Note: Descriptions are shown in the official language in which they were submitted.
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SELF-CONTAINED MICROMECHANICAL VENTILATOR
This application is a continuation-in-part of
10/228,166, filed August 26, 2002.
BACKGROUND OF THE INVENTION
Immediate medical care can save the lives of
countless accident victims and military personnel. In the
emergency medical services arena, there has long been an
emphasis on the golden hour during which a patient must
receive definitive medical attention. However, definitive
medical attention is often limited, because of the lack
of necessary equipment. While state of the art medical
equipment can be found in medical facilities, such is not
the case in emergency situations or military
applications. This is particularly true in the area of
ventilators.
Inspiration- only ventilators are known and widely
used in hospit al settings as they provide useful
breathing circuit s while minimizing the amount of oxygen
utilized in treat ing the patient.
Current ventilators are generally designed for
stationary, medical facilities. They are heavy,
cumbersome and ill suited for portable applications. Most
ventilators utilize medical grade air or highly
flammable, compressed canisters of oxygen for its oxygen
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sources. These tanks a ir/oxygen are heavy, oumbersome,
and unsuitable for trans port. Prior-art ventilators also
require large power sources, making them even less
suitable for quick, on -site use. Zastly, most known
ventilators require ope ration by trained personnel in
treatment environments, where additional equipment and
resources are easily available.
For example, U.S. Patent 5,664,563 to Schroeder, et
al., disclose a compute r controlled pneumatic ventilator
system that includes a double venturi drive and a
disposable breathing cir suit. The double venturi drive
provides quicker compl a tion of the exhalation phase
leading to an overall improved breathing circuit. The
disposable breathing cir cult allows the ventilator to be
utilized by multiple patients without risk of
contamination. This de~aice utilizes canistered oxygen
sources. This device al so would be rendered inoperable
under the conditions anticipated by the present
invention.
Therefore, there is a need for portable ventilators
that overcome the disadvantages of the existing
stationary ventilators.
The following portable ventilators address some of
the needs discussed a bone. U.S. Patents 6,152,135,
5,881,722.and 5,868,133 to DeVries, et al., discloses a
portable ventilator dev-ice that utilizes ambient air
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through a filter and a compressor system. The compressor
operates continuously to provide air only during
inspiration. The DeVries, et al., devices are utilized in
hospital settings and are intended to provide a patient
with mobility when using the ventilator. Since these
devices are not directed to on-site emergency use, they
provide closed loop control, sophisticated valve systems
and circuitry that would render them inoperable under the
types of emergency conditions anticipated by the present
invention.
The references cited above recognize the need for
portable ventilators that provide a consistent breathing
circuit. As is the case with most portable ventilators,
these devices provide breathing circuits including valve
systems and an oxygen source. However, these devices
lack the means by which they can be quickly facilitated
in emergency situations where there are no stationary
sources of power. Secondly, most of these devices depend
on canister-style oxygen sources, which are cumbersome,
and lessen the ability of the ventilators to be truly
portable. Thirdly, the prior art ventilators do not
provide breathing circuits that can be continuously used
in the absence of stationary power sources. These and
other drawbacks are overcome by the present invention as
will be discussed, below.
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SUNaKARY OF THE INVENTION
It is therefore an objective of this invention to
provide a portable ventilator that provides short-term
ventilatory support.
It is another obj ective of the present invention to
provide a portable ventilator that irzcludes a pneumatic
subsystem, a power subsystem and a sens or subsystem.
It is another objective of the present invention to
provide a portable ventilator wherein the pneumatic
subsystem includes two dual head compressor for increased
air output.
It is another objective of the present invention to
provide a portable ventilator where in the pneumatic
subsystem includes an accumulator.
It is another objective of the present invention to
provide a portable ventilator that is a disposable one-
use device having an indefinite shelf Life.
It is also another objective of tl-ie present invention to
provide a portable ventilator that includes a pneumatic
subsystem, a power subsystem, a control subsystem and an
alarm subsystem.
