U.S. patent application number 17/680093 was filed with the patent office on 2022-07-07 for device for measuring a user's oxygen-consumption.
This patent application is currently assigned to VO2 Master Health Sensors Inc.. The applicant listed for this patent is VO2 Master Health Sensors Inc.. Invention is credited to Joshua Brinkerhoff, Kenneth Chau, Kyle Halliday, Peter O'Brien.
Application Number | 20220211295 17/680093 |
Document ID | / |
Family ID | 1000006223213 |
Filed Date | 2022-07-07 |
United States Patent
Application |
20220211295 |
Kind Code |
A1 |
O'Brien; Peter ; et
al. |
July 7, 2022 |
DEVICE FOR MEASURING A USER'S OXYGEN-CONSUMPTION
Abstract
There is provided a device for measuring a user's
oxygen-consumption. The device includes a tubular member with a
first tapered portion through which an exhalation of air enters
into the device, a second tapered portion, and a constriction
between the portions thereof. The devices includes a flow sensing
mechanism in communication with the first tapered portion of the
tubular member. The device includes an oxygen sensor in
communication with the first tapered portion of the tubular member.
The device is configured such that the oxygen sensor is passively
supplied a portion of the exhalation of air by means of positive or
negative differential pressure referenced between the first tapered
portion and at least one of ambient air and the constriction of the
tubular member.
Inventors: |
O'Brien; Peter; (Vernon,
CA) ; Halliday; Kyle; (Ladysmith, CA) ; Chau;
Kenneth; (Kelowna, CA) ; Brinkerhoff; Joshua;
(Kelowna, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VO2 Master Health Sensors Inc. |
Vernon |
|
CA |
|
|
Assignee: |
VO2 Master Health Sensors
Inc.
Vernon
CA
|
Family ID: |
1000006223213 |
Appl. No.: |
17/680093 |
Filed: |
February 24, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16093853 |
Oct 15, 2018 |
11284814 |
|
|
PCT/CA2017/050467 |
Apr 13, 2017 |
|
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17680093 |
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62322563 |
Apr 14, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2560/0257 20130101;
A61B 5/7278 20130101; A61B 5/0833 20130101; A61B 5/091 20130101;
A61B 5/0878 20130101; A61B 2560/0252 20130101; A61B 5/6803
20130101; A61B 5/097 20130101; A61B 2562/0247 20130101; A61B 5/087
20130101 |
International
Class: |
A61B 5/083 20060101
A61B005/083; A61B 5/097 20060101 A61B005/097; A61B 5/091 20060101
A61B005/091; A61B 5/00 20060101 A61B005/00; A61B 5/087 20060101
A61B005/087 |
Claims
1. A device for measuring a user's oxygen-consumption, the device
comprising: a tubular member including a first tapered portion
through which an exhalation of air enters into the device,
including a second tapered portion, and including a constriction
between said portions thereof; a flow sensing mechanism in
communication with the first tapered portion of the tubular member;
and an oxygen sensor in communication with the first tapered
portion of the tubular member, wherein the device is configured
such that the oxygen sensor is passively supplied a portion of the
exhalation of air by means of positive or negative differential
pressure referenced between the first tapered portion and at least
one of ambient air and the constriction of the tubular member.
2. The device as claimed in claim 1, wherein the flow sensing
mechanism passively samples the exhalation of air by means of
positive or negative differential pressure referenced between the
first tapered portion of the tubular member and the at least one of
the ambient air and the constriction of the tubular member.
3. The device as claimed in claim 1, wherein the flow sensing
mechanism enables breath flow rate to be determined.
4. The device as claimed in claim 1, wherein the flow sensing
mechanism is a pressure sensor.
5. The device as claimed in claim 4 wherein the pressure sensor is
in communication with the constriction of the tubular member.
6. The device as claimed in claim 1, wherein the flow sensing
mechanism is a differential pressure sensor.
7. The device as claimed in claim 1 wherein the tubular member is
asymmetrical.
8. The device as claimed in claim 1 further including a processor
that determines a flow rate through the device from an output of
the flow sensing mechanism, and wherein the processor receives
input from the oxygen sensor to determine a change in oxygen
concentration.
9. The device as claimed in claim 1 further including a wired or
wireless system that enables the device to selectively upload data
therefrom to one or more of a smart phone, a computer and a remote
server.
10. The device as claimed in claim 1 further including an oxygen
sensor micro mixing chamber.
11. The device as claimed in claim 1 further including an
environmental sensor which outputs relative humidity data for at
least one of flow and oxygen measurement correction.
12. The device as claimed in claim 1, further including a housing
within which the oxygen sensor, the flow sensing mechanism and the
tubular member are enclosed at least in part.
13. The device as claimed in claim 1, wherein the device further
includes a processor which receives input from the flow sensing
mechanism and the oxygen sensor, and wherein the tubular member,
the processor, the flow sensing mechanism and the oxygen sensor are
coupled together.
14. The device as claimed in claim 1, wherein the device is compact
and portable.
15. In combination, the device as claimed in claim 1 and a facemask
coupled thereto.
16. A device for measuring a user's oxygen-consumption, the device
comprising first and second portions through which an exhalation of
air passes, a region of reduced cross-sectional area relative to
that of and positioned between the portions of the device, a flow
sensing mechanism and an oxygen sensor in communication with the
first portion of the device, the oxygen sensor being supplied the
exhalation of air by means of positive or negative differential
pressure referenced between the first portion of the device and one
of ambient air, the region of reduced cross-sectional area and the
second portion of the device.
17. The device as claimed in claim 16, wherein the flow sensing
mechanism is in fluid communication with the first portion of the
device.
18. The device as claimed in claim 16, wherein the flow sensing
mechanism passively samples the exhalation of air by means of
positive or negative differential pressure referenced between the
first portion of the device and one of the ambient air, the region
of reduced cross-sectional area and the second portion of the
device.
19. A device for measuring a user's oxygen-consumption, the device
comprising a venturi tube shaped to receive therethrough an
exhalation of air, a flow sensor and an oxygen sensor, whereby the
oxygen sensor is in fluid communication with the venturi tube and
passively samples the exhalation of air via a positive or negative
pressure differential referenced between the venturi tube and
ambient air or referenced between two longitudinally spaced-apart
regions of different cross-sectional area of the venturi tube.
20. The device as claimed in claim 19, wherein at least one of: the
first portion and the second portion are tapered; and the flow
sensing mechanism is a pressure sensor.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] There is provided a measuring device. In particular, there
is provided a device for determining a user's
oxygen-consumption.
Description of the Related Art
[0002] A conventional oxygen consumption ("VO2") monitor device may
use a pump to draw air away from the user's air stream. The device
may further include a desiccation system, a relatively large mixing
chamber, and an oxygen sensor. It may be undesirable for the user
to have attached to their face the entirety of a conventional VO2
monitor due to the excessive vibration, weight, and noise. To
mitigate against this, such assemblies may be split into two parts:
a face mask for flow measurement, and an external box located
either in a backpack or table-top unit with a tube connecting the
two parts. The mixing chamber is typically needed to stabilize a
gas sample prior to analysis, and/or to remove physical vibration
caused by a pump.
[0003] Such assemblies may thus require a relatively large number
of parts and may be bulky as well as expensive.
[0004] There may accordingly be a need for an improved device that
overcomes the above disadvantages.
BRIEF SUMMARY OF INVENTION
[0005] There is accordingly provided a device for measuring a
user's oxygen-consumption. The device includes a venturi, which may
be called and in this description will hereafter be referred to as
a venturi tube. The venturi tube has a first tapered portion, a
second tapered portion that is more tapered compared to the first
tapered portion, and a constriction between said portions thereof.
The device includes at least one pressure sensor in communication
with the first tapered portion of the venturi tube. The device
includes an oxygen sensor in communication with the first tapered
portion of the venturi tube.
[0006] There is also provided a device for measuring a user's
oxygen-consumption according to a further aspect. The device
includes a venturi tube. The venturi tube has a constriction and is
shaped to promote laminar flow through an exhale-receiving portion
thereof. The device includes at least one pressure sensor in
communication with the constriction and the exhale-receiving
portion of the venturi tube. The device includes a desiccant tube
in communication the exhale-receiving portion of the venturi tube.
A drying agent surrounds the tube in this example. The device
includes an oxygen sensor. The desiccant tube is between and in
communication with the oxygen sensor and the exhale-receiving
portion of the venturi tube.
[0007] There is further provided a method of calibrating one of the
above devices to obtain an ambient oxygen sensor value. The oxygen
sensor emits an oxygen sensor signal. The method includes
normalizing the oxygen sensor signal with ambient pressure and
temperature to inhibit drift caused by changes in elevation and
environment. The method may further include normalizing the oxygen
signal with relative humidity to inhibit drift caused by changes in
elevation and environment. The method includes purging the venturi
tube by having a user take two or more slow, large-volume inhales
of air through the device successively without exhaling through the
device. The method includes measuring and storing via a processor
the ambient oxygen sensor value thereafter.
[0008] There is yet further provided a device for measuring a
user's oxygen-consumption. The device includes a replaceable
venturi tube having a proximal end connectable to a
breath-receiving member and a distal end through which air enters
during inhalation. The device includes a sensor assembly comprising
two parts hingedly connected together and between which the venturi
tube is selectively received.
[0009] There is also provided a kit for measuring a user's
oxygen-consumption. The kit includes a plurality of replaceable
venturi tubes of different shapes, with the kit thus being
customizable to desired test conditions and criteria. Each venturi
tube has a proximal end connectable to a breath-receiving member
and a distal end through which air enters during inhalation. The
kit includes a sensor assembly to which respective ones of the
venturi tubes are selectively received.
[0010] There is additionally provided a device for measuring a
user's oxygen-consumption. The device includes a tubular member
with a first tapered portion through which an exhalation of air
enters into the device, a second tapered portion, and a
constriction between the portions thereof. The devices includes a
flow sensing mechanism in communication with the first tapered
portion of the tubular member. The device includes an oxygen sensor
in communication with the first tapered portion of the tubular
member. The device is configured such that the oxygen sensor is
passively supplied a portion of the exhalation of air by means of
positive or negative differential pressure referenced between the
first tapered portion and at least one of ambient air and the
constriction of the tubular member.
