Methods and apparatus for passive, proportional, valveless gas sampling and delivery

Patent metadata

Field	Value
Publication number	US-11259717-B2
Application number	US-201916413980-A
Country	US
Kind code	B2
Filing date	May 16, 2019
Priority date	May 16, 2018
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

A fluid dynamic valve passively allows fluid flow out of a moving stream in one flow direction and not in the reverse. This allows the collection of fluid from a single direction of an AC fluid flow. The siphoned portion of the flow has a flow rate proportional to the mainstream flow. This device can collect exhaled breath or selective entrenchment during inhale. In one orientation, it can meter aerosolized particles into an inhale breath stream for pulmonary delivery, without complicated breath timing or drug loss due to drug adsorption to the back of the throat. Alternatively, a user can breathe through the device and a proportional amount, relative to the volumetric flow rate, of each exhale can flow into an auxiliary chamber for analysis. In addition, the device has a low respiratory burden and is comfortable to use.

First claim

The invention claimed is:

1. A closed-loop sampling system for sampling an exhalation of a person, the closed-loop sampling system comprising:
a flow tube to receive the exhalation of the person, the flow tube defining a lumen having an inlet and an outlet, the lumen defining an impedance between the inlet and the outlet, a first port between the inlet and the impedance, and a second port at or between the impedance and the outlet, the impedance causing a fraction of the exhalation to pass through the first port in proportion to an instantaneous flow rate of the exhalation; and
a valveless mixing chamber, in fluid communication with the first port and the second port, to measure at least one of a volumetric flow rate, an oxygen content, a carbon dioxide content, a nitrogen content, a volatile organic compound, or a water vapor content of the fraction amount of the exhalation.

2. The closed-loop sampling system of claim 1 , wherein the lumen is shaped to prevent gas from flowing into the valveless mixing chamber during inhalation of the person.

3. The closed-loop sampling system of claim 1 , wherein the lumen is shaped to produce a null pressure difference between the first port and the second port during an inhalation of the person.

4. The closed-loop sampling system of claim 1 , wherein the impedance comprises at least one of a constriction or an obstruction.

5. The closed-loop sampling system of claim 1 , wherein the second port is located at a vena contracta of the lumen.

6. The closed-loop sampling system of claim 1 , wherein volume concentrations of gases in the fraction of the exhalation are the same volume concentrations of gases in the exhalation.

7. The closed-loop sampling system of claim 1 , wherein the valveless mixing chamber is configured to volume average fractions of a plurality of exhalations.

8. The closed-loop sampling system of claim 1 , wherein the valveless mixing chamber is configured to mix an incoming volume with a plurality of exhalations.

9. The closed-loop sampling system of claim 1 , wherein the valveless mixing chamber is configured to average the volatile organic compound over a plurality of exhalations.

10. The closed-loop sampling system of claim 1 , wherein a volumetric flow through the lumen is measured by the flow into the valveless mixing chamber.

11. The closed-loop sampling system of claim 1 , wherein the valveless mixing chamber is configured to perform volumetric averaging over a plurality of exhalations and sense the oxygen content, the carbon dioxide content, the nitrogen content, the volatile organic compound, and/or the water vapor content of the proportional amount of the exhalation.

12. The closed-loop sampling system of claim 1 , further comprising:
an oxygen sensor, disposed in the valveless mixing chamber, to measure the oxygen content of the fraction amount of the exhalation at a sampling rate of 0.2 Hz to 20 Hz; and
a carbon dioxide sensor, disposed in the valveless mixing chamber, to measure a carbon dioxide content of the fraction amount of the exhalation at a sampling rate of 0.2 Hz to 20 Hz.

13. The closed-loop sampling system of claim 1 , further comprising:
a perforated circuit board, disposed in the valveless mixing chamber, to hold electronic components in the valveless mixing chamber and to aid in mixing the fraction amount of the exhalation.