It is another objective of the present invention to
provide a portable ventilator wherein the pneumatic subsystem
includes one dual head compressor for increased air output
and a means for relieving air manifold pressure with a single
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head compressor, thereby eliminating the need for an
accumulator.
It is another objective of the present invention to
provide a portable ventilator wherein the power subsystem
includes a battery source and a jack that allows the
ventilator to access an external power source, where the
battery or the external power source is used to power the
pneumatic, control and alarm subsystems.
It is another objective of the present invention to
provide a portable ventilator wherein the power subsystem
also includes a power conditioning circuit to eliminate
fluctuating voltages to the control subsystem.
It is also another objective of the present invention to
provide a portable ventilator wherein the control subsystem
includes a timing circuit and a relay switch to control the
on-off cycle of the dual-head and single head compressors.
It is also another objective of the present invention to
provide a portable ventilator wherein the alarm subsystem is
capable of visually indicating repairable, non-repairable and
patient based problems as well as an audible alarm.
It is another objective of the present invention to
provide a portable ventilator that is a disposable one-use
device or a refurbished device having an indefinite shelf
life.
These and other objectives have been described in
the detailed description provided below.
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DESCRIPTION THE DRAWINGS
OF
Figure is schematic of the portable ventilator,
1 a the
pneumatic subsystem,
the
power
subsystem
and
the
sensor
subsystem .
Figure is schematic of the pneumatic subsystem shown
2 a
in figure 1.
Figure is schematic of the power subsystem shown
3 a in
figure
1.
10Figure is schematic of the sensor subsystem shown
4 a in
figure
1.
Figure is drawing the portable ventilator shown
5 a of in
figure
1.
Figure is schematic of the portable ventilator,
6 a the
15pneumatic subsystem,
the
power
subsystem,
the
control
subsystem and the alarm
subsystem.
Figure is a drawing of the portable ventilator shown
6a
in figure 6.
Figure is schematic of the pneumatic subsystem shown
7 a
20in figure 6.
Figure is schematic of the power subsystem shown
8 a in
figure
6.
Figure is schematic of the control subsystem shown
9 a in
figure
6.
25Figure is the dual head compressor on-off
9a a
graph
of
cycle.
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Figure 9b is a graph of resistors and capacitor charging
and discharging timing cycle.
Figure 9c is a graph of the output of the timing circa it.
Figure 9d is a graph of the higher power on-off cycle
from the relay switch to the dual head compressor.
Figure 9e is a graph of the higher power on-off cycle
from the relay switch to the single head compressor.
Figure 10 is a schematic of the alarm subsystem showrz in
figure 6.
DETAINED DESCRIPTION OF THE EMBODIMENTS
The present invention is a portable ventilator -that
provides short-term ventilatory support to one or more
patients for the management of trauma or respira-t ory
paralysis. As shown in figure l, the portable ventila for
V assures consistent tidal volume and respiratory rate
and provides hands free operational capabilities. The
portable ventilator V is a fully functional mufti-mode
device suited for field hospital or forward surge cal
units, where experienced personnel can utilize the mud ti-
mode capabilities unique to this device. Portable
ventilator V is also suitable for use by untra~.ned
personnel, and in particularly useful in resource-lim~.ted
environments. Additionally, the portable ventilator V can
be configured as a disposable one-use device that has an
indefinite shelf life.
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Also in figure 1, the portable ventilator V of the
present invention includes a pneumatic subsystem N, a
power subsystem P, and a sensor subsystem S. Each of
these systems shall be described below.