[0011] There is yet additionally provided a device for measuring a
user's oxygen-consumption. The device includes a tubular member
with a first portion through which an exhalation of air enters into
the device, a second portion, and a region of reduced effective
cross-sectional area relative to that of and positioned between
said portions thereof. The device includes a flow sensing mechanism
in fluid communication with the first portion of the tubular
member. The flow sensing mechanism passively samples the exhalation
of air by means of positive or negative differential pressure
referenced between the first portion of the tubular member and at
least one of ambient air and said region of reduced cross-sectional
area. The device includes an oxygen sensor in fluid communication
with the first portion of the tubular member. The oxygen sensor
passively samples the exhalation of air by means of positive or
negative differential pressure between referenced the first portion
of the tubular member and at least one of ambient air and said
region of reduced cross-sectional area.
[0012] There is further provided a device for measuring a user's
oxygen-consumption. The device includes first and second portions
through which an exhalation of air passes. The device includes a
region of reduced cross-sectional area relative to that of and
positioned between the portions of the device. The device includes
a flow sensing mechanism and an oxygen sensor in communication with
the first portion of the device. The oxygen sensor is supplied the
exhalation of air by means of positive or negative differential
pressure referenced between the first portion of the device and one
of ambient air, the region of reduced cross-sectional area and the
second portion of the device.
[0013] There is yet also provided a device for measuring a user's
oxygen-consumption. The device includes a venturi tube shaped to
receive therethrough an exhalation of air. The device includes an
oxygen sensor and at least one of a flow sensor and a pressure
sensor. Each said sensor is in fluid communication with the venturi
tube and passively samples the exhalation of air via a positive or
negative pressure differential referenced between the venturi tube
and ambient air or referenced between two longitudinally
spaced-apart regions of different cross-sectional area of the
venturi tube.
BRIEF DESCRIPTION OF DRAWINGS
[0014] The invention will be more readily understood from the
following description of preferred embodiments thereof given, by
way of example only, with reference to the accompanying drawings,
in which:
[0015] FIG. 1 is a top, right side perspective view of a facemask
with an oxygen-consumption measuring device coupled thereto, the
device including a venturi tube and a sensor assembly extending
about the venturi tube;
[0016] FIG. 2 is a top, left side perspective view of the device of
FIG. 1, with the sensor assembly being shown in an open position
and positioned above the venturi tube;
[0017] FIG. 3 is a top, right side perspective view of the venturi
tube of FIG. 2;
[0018] FIG. 4 is a distal end elevation view of the venturi tube of
FIG. 3;
[0019] FIG. 5 is a proximal end elevation view of the venturi tube
of FIG. 3;
[0020] FIG. 6 is a cross-sectional view taken along lines 6-6 of
the venturi tube shown in FIG. 4;
[0021] FIG. 7 is a cross-sectional view taken along lines 7-7 of
the venturi tube shown in FIG. 4;
[0022] FIG. 8 is a top, right side perspective view of the device
of FIG. 1;
[0023] FIG. 9 is a schematic diagram of the device of FIG. 1
showing the process of exhalation through the device;
[0024] FIG. 10 is a schematic diagram of the device similar to FIG.
9 showing the process of inhalation through the device;
[0025] FIG. 11 is a cross-section view taken along lines 11-11 of
the facemask and the device of FIG. 1, the facemask and the device
being shown partially in fragment;
[0026] FIG. 12 is a top, right perspective view of the sensor
assembly of the device of FIG. 1, with the venturi tube thereof
being removed;
[0027] FIG. 13 is a front elevation view of the sensor assembly of
FIG. 12;
[0028] FIG. 14 is a rear elevation view of the sensor assembly of
FIG. 12;
[0029] FIG. 15 is a top, left side cross-sectional view taken along
lines 15-15 of the sensor assembly of FIG. 12;
[0030] FIG. 16 is a top, right side perspective view of the sensor
assembly of FIG. 12, with an outer shell of a first part of the
sensor assembly being removed to reveal a circuit board cover, and
a battery and circuit board of the device mounted onto the circuit
board cover;
[0031] FIG. 17 is a top, right side perspective view of the sensor
assembly similar to FIG. 16, with the battery now also being
removed to reveal additional features of the circuit board of the
device;
[0032] FIG. 18 is a first side elevation view of the circuit board
of FIG. 17;
[0033] FIG. 19 is a second side elevation view of the circuit board
of FIG. 18;
[0034] FIG. 20 is a top, right side perspective view of the sensor
assembly similar to FIG. 17, with the circuit board now
additionally being removed to reveal the outer side of the circuit
board cover, the circuit board cover including an environmental
sensor inlet and pressure sensor inlets;
[0035] FIG. 21 is an outer side elevation view of the first part of
the sensor assembly of FIG. 20, with channels and sample ports
thereof being shown in ghost, and with the ends of the venturi tube
of FIG. 1 also being shown and the rest of the venturi tube being
not show;
[0036] FIG. 22 is a cross-sectional view taken along lines 22-22 of
the device of FIG. 8, with sectional aspects of the venturi tube
being shown in ghost to reveal the inner side elevation view of an
oxygen sensor cover of a second part of the sensor assembly of the
device;
[0037] FIG. 23 is a cross-sectional view taken of the second part
of the sensor assembly of the device similar to FIG. 22, with
sectional aspects of the second part of the venturi tube being
shown in ghost to reveal oxygen sensor cover ports and oxygen
passageways connected thereto;
[0038] FIG. 24 is a cross-sectional view taken of the second part
of the sensor assembly of the device similar to FIG. 23, with
sectional aspects of the second part of the venturi tube being
shown in ghost to reveal desiccant tubes of the device as well
inner-plate flow channels linking the desiccant tubes to oxygen
sensor ports, each of the desiccant tubes being surrounded by a
drying agent;
[0039] FIG. 25 is a front, inner side perspective view of the
second part of the sensor assembly of the device, with the oxygen
sensor cover being removed to better reveal the oxygen sensor and
related components including an oxygen sensor holster plate;
[0040] FIG. 26 is a top, front, inner side perspective view of the
oxygen sensor and the oxygen sensor holster plate of FIG. 25;
[0041] FIG. 27 is a top, rear, inner side perspective view of the
oxygen sensor and the oxygen sensor holster plate of FIG. 25;
[0042] FIG. 28 is a top, front, outer side perspective view of the
oxygen sensor and the oxygen sensor holster plate of FIG. 25;
[0043] FIG. 29 is a graph showing output data from a differential
pressure sensor of the device, the output data showing changes in
differential pressure while the user inhales through the
device;
[0044] FIG. 30 is a graph showing output data from an environmental
sensor of the device, the output data showing changes in absolute
pressure while a user inhales through the device;
[0045] FIGS. 31A to 31D are flow charts showing various algorithms
and communication means for the device of FIG. 1;
[0046] FIG. 32 is a distal end elevation view of a venturi tube
according to a second embodiment;
[0047] FIG. 33 is a proximal end elevation view thereof;
[0048] FIG. 34 is a cross-sectional view taken along lines 34-34 of
the venturi tube shown in FIG. 32;
[0049] FIG. 35 is a cross-sectional view taken along lines 35-35 of
the venturi tube shown in FIG. 32;
[0050] FIG. 36 is a distal end elevation view of a venturi tube
according to a third embodiment;
[0051] FIG. 37 is a proximal end elevation view thereof;
[0052] FIG. 38 is a cross-sectional view taken along lines 38-38 of
the venturi tube shown in FIG. 36;
[0053] FIG. 39 is a cross-sectional view taken along lines 39-39 of
the venturi tube shown in FIG. 36;
[0054] FIG. 40 is a schematic diagram of an oxygen-consumption
measuring device according to a fourth embodiment;
[0055] FIG. 41 is a top, right side perspective view of a facemask
with an oxygen-consumption measuring device coupled thereto
according to a fifth embodiment, the device including a venturi
tube and a sensor assembly extending about the venturi tube;
[0056] FIG. 42 is a rear, top, side perspective view of the device
shown in FIG. 41;
[0057] FIG. 43 is a front elevation view of the device shown in
FIG. 42;
[0058] FIG. 44 is a cross-sectional view taken along lines 44-44 of
the device shown in FIG. 43;
[0059] FIG. 45 is a cross-sectional view taken along lines 45-45 of
the device shown in FIG. 43;
[0060] FIG. 46 is a schematic diagram of the device of FIG. 41;
and
[0061] FIG. 47 is a schematic diagram of an oxygen-consumption
measuring device according to sixth embodiment; and
[0062] FIG. 48 is a schematic diagram of an oxygen-consumption
measuring device according to a seventh embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0063] Referring to the drawings and first to FIG. 1, there is
shown a device 50 for measuring a user's oxygen-consumption. As
seen in FIG. 8, the device includes a top 52, a bottom 54, a rear
56, a front 58, a right side 60 and a left side 62. The front,
rear, top and bottom of the device 50 extend between the sides of
the device. The top 52 and bottom 54 of the device extend from the
front 58 and rear 56 of the device.
[0064] As seen in FIG. 2, the device 50 includes an asymmetrical,
replaceable tubular member, in this example a venturi, which may be
referred to and herein after described as a venturi tube 64.
Referring to FIG. 3, the venturi tube has a proximal end 66 through
which a user's exhalations of air enter into the device. The
proximal end of the venturi tube 64 aligns with the rear 56 of the
device 50 seen in FIG. 1. The venturi tube includes a pair of
spaced-apart, radially-outwardly extending flanges 68 and 70,
flange 68 of which is adjacent to the proximal end thereof. As seen
in FIG. 3, flange 68 includes a plurality of circumferentially
spaced-apart, arced shaped recesses 72 in this example. The venturi
tube 64 includes an annular groove 74 positioned between flanges 68
and 70.
[0065] Referring to FIG. 1, the rear 56 of the device 50 is
connectable to a breath-receiving member, in this example a
facemask 76 shaped to cover a user's mouth and nose. In this
example, the facemask is an off-the-shelf component of a 7450
V2-type which may be purchased at Hans Rudolf, Inc., having an
address of 8325 Cole Parkway Shawnee, Kans., 66227, United States
of America. However, this is not strictly required and other types
facemasks or mouth and/or nose engagement mechanisms may be used in
other embodiments, such as a snorkel mouthpiece with a nose clamp,
for example.
