Note: Descriptions are shown in the official language in which they were submitted.
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GASANALYZER
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority of U.S. Provisional Patent Application No.
60/893,685, filed on March 8, 2007, the entire contents of which are hereby
incorporated by
reference.
BACKGROUND OF THE INVENTION
Gas analyzers, particularly breath analyzers, are known in the prior art for
detecting
levels of toxins or other undesired substances in a person's body based on
analysis of a
person's expelled breath. A common form of breath analyzer is an alcohol
breath analyzer
which detects the level of alcohol in a person's blood stream based on
measurements taken
from the person's breath. Other forms of detectors are also known.
Carbon monoxide (CO) poisoning is common amongst individuals exposed to smoke,
particularly fire victims and firefighters. Studies have found that levels of
carbon monoxide
in a person's blood stream can be detected by breath analysis. Such tests are
typically done
in a clinical or laboratory setting with results not being obtainable
instantaneously.
Hydrogen cyanide (HCN) is a toxic gas which is generated through combustion of
certain organic and synthetic materials. Individuals exposed to smoke are at
risk of being
poisoned with hydrogen cyanide. It has been found that breath analysis may
provide an
indication of hydrogen cyanide levels in a person's blood stream. See, e.g.,
U.S. Patent No.
5,961,469 to Roizen et al., Col. 7 - Col. 8.
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SUMMARY OF THE INVENTION
The subject invention is directed to a breath analyzer which is capable of
detecting
toxic gas levels from breath analysis. The subject invention includes a
mouthpiece which is
in communication with a plurality of discrete chambers, such as first and
second discrete
chambers, each being provided with a separate probe for breath analysis. The
probes are
connected to analyzers for determining detected levels of gas. In a first
embodiment, a first
probe may be provided for carbon monoxide detection with a second probe being
provided
for hydrogen cyanide detection. Advantageously, with this arrangement, breath
analysis may
be conducted on-site, for example at the site of a fire, to quickly and
simultaneously
determine carbon monoxide and hydrogen cyanide levels in a person's blood
stream.
In a second embodiment, a first probe may be provided for detection of carbon
monoxide and a second probe may be provided for detection of hydrogen. With
this
arrangement, a calibrated correction of measured carbon monoxide data can be
made to
correct for improperly detected hydrogen. As such, a highly accurate on-site
measurement
for carbon monoxide can be achieved.
These and other features of the invention will be better understood through a
study of
the following detailed description and accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a breath analyzer formed in accordance with
the
subject invention;
Figure 2 is a plan view of two chambers useable with the subject invention;
Figure 3 is a schematic of two chambers useable with the subject invention;
Figure 4 is a schematic of three chambers useable with the subject invention;
Figure 5 is a schematic of an electronic configuration useable with the
subject
invention; and,
Figure 6 is a schematic of a possible display arrangement useable with the
subject
invention.
DETAILED DESCRIPTION OF THE INVENTION
A breath analyzer 10 is provided herein which generally includes a housing 12
operatively coupled to a breath passage 14. The breath passage 14 includes a
mouthpiece 16
which is open and formed to be comfortably accommodated by the mouth of a
user. To use
the breath analyzer 10, a user blows into the mouthpiece 16 of the breath
passage 14. As
shown in Figure 1, the breath passage 14 may be a separate component from the
housing 12
and be coupled thereto. Alternatively, the breath passage 14 may be disposed
within the
housing 12. It is preferred that the breath analyzer 10 be portable and be
hand-held.
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With reference to Figure 2, the breath passage 14 includes a channel 18 that
extends
from the mouthpiece 16 and terminates at divider 20. The mouthpiece 16 may be
a "drool-
free" mouthpiece to minimize delivery of saliva into the channel 18. In
addition, the
mouthpiece 16 may be formed removable and replaceable for hygienic
considerations.
Single use of the mouthpiece 16 is preferred, although the mouthpiece 16 may
be sterilized or
otherwise cleaned between users.
The divider 20 is situated in the breath passage 14 to define at least first
and second
discrete chambers 22, 24. The first and second chambers 22, 24 can be formed
with various
configurations, but are preferably elongated (e.g., cylindrical) to provide an
unobstructed
flow path for entrapped breath. The chambers 22, 24 may be arranged parallel
and may be
arranged to be generally side-by-side. It is preferred that the divider 20 be
located to divide
breath directed down the channel 18 into equal portions into the first and
second chambers
22, 24. With reference to Figure 3, it is preferred that the divider 20 be
located centrally
relative to the channel 18. As represented by the arrows in Figure 3, breath
delivered down
the channel 18 is diverted into the first and second chambers 22, 24. As will
be appreciated
by those skilled in the art, and as discussed below, additional chambers may
be provided,
with the divider 20 being preferably formed centrally to direct equal amounts
of delivered
breath to the chambers.
