Note: Descriptions are shown in the official language in which they were submitted.
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
Express Mail No. EJ276138509US
DEVICE AND METHOD OF REDUCING BIAS FLOW IN OSCILLATORY
VENTILATORS
This application claims priority to U.S. provisional patent application
60/353,461 filed on February 1, 2002 and is also a continuation in part of
U.S.
patent application no. 09/631,464 filed on August 3, 2000 which in turn claims
priority to U.S. provisional application no. 60/146,863, filed on August 3,
1999, the
disclosures of which are incorporated herein by reference.
. FILED OF THE INVENTION
The present invention relates generally to ventilators for supporting
breathing
in animals. More particularly, the present invention provides a device and
method
of ventilating.
DISCUSSION OF RELATED ARTS
There are many situations in which normal breathing by an animal patient is
impaired and must be assisted by external means. Oscillatory ventilators are
used to
facilitate breathing in such situations. Among the types of ventilators
available are
high frequency oscillating ventilators. U.S. Fatent 4,719,910 describes a high
frequency oscillating ventilator. A flow of gas is conducted from a gas source
to a
high frequency oscillator. The high frequency oscillator comprises a housing
including a magnet and having a diaphragmatically sealed piston mounted
therein,
an inlet connecting the space within the housing on the first side of the
diaphragm to
the gas conducting means, and a coil mounted to the first side of the
diaphragm.
Circuitry is provided which is operable to reverse the polarity of the flow of
the
current in the coil, thereby causing the diaphragm to move back and forth
within the
housing. A tube connecting the space on the second side of the diaphragm to
the gas
source and the patient's airway is provided.
In the prior art, inspiratory gas is moved into and out of the patient via a U-
shaped tube and movement of