[0066] The facemask has a central aperture 78. As seen in FIG. 11,
the facemask 76 includes a pair of spaced-apart,
inwardly-extending, annular male members 80 and 82 positioned
adjacent to the central aperture of the mask. Groove 74 of the
venturi tube 64 is shaped to selectively receive male member 82 in
this example between flanges 68 and 70. Flange 68 is shaped to at
least partially extend between male members 80 and 82. In this
manner, the venturi tube 64, and thus the device 50, selectively
couples to the facemask 76.
[0067] As seen in FIG. 3, the venturi tube 64 has a distal end 84
spaced-apart from the proximal end 66 thereof. The distal end of
the venturi tube receives air therethrough during inhalation by the
user. The venturi tube 64 includes an outwardly-extending flange 86
which aligns with the distal end 84 and which extends towards the
proximal end of the venturi tube. Flange 86 has indicia 88 thereon
indicating the size of the venturi tube shown, in this example
displaying the word "MEDIUM".
[0068] Still referring to FIG. 3, the venturi tube 64 includes a
top 90, a bottom 92, a right side 94 and a left side 96. The top,
bottom, right and left sides of the venturi tube extend between the
proximal end 66 and distal end 84 of the venturi tube. The sides 94
and 96 of the venturi tube 64 extend from the top 90 to the bottom
92 of the device. As seen in FIG. 4, the venturi tube 64 has a
laterally-extending, cross-sectional first or vertical plane 89 and
a laterally-extending, cross-sectional second or horizontal plane
91 which extends perpendicular to the vertical plane.
[0069] As seen in FIG. 3, the venturi tube 64 includes an outer
surface 98 extending between the flanges 70 and 86. The outer
surface of the venturi tube is oval-shaped in cross-section.
[0070] As seen in FIG. 7, the venturi tube 64 includes a pair of
spaced-apart orientation tabs 93 and 95 located adjacent to flange
86. The tabs extend outwards from the outer surface 98 of the
venturi tube. Tab 93 extends towards the right side 94 of the
venturi tube and tab 95 extends towards the left side 96 of the
venturi tube. The tabs are generally rectangular prisms in shape in
this example.
[0071] As seen in FIG. 6, the venturi tube has a height H between
its flanged ends 86 and 70 thereof that extends in the vertical
direction between the top 90 and bottom 92 of the venturi tube 64.
As seen in FIG. 7, the venturi tube 64 has a width W between its
flanged ends 68 and 84 that extends between sides 94 and 96 of the
venturi tube. The height H of the venturi tube seen in FIG. 6 is
greater than the width W of the venturi tube seen in FIG. 7 in this
example.
[0072] Referring to FIG. 6, the venturi tube 64 includes an annular
first inner surface 99 that extends from the proximal end 66
towards the distal end 84 thereof. The venturi tube includes an
annular second inner surface 100 that extends from the distal end
84 towards the proximal end 66 thereof. The inner surfaces 99 and
100 of the venturi tube are in fluid communication with each other.
The venturi tube 64 includes a constriction 102 interposed between
the inner surfaces thereof. The constriction may also be referred
to as a throat of the venturi tube. As seen in FIG. 5, the
constriction 102 is generally circular in cross-section in this
embodiment. The constriction has a width C.sub.W and a height
C.sub.H. The width and height of the constriction 102 are generally
equal in size to each other in this embodiment.
[0073] The first inner surface 99 of the venturi tube 64 tapers in
the vertical plane 89 in this example from the proximal end 66 of
the venturi tube to the constriction 102. The first inner surface
of the venturi tube defines a first tapered portion or
exhale-receiving portion 104. The venturi tube 64 is shaped to
promote laminar flow through the exhale-receiving portion thereof.
As seen with references to FIGS. 5 to 7, the exhale-receiving
portion 104 of the venturi tube 64 in this example is circular in
shape at the proximal end 66 of the venturi tube. As seen in FIG.
7, the exhale-receiving portion of the venturi tube has a flared
section 105 adjacent to the proximal end 66 of the venturi tube.
The exhale-receiving portion 104 of the venturi tube 64 has a
substantially constant diameter that is oval-shaped in
cross-section thereafter in this example in the horizontal plane 91
as the exhale-receiving portion of the venturi tube 64 extends past
the flared portion 105 and to the constriction 102.
[0074] As seen in FIG. 6, the second inner surface 100 of the
venturi tube 64 tapers in the vertical plane 89 in this example
from the distal end 84 of the venturi tube to the constriction 102.
As seen in FIG. 7, the second inner surface of the venturi tube
also tapers in the horizontal plane 91 from the distal end of the
venturi tube to the constriction. The second inner surface 100 of
the venturi tube defines a second tapered portion or
inhale-receiving portion 106. The inhale-receiving portion of the
venturi tube 64 is more tapered compared to the exhale-receiving
portion 104 of the venturi tube in this example. As seen with
reference to FIGS. 4, 6 and 7, the inhale-receiving portion 106 of
the venturi tube is generally circular in cross-section in this
example.
[0075] As seen in FIG. 7, the venturi tube 64 includes a pair of
proximal sample ports 108 and 110. The sample ports extend through
the venturi tube from the outer surface 98 to the inner surface 99
of the venturi tube. The proximal sample ports 108 and 110 are
positioned near the proximal end 66 of the venturi tube and
adjacent to the flared section 105 of the exhale-receiving portion
104 of the venturi tube. The ports are thus in fluid communication
with the exhale-receiving portion of the venturi tube. Port 108 is
positioned adjacent to the right side 94 of the venturi tube 64 and
port 110 is position adjacent to the left side of the venturi tube.
Referring to FIG. 3, the proximal sample ports are positioned
between the top and bottom of the venturi tube 64 in this example,
as seen by port 108 positioned between top 90 and bottom 92.
[0076] As seen in FIG. 7, the venturi tube 64 includes a pair of
constriction sample ports 112 and 114, which may also be referred
to as throat sample ports. The sample ports extend through the
venturi tube from the outer surface 98 to the inner surface 99
thereof. The constriction sample ports 112 and 114 are positioned
adjacent to, align with and are in fluid communication with the
constriction 102 of the venturi tube. Port 112 is positioned
adjacent to the right side 94 of the venturi tube 64 and port 114
is position adjacent to the left side of the venturi tube.
Referring to FIG. 3, the constriction sample ports are positioned
between the top and bottom of the venturi tube 64 in this example,
as seen by port 112 positioned between top 90 and bottom 92.
[0077] Still referring to FIG. 3, the venturi tube 64 includes in
this example a pair of spaced-apart laterally-extending flow
channels 116 and 118. The flow channels extend from the right side
94 to the left side 96 of the venturi tube 64. Flow channel 116 is
adjacent to the top 90 of the venturi tube and flow channel 118 is
adjacent to the bottom 92 of the venturi tube in this example.
Channels 116 and 118 align adjacent and to the right of the
constriction ports 112 in this example from the perspective of FIG.
3. As seen in FIG. 6, channels 116 and 118 are separated from and
not in communication with the main air stream flowing through
constriction 102 of the venturi tube 64.
[0078] As seen in FIG. 8, device 50 further includes a sensor
assembly 120. The sensor assembly includes two parts 122 and 124
hingedly connected together. Referring to FIG. 12, parts 122 and
124 of the assembly 120 include housings 126 and 127. The housings
include outer shells 128 and 129, respectively. The outer shells
128 and 129 include arcuate-shaped front walls 130 and 131,
respectively. The front walls align adjacent to the front 58 of the
device 50.
[0079] The walls 130 and 131 have centrally positioned recessed
portions 117 and 119, respectively, which face each other and which
extend radially outwards. The recessed portions are generally
rectangular prisms in shape in this example. The recessed portions
117 and 119 are shaped to receive the orientation tabs 93 and 95 of
the venturi tube 64 seen in FIG. 7. The tabs and recessed portions
so shaped and positioned thus promote the correct orientation of
the venturi tube relative to the outer shells 128 and 129.
[0080] As best seen in FIG. 14, the outer shells 128 and 129
include arcuate-shaped rear walls 132 and 133, respectively. The
rear walls align adjacent to and with the rear 56 of the device.
The front and rear walls of the outer shells include inner and
outer peripheral edges. This is seen by inner peripheral edge 134
and outer peripheral edge 136 for rear wall 132 of outer shell 128
and by inner peripheral edge 135 and outer peripheral edge 137 for
rear wall 133 of outer shell 129. The inner peripheral edges of the
front and rear walls of the outer shells have a curvature that is
less than that of the outer peripheral edges of the front and rear
walls of the outer shells in this example. The inner peripheral
edges 134 of the front and rear walls of outer shell 128 face the
inner peripheral edges 135 of the front and rear walls of outer
shell 129 in this example.
[0081] Referring to FIG. 12, the outer shells 128 and 129 include
curved outer walls 138 and 139, respectively. The outer walls are
arcuate-shaped in lateral cross-section in this example. Outer wall
138 of outer shell 128 extends between and is integrally formed
with the front wall 130 and rear wall 132 of the outer shell in
this example. The outer wall 138 aligns with the side 60 of the
device 50 and extends from the top 52 to the bottom 54 of the
device in this example. Outer wall 139 of outer shell 129 extends
between and is integrally formed with the front wall 131 and rear
wall 133 of the outer shell in this example. The outer wall 139
aligns with the side 62 of the device 50 and extends from the top
52 to the bottom 54 of the device in this example.
[0082] As seen in FIG. 12, the outer shells 128 and 129 have first
or upper ends 148 and 150, respectively, which align with the top
52 of the device 50. The outer shells 128 and 129 have second or
lower ends 154 and 156, respectively, which align with the bottom
54 of the device 50. In this example, the upper ends 148 and 150 of
the outer shells hingedly couple together via a hinge mechanism
152.