The divider 20 is formed with a leading edge 26 shown to be a flat surface
disposed
generally perpendicularly to the longitudinal axis of the channel 18. The
leading edge 26 can
be formed with various configurations, such as being wedge shaped or rounded
to provide
minimal backward deflection of delivered breath (i.e., deflection back towards
the channel
18).
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The first chamber 22 is provided with a first probe 28 while the second
chamber 24 is
provided with a second probe 30. Any probe known in the art for detecting gas
levels is
usable with the subject invention. To ensure movement of delivered breath
across the
respective probe 28, 30, a vent 32 may be provided at the rear portion of each
of the first and
second chambers 22, 24. With this arrangement, an unobstructed air flow from
the channel
18, through the first and second chambers 22, 24, and across the first and
second probes 28,
30 may be achieved.
The first and second probes 28, 30 may be selected to detect simultaneously
two
different types of gas. In a preferred arrangement, the first probe 28 may be
a carbon
monoxide probe, while the second probe 30 may be a hydrogen cyanide probe.
Carbon
monoxide probes are known in the prior art and may be selected from
electrochemical,
infrared and semiconductor-base probes, although electrochemical probes are
preferred
herein. In addition, it is preferred that the carbon monoxide probes be three-
electrode probes
and that the probes be capable of detecting 0-500 (parts per million (ppm)),
more preferably
0-200 ppm, of carbon monoxide. It is preferred that the carbon monoxide probe
have a high
resolution over the entire detection range, preferably a resolution of 1 ppm
increments.
Hydrogen cyanide probes are known in the prior art and have been used in
various
industries, including the electroplating industry, and may be selected from
electrochemical,
infrared and semi-conductor base probes, preferably electrochemical probes. It
is also
preferred that the probes be three-electrode probes and that the probes be
capable of detecting
0-50 (parts per million (ppm)), more preferably 0-30 ppm, of hydrogen cyanide.
It is
preferred that the hydrogen cyanide probe have a high resolution over the
entire detection
range, preferably a resolution of 200 (parts per billion (ppb)) increments.
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Any probes selected for use with the breath analyzer 10 are preferably probes
which
detect a level of a target gas and produce a corresponding electrical signal
which may be
processed. Probes capable of detecting other toxic gases may also be utilized.
In a second arrangement, the first probe 28 may be a carbon monoxide probe
with the
second probe 30 being a hydrogen probe. Any known hydrogen probe may be
utilized. With
this arrangement, the second probe 30 may be used to detect hydrogen levels in
the delivered
breath. Carbon monoxide probes may have cross-sensitivity to hydrogen and
improperly
detect hydrogen along with carbon monoxide in providing errant readings. This
is a
particular concern with lactose-intolerant individuals who expel higher than
normal levels of
hydrogen. The detected. levels of carbon monoxide by the first probe 28 may be
corrected to
take into account the actual detected hydrogen levels. In particular, hydrogen
may cause a
5%-30% error in the carbon monoxide reading. Thus, it is preferred that a
hydrogen
correction factor be determined by calculating a predetermined value in the
range of 5%-
30%, more preferably in the range of 10%-12%, of the detected hydrogen level.
For
example, with a 10% correction factor, a hydrogen correction factor is
determined by
multiplying.10 times the detected hydrogen level. The determined hydrogen
correction
factor is then subtracted from the detected carbon monoxide level to obtain a
corrected
carbon monoxide level. The corrected level is taken as the actual detected
level. The actual
correction factor may be determined during calibration of the analyzer 10. A
more accurate
carbon monoxide measurement may be obtained with the simultaneous use of the
first and
second probes 28, 30.
With reference to Figure 4, a third chamber 31 may be provided, formed in
similar
manner to the first and second chambers 22, 24. The third chamber 31 is
preferably
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elongated (e.g., cylindrical); arranged parallel to one or both of the first
and second chambers
22, 24; and, arranged side-by-side to one or both of the first and second
chambers 22, 24.