The pneumatic subsystem:
As shown in figure 2, the pneumatic subsystem N
includes two dual head air compressors 1a and 1b for
increased air output. Ambient or NVC filtered air is
drawn into the dual head compressors 1a and 1b and
compressed. The compressed air exits 1a and 1b and
enters into the accumulator tank 2. An accumulator tank
2 is connected to each of the compressors 1a and 1b to
act as a pneumatic holding area for the combined outputs
(4 in total) of compressors 1a and 1b. The accumulator
tank 2 overcomes the inconsistent nature of the phasing
of the pressure waves inherent with dual head air
compressors and prevents compressors 1a and 1b outputs
from canceling each other. The accumulator tank 2 is
further connected to a connector system 3. Since the
compressors 1a and 1b function as constant-flow rates
over a wide range of physiologic pressures, the connector
system 3 provides constant, total airflow through the
accumulator 2 to the user, for a necessary period of
time. The periods of time are controlled through a timing
circuit T that is part of a logic board B.
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The logic board:
The logic board B includes timing circuit T and is
connected to the power subsystem P. Logic board B
controls power to compressors la and 1b in order to turn
1a and 1b on and off. Duration of the on-time of
compressors 1a and 1b determines the amount of air that
is delivered to the user. The logic board B utilizes
analog logic and does not require microprocessor control.
The logic board B is also connected to the sensor
subsystem S.
The sensor subsystem:
As shown in figure 3, the portable ventilator V
includes a sensor subsystem S that provides critical care
monitoring and support critically ill patients in the
emergency situations. The sensor subsystem S includes an
airflow sensor 4 that detects loss of connection of the
portable ventilator V from the patient's face mask or
endotracheal tube. The sensor subsystem S also includes
an airway pressure sensor 5. The pressure sensor 5
provides the desirable function of detecting the end of a
previous breath (inhaled) in the user, so that air
delivery can be delayed until the completion of the
previous breath. An airflow sensor 6 is used to detect
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the cessation of exhalation of the previous breath if the
scheduled start time for the next breath is not
completed. The sensor subsystem S may be located within
the ventilator V or be exterior to ventilator V.
The power subsystem:
As shown in figure 4, the power subsystem P of the
portable ventilator V include disposable or rechargeable
batteries 7 that are capable of operating under high
capacity, wide temperature ranges and are compatible with
the pneumatic subsystem N and the sensor subsystem S. In
a preferred embodiment, the portable ventilator V of the
present invention utilizes conventional lead-acid
rechargeable batteries 7. The batteries 7 must provide
at least 30 to 60 minutes of operating time.
The portable ventilator:
As shown in figure 5, the pneumatic subsystem N is
connected to the sensor subsystem S and the power
subsystem P and enclosed within housing 8 of the portable
ventilator V. Housing 8 includes an rigid frame structure
8a that is made of either plastic or metals and capable
of withstanding physical and mechanical pressures.
Portable ventilator V includes an input port 8b that
allows rechargeable batteries 7 to be powered using an
external power source or an AC power source.
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Alternatively, batteries 7 may include disposable type
batteries.
Housing 8 also a recessed control panel 8c. Control
panel 8c includes ports for providing air to the user
through known means. The panel 8c also includes a switch
for selecting desired air flow rates, an on/off switch,
and can include a switch for recharging the batteries 7.
The control panel 8c is recessed to prevent damage to any
instrumentation positioned thereon.
The portable ventilator V of the present invention
implements controlled ventilation and assists control
ventilation to a patient. Example 1 below shows
functionality and performance of two portable ventilators
V described above.
Example 1:
The Sekos 2 and 3 ventilators were tested. All
tidal volumes, respiratory rates and other parameters
were within ~100 of the settings existing on the
ventilator V.
