Respiratory function monitor

• US 6,203,502 B1
• Filed: 03/27/1998
• Issued: 03/20/2001
• Est. Priority Date: 03/31/1997
• Status: Expired due to Fees

• Current Assignee: Welch Allyn Protocol Incorporated (Welch Allyn Incorporated)
• Original Assignee: Pryon Corp (Protocol Systems Inc)
• Inventors: Tran, Son Duc, Pruzina, Steven P., Storsved, Mark, Hilgendorf, Edwin J.
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): ASTORINO, MICHAEL C
• Application Number:
  US09/049,166
• Time in Patent Office: 1,089 Days
• Field of Search: 128/200.11, 128/207.29, 73/10--, 600/528-541
• US Class Current: 600/538
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity

Abstract

A respiratory function monitoring device comprising a flow sensor and a conversion device is herein disclosed. Also disclosed are structures for carrying out an auto-zero calibration, a purging function, and temperature compensation. Methods for implementing the auto-zero calibration, the purge function, and the temperature compensation are also disclosed.

Claims

1. A respiratory function monitoring device comprising:

a flow sensing device in fluidic communication with a first and a second pressure transducer, the first pressure transducer arranged to measure a differential pressure corresponding to a gas flow rate, the second pressure transducer arranged to measure a static pressure;

amplifying means electrically connected to the first and second pressure transducers, the amplifying means for amplifying voltage signals output by the pressure transducers;

an analog to digital converter for translating the analog voltage valves derived from the first and second pressure transducers;

a central processing unit arranged to communicate with the analog to digital converter, the central processing unit being capable of executing a program, the program being designed to convert the digital voltage values from the first pressure transducer into flow rate data and the voltage values from the second pressure transducer into pressure data; and

an input/output means for communicating the flow rate and pressure data to a host system wherein the flow sensing device comprises a hollow cylindrical body having a bore with a first end and a second end, the first and second ends arranged for connection between a ventilator and a patient;

a strut disposed within the bore of the body across the entire diameter of the bore and parallel to the axis of symmetry of the bore, the strut having symmetrical end portions flowing aerodynamically from a center portion, the symmetrical end portions each having a leading edge with a groove formed therein.

2. The respiratory function monitor of claim 1 wherein the flow sensing device comprises:

a pair of lumens coupled to an outer surface of the body of the flow sensing device, each lumen communicating with a respective groove so as to permit the measurement, across the strut, of a differential pressure of a gas flowing through the flow sensing device.

3. The respiratory function monitor of claim 2 wherein the respective grooves of the flow sensing device extend across substantially the entire height of the strut.

4. The respiratory function monitoring device of claim 1 wherein the conversion device further comprises:

a third transducer arranged to receive pressure signals from an esophageal pressure sensing device, the voltage signals of the third transducer being amplified by the amplifying means, the amplified analog voltage signals derived from the third transducer being translated by the analog to digital converter into digital voltage data, the digital voltage data being processed by the central processing unit into pressure data that is transferred to the host system.

5. The respiratory function monitoring device of claim 1 wherein the conversion device further comprises:

a temperature indicating means arranged so as to give the temperature of the conversion device.

6. The respiratory function monitoring device of claim 1 wherein the analog to digital converter of the conversion device has at least four input channels.

7. The respiratory function monitoring device of claim 1 wherein the conversion device further comprises a purge system, the purge system comprising:

a first valve means;

a second valve means;

a third valve means;

an air pump having an inlet and an outlet, the outlet of the air pump being coupled by a first and second fluidic connection means to the first valve means and the second valve means, respectively;

the third valve means coupled to a first lumen via a third fluidic connection means and to a first input port of a flow transducer via a fourth fluidic connection means, the third valve means selectively permitting communication between the first lumen and the first input port;

the second valve means being also coupled to a second lumen through a fifth fluidic connection means and to a second input port via a sixth fluidic connection means;

the first valve means being also coupled by a seventh fluidic connection means to the third fluidic connection means adjacent the third valve means between the third valve means and the first lumen;

an eighth fluidic connection means being coupled between the second and third valve means such that the second and third valve means may selectively permit communication between the first input port and the second input port.

8. The purge system of claim 7 wherein the valve means comprise a solenoid activated three-way air valve.

9. The purge system of claim 7 wherein the fluidic connection means are comprised of discrete tubes.

10. The purge system of claim 7 wherein the fluid connection means comprise channels formed within a solid valve manifold, the solid valve manifold being further arranged to receive the valve means.

11. A respiratory function monitoring device comprising:

a flow sensing device having a hollow cylindrical body with a bore and a first end and a second end, the first and second ends arranged for connection between a ventilator and a patient;

a strut disposed within the bore of the body of the flow sensing device, the strut having symmetrical end portions flowing aerodynamically from a center portion, the symmetrical end portions each having a leading edge with a groove formed therein, the respective grooves extending across substantially the entire height of the strut;

a pair of lumens coupled to an outer surface of the flow sensing device, each lumen communicating with a respective groove so as to permit the measurement of a differential pressure of a gas flowing through the flow sensing device;

the flow sensing device being in fluidic communication via the pair of lumens with a pair of differential pressure transducers, a first of the pair of transducers arranged to measure a differential pressure corresponding to a gas flow rate a second of the pair of transducers arranged to measure a static pressure;

amplifying means for amplifying voltage signals output by the transducers;

an analog to digital converter for translating the analog voltage valves derived from the transducers;

a central processing unit arranged to communicate with the analog to digital converter, the central processing unit being capable of executing a program, the program being designed to convert the digital voltage values from the first transducer into flow rate data and the voltage values from the second transducer into pressure data; and

an input/output means for communicating flow rate and pressure data to a host system.