The third chamber 31 may be also provided with a vent. It is preferred that
the divider 20 be
arranged centrally to generally direct equal amounts of breath into each of
the three chambers
28, 30, 31. A third probe 33 may be provided in the third chamber 31, e.g., to
permit
simultaneous detection of carbon monoxide, hydrogen and hydrogen cyanide.
With reference to Figure 1, the breath passage 14 may be rigidly fixed to the
housing
12 by connector 34. Any mode of forming a connection is useable with the
subject invention.
The housing 12 accommodates circuitry and power supply to collect data from
the
first, second and third probes 28, 30, 33 and to calculate the detected levels
of gas. The first,
second and third probes 28, 30, 33 are electrically coupled to the circuitry
within the housing
12 preferably through the connector 34 which is hollow. As will be appreciated
by those
skilled in the art, any type of circuitry which is capable of manipulating the
detected data is
usable with the subject invention. A display 40 is provided to display the
detected levels of
gas.
To permit use of the breath analyzer 10 on-site at hazardous locations,
particularly at
the site of a fire, the housing 12 is preferably formed of robust and durable
materials which
protect the contained circuitry from water damage, heat and other hazardous
conditions. In
addition, the breath passage 14, the mouthpiece 16 and the connector 34 are
formed from
robust materials to also withstand such conditions. It is preferred that the
mouthpiece 16 be
formed from a durable plastic material to be more comfortably used. The
mouthpiece 16 may
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be formed of an acetal resin, such as that sold under the trademark "DELRIN"
by DuPont
Corporation.
By way of non-limiting example, and with reference to Figure 5, the housing 14
may
accommodate a microprocessor, microcontroller or any other CPU variant 42. The
microprocessor 42 may be electrically coupled to the first, second and third
probes 28, 30, 33
via amplifiers 44 (e.g., high-precision amplifiers). Low-level current signals
generated by the
probes 28, 30, 33 (e.g., on a nano-amp range) in response to gas detection may
be converted
to working voltage levels by the amplifiers 44. The converted analog voltage
levels are
further processed by analog-to-digital converters (ADC) 45 to produce digital
signals which
may be manipulated by the microprocessor 42. The signal from each of the
probes 28, 30, 33
is preferably separately processed. Connections between the probes 28, 30, 33
and the
microprocessor 42 are preferably assembled to be hidden from ambient exposure,
for
example, in the breath passage 14 and the connector 34.
The microprocessor 42 is configured to obtain raw data from the probes 28, 30,
33
and to evaluate blood stream gas levels from the raw data. The breath analyzer
10 may also
be provided with an electronic storage or memory 36 to record obtained data
(raw data as
measured by the probes and/or data which has been calculated by the
microprocessor 42).
The memory 36 may be a memory chip, such as an EPROM or flash memory. It is
preferred
that obtained data alone not be stored, but be stored along with a time and
date stamp. As
such, a timer 46 is also preferably included with the breath analyzer 10.
Other identifiers
may be saved with the obtained data. To permit inputting of other identifiers,
an input device
38, such as a key pad, track pad, and/or buttons, may be mounted onto the
housing 12.
Through coordination of the input device 38 and the display 40, identifying
information such
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as name, weight, height, age, sex, medical conditions, health conditions
(e.g., smoker vs. non-
smoker), or alerts (e.g., allergies) may be inputted into the breath analyzer
10 for association,
and storage, with the corresponding obtained data.
The probes 28, 30, 33, depending on their configuration, may be continuously
activated (i.e., continuously detecting) or may be selectively activatable
(e.g., activated to an
activation state for monitoring). In either regard, the probes 28, 30, 33 need
to be fully
activated to operate properly for detection. With full activation, the probes
28, 30, 33 may be
brought to a "ready" state where the output signals of the probes 28, 30, 33
may be
transmitted to the microprocessor 42, as discussed above. In a non-ready
state, the output
signals need not be transmitted to the microprocessor 42 (thus possibly saving
power). The
input device 38 may be configured to activate a ready state for the analyzer
10.
Prior to, or once, ready, it is preferred that the analyzer 10 conduct a
baseline test to
evaluate ambient conditions. The baseline test is conducted with the
mouthpiece 16 open and
unobstructed. Ambient conditions of the analyzer 10 may include toxic gas. For
the baseline
test, the probes 28, 30, 33 detect levels of ambient gas, and these levels are
stored in the
memory 36. Thereafter, the analyzer 10 is readied for actual testing, and
actual testing is
conducted, as described below, with the probes 28, 30, 33 detecting gas levels
in a person's
expelled breath. The detections by the probes 28, 30, 33 may be conducted over
predetermined intervals of time, e.g. determined by the timer 46.
