to any one of claims 8 to 10 wherein the first position in the upper airways is in the nasal region and another position spaced from the first position is in the upper chest region below the neck and above the lung.

12. A method according to any one of claims 1 to 7 for monitoring lung condition in situ said method comprising:

introducing an audible sound transthoracically so that the sound travels from one side of the thorax, through the lung, to another side of the thorax;

measuring the velocity and attenuation of the sound as it travels from one side of the thorax, through and across the lung, to the other side of the thorax; and

correlating the attenuation and sound velocity and velocity dispersion to lung condition.

13. A method according to claim 12 wherein the lung condition is selected from the group including:

(a) lung tissue density;

(b) lung gas volume;

(c) regional collapse (atelectasis);

(d) regional blood volume, interstitial oedema; and

(e) focal lung pathology including tumour and global lung disease.

14. A method according to any one of claims 1 to 7 for measuring lung inflation, said method including:

introducing an audible sound transthoracically so that the sound travels from one side of the thorax, through the lung, to another side of the thorax;

measuring the velocity and attenuation of the sound as it travels from one side of the thorax, through and across the lung, to the other side of the thorax; and

correlating changes in sound velocity and attenuation with lung volume and inflation.

15. A method according to any one of claims 1 to 7 for predicting chronic lung disease in infants said method including:

introducing an audible sound transthoracically so that the sound travels from one side of the thorax, through the lung, to another side of the thorax;

measuring the velocity and attenuation of the sound as it travels from one side of the thorax, through and across the lung, to the other side of the thorax; and

comparing the measured sound velocity and attenuation with that of a normal lung in the absence of chronic lung disease.

16. A method according to any one of claims 1 to 7 for diagnosing lung disease, said method including measuring lung density including:

introducing an audible sound transthoracically so that the sound travels from one side of the thorax, through the lung, to another side of the thorax;

measuring the velocity and attenuation of the sound as it travels from one side of the thorax, through and across the lung, to the other side of the thorax; and

correlating sound velocity and attenuation with lung density and comparing the density of the lung being diagnosed with the density of a normal lung to determine if the lung being diagnosed is diseased.

17. A method according to claim 16 wherein the lung disease is selected from the group including emphysema, asthma, regional collapse (atelectasis), interstitial oedema, focal lung disease and global lung disease.

18. A method according to any one of claims 1 to 7 for preventing lung injury, said method including monitoring lung condition by:

introducing an audible sound transthoracically so that the sound travels from one side of the thorax, through the lung, to another side of the thorax;

measuring the velocity and attenuation of the sound as it travels from one side of the thorax, through and across the lung, to the other side of the thorax;

correlating the sound velocity and attenuation with lung volume; and

maintaining a lung volume at an optimal volume such that the lung is substantially free of atelectasis or over-inflation (volutrauma).

23. A method according to claim 1 substantially as hereinbefore described with reference to the examples.

19. An apparatus for determining characteristics of tissue of the respiratory system in situ, the apparatus including:

a sound generating device which generates an audible sound;

a recording device which records the sound after it has travelled from one position of the respiratory system tissue, through the tissue and to another position of the tissue;

an analysis device which calculates the velocity and attenuation with which the sound travels through the tissue.

21. An apparatus according to claim 19 or 20 wherein the audible sound generated is in the range of 20 Hz to 20 kHz.

22. An apparatus according to any one of claims 19 to 21 wherein the analysis device further performs spectral analysis on the data recorded.

20. An apparatus for monitoring lung condition, said apparatus including:

a sound generating means to generate an audible sound transthoracically so that the sound travels from one side of the thorax, through the lung, to another side of the thorax;

a recording means to record the sound after it has travelled from one side of the thorax, through and across the lung, to the other side of the thorax;

an analysis device which calculates the attenuation and velocity with which the sound travels from one side of the thorax, through and across the lung, to the other side of the thorax.