[0083] As seen in FIG. 2, the sensor assembly 120 has an open
position in which the parts 122 and 124 thereof are angled outwards
from each other. In this case, the lower ends 154 and 156 of the
outer shells 128 and 129, respectively, are spaced-apart from each
other when the sensor assembly is in the open position. The hinge
mechanism 152 enables the sensor assembly 120 to be moveable from
the open position to a closed position seen in FIGS. 8 and 12 to
14, for example. As seen in FIG. 13, the lower ends 154 and 156 of
the outer shells 128 and 129 are adjacent to each other when the
sensor assembly is in the closed position. Parts 122 and 124 of the
sensor assembly 120 when in the closed position form an aperture
158. The aperture is oval-shaped in cross-section in this example.
As seen with reference to FIGS. 2 and 8, the aperture is shaped to
receive the annular outer surface 98 of venturi tube 64 as the
sensor assembly 120 moves to the closed position. In this manner,
the venturi tube is thus selectively received between the two parts
122 and 124 of the sensor assembly.
[0084] The selectively opening and closing of the sensor assembly
enables a user to selectively replace the venturi tube 64. This may
thereby effectively result in a device 50 in which all parts that
directly touch the user's air stream are replaceable. The device so
configured may thus allow multiple people to use the same device
without sharing or exchanging germs.
[0085] As seen in FIG. 15, the sensor assembly 120 includes a latch
mechanism 160 located adjacent to the bottom 54 of the device 50.
As seen in FIG. 21, the latch mechanism is centrally disposed
between the rear 56 and front 58 of the device. Referring back to
FIG. 15, the latch mechanism includes a male member, in this
example in the form of a hook 162. The hook in this example is
coupled to and extends from lower end 154 of outer shell 138 in
this example. The latch mechanism 160 further includes a female
member, in this example in the form of a grooved seat 164
positioned adjacent to the lower end 156 of outer shell 139.
Grooved seat 164 is shaped to selectively receive hook 162. In this
manner, the parts 122 and 124 of the sensor assembly may
selectively couple together in the closed position of the sensor
assembly seen in FIG. 15.
[0086] Still referring to FIG. 15, the outer shells 128 and 129
include openings 142 and 143, respectively, which extend between
outer walls 138 and 139, respectively. Housings 126 and 127 include
inner planar members, in this example a circuit board cover 144 and
an oxygen sensor cover 145, respectively. The circuit board cover
is shaped to be received within opening 142 of outer shell 138. The
oxygen sensor cover 145 is shaped to be received within opening 143
of outer shell 139.
[0087] The covers 144 and 145 have curved inner surfaces 146 and
147 that face each other in this example. As seen in FIG. 13, the
inner surfaces of the covers are arcuate-shaped in cross-section
and extend between the top 52 and the bottom 54 of the device 50.
As seen in FIG. 12, recessed portions 117 and 119 of walls 130 and
131 are adjacent to inner surfaces 146 and 147 of the covers 144
and 145, respectively.
[0088] As seen in FIG. 14, the inner surface 146 of cover 144 of
housing 126 has a curvature that is substantially similar to and
aligned with the inner peripheral edges 134 of the front and rear
walls of the outer shell 128. The curvature of inner surface 146 of
the cover is less than that of the outer wall 138 of the housing in
this example. Similarly, the inner surface 147 of cover 145 of
housing 127 has a curvature that is substantially similar to and
aligned with the inner peripheral edges 135 of the front and rear
walls of the outer shell 129. The curvature of inner surface 147 of
the cover is less than that of the outer wall 139 of the housing in
this example. Aperture 158 is enclosed by the inner surfaces 146
and 147 of covers 144 and 145 in this example. As seen with
reference to FIGS. 2 and 8, the inner surfaces of the covers abut
the outer surface 98 of the venturi tube 64 when the sensor
assembly 120 is in the closed position.
[0089] Referring to FIG. 20, circuit board cover 144 has an outer
surface 166 opposite its inner surface 146. The outer surface of
the cover is substantially rectangular in shape in this example.
The device 50 includes a pair of inlets, in this example pressure
sensor inlets 168 and 170. The pressure sensor inlets extend
through the cover 144 from the inner surface 146 towards the outer
surface 166 thereof. The pressure sensor inlets 168 and 170 are
positioned between the rear 56 and front 58 of the device 50 in
this example. Sensor inlet 170 is positioned adjacent to the bottom
54 of the device in this example, and sensor inlet 168 is
positioned adjacent to and above sensor inlet 170 from the
perspective of FIG. 20. As seen in FIG. 21, pressure sensor inlet
168 is positioned below proximal sample port 108 of the venturi
tube 64 in this example. Pressure sensor inlet 170 is position
below constriction sample port 112 in this example.
[0090] Still referring to FIG. 21, cover 144 includes a pair of
conduits, in this example channels 172 and 174. The channels are in
communication with, recessed relative to and extend inwards
relative to the inner surface 146 of the cover. Channel 172 extends
between pressure sensor inlet 168 and proximal sample port 108 of
the venturi tube 64. In this manner, pressure sensor inlet 168 and
proximal sample port 108 are thus in fluid communication with each
other via channel 172. Channel 174 extends between pressure sensor
inlet 170 and constriction sample port 112 of the venturi tube 64.
In this manner, pressure sensor inlet 170 and constriction sample
port 112 are thus in fluid communication with each other via
channel 174. Channels 172 and 174 are also shown schematically in
FIG. 9. The channels are positioned so that the sample ports are of
equal distance from the air stream.
[0091] Referring back to FIG. 21, cover 144 includes an additional
conduit, in this example channel 175 in communication with,
recessed relative to and extending inwards relative to the inner
surface 146 of the cover. Channel 175 extends between constriction
sample port 112 of the venturi tube 64 and laterally-extending flow
channel 116 of the venturi tube. In this manner, constriction
sample port 112 and channel 116 are thus in fluid communication
with each other via channel 175.
[0092] As seen in FIG. 9, the device 50 includes a flow sensing
mechanism, in this example a pressure sensor, in this case a
differential pressure sensor 176. The differential pressure sensor
in this example is an off-the-shelf product, in this case an
AMS5915-type pressure sensor that may be purchased at Analog
Microelectronics GmbH, having an address of An der Fahrt 13, 55124
Mainz, Germany. However, this is not strictly required and other
types of pressure sensors may be used in other embodiments.
[0093] The pressure sensor 176 is in fluid communication with the
constriction 102 of the venturi tube 64 via constriction sample
port 112, channel 174 and pressure sensor inlet 170. The pressure
sensor is in fluid communication with the exhale-receiving portion
104 of the venturi tube 64 adjacent to the proximal end 66 of the
tube via proximal sample port 108, channel 172 and pressure sensor
inlet 168. The pressure sensor 176 in this example measures the
difference in pressure at inlets 168 and 170 and emits a pressure
sensor signal in response thereto. The pressure sensor 176 so
configured measures the flow rate through the venturi tube 64 as
well as the breath state, namely, a no breath state, an
inhale-breath state, or an exhale-breath state.
[0094] Referring to FIG. 20, cover 144 further includes an
environmental sensor inlet 178. The environmental sensor inlet
extends from the outer surface 166 towards the inner surface 146 of
the cover. As seen in FIG. 21, the environmental sensor inlet 178
is aligned and in communication with constriction sample port 112.
However, this is not strictly required, and the sensor inlet may
alternatively align with and be in communication with constriction
sample port 114 as seen in FIGS. 9 and 10. Referring back to FIG.
20, the environmental sensor inlet 178 is positioned adjacent to
the front 58 of the device 50 in this example. As seen with
reference to FIGS. 21 and 22, the environmental sensor inlet is
positioned adjacent to and aligns with the constriction 102 of the
venturi tube 64 in this example. Referring to FIG. 20, the
environmental sensor inlet 178 is positioned between the top 52 and
bottom 54 of the device 50 in this example.
[0095] As seen in FIG. 9, the device 50 includes an environmental
sensor 180. The environmental sensor in this example is an
off-the-shelf product, in this case a BME280-type environmental
sensor which may be purchased at Bosch Sensortec GmbH, having an
address of Gerhard-Kindler-StraBe 9, 72770 Reutlingen/Kusterdingen,
Germany. However, this is not strictly required and other types of
environmental sensors may be used in other embodiments. As seen in
FIG. 9, the environmental sensor 180 has a port 181 connected to
and in fluid communication with the constriction port 114 via
conduit 183 in this example.
[0096] The environmental sensor 180 outputs an absolute pressure
signal as shown in FIG. 30. During an inhale seen in FIG. 10, the
differential pressure sensor 176 is subject to turbulence seen in
FIG. 29 that is absent in the environmental sensor's pressure
output seen in FIG. 30. The device 50 is thus configured to use the
change in the environmental sensor's absolute pressure output to
determine the inhale flow. This circumvents signal noise which may
otherwise occur in the differential pressure sensor signal during
inhales. Referring to FIG. 9, flow through the device 50 is thus
measured bi-directionally via the differential pressure sensor 176
for exhalations and breath state detection, and via the
environmental sensor 180 for inhalations. The environmental sensor
also outputs temperature and relative humidity data for flow
calculations and oxygen sensor signal correction.
[0097] As mentioned above, the pressure sensor output is used for
breath state detection and exhale flow calculations. The pressure
sensor 176 is used to detect breath state by means of a
zero-crossing check of the differential pressure sensor output with
consideration to the sensor's signal noise threshold. If the breath
state is in an exhale direction, the differential pressure sensor
output is used to compute the instantaneous flow rate between data
samples. If the breath state is in an inhale direction, the
difference between the environmental sensor pressure output and
ambient pressure is used to compute an instantaneous flow rate
between data samples. Ambient pressure is the last environmental
sensor pressure output where no breathing has occurred. The
instantaneous flow volume between data samples is calculated using
each gap's instantaneous flow rate. When the breath state returns
to no breathing, all of the instantaneous flow volumes for the
completed breath segment are summed. This sum is known by those
skilled in the art as tidal volume (Tv(L)). Breath segment
frequency is then calculated using the following formula: (segment
Rf)=30 s/(breath segment time(s)). The ventilation (Ve) of the
breath segment is calculated using the following formula: Ve
(L/min)=(breath segment frequency).times.(breath segment tidal
volume (L)). For each pair of inhale and exhale segments, average
breath segment frequency (Rf), Tv, and Ve are determined as the
final flow metrics for the whole breath.
[0098] As seen in FIG. 16, the device 50 includes a circuit board
182. The circuit board mounts to the outer surface 166 of cover 144
via a pair of spaced-apart fasteners, in this example screws 184
and 186. The circuit board has an inner side 187, best seen in FIG.