14. The closed-loop sampling system of claim 13 , further comprising:
a perforated baffle, disposed in the valveless mixing chamber, to aid in mixing the fraction amount of the exhalation.

15. The closed-loop sampling system of claim 1 , wherein the valveless mixing chamber further comprises ports for high-pressure and low-pressure measurements.

16. A method of sampling an exhalation of a person, the method comprising:
receiving the exhalation of the person in a flow tube defining a lumen having an inlet and an outlet, the lumen defining an impedance between the inlet and the outlet, a first port between the inlet and the impedance, and a second port at or between the impedance and the outlet, the impedance causing a fraction of the exhalation to pass through the first port to a valveless mixing chamber in proportion to an instantaneous flow rate of the exhalation;
mixing the fraction of the exhalation with fractions of other exhalations of the person in the valveless mixing chamber to yield mixed fractions;
measuring at least one of a volumetric flow rate, an oxygen content, a carbon dioxide content, a nitrogen content, a volatile organic compound, or a water vapor content of the mixed fractions;
conveying the mixed proportional amounts from the valveless mixing chamber to the second port of the flow tube; and
discharging the mixed fractions from the outlet.

17. The method of claim 16 , further comprising:
preventing, with the impedance, gas from flowing into the valveless mixing chamber during inhalation of the person.

18. The method of claim 16 , further comprising:
producing, with the impedance, a null pressure difference between the first port and the second port during an inhalation of the person.

19. The method of claim 16 , wherein mixing the fraction of the exhalation with fractions of other exhalations of the person comprises volume averaging the fraction of the exhalation with the fractions of the other exhalations.

20. The method of claim 16 , further comprising:
estimating a volumetric flow through the lumen based on a volumetric flow into the valveless mixing chamber.

21. A passive, proportional, closed-loop metabolic sampling system comprising:
a flow tube having:
a proximal end to receive exhaled breaths from a person;
a distal end to discharge the exhaled breaths;
an inner lumen extending from the proximal end to the distal end to convey the series of exhaled breaths from the proximal end to the distal end, the inner lumen defining a vena contracta between the proximal end and the distal end;
a first port between the proximal end and the vena contracta; and
a second port between the vena contracta and the distal end;

a valveless mixing chamber, in fluid communication with the first port and the second port, to mix fractions of the exhaled breaths;
a first conduit, connecting the first port to the valveless mixing chamber, to convey the fractions of the exhaled breaths from the flow tube to the valveless mixing chamber;
a second conduit, connecting the valveless mixing chamber to the second port, to convey gas from the valveless mixing chamber to the flow tube; and
at least one sensor, disposed in the mixing chamber, to measure at least one of a volumetric flow rate, an oxygen content, a carbon dioxide content, an oxygen partial pressure, or a carbon dioxide partial pressure of the fractions of the exhaled breaths.

22. The passive, proportional, closed-loop metabolic sampling system of claim 21 , wherein the vena contracta is configured to produce a finite pressure difference on exhalation by the person between the first port and the vena contracta that draws the fractions of the exhaled breaths into the valveless mixing chamber.

23. The passive, proportional, closed-loop metabolic sampling system of claim 22 , wherein the vena contracta is further configured to produce a null pressure difference on inhalation by the person between the first port and the second port that prevents air from flowing into the valveless mixing chamber.

24. The passive, proportional, closed-loop metabolic sampling s

Assignees

• Massachusetts Inst Technology

Inventors

• Thompson Kyle
• Shaw Gary A
• Siegel Andrew M
• Candell Lawrence M

Classifications

• A61M11/06

  of the injector type · CPC title

• A61M2230/42

  Rate · CPC title

• A61M2205/3334

  Measuring or controlling the flow rate · CPC title

• A61M15/0093

  without arming or cocking, e.g. acting directly on the delivery valve · CPC title

• A61M15/0065

  Inhalators with dosage or measuring devices (A61M15/0028 takes precedence; dosage devices incorporated in aerosol cans B65D83/52) · CPC title