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PERFORMANCE SEKOS 2 SEKOS 3
PARAMETER
APPROX. WEIGHT 12 <6
(1b0
APPROX. SIZE 10.75W X 9.75D5.7W X 11.5D
(in.) X 7 H X 3.5H
PHYSICAL VOLUME733 230
(in')
BATTERY TYPE/SIZE3.4 Ah lead 1.3 Ah lead
acid acid
OPERATING LIFE 1.5-3 0.3-1
(h)
COMPRESSORS 2 2
CONTROLLABLE No No
I:E
RATIO
RESP. RATE 6-30 10 OR 20 ONLY
ADJUSTMENT (b
m)
TIDAL VOLUME 200-1200 300, 900, OR
(ml) 1200
MAX MINUTE VOLUME20 (NOT YET 20 (NOT YET
(L/m) TESTED) TESTED)
TNSPIRATORY No No
FLOW
MEASUREMENT
EXPIRATORY FLOWYes Yes
MEASUREMENT
The portable ventilators tested above, have been
shown to be superior in performance to traditional "ambu-
bags". These and other portable ventilators having the
features discussed above are within the scope of this
invention.
The present invention includes a preferred
embodiment as shown in figure 6. The portable ventilator
V~, as shown in figure 6, includes a pneumatic subsystem
N2, a power subsystem P2, a control subsystem CZ and an
alarm subsystem Az.
The portable ventilator V2 as shown in figure 6(a)
includes a hard shell housing 100 having an exterior
surface 100a and an interior surface 100b.
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The pneumatic subsystem N2:
As shown in figure 7, the pneumatic subsystem NZ
includes at least one dual head air compressor 101 for
increased air output and a single head compressor 102 for
closing a flutter valve 103. The pneumatic subsystem N2 is
responsible for the inhalation and exhalation cycles of
the portable ventilator V~. During the inhalation cycle,
ambient air a is drawn into the dual head compressor 101
through the air input port 104. Ambient air a may also
be passed through an NBC filter NBC to remove
contaminants, before passing through air input port 104.
Alternatively, a small adapter (not shown) may be
connected to the air input port 104 to allow the
ventilator V2 to operate by drawing air a from a purified
source (not pictured). Upon entering the portable
ventilator V2, ambient air a is divided into two air flow
paths by y-shaped medical grade tubing 105. The tubing
105 may also be pre-manufactured plastic or metal. As is
understood by one of ordinary skill in the art, tubing
105 includes all necessary fittings and attachments.
Additionally, tubing 105 may be an integral part of an
interior portion 100b of the hard shell housing 100,
shown in figure 6a. Ambient air a enters the dual head
compressor 101, from tubing 105, through dual-head
compressor input ports 101a and 101b. Dual head
compressor 101 compresses ambient air a. It is important
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to note that combination of using a dual head compressor
101 with a single head compressor 102 is critical to the
portable Ventilator VZ of the preferred embodiment of this
invention as disclosed in figures 6 through 10. It is
also important to note that multiple single head
compressors in place of the dual head compressor 101, as
disclosed in the preferred embodiment of figures 6
through 10, are outside the scope of this present
invention. This is because dual-head compressors provide
for increased efficiency and smaller size. This factor
is essential to the proper design and function of the
portable ventilator V2.
Example 2:
For an equivalent tidal volume output:
Dual Head Compressor: weight - 14.2 oz, size - 28.9 cubic
inches.
2 Single Head Compressors: weight - 20.4 oz, size - 32.0
cubic inches.
Dual-head compressors draw in outside air
and increase pressure within, to allow for the proper
tidal volumes to be pushed through a small amount of
space. Using the ideal gas law PV=nRT, where (P) -
pressure, (V) - volume, (n) - number of molecules, (R) -
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gas law constant, and (T) - temperature, the values nRT
must remain constant when dual head compressor 101 is
operational. Thus, as necessitated by the proper
operation of ventilator V2, obtaining particular volumes
(V) of air from the environment into a small, fixed
volume of the ventilator V2, requires that the pressure
(P) of the air a must be increased to keep nRT the same.
The increased pressure of air a forces the air a through
the ventilator VZ into the lungs of the patient H. This
is due to the tendencies of fluids, here the compressed
air a, to flow from the area of greater pressure of the
ventilator VZ to the area of lower pressure of the lungs
of the patient H, thereby filling them.
