Spirometer

• US 7,094,208 B2
• Filed: 04/03/2002
• Issued: 08/22/2006
• Est. Priority Date: 04/03/2002
• Status: Expired due to Fees

• Current Assignee: Illinois Institute of Technology
• Original Assignee: Illinois Institute of Technology
• Inventors: Williams, David R., Mansy, Hansen A., Meade, Kevin Philip, Wilson, Nicole April
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US10/115,263
• Publication Number:
  US 20030191407A1
• Time in Patent Office: 1,602 Days
• Field of Search: 600538-542, 738/611.9
• US Class Current: 600/538
• CPC Class Codes: A61B 5/087 Measuring breath flow

Abstract

A spirometer for measuring fluid flow, particularly associated with exhalation of respiratory patients. The spirometer of this invention preferably has a fluidic oscillator wherein the fluid oscillates within a chamber of the fluidic oscillator. An oscillation frequency of the fluid flow within the chamber is correlated to a flow rate. A computer is used to process input data, such as data representing frequency of the oscillatory flow within the chamber, to a flow rate passing through the spirometer. The spirometer of this invention may have no moving parts, which results in the need for only a design calibration and no periodic calibrations throughout use of the spirometer.

Claims

1. An apparatus for determining an entire exhalation flow rate of a respiratory system, the apparatus comprising:

a spirometer having an inlet for accepting the entire exhalation flow rate and having an outlet, a nozzle in communication with the inlet, a fluidic flow oscillator in communication with the inlet and the outlet, and the fluidic flow oscillator passing the entire exhalation flow rate at a maximum pressure drop across the spirometer that is less than 1.5 cmH₂O per L/s between a flow rate of zero and 14 L/s.

2. The spirometer according to claim 1, wherein the fluidic oscillator flowmeter has a chamber, and in a use condition a fluid flow passing through the spirometer oscillates in the chamber.

3. The spirometer according to claim 2, further comprising a computer, a sensor positioned within the chamber, the sensor detecting an oscillation frequency of the fluid flow within the chamber and emitting a corresponding input signal to the computer.

4. The spirometer according to claim 3, wherein the wedge elements are shaped so that the oscillation frequency of the fluid flow in the chamber is linearly proportional to a flow rate of the fluid flow.

5. The spirometer according to claim 3 wherein the sensor comprises an analog sensing circuit that emits the input signal as an analog signal, and the computer comprises a microcontroller and a convertor that receives and converts the analog signal to a digital signal for the microcontroller to process.

6. The spirometer according to claim 5, further comprising an output device displaying a processed signal emitted by the microcontroller, and the output device mounted with respect to a body of the fluidic oscillator flowmeter.

7. The spirometer according to claim 2, wherein the fluidic oscillator flowmeter has two wedge shaped elements positioned opposite each other, and a gap is formed between the wedge elements.

8. The spirometer according to claim 1, further comprising a mouthpiece mounted with respect to a body of the fluidic oscillator flowmeter and in communication with the nozzle.

9. The spirometer according to claim 1, further comprising a mouthpiece in communication with the nozzle.

10. A method for determining an exhalation flow rate of a respiratory system, the method comprising:

discharging an entire exhalation fluid flow into a nozzle of a spirometer, and passing the entire exhalation fluid flow from the nozzle into and through a fluidic oscillator flowmeter at a maximum pressure drop across the spirometer that is less than 1.5 cmH₂O per L/s between a flow rate of zero and 14 L/s.

11. The method according to claim 10, wherein the entire exhalation fluid flow passes from the nozzle through an inlet of the fluidic oscillator flowmeter and into a chamber of the fluidic oscillator flowmeter.

12. The method according to claim 10, wherein the entire exhalation fluid flow oscillates within a chamber of the fluidic oscillator flowmeter.

13. The method according to claim 12, wherein an oscillation frequency of the entire exhalation fluid flow is detected within the chamber.

14. The method according to claim 13, wherein an input signal representing the oscillation frequency is computed into an output signal.

15. The method according to claim 14, wherein the output signal correlates to a flow rate of the entire exhalation fluid flow which is linearly proportional to the oscillation frequency.

16. The method according to claim 15, wherein the flow rate is calculated as a linear function of the oscillation frequency.

17. The method according to claim 14, wherein the output signal is delivered to an output device.