Alternatively, or in
addition, a stop signal may be manually entered. In this manner, start and
stop of a detection
cycle may be defined. The highest readings detected by the probes 28, 30, 33
during a testing
interval (ambient or actual) are taken as the detected levels. The baseline
results may be
utilized to adjust the actual obtained results to correct for ambient
conditions. The baseline
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results may be directly subtracted from the actual results or the baseline
results may be
applied to the actual results in the same manner as the detected hydrogen
levels are applied to
the carbon monoxide levels for correction, as described above. The application
of the
baseline results may be determined during calibration of the analyzer 10.
As is known in the prior art, the microprocessor 42 may be electrically
coupled to the
probes 28, 30, 33; the memory 36; the input device 38; the display 40; and,
the timer 46. The
microprocessor 42 may be formed to control and coordinate all of these
elements, as is
known in the prior art. In addition, a power supply 48 is provided which is
preferably
rechargeable, such as a lithium-ion cell. Any known mechanism for activating
and
deactivating electronic circuitry may be utilized with the subject invention.
To permit access to the stored data, any known technology or technique may be
utilized. For example, a port 50, such as a USB port, may be provided to
permit a hard-wire
connection to the breath analyzer 10 for downloading of collected information.
Other means,
such as an infrared transmitter/receiver or wireless transmitter/receiver may
also be utilized.
Test results provided by the probes 28, 30, 33 and obtained by the
microprocessor 42
may require conversion or other manipulation to appreciate a dangerous blood
level content.
For example, a detected carbon monoxide level requires manipulation to produce
a percent
carboxyhemoglobin (% COHb) number which is an indication of a person's state
of carbon
monoxide level in his hemoglobin. Carbon monoxide can cause hemoglobin to
convert to
carboxyhemoglobin; carboxyhemoglobin prevents the associated hemoglobin from
delivering
oxygen to various areas of the body. Excessive carboxyhemoglobin may result in
dangerous
levels of oxygen deprivation. To obtain a carboxyhemoglobin percentage, the
actual detected
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carbon monoxide (CO) level (detected in units of parts per million (ppm)) is
mathematically
manipulated as follows: % COHb =(.16 x (CO ppm)) + .5. The calculated % COHb
may be
displayed on the display 40. As recognized by those skilled in the art, any %
COHb number
above 10% may be symptomatic, whereas, even 5% may be an indication of danger.
If
desired, the actual measured CO level (ppm) may be displayed on the display
40. Both the
measured CO level (ppm) and the carboxyhemoglobin level (% COHb) may be stored
in the
memory 36 for later analysis.
If hydrogen levels are measured, the detected carbon monoxide levels may be
corrected, as described above, prior to calculation of carboxyhemoglobin
levels. The un-
corrected and corrected CO levels may be saved along with the % COHb.
With respect to the detection of hydrogen cyanide, a direct correlation
between a
blood stream level and breath content has not been determined. However,
hydrogen cyanide
is foreign to the body, and its presence in the body indicates some level of
toxicity. It is
possible to display on the display 40 the actual detected level of hydrogen
cyanide (parts per
million (ppm)). The actual detected level will provide medical or emergency
personnel with
an indication of the possible level of hydrogen cyanide poisoning. Emergency
treatment may
be determined based on the evaluation of the actual detected level.
As shown in Figure 6, the display 40 may include one or more numeric fields 52
for
displaying numeric values. Indicators 54 may be provided to indicate the
measured item
(e.g., CO level; HCN level; % COHb) corresponding to the displayed numeric
value in one or
one of the numeric fields 52. There can be a one-to-one correspondence of the
numeric fields
52 to the various items being evaluated by the breath analyzer 10 (e.g., three
possible outputs
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(CO level; HCN level; % COHb) equal three numeric fields). A less than one-to-
one
correspondence can be utilized with the indicators 54 being provided as
needed. It is noted
that the displayed numeric amount can be evaluated outside of the breath
analyzer 10. For
example, a user may have a chart or other guide which correlates a displayed
amount to a
convertible standard (e.g., for detecting toxic levels).