As shown in figure 7, compressed air a exits the
compressor 101 through compressor output ports 101c and
101d and into the air manifold 106. Air manifold 106 is
manufactured from plastic or metal. Air manifold 106 may
also be an integral part of the interior portion 100b. As
is understood by one of ordinary skill in the art, air
manifold 106 includes all necessary fittings and
attachments. A pressure sensor 107 is connected to the
air manifold 106 to monitor the pressure of air a
delivered to the patient H. The pressure sensor 107
gauges the air pressure of compressed air a within air
manifold 106. When air a exceeds a known threshold, the
dual head compressor 101 is stopped and the single head
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compressor 102 is started, and air is no longer delivered
to the patient H, as discussed below. As shown in figure
7, the air manifold 106 is also connected to the flutter
valve 103. Flutter valve 103 allows compressed air a to
enter through input port 103a and be delivered to the
patient H through bi-directional port 103b. When
compressed air a is being delivered to the patient H
through bidirectional port 103b, exhale port 103c remains
closed. When the patient H exhales however, the input
port 103a is closed off, and exhale port 103c is open to
allow exhaled air to be removed from the portable
ventilator V2. The exhalation cycle is described below.
Compressed air a, that is delivered to the patient H,
passes through medical grade tubing 108, flutter valve
103 and further through medical grade tubing 109 that is
connected to the patient H through valve port 110. It is
important to note that tubing 108 is integral to air
manifold 106, and is shown in figure 7 as a separate
element for descriptive purposes. Medical grade tubings
108 and 109 may also be pre-manufactured plastic or
metal. As is understood by one of ordinary skill in the
art, tubings 108 and 109 include all necessary fittings
and attachments. Tubings 108 and 109 may be integral to
interior portion 100b. A standard medical grade, patient
endotracheal tube (not shown) or tubing to a respiratory
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mask (not shown) is connected between the portable
ventilator VZ and the patient H at patient valve port 110.
During the exhalation cycle, exhaled air ae is
returned from the patient H through the patient valve
port 110, tubing 109 and the bi-directional port 103b.
The single head compressor 102 causes flutter valve 103
to close input port 103a, thereby directing the exhaled
air ae into exhaust port 103c. Exhaled air ae passes from
exhaust port 103c into medical grade tubing 111. Tubing
111 may be premanufactured plastic or metal and may be
integral to interior portion 100b. As is understood by
one of ordinary skill in the art, tubing 111 includes all
necessary fittings and attachments. Tubing 111 includes a
t-junction llla that directs the exhaled air ae into a
second pressure sensor 112. Second pressure sensor 112
verifies whether patient H is exhaling. In an alternate
embodiment, t-junction 111a and pressure sensor 112 can
be replaced with an in-line flow sensor (not shown). The
exhaled air ae is directed to a patient exhale port 115,
positioned on the ventilator housing 100. Prior to
reaching the exhale port 115, the exhaled air ae is
directed through an in-line capnography chamber 113. The
capnography chamber 113 is used to detect the presence of
exhaled CO~ in exhaled air ae. The exhaled air ae travels
from the capnography chamber 113 through medical grade
tubing 114. Tubing 114 may be premanufactured plastic or
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metal and may be integral to interior portion 100b. As is
understood by one of ordinary skill in the art, tubing
114 includes all necessary fittings and attachments. An
additional colorimetric or chemical capnography sensor CS
may be connected externally to portable ventilator V2 at
exhale port 115, to further monitor ventilation
efficiency. As shown in figure 7, the single head
compress or 102, is connected to the flutter valve 103 and
the air manifold 106 through medical grade tubing 116. It
is important to note that tubing 116 is integral to air
manifold 106, and is shown in figure 7 as a separate
element for descriptive purposes. Tubing 116 may be
premanuf:actured plastic or metal and may be integral to
interior portion 100b. As is understood by one of
ordinary skill in the art, tubing 116 includes all
necessary fittings and attachments. The single head
compress or 102 operates only when the dual-head
compress or 101 is not running. The single-head
compressor 102 is used in this manner to ensure that the
flutter valve input port 103a remains fully closed and
the exhaust port 103c to be fully open in the exhalation
cycle. This alternating operation of the dual head
compress or 101 and the single head compressor 102 allows
for dead volumes of air located in air manifold 106 to be
evacuate d through tubing 116, medical grade tubing 117
and exhaust port 118, between the inhalation cycles.