19, which faces the outer surface 166 of the cover seen in FIG. 16.
Differential pressure sensor 176 and environmental sensor 180
couple to the inner side of the circuit board 182 in this
example.
[0099] As seen in FIG. 18, the device 50 includes a processor, in
this example a microprocessor 190 coupled to the outer side 188 of
the circuit board. In this case, the microprocessor is an
off-the-shelf component of a NRF51422-type which may be purchased
at Nordic Semiconductor ASA, having an address of P.O. Box 436,
Skoyen, 0213, Oslo, Norway. However, this is not strictly required
and other types of processors may be used in other embodiments. The
microprocessor 190 operatively couples with the differential
pressure sensor 176 and environmental sensor 180 seen in FIG. 19
and receives data therefrom. The circuit board 182 connects to the
analog output of the oxygen sensor by the means of two wires in
communication with the two thru-hole connections labeled "OXYGEN
SENSOR CONNECTION".
[0100] As seen in FIG. 18, the device 50 further includes a USB
connector 192 coupled to the outer side 188 of the circuit board
182. The USB connector is operatively connected to the
microprocessor and enables selective uploading of data from the
processor to a remote server or computer, for example. As seen in
FIG. 16, the device 50 additionally includes a battery 194 for
supplying power thereto. In this example, the battery is a
lithium-polymer rechargeable type battery; however, this is not
strictly required and other types of batteries or power sources may
be used in other embodiments. The battery operatively connects to
the microprocessor 190.
[0101] The device 50 includes an on/off switch, in this example in
the form of an on/off plunger switch 196 coupled to the circuit
board 182. The switch is configured to cut off power to the device
upon the switch being pushed inwards towards the circuit board.
[0102] As seen in FIG. 15, a pair of spaced-apart flanges 198 and
200 extend inwards from the front wall 130 of outer shell 128. The
flanges are shaped to receive battery 194 therebetween.
[0103] The oxygen sensor cover 145 includes an outer side 202
opposite the inner surface 147 thereof. The cover includes a pair
of spaced-apart upper and lower receptacles 204 and 206 and a
central receptacle 208 between the peripheral receptacles in this
example. The receptacles are situated along the outer side 202 of
the oxygen sensor cover 145.
[0104] As seen in FIG. 22, cover 145 includes a conduit, in this
example a cover plate flow channel 210 that is in communication
with, recessed relative to and outwardly extending relative to the
inner surface 147 of the cover. The cover further includes a first
oxygen sensor cover plate port 212 that extends from the inner
surface 147 of the cover through to the outer side 202 of the cover
seen in FIG. 15 in this example. Referring to FIGS. 21 and 22,
constriction sample port 112 seen in FIG. 21 is thus in
communication with oxygen sensor cover plate port 212 seen in FIG.
22 via channel 175 of the circuit board cover 144 seen in FIG. 21,
flow-channel 116 of the venturi tube 64 seen in FIG. 22, and
channel 210 of the oxygen sensor cover 145 seen in FIG. 22.
[0105] As seen in FIG. 24, the device 50 includes in this example a
pair of spaced-apart desiccant plates 214 and 216 adjacent to the
rear 56 and front 58 of the device. The plates are generally
rectangular prisms in this example and operatively couple to the
outer side 202 of the oxygen sensor cover 145 seen in FIG. 15.
[0106] Referring back to FIG. 24, plate 214 includes a first or
upper conduit extending therein, in this example a channel 218
which is adjacent to the top 52 of the device 50. The channel is in
fluid communication with the oxygen sensor cover plate port 212
seen in FIG. 23.
[0107] Still referring to FIG. 23, the oxygen sensor cover has a
second oxygen sensor cover plate port 220 that is in fluid
communication with proximal sample port 110 seen in FIG. 22.
Referring back to FIG. 23, plate 214 includes a second or lower
conduit extending therein, in this example a channel 222. The
channel is adjacent to the bottom 54 of the device 50 and is in
fluid communication port 220.
[0108] Plate 216 includes a first or upper conduit extending
therein, in this example a first u-shaped channel 224 seen in FIG.
24 adjacent to the top 52 of the device 50. The plate 216 includes
a second or lower conduit extending therein, in this example a
second u-shaped channel 226 adjacent to the bottom 54 of the device
50.
[0109] As seen in FIG. 24, the device 50 includes a pair of
desiccants, in this example a pair of desiccant tubes 228 and 230.
In this example, the desiccant tubes are off-the-shelf components
of Nafion.TM.-type tubing, which may be purchased at Perma Pure
LLC, having an address of 1001 New Hampshire Ave., Lakewood, N.J.,
08701, United States of America. However, this is not strictly
required and other desiccant tubes and/or other types of desiccants
may be used in other embodiments.
[0110] Desiccant tube 228 extends between channels 218 and 224. The
tube is thus in fluid communication with the constriction 102 of
the venturi tube 64 seen in FIG. 22 via: port 112, channel 175 and
channel 116 seen in FIG. 21; channel 210 and port 212 seen in FIG.
22; and channel 218 seen in FIG. 24. As seen in FIG. 15, tube 228
is received within and extends along receptacle 204 of the oxygen
sensor cover 145 in this example.
[0111] As seen in FIG. 24, desiccant tube 230 extends channels 222
and 226. The tube is thus in fluid communication with the
exhale-receiving portion 104 of the venturi tube 64 seen in FIG. 22
via: port 110 seen in FIG. 22; and port 220 and channel 222 seen in
FIG. 23. As seen in FIG. 15, tube 230 is received within and
extends along receptacle 206 of the oxygen cover 145 in this
example.
[0112] As seen in FIG. 10, the device 50 further includes a pair of
drying agents 231 and 233 adjacent to and surrounding respective
desiccant tubes 228 and 230. Each of the drying agents is in the
form of silicate gel beads in this example. However, this is not
strictly required and other drying agents may be used in other
embodiments.
[0113] As seen in FIG. 15, the device 50 includes an oxygen sensor
232. In this example, the oxygen sensor is a passive sensor and is
an off-the-shelf component of the galvanic fuel cell type, which
may be purchased at Analytical Industries Inc., having an address
of 2855 Metropolitan Place, Pomona, Calif., 91767, United States of
America. However, this is not strictly required and other types of
oxygen sensors may be used in other embodiments. Receptacle 208 of
cover 145 is shaped to at least partially receive the oxygen sensor
232 therein.
[0114] As seen in FIG. 24, the oxygen sensor has a pair of oxygen
sensor ports 234 and 236 that are in fluid communication with
channels 224 and 226, respectively. As seen in FIG. 10, the oxygen
sensor 232 is thus in fluid communication with the constriction 102
and the exhale-receiving portion 104 of the venturi tube 64. As
seen in FIG. 24, the oxygen sensor is positioned between and in
fluid communication with the desiccants tubes 228 and 230.
[0115] As seen in FIG. 25, the device 50 includes an oxygen sensor
micro mixing chamber 238 that is adjacent to and in communication
with oxygen sensor ports 234 and 236 seen in FIG. 24. The device 50
includes an oxygen sensor electrical output spring connector
mechanism 240 through which the oxygen sensor may emit an oxygen
sensor signal.
[0116] As seen in FIGS. 26 to 28, the device includes an oxygen
sensor holster 242 in this example shaped to receive the oxygen
sensor 232 at least in part. As seen in FIG. 15, the holster is
positioned between the outer shell 139 and oxygen sensor cover
plate 145. The holster 242 is shaped to be selectively removable
from the rest of the device 50.
[0117] The device 50 so shaped and described herein results in a
gas channel flow rate that may be drastically lower than in
previous known prior art systems. As a result, by using small
desiccant tubes 228 and 230 seen in FIG. 10, the device 50 as
herein described may desiccate sample gas prior to it reaching the
oxygen sensor 232.
[0118] In operation and referring to FIG. 31A, the main routine
associated with the device 50 begins with initializing the
microcontroller (box 246), initializing the sensors (box 248),
initializing the universal serial bus (USB) and wireless system
such as Bluetooth.RTM. (box 250), and initially setting the current
state of the device to idle. Thereafter, the software polls the USB
and Bluetooth.RTM. communication ports awaiting connection from a
parent device. The parent device may be a smartphone or personal
computer 255 as seen in FIG. 31D, for example. Serial communication
252 enables the device 50 to communicate with the parent computer
255, sharing information such as respiratory data 257, device
information 259, device error data 261 and device state and
settings data 263. The latter may include venturi size and the
like. Respiratory data may include metrics such as Time,
Respiratory Frequency, Tidal Volume, Ventilation, Fraction of
Expired Oxygen, Fraction of Inspired Oxygen, or Volume of Oxygen
Consumed (VO2). The computer 255 will at some point order the
software to begin a recording. The software determines the current
state of the device (box 252): an idle/default state (box 254); a
calibrating state (box 256); or a recording state (258). If the
device is determined to be in an idle/default state, the loop of
the routine continues as before (box 260).
[0119] When commanded by the parent device to enter a RECORD state,
the software may determine that calibration of the sensors has not
yet been performed, and thusly cause the device 50 to enter the
calibration state. If the software determines that calibration has
already occurred, it may directly enter recording state without
re-calibrating. If the device is determined to be in a calibration
state (box 256), the system is updated (box 259) periodically, such
as every 20 milliseconds for example. This means all sensor
intermediate data is updated. Once calibration of all mentioned
sensors is complete, the device 50 automatically switches to the
RECORD state.
[0120] Referring to FIG. 31B, the differential pressure sensor is
first polled (box 261) by the device's software to determine the
status thereof. The environmental sensor is next polled by the
device's software for absolute pressure, temperature and relative
humidity (box 262). The oxygen sensor temperature-compensated
analog output is next polled by the device's software, as indicated
by box 264. The device's processor determines and stores ambient
pressure data from the absolute pressure signal (box 266). The
device's processor next determines and stores the
environmentally-normalized oxygen concentration value (box 268).
The environmental sensor 180 and differential pressure sensor 176
seen in FIG. 9 are thus calibrated to their ambient measurements,
as shown by box 270 in FIG. 31A. This is done to effectively track
sensor signal drift over time due to change in environment.