In addition to, or as an alternative, one or more graphic representations 56
may be
utilized to graphically indicate the measured level of a particular gas. The
graphic
representations 56 may provide graphically general areas of possible results
(e.g., High Risk;
Medium Risk; Low Risk) with an indication of where actual detected levels
fall. By way of
non-limiting examples, the graphic representation 56 may be a bar or linear
graph, a wheel, a
needle gauge, or combinations thereof. All or portions of the graphic
representations 56 may
be colored, particularly to indicate different levels of concern (e.g., green
to indicate safe
level and red to indicate dangerous level). As with the numeric fields 52, any
quantity of the
graphic representations 56 may be utilized, and the graphic representations 56
may be used in
conjunction with the indicators 54.
The following is an exemplary manner of operating the breath analyzer 10
(having the
configuration of a carbon monoxide probe and a hydrogen cyanide probe):
- activate the breath analyzer 10 and permit the device to come to a fully
activated state (i.e., permit the breath analyzer 10 to fully warm up);
the breath analyzer 10 automatically conducts an ambient reading to determine
baseline measurements of gas (e.g., ambient levels of carbon monoxide and
hydrogen
cyanide will be determined);
- patient data may be inputted;
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- instruct patient to take and hold a deep breath for approximately 15 seconds
prior to testing;
the breath analyzer 10 is activated to a ready state and the patient exhales
into
the mouthpiece 16 of the breath passage 14 with the patient's full tidal
breath being
captured within the breath passage 14;
the breath analyzer 10 determines the detected levels of gas; the detected
levels may be adjusted for the pre-determined baseline measurements (e.g., the
baseline measurements may be subtracted from the detected levels); and,
the mouthpiece 16 may be replaced, wiped or sterilized prior to a next patient
using the breath analyzer 10.
Other configurations of the breath analyzer 10 may operate in similar fashion.
Over a course of repeated tests, the breath analyzer 10 may be configured to
re-test
ambient conditions to re-set the baseline measurements. Ambient testing can be
conducted
before each patient test. Also, the breath analyzer 10 may be configured to
test from zero
and over a range. Alternatively, the analyzer 10 may be configured with
minimum threshold
levels so that only measurements above the threshold values will register, be
displayed and/or
be stored. For example, a carbon monoxide level of one part per million (ppm)
and a
hydrogen cyanide level of one part per billion (ppb) may be set as the minimum
threshold
values.
If a patient provides a test result of concern, it is recommended that an
interval of time
be waited and that the patient be re-tested. Repeated testing will provide an
opportunity to
ensure accurate detection and the possibility of identifying an actual peak
reading. It is also
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recommended that at least 10 minutes be waited after a patient smokes before
being tested to
avoid false readings.
The subject invention allows for simultaneous elevation of at least two
different gases
from a person's expelled breath. Under emergency conditions, rapid and
simultaneous
recognition of poisoning may be critical to treatment. The analyzer 10 permits
simultaneous
evaluation of two toxic gases (e.g., CO and HCN) in a quick and efficient
manner.
The breath analyzer 10 may be also utilized as a free-standing detector which
measures toxic gas levels of surrounding ambient air. For example, the breath
analyzer 10
may be located in or near an infant's crib to monitor toxic gas levels,
particularly carbon
monoxide. With this arrangement, breath is not required to be blown into the
breath passage
14. Rather, testing of ambient air is conducted. It is preferred that the
second arrangement
discussed above, which includes the carbon monoxide probe and the hydrogen
probe, be
utilized as a free-standing detector to provide accurate carbon monoxide
readings. The timer
46 may be configured to trigger automatic readings at fixed intervals, with
such readings
being recorded into the memory 36. The recorded data is then reviewable to
ascertain
exposure to toxic gas. Continuous monitoring is also possible with a warning
signal being
emitted upon sufficiently high levels of toxic gas being detected. For ambient
testing, it is
preferred that the probe(s) be selected to have high sensitivity and be able
to detect low levels
of gas, such as, for example, less than 30 parts per million (ppm) of carbon
monoxide or 200
parts per billion (ppb) of hydrogen cyanide. Prior art carbon monoxide
detectors are
configured to detect relatively high levels of carbon monoxide. These devices
have "offsets"
or minimum thresholds before carbon monoxide levels are actually detected and
determined.
The device of the subject invention allows for not only low levels of
detection without any
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offsets, but also detection up to zero or nil levels. These detections can be
for any gas being
detected, including carbon monoxide and hydrogen cyanide. Measurements of
toxic gas from
ambient air do not require manipulation to determine correlation to levels of
the toxic gas in a
person's blood stream, such as that required with breath analysis.