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Tubing 117 may be premanufactured plastic or metal and
may be integral to interior portion 100b. As is
understood by one of ordinary skill in the art, tubing
117 includes all necessary fittings and attachments. It
is important to note that the single head compressor 102
functions to mechanically close flutter valve 103. This
mechanism is preferred over electronically controlled
valves, as they lead to pressure losses. This mechanism
is preferred over other venting systems and pressure
relief valves to reduce loss of inspiration air and
pressure gradients. Secondly, use of the single head
compressor 102 forcibly pulls air a out of air manifold
106, thereby allowing for the next inhalation cycle to
begin unimpeded by dead air within air manifold 106.
Thirdly, the single head compressor 102 provides a brief
instance of negative pressure during the closure of input
port 103a that assists the patient H to exhale. In
addition, the operation of this dual head compressor 101
and the single head compressor 102 precludes the use of
the accumulator 2, as discussed in the embodiments of
figure 1, above. In an alternate embodiment, single head
compressor 102, tubing 117 and exhaust port 118 can be
used to relieve pressure and/or heat buildup within the
portable ventilator V2. Exhaust port 118 also protects the
portable ventilator V2 from contamination in extreme
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environmental hazards, as well as contamination from
water, dust, mud, etc.
It is important to note that the exhaust port 118 is
positioned away from exhaust port 115 so as not to alter
capnography meal urements obtained from capnography
sensors 113 and CS.
The power subsystem P2:
The power subsystem P2, as shown in figure 8, is
discussed below. The power subsystem P2 provides power to
the portable ventilator V2. The power subsystem P2
includes a battery source 201 and a power jack 202 that
accepts an external power source EP. A 12-14 volt
rechargeable battery is preferred as the battery source
201. However, replaceable batteries may also be utilized.
Power jack 202 i s connected to electronic circuit 203
that is further connected to the battery source 201. The
electronic circuit 203 accepts power from the external
power source EP through the power jack 202 to regulate
voltage necessary to recharge battery source 201 and/or
bypass battery source 201. When an external power source
EP is connected to the power jack 202, the by-pass from
the electronic cir suit 203 allows the portable ventilator
V~ to operate if battery 201 is missing, inoperational or
recharging. Power is directed from either the battery 201
or the electronic circuit 203 into a power switch 204.
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When the power is turne d on, it is directed from the
power switch 204 to a voltage regulator circuit 205 that
provides power for the subsystems within the ventilator
V2.
The power subsystem PZ utilizes the voltage regulator
circuit 205 to eliminate fluctuating voltages to the
control subsystem C2. Fo r components in the control and
alarm subsystems C2 and A2, respectively, that require a
lower voltage, a second voltage regulator circuit 206 is
utilized. Additionally, the power subsystem PZ provides
driving voltage through the control subsystem C2 to the
dual head compressor 101 and the single head compressor
102 of the pneumatic subs ystem N2.
