Method and system for analysing respiratory tract air flow

• US 20050182337A1
• Filed: 02/04/2004
• Published: 08/18/2005
• Est. Priority Date: 02/04/2004
• Status: Active Grant

• Current Assignee: Deep Breeze, Ltd.
• Original Assignee: Deep Breeze, Ltd.
• Inventors: Kushnir, Igal, Botbol, Meir
• Granted Patent: US 7,033,323 B2
• Time in Patent Office: Days
• US Class Current: 600/538
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise

Abstract

A method for determining airflow in a portion of a respiratory tract comprising determining a total acoustic energy in a region of a body surface overlying the portion of the respiratory tract. The airflow may be integrated over a time interval in order to determine an air volume that has flowed in the portion of the respiratory tract during the time interval. A graph of the flow rate as a function of the volume may be displayed and analyzed as in spirometry. The invention also provides a system for carrying out the method.

Claims

1. A method for determining airflow in a portion of a respiratory tract comprising determining a total acoustic energy in a region of a body surface overlying the portion of the respiratory tract.

2. The method according to claim 1 wherein the total acoustic energy is determined in a process comprising:

(a) obtaining signals P(x_i,t) from N transducers placed at predetermined locations x_i for i from 1 to N in the region of the body surface;

(b) determining an average acoustic energy {tilde over (P)}(x,t_i,t_i+1) over one or more time intervals ti to t_i+1, at a plurality of locations x in the region in a calculation involving at least one of the signals P(x_i,t) and

(c) integrating the functions {tilde over (P)}(x,t_i,t_i+1) with respect to x,

$\underset{x}{\sum <br><br>}<br><br>\tilde{P}<br><br>\left(x,t_i,t_{i+1}\right)$

in order to obtain an airflow in the region during each of the time intervals.

3. The method according to claim 2 further comprising integrating the functions

$\sum _{}$

x ⁢

P ~ ⁡

( x , t i , t i + 1 )

with respect to time,

$\stackrel{t_k}{\underset{t_0}{\sum <br><br>}}<br><br>\underset{x}{\sum <br><br>}<br><br>\tilde{P}<br><br>\left(x,t_i,t_{i+1}\right)$

in order to obtain a total volume of air that has flowed in the region from t₀ to t_k, for each k from 1 to m.

4. The method according to claim 3 further comprising displaying on a display device a plot of the flow rate

$\sum _{}$

x ⁢

P ~ ⁡

( x , t i , t i + 1 )

as a function of the volume

$\stackrel{t_k}{\underset{t_0}{\sum <br><br>}}<br><br>\underset{x}{\sum <br><br>}<br><br>\tilde{P}<br><br>\left(x,t_i,t_{i+1}\right).$

5. The method according to claim 1, wherein the region is a single lung or a lobe of a lung.

6. The method according to claim 1 further comprising calculating a logarithm of an acoustical energy.

11. The system according to claim 1, wherein the region is a single lung or a lobe of a lung.

7. A system for determining airflow in a portion of a respiratory tract comprising a processor configured to determine a total acoustic energy in a region of a body surface overlying the portion of the respiratory tract.

8. The system according to claim 7 wherein the total acoustic energy is determined in a process comprising:

(a) obtaining signals P(x_i,t) from N transducers placed at predetermined locations x_i for i from 1 to N in the region of the body surface;

(b) determining an average acoustic energy {tilde over (P)}(x,t_i,t_i+1) over one or more time intervals ti to t_i+1, at a plurality of locations x in the region in a calculation involving at least one of the signals P(x_i,t) and

(c) integrating the functions {tilde over (P)}(x,t_i,t_i+1) with respect to x,

$\underset{x}{\sum <br><br>}<br><br>\tilde{P}<br><br>\left(x,t_i,t_{i+1}\right)$

in order to obtain an airflow in the region during each of the time intervals.

9. The system according to claim 8 wherein the processor is further configured to integrate the functions

$\sum _{}$

x ⁢

P ~ ⁡

( x , t i , t i + 1 )

with respect to time,

$\underset{t_0}{\overset{t_k}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{x}{\sum <br><br>}<br><br>\tilde{P}<br><br>\left(x,t_i,t_{i+1}\right)$

in order to obtain a total volume of air that has flowed in the region from t₀ to t_k, for each k from 1 to m.

10. The system according to claim 9 further comprising display device and wherein the processor is further configured to displaying on the display device a plot of the flow rate

$\sum _{}$

x ⁢

P ~ ⁡

( x , t i , t i + 1 )

as a function of the volume

$\underset{t_0}{\overset{t_k}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\underset{x}{\sum <br><br>}<br><br>\tilde{P}<br><br>\left(x,t_i,t_{i+1}\right).$

12. The system according to claim 7 wherein the processor is further configured to calculate a logarithm of an acoustical energy.