[0121] For the calibration state, a pre-workout calibration method
is needed to sample ambient oxygen concentration in order to create
a linear oxygen concentration conversion scale for the workout.
Calibration must be performed prior to each workout. In order to
obtain a passive oxygen concentration measurement, there is further
provided a method of calibrating the device to obtain an ambient
oxygen sensor value. The method includes normalizing the oxygen
sensor signal with ambient pressure, temperature, and relative
humidity to inhibit drift caused by changes in environment, such as
changes in elevation, as shown by box of numeral 272 in FIG. 31A.
The method includes purging the venturi tube 64 by having a user
take two slow, large-volume inhales of air through the device
successively without exhaling through the device. In other
embodiments, this could be three breaths or more. The method
further includes measuring and storing via a processor the ambient
oxygen sensor value thereafter. With this data point a linear scale
is realized to measure any oxygen sensor output in percent
concentration.
[0122] Referring to FIG. 31A, one can thereafter begin recording
data (box 258). The oxygen sensor has a response delay of T90=1
second according to one example.
V = V 0 .times. e - RC t ##EQU00001##
where: V is extrapolated O.sub.2%; [0123] V.sub.0 is the change in
O.sub.2 from a breath segment from start to end; [0124] e is the
natural log constant; [0125] t is the time delta between O.sub.2
delta start to end; and [0126] RC is an experimentally determined
correction constant. Using the above formula, for each inhale and
exhale breath segment, the microprocessor extrapolates at what
value the oxygen sensor would settle were it given the time to do
so prior to the upcoming breath segment. This extrapolated value is
the oxygen concentration of the given breath segment (FeO2 for
exhale and FiO2 for inhale).
[0127] The oxygen sensor measures inspired and expired oxygen
concentrations (FiO2 & FeO2) breath-by-breath. Using the
passive oxygen concentration measurement and the bidirectional flow
measurement processes to acquire intermediate data, compute oxygen
consumption using this formula: VO2=Ve*(AmbientO2-FeO2)/100, where
VO2 (mL/min) is oxygen consumption, AmbientO2(%) is the ambient
oxygen concentration of the environment, and FeO2(%) is the oxygen
concentration of the user's expired breath. One divides by 100 to
convert the 0-21% oxygen delta into a 0.0-1.0 coefficient.
[0128] The device 50 measures both inhale and exhale flow and
oxygen concentrations, but only considers exhale-phase metrics to
produce final values for the breath. This is due to the
asymmetrical shape of the venturi tube which causes exhale metrics
to be much more accurate and repeatable. Less venturi turbulence on
the exhale means greater flow through the oxygen sensor. Inhale
flow measurement for the device 50 is only used to check for mask
leaks. Inhale flow is used in comparison with that of exhale to
detect mask leaks.
[0129] The device as herein described is compact and requires low
power, with a 30 mA current draw according to one example. The
device 50 as herein described uses passive sampling of metrics.
This as a result may reduce power requirements. The device 50 so
configured may also thus inhibit external vibration by eliminating
the need for a sampling pump and mixing chamber. Such a sampling
system may decrease the total size of the device and also increase
oxygen sensor response time.
[0130] The device as herein described provides a mixing chamber
that is relatively small. The passive sampling system of the device
may thus provide significantly improved oxygen sensor reaction time
due to the reduced dead space between the main air stream and
sensor.
[0131] Coupled with a differential pressure sensor that measures
bidirectional flow, this compact, portable device 50 as herein
described may thus produce at least the following ventilatory and
oxygenation metrics: [0132] a. tidal volume, namely, the volume of
air that is moved per breath ("TV"); [0133] b. respiratory
frequency in breaths per minute ("RF"); [0134] c. minute
ventilation, namely, the amount of air moved in and out of the
lungs in litres per minute ("VE"); [0135] d. the fraction of
expired air that is oxygen ("FEO2"); [0136] e. the fraction of
inspired air that is oxygen ("FIO2"); [0137] f. volume of oxygen
consumed ("VO.sub.2")=O2 volume inspired-O2 volume expired in
mL/min; and [0138] g. maximum oxygen consumption
("VO.sub.2MAX").
[0139] The asymmetrical, ovular shape of the venturi tube 64 may
increase accuracy of exhale metrics, while decreasing the accuracy
of inhale metrics. The device 50 as herein described includes an
asymmetrical venturi that drastically reduces turbulence in the
exhale phase while increasing turbulence in the inhale phase. Less
turbulence means greater flow through the respiratory flow channel,
resulting in an oxygen sensor that is better purged with expired
air during regular breathing. Referring to FIG. 10, the greater
length between proximal ports 108 and 110 and constriction ports
112 and 114 of the venturi tube 64 may allow for a slower change in
inner diameter, thereby creating air flow having less turbulence.
Air turbulence along a concave wall may be proportional to its
angle. The ports 108 and 110 are thus located on the flattest side
of the ellipse cross-section.
[0140] Venturi tube 64 of the embodiment shown in FIGS. 1 to 31C is
shaped to perform measurements and acquire data during sub-maximal
exercise testing, such as when a user is hiking, for example.
[0141] Referring to FIG. 31A, in the recording state (box 258),
after an update (box 259) of the device data has occurred, the data
is next processed (box 273). Referring to FIG. 31C, a flow chart of
the processing of data is shown. The device 50.1 determines breath
state (box 274) by evaluating differential pressure data. The
device may also use environmental data to this end. The processor
may determine based on this data that there is a no breath (box
276), an inhale breath state (box 278), or an exhale breath state
(box 279).
[0142] Where the processor determines that there is an inhale
breath state, sensor data is used to determine flow volume since
the previous loop execution (box 280). Put another away, the
processor determines the volume of air that has passed through the
venturi tube since the previous loop execution using the
differential pressure waveform or absolute pressure waveform from
the environmental sensor. The processor thereafter determines the
sum of the flow volume of the inhale breath since the beginning of
the breath segment (box 282). The processor next determines if the
breath state has just been switched from an exhale breath state
(box 284) using differential pressure data. If so, the processor
then determines the final metrics for the entire previous exhale
breath segment (286). Thereafter, the flow chart returns to being
the loop (box 260) once more as seen in FIG. 31A. Alternatively, if
the processor determines that there has not been a recent switch in
breath state, such calculations are omitted and here too the flow
chart returns (box 287) to the begin loop state (box 26) of FIG.
31A.
[0143] If the processor determines that there is an exhale state
(box 279), sensor data is used to determine flow volume since the
previous loop execution (box 288)) using the differential pressure
waveform or absolute pressure waveform from the environmental
sensor. Put another away, the processor determines the volume of
air that has passed through the venturi tube since the previous
loop execution. The processor thereafter determines the sum of the
flow volume of the exhale breath since the beginning of the breath
segment (box 290). The processor next determines if the breath
state has just been switched from an inhale breath state (box 292)
using differential pressure data. If so, the processor then
determines both the final metrics for the entire previous inhale
breath segment and the final metrics for the entire previous breath
(294). Thereafter, the flow chart returns (box 287) to being the
loop (box 260) once more as seen in FIG. 31A. Alternatively, if the
processor determines that there has not been a recent switch in
breath state, such calculations are omitted and here too the flow
chart returns to the begin loop state (box 26) of FIG. 31A.
[0144] FIGS. 32 to 36 show a venturi tube 64.1 for a device 50.1
for measuring a user's oxygen-consumption according to a second
aspect. Like parts have like numbers and functions as the tube 64
and device 50 shown in FIGS. 1 to 31C with the addition of decimal
extension ".1". The device 50.1 and venturi tube 64.1 are the same
as described for tube 64 and device 50 with the following
exceptions.
[0145] As seen in FIG. 33, constriction 102.1 of venturi tube 64.1
is oval-shaped in cross-section. The width C.sub.W.1 of the
constriction is substantially the same as width C.sub.W of
constriction 102 for tube 64 seen in FIG. 5. The height C.sub.H.1
of the constriction 102.1 of the venturi tube is longer than its
width C.sub.W1 and longer than that of height C.sub.H of the
constriction 102 of tube 64 seen in FIG. 5. The cross-sectional
area of constriction 102.1 is larger than that of constriction 102
for tube 64 seen in FIG. 5. Tube 64.1 shown in FIGS. 32 to 35 is
shaped to perform measurements and acquire data during maximal
tests or high-intensity exercise while running or biking. Tube 64.1
is thus shaped for high flow rates.
[0146] FIGS. 36 to 39 show a venturi tube 64.2 for a device 50.2
for measuring a user's oxygen-consumption according to a third
aspect. Like parts have like numbers and functions as the tube 64
and device 50 shown in FIGS. 1 to 31C with the addition of decimal
extension ".2". The device 50.2 and venturi tube 64.2 are the same
as described for tube 64 and device 50 with the following
exceptions.
[0147] As seen in FIG. 37, constriction 102.2 of venturi tube 64.2
is oval-shaped in cross-section. The width C.sub.W.2 of the
constriction is substantially the same as width C.sub.W of
constriction 102 for tube 64 seen in FIG. 5 and substantially the
same as width C.sub.W.1 of constriction 102.1 for tube 64.1 seen in
FIG. 33. The height C.sub.H.2 of the constriction 102.2 of the
venturi tube is shorter than its width C.sub.W2 and shorter than
that of height C.sub.H of the constriction 102 of tube 64 seen in
FIG. 5.
[0148] The cross-sectional area of constriction 102.2 is smaller
than that of constriction 102 for tube 64 seen in FIG. 5 and
smaller than that of constriction 102.1 of tube 64.1 seen in FIGS.
33 to 36. Tube 64.2 of the embodiment shown in FIGS. 36 to 39 is
shaped to perform measurements and acquire data when the user is
resting or walking. Tube 64.2 is thus shaped for low flow
rates.
[0149] The sensor assembly 120 and tubes 64, 64.1 and 64.2 as
herein described may thus be part of a kit comprising the assembly
and venturi tubes of varied shapes. The device so configured may
thus be customizable to desired test conditions and criteria. This
is advantageous because it allows for tubes having different flow
ranges for each size. The replaceability of the venturi tube, while
keeping the rest of the device the same as before, may function to
reduce overall costs and improve the versatility of the device.