The control subsystem C2:
As discussed under the pneumatic subsystem N2 above,
the on-off cycle betwee n dual head compressor 101 and
single head compressor 1 02 is critical to the operation
of the preferred embodiment as shown in figure 6. As
shown in figure 9, the control subsystem C2 includes a
timing circuit 401 that is used to control a mechanical
relay switch 402 that in turn determines the on/off cycle
between dual head compressor 101 and the single head
compressor 102. The relay is configured as an
electronically controlled single-pole double-throw switch
402. In a preferred embodiment, timing circuit 401 is a
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"555" circuit. The relay s witch 402 is in turn connected
to the single head compressor 102 of the pneumatic
subsystem N2 through a relay switch bar 402a and a first
connector position 402b. Relay switch 402 and relay
switch bar 402a are preferably mechanical. The relay
switch 402 is also connected to the dual head compressor
101 through the switch bar 402a and second connector
position 402c. The timing circuit 401 is connected to a
relay control 402d, that is used to move the relay switch
bar 402a between first connector position 402b and second
connector position 402c, based upon a breath-timing cycle
generated by the timing circuit. The breath-timing cycle
is discussed below. The timing circuit 401 is also
connected to a capacitor 403, a first resistor 404 and a
second resistor 405. Second resistor 405 is in turn
connected to the power subsystem P2. The connection
between the power subsystem P2 and the pneumatic subsystem
NZ is not shown in figure 9.
The breath-timing cycle is defined by the
respiratory rate and the tidal volume, the values for
which have been selected in accordance with American
Medical Association guidelines.
As shown in figure 9a, t1 represents the desired on
time of compressor 101, correlating to the inhalation
time, and tz represents the desired off time of compressor
101, correlating to the exhalation time. The sum of the
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inhalation and exhalation times (tl + t2) is one complete
breath-timing cycle.
The respiratory rate is the number of complete
breath-timing cycles per minute. Th a tidal volume is
determined by the amount of air de1 ivered during the
inspiration phase in one breath-timing cycle. Tidal
volume is the product of the flow rate of the compressor
101 by the on time ti of compressor 101_ Therefore:
(1) tl = TV/f
where TV= tidal volume, f=flow rat a of compressor
101;
(2) ti + t2 = 60 seconds/RR
where RR=respiratory rate, the number of breaths per
minute;
(3) t2 = 60/RR - tl = 60/RR - TV/f .
The values for tl and t2 are thus determined by using
the AMA's respiratory rate and tidal volume guidelines,
as well as the flow rate of compressor 1 01. Diode 406 is
used to allow the possibility that tl less than t2.
As would be understood by one of ordinary skill in
the art, the capacitor 403, first resistor 404 and second
resistor 405 form a charging and discharging timing
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circuit. In the present invention, as sh own in figure
9b, the charge cycle duration is selected to be equal to
the desired inhalation time tl. The dis charge timing
cycle is selected to be equal to the determined
exhalation time t2. Thus:
( 4 ) tl = . 6 93 ( rl + r~ ) c1 and
(5) t2 = . 693 (r2) cl:
where rl is the value of the first resi sf or 404, r~
is the value of the second resistor 405 and cl is the
value of the capacitor 403.
Because the output of the charging and discharging
circuit is indeterminate with respect to an on or off
state of compressor 101, timing circuit 40 1 is utilized
to establish a clear demarcation of on and off states, as
shown in figure 9e, triggered by the output of the
charging and discharging circuit.
It is important to note that timing circuit 401 is
not powerful enough to operate compressors 101 and 102
directly. Therefore, the relay 402 is used where the
output of timing circuit 401, as shown in figure 9c, is
the control input to the relay 402. A re s istor 407 is
used to prevent an electrical short, when the output of
timing circuit 401 is on.
As shown in figure 9d, the output of the charging
and discharging circuit from timing circuit 401 controls
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the relay 402 such that the on-cycle of circuit 401
causes the relay 402 to create a pathway to delive r a
high power on-cycle to dual head compressor 101.
As shown in figure 9e, the off-cycle of timing
circuit 401 pauses the relay 402 to create a pathwa y to
single head compressor 102. The on-cycle of compressor
101 and off cycle of compressor 102 make up the on -off
cycle discussed above.
It is also important to note that the ti wing
characteristics, as shown in figures 9c and 9d, must
correspond to the desired timing characteristics in
figure 9a for the proper operation of portable ventilator
V2.
The alarm subsystem A~:
As shown in figure 10, the alarm subsystem A2
includes a light alarm suppression switch 501 connected
to a repairable LED indicator 502, a non-repairable LED
indicator 503 and a patient problem LED indicator 504.