[0150] FIG. 40 shows a schematic diagram of a device 50.3 for
measuring a user's oxygen-consumption according to a fourth aspect.
Like parts have like numbers and functions as the tube 64 and
device 50 shown in FIGS. 1 to 31C with the addition of decimal
extension ".3". The device 50.3 is the same as described for device
50 with the following exceptions.
[0151] In this embodiment, a second environmental sensor 244 for
oxygen correction is employed right at the oxygen sensor 232.2 in
order to achieve an improved environmental correction. The sensor
is interposed between and in communication with dessicant tube
228.3 and oxygen sensor port 234.3 of oxygen sensor 232.3.
[0152] Environmental sensor 180.3 is used for flow correction in
this embodiment. The sensor is interposed between and in
communication with constriction sample port 112.3 and pressure
sensor inlet 170.3 of differential pressure sensor 176.3.
[0153] FIGS. 41 to 46 show a device 50.4 for measuring a user's
oxygen-consumption according to a fifth aspect. Like parts have
like numbers and functions as the tube 64 and device 50 shown in
FIGS. 1 to 31C with the addition of decimal extension ".4". The
device 50.4 is the same as described for device 50 with the
following exceptions.
[0154] As seen in FIG. 41, the sensor assembly 120.4 is generally a
hollow rectangular prism in shape in this example. The top 52.4,
bottom 54.4 and sides 60.4 and 62.4 of the device are rectangular,
with the top and bottom being wider than said sides in this
example. As seen in FIG. 42, the sensor assembly 120.4 includes a
mouth piece 300 located at the rear 56.4 of the device 50.4. The
mouth piece includes a pair of spaced-apart flanged side members
302 and 304 which align with sides 60.4 and 62.4, respectively, of
the device. The proximal end 66.4 of the venturi tube 64.4 is
centrally located between and partially enclosed by the side
members of the mouth piece 300 in this example. As seen in FIG. 45,
annular groove 74.4 is formed in this example via flange 68.4 of
the venturi tube 64.4 and an outer end 306 of the circuit board
cover 144.4. The groove couples with corresponding flanges of the
face mask 76.4 in a substantially similar manner as described in
FIG. 11 for device 50.
[0155] Referring to FIG. 42, the device 50.4 with its mouth piece
is shaped to also enable a patient to operate the device by
wrapping their lips about the proximal end of the venturi tube. The
side members 302 and 304 are shaped for alignment with the
mask.
[0156] As seen in FIG. 41, the sensor assembly 120.4 comprises a
single, integrated curved outer wall 138.4 in this example. The
front walls 130.4 and 131.4 of the sensor assembly are likewise
integrally formed and comprising a unitary whole. As seen in FIG.
45, the circuit board cover 144.4, oxygen sensor cover 145.4 and
mouth piece 300 are integrally coupled together and form a unitary
whole in this example.
[0157] As seen in FIG. 46, the oxygen sensor 232.4 of device 50.4
includes a first oxygen port 234.4 connected to and in fluid
communication with the proximal end 66.4 of the venturi tube 64.4
via proximal sample port 110.4 in this example. The second oxygen
port 236.4 of the oxygen sensor is connected to and in fluid
communication with the ambient air/atmosphere 308 via conduit 222.4
and open air port 310. The oxygen sensor 232.4 of device 50.4 is
thus in communication with ambient air in this embodiment. Device
50.4 so configured may allow for better purging of the oxygen
sensor 232.4. As seen in FIG. 41, the open air port extends through
the outer wall 138.4 of sensor assembly 120.4 and is adjacent to
the top 52.4, side 60.4 and front 58.4 of the device 50.4 in this
example.
[0158] Referring to FIG. 46, the differential pressure sensor 176.4
of the device includes a first pressure sensor inlet 170.4
connected to and in fluid communication with the proximal end 66.4
of the venturi tube 64.4 via proximal sample port 108.4 in this
example. The other pressure sensor inlet 168.4 is connected to and
in fluid communication with the ambient air/atmosphere 308 via
conduit 172.4 and open air port 312, which may be the same as open
air port 310. The pressure sensor 176.4 of device 50.4 is thus in
communication with ambient air in this embodiment. Device 50.4 so
configured may result in a more reliable differential pressure
reading, thereby resulting in more accurate flow measurement.
[0159] As seen in FIGS. 44 and 45, the second tapered portion 106.4
of the venturi tube 64.4 has a flared section 103. The flared
section extends from the distal end 84.4 of the venturi tube
towards the proximal end 66.4 of the tube. As seen in FIG. 41, the
flared section 103 of the second tapered portion 106.4 of the tube
is generally annular.
[0160] Still referring to FIG. 41, the constriction 102.4 of
venturi tube 64.4 is generally rectangular in cross-section in this
example, with rounded corners as seen by corners 109 in FIG. 43.
Referring back to FIG. 41, the second tapered portion 106.4 of the
venturi tube 64.4 is thus generally rectangular in lateral
cross-section at least in part, in a region inwardly positioned
from flared section 103 in this example. However, this is not
strictly required.
[0161] Referring to FIGS. 44 and 45, the first tapered portion
104.4 of the venturi tube 64.4 is also generally rectangular in
lateral cross-section at least in part in this embodiment. However,
here too this is not strictly required.
[0162] FIG. 47 shows a device 50.5 for measuring a user's
oxygen-consumption according to a sixth aspect. Like parts have
like numbers and functions as device 50.4 shown in FIGS. 41 to 47
with decimal extension ".5" replacing decimal extension ".4" and
being added for like parts not previously having decimal numbers.
The device 50.5 is the same as described for device 50.4 with the
following exceptions.
[0163] Device 50.5 further includes an electromechanically operated
valve, in this example a solenoid valve 314. The solenoid valve is
an off-the-shelf component, in this example an 8 mm latching Series
LX.TM. solenoid valve which may be purchased at Parker Hannifin
Corp, having an address of Milton Parker Canada Division, 160
Chisholm Drive, Milton, Ontario, Canada. However, this is not
strictly required and other types of electromechanically operated
valve and/or solenoid valves may be used in other embodiments.
[0164] A first port 316 of the valve is connected to and in fluid
communication with proximal sample port 110.5 in this example via
conduit 318. A second port 320 of the valve 314 is connected to and
in fluid communication with port 181.5 of the environmental sensor
180.5. The second portion of the valve is also connected to and in
fluid communication with oxygen sensor port 234.5 of oxygen sensor
232.5. The valve 314 is in communication with and interposed
between the oxygen sensor 232.5 and the first tapered portion 104.5
of the venturi tube 56.5. The environmental sensor 180.5 is in
communication with the solenoid valve and the oxygen sensor
232.5.
[0165] The valve 314 has a closed position in which fluid
communication between the oxygen sensor 232.5 and the proximal
sample port 110.5 is inhibited. Fluid communication between the
environmental sensor 180.5 and the proximal sample port is also
inhibited when the valve is closed.
[0166] The valve 314 is configured to be selectively actuated to
open. The valve when opened promotes fluid communication between
the oxygen sensor 232.5 and the proximal sample port 110.5. The
valve 314 also enables fluid communication between the
environmental sensor 180.5 and the proximal sample port when the
valve is open.
[0167] The solenoid valve positioned between the oxygen sensor
232.5 and proximal end 66.5 of the venturi tube 56.5 allows device
50.5 to control when the oxygen sensor 232.5 is purged with new
gas. This allows the device to run in three modes: a calibration
mode, a regular operation mode, and a humid operation mode.
[0168] Device 50.5 may comprise a different method of calibrating
to obtain an ambient oxygen concentration level. The method
includes normalizing the oxygen sensor signal with ambient
pressure, temperature and relative humidity to inhibit drift caused
by changes in elevation and environment. The method includes
actuating the solenoid valve 314 to open only during a user
inhale-phase in which the user inhales air through the device 50.5
with the air passing from the second tapered portion 106.5 thereof
to the first tapered portion 104.5 thereof. The oxygen sensor 232.5
is in communication with ambient air, as shown by arrow of numeral
239, and determines the ambient oxygen concentration level
thereby.
[0169] According to one example, the solenoid valve 314 is only
open during user inhale-phase for three consecutive breaths,
allowing the oxygen cell to settle at exactly the ambient oxygen
concentration level. After the end of the third breath, the
device's processor determines whether a signal from the oxygen
sensor is stable based on a pre-set threshold. If so, the processor
uses this information as a baseline for measurement by assuming
whatever value measured is an ambient oxygen level concentration.
Thereafter, the device records pressure, temperature, and relative
humidity information for said baseline via the environmental
sensor. The processor uses one or more oxygen sensor compensation
algorithms which take into account relative change in trend from
the baseline.
[0170] This ambient concentration level, combined with the absolute
pressure, temperature, and humidity measurements determined by the
environmental sensor 180.5, are used to calibrate the oxygen sensor
for the current recording. This is similar to the calibration
method for the device 50 of FIGS. 1 to 31C, but instead of the user
having to take four consecutive inhales, the solenoid valve 314
calibrates during regular, bidirectional user breathing. The unit
may decide to recalibrate mid-way through a recording, should the
elevation change by more than 100 meters, or the temperature change
more than 5 degrees Celsius, for example.
[0171] The device 50.5 further includes a method of operation to
obtain an oxygen concentration of the user's expired breath. The
method includes actuating the solenoid valve 314 to open only
during a user exhale-phase in which the user exhales air through
the device with the air passing from the first tapered portion
thereof 104.5 to the second tapered portion 106.5 thereof. The
oxygen sensor 236.5 is in communication with the air passing
through conduit 222.4 from proximal sample port 110.4 to open air
port 310, as shown by arrow of numeral 241, and determines the
oxygen concentration of the user's expired breath thereby.
[0172] The device 50.5 alternates between exhale-only sampling, and
inhale-only sampling. During exhale-only sampling, the solenoid
valve 314 is only open when the pressure sensor 176.5 determines
that an exhale is occurring. The device 50.5 alternates between
exhale-only sampling and inhale-sampling for three consecutive
breaths before taking a stable expired oxygen concentration (FeO2)
measurement and switching to inhale-only sampling. Sampling three
consecutive exhales, instead of one-exhale one-inhale, may allow
for a more accurate FeO2 reading, resulting in more accurate
measurement of conventional oxygen consumption (VO2). During
inhale-only sampling, the solenoid valve 314 is only open when the
pressure sensor 176.5 determines that an inhale is occurring. This
inhale phase serves to desiccate the gas sample line with dry
ambient air to ensure that the oxygen sensor 232.5 does not get too
humid or flooded with water accidentally.