The LED indicators 502, 503 and 504 are configured to
indicate repairable problems, non-repairable problems,
and patient based problems, respectively, within the
portable ventilator V2. The LED indicators 502, 503 and
504 are positioned on the outer surface 100a of hard
shell 100 of portable ventilator V2. The alarm
suppression switch 501 is accessible to the user U and
CA 02556695 2006-08-16
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used to disengage LED alarms 502, 503 and 504 when
necessary. An audible alarm suppression switch 505
connected to an audible alarm switch 506. The audible
alarm switch 506 is positioned on the outer surface 100a
S of hard shell 100. The audible alarm suppression switch
505 is accessible to the user U and used to disengage
audible alarm 506 when necessary.
A low voltage detect circuit 507 is connected to the
battery 201 and the power switch 205 of the power
subsystem PZ to indicate when voltage is too low. Low
voltage detect circuit 507 is also connected to the light
alarm suppression switch 501 and repairable LED indicator
502 to denote a repairable problem to the user U. The low
voltage detect circuit 507 is also conneoted to the
audible alarm suppression switch 505 and the audible
alarm to indicate a sound-based alarm to the user U.
A missing pulse/device/component failure detect
circuit 508 is connected to the control subsystem C2. The
missing pulse/device/component failure detect circuit 508
is also is also connected to the light alarm suppression
switch 501 and non-repairable LED indioator 503 to denote
a non-repairable problem to the user U, ie portable
ventilator V2 must be replaced. The missing
pulse/device/component failure detect circuit 508 is also
connected to the audible alarm suppression switch 505 and
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the audible alarm to indicate a sound-based alarm to the
user U.
Carbon dioxide detect circuit 509 is connected to a
carbon dioxide event counter 510 and a carbon dioxide
event trigger 511. The circuit 509, counter 510 and
trigger 511 is connected to the capnography sensor 113 of
the pneumatic subsystem N2 to indicate insignificant
carbon dioxide concentrations in exhaled air ae. The
carbon dioxide event trigger 511 is further connected to
the light alarm suppression switch 501 and patient
problem LED indicator 502 to denote a improper connection
or patient distress to the user U. The circuit 509,
counter 510 and trigger 511 are also connected to the
audible alarm suppression switch 505 and the audible
alarm to indicate a sound-based alarm to the user U.
An exhale airflow detect circuit 512 is connected to
an exhale event counter 513 and an exhale event trigger
514. The exhale circuit 512, event counter 513 and event
trigger 514 is connected to the pressure sensor 112 of
the pneumatic subsystem N2. The exhale event trigger 514
is further connected to the light alarm suppression
switch 501 and patient problem LED indicator 502 to
denote a improper connection or patient distress to the
user U. The exhale circuit 512, event counter 513 and
event trigger 514 are also connected to the audible alarm
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suppression switch 505 and the audible alarm to indicate
a sound-based alarm to the user U.
An inspiration pressure detect circuit 515 is
connected to an inspiration event counter 516 and
inspiration event trigger 517 to generate an alarm
response when the ambient air, a, pressure is too high or
too low. The inspiration circuit 515 is connected to the
pressure sensor 107 of the pneumatic subsystem N2. The
inspiration event trigger 517 is further connected to the
light alarm suppression switch 501 an d patient problem
ZED indicator 502 to denote a improper connection or
patient distress to the user U. The in s piration pressure
detect circuit 515, inspiration event counter 516 and
inspiration event trigger 517 are also connected to the
audible alarm suppression switch 505 and the audible
alarm to indicate a sound-based alarm to the user U. This
inspiration pressure detect circuit 5L 5 can also cause
the relay control switch 402d to immediately switch from
operating the dual head compressor 101 to operating the
single head compressor 102 when a preset pressure
threshold is exceeded, to prevent harm t o patient H.
What is claimed is:
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