[0173] In humid operation mode, if the environmental sensor
humidity reading exceeds some level--for example 80% relative
humidity--then the device will perform a modified regular
operation. Instead of three exhales followed by three inhales, the
device will monitor/measure three exhales followed by six inhales,
until the environmental sensor humidity reading has decreased to a
safe level (70% relative humidity). If the relative humidity
exceeds 90%, the device 50.5 will enter inhale-only purge mode,
until the relative humidity has decreased below 80%.
[0174] FIG. 48 shows a device 50.6 for measuring a user's
oxygen-consumption according to a seventh aspect. Like parts have
like numbers and functions as device 50.5 shown in FIG. 47 with
decimal extension ".6" replacing decimal extension ".5" and being
added for like parts not previously having decimal numbers. The
device 50.6 is the same as described for device 50.5 with the
following exceptions.
[0175] The device includes a desiccant tube 228.6 positioned along
conduit 318.6. The device 50.6 further includes a drying agent
231.6 adjacent to and surrounding the desiccant tube 228.6. The
drying agents is in the form of silicate gel beads in this example.
However, this is not strictly required and other drying agents may
be used in other embodiments.
[0176] The desiccant tube 228.6 is between and in communication
with the environmental sensor 180.6 and the proximal end 66.6 of
the venturi tube 64.6 via proximal sample port 110.6. The desiccant
tube 228.6 is also between and in communication with the oxygen
sensor 232.6 and the proximal sample port.
[0177] Solenoid valve 314.6 is between oxygen sensor port 236.6 and
open air port 310.6 in this embodiment. The solenoid valve is thus
between and in communication with the oxygen sensor 232.6 and
ambient air. The solenoid valve 314.6 is also between and in
communication with the environmental sensor 180.6 and ambient
air.
[0178] The solenoid valve so positioned and when closed, inhibits
ambient air from passively diffusing into the oxygen sensor 232.6,
whereas the conduits 222.6, 224.6 and 318.6 are sufficient long
that that air from the venturi tube 64.6 does not have the same
effect on the oxygen sensor in this embodiment.
[0179] It will be appreciated that many variations are possible
within the scope of the invention described herein. For example,
various screws are shown and described to hold the various parts of
the device 50 together in the embodiments herein described;
however, this is not strictly required.
[0180] In an alternative embodiment, the user may directly operate
the device without a mask, for example.
Additional Description
[0181] Examples of devices for measuring a user's
oxygen-consumption have been described. The following clauses are
offered as further description. [0182] (1) A device for measuring a
user's oxygen-consumption, the device comprising: a venturi tube
including a first tapered portion, a second tapered portion that is
more tapered compared to the first tapered portion, and a
constriction between said portions thereof; a pressure sensor in
communication with the first tapered portion of the venturi tube;
and an oxygen sensor in communication with the first tapered
portion of the venturi tube. [0183] (2) The device of clause 1,
wherein the oxygen sensor is a passive sensor. [0184] (3) The
device of any preceding clause, wherein the pressure sensor is a
differential pressure sensor. [0185] (4) The device of any
preceding clause, wherein the pressure sensor is in communication
with the constriction. [0186] (5) The device of any preceding
clause, wherein the oxygen sensor is in communication with the
constriction. [0187] (6) The device of any one of clauses 1 to 3,
wherein the pressure sensor is in communication with ambient air.
[0188] (7) The device of any one of clauses 1 to 3, wherein the
oxygen sensor is in communication with said ambient air. [0189] (8)
The device of any preceding clause, wherein the venturi tube has a
proximal end through which exhalations enter into the device and a
distal end through which inhalations enter into the device. [0190]
(9) The device of any preceding clause, wherein the first tapered
portion of the venturi tube is substantially oval-shaped in lateral
cross-section. [0191] (10) The device of any preceding clause,
wherein the second tapered portion of the venturi tube is
substantially circular in lateral cross-section. [0192] (11) The
device of any one of clauses 1 to 6, wherein the venturi tube has a
laterally-extending, cross-sectional first plane and a
laterally-extending, cross-sectional second plane which extends
perpendicular to the first plane, and wherein the first tapered
portion of the venturi tube tapers in a direction extending along
the first plane and has a substantially constant diameter at least
in part in a direction extending along the second plane. [0193]
(12) The device of any one of clauses 1 to 6, wherein the venturi
tube has a proximal end through which exhalations enter into the
device, the first tapered portion being adjacent to said proximal
end of the venturi tube, wherein the venturi tube has a
laterally-extending, cross-sectional first plane along which the
first tapered portion of the venturi tube tapers and wherein the
venturi tube has a laterally-extending, cross-sectional second
plane which extends perpendicular to the first plane, the first
tapered portion of the venturi tube in a direction extending along
the second plane being flared adjacent to the proximal end of the
venturi tube and having a substantially constant diameter as the
first tapered portion of the venturi tube extends to the
constriction. [0194] (13) The device any one of clauses 4 to 5,
further including a first pair and a second pair of conducts,
wherein the pressure sensor is in communication with the
constriction and the proximal end of the venturi tube via the first
pair of conduits and wherein the oxygen sensor is in communication
with the constriction and the proximal end of the venturi tube via
the second pair of conduits. [0195] (14) The device of any
preceding clause, wherein the first tapered portion of the venturi
tube is substantially oval-shaped in lateral cross-section and
wherein the venturi tube includes sample ports located in regions
of the first tapered portion of the venturi tube that are flattest.
[0196] (15) The device of any preceding clause, further including a
processor that receives input from the pressure sensor to determine
measure the instantaneous flow rate through the device, the
processor also receiving input from the oxygen sensor to determine
change in oxygen concentration between inhalations and exhalations
of air through the device, volume measurement being determined
thereby. [0197] (16) A device for measuring a user's
oxygen-consumption, the device comprising: a venturi tube having a
constriction and being shaped to promote laminar flow through an
exhale-receiving portion thereof; a pressure sensor in
communication with the constriction and the exhale-receiving
portion of the venturi tube; a first desiccant tube in
communication with the constriction and a second desiccant tube in
communication the exhale-receiving portion of the venturi tube; and
an oxygen sensor between and in communication with said desiccants
tubes. [0198] (17) A method of calibrating the device of clause 12
to obtain an ambient oxygen sensor value or environmental value,
the oxygen sensor emitting an oxygen sensor signal, and the method
comprising: normalizing the oxygen sensor signal with ambient
pressure, temperature and relative humidity to inhibit drift caused
by changes in elevation and environment; purging the venturi tube
by having a user take two or more consecutive, deep inhales of air
through the device without exhaling through the device; measuring
and storing via a processor the ambient oxygen sensor value or
environmental value thereafter. [0199] (18) The device of any one
of clauses 1 to 15, further including an electromechanically
operated valve in communication with and interposed between the
oxygen sensor and the first tapered portion of the venturi tube.
[0200] (19) The device of clause 18 wherein the valve is a solenoid
valve. [0201] (20) A device for measuring a user's
oxygen-consumption, the device comprising: a replaceable venturi
tube having a proximal end connectable to a breath-receiving member
and a distal end through which air enters during inhalation; and a
sensor assembly comprising two parts hingedly connected together
and between which the venturi tube is selectively received. [0202]
(21) The device of clause 20 wherein each of the parts is
arc-shaped in cross-section. [0203] (22) The device of any one of
clauses 20 to 21, wherein the parts of the sensor assembly hingedly
connect together at first ends thereof and include a latch
mechanism at second ends thereof for selectively coupling together.
[0204] (23) The device of any one of clauses 20 to 22, wherein the
ends of the venturi tube are outwardly extending flanges and
wherein the venturi tube includes an annular outer surface
extending between the flanges and about which the sensor assembly
selectively extends, the outer surface of the venturi tube being
oval-shaped in cross-section. [0205] (24) The device of any one of
clauses 20 to 23, wherein the sensor assembly is moveable from an
open position in which the parts thereof angled outwards from each
other, to a closed position, the parts of the sensor assembly when
in the closed position forming an aperture through the venturi tube
is received. [0206] (25) The device of any one of clauses 20 to 24,
wherein the aperture is oval-shaped in cross-section. [0207] (26) A
kit comprising the device of any one of clauses 20 to 25, and
further including additional venturi tubes of varied shapes, the
kit thus being customizable to desired test conditions and
criteria. [0208] (27) In combination, a breath-receiving member and
the device of any one of clauses 20 to 25, the breath-receiving
member being a facemask. [0209] (28) A kit for measuring a user's
oxygen-consumption, the kit comprising: a plurality of replaceable
venturi tubes of different shapes, each having a proximal end
connectable to a breath-receiving member and a distal end through
which air enters during inhalation; and a sensor assembly
comprising two parts hingedly connected together and between which
a respective one of the venturi tubes is selectively received.
[0210] (29) The kit of clause 28, wherein first and second ones of
the venturi tubes have constrictions that are oval-shaped in
cross-section, the constriction of the first one of the venturi
tubes being larger in cross-section relative to the constriction of
the second one of the venturi tubes, and wherein a third one of the
venturi tubes has a constriction that is circular in cross-section,
the third one of the venturi tubes has a cross-sectional area that
is smaller than that of the first one of the venturi tubes and
larger than that of the third one of the venturi tubes. [0211] (30)
The kit of any one of clauses 28 and 29, wherein each of the
venturi tubes includes a first tapered portion, a second tapered
portion and a constriction in communication with and between said
tapered portions, each of the constrictions have a width and a
height, the widths of the constrictions being substantially the
same, the constriction of a high-intensity exercise type one of the
venturi tubes being longer than that of the other ones of the
venturi tubes, and the constriction of a resting/walking type one
of the venturi tubes being shorter than the rest of the venturi
tubes.
[0212] It will further be understood by someone skilled in the art
that many of the details provided above are by way of example only
and are not intended to limit the scope of the invention which is
to be determined with reference to at least the following
claims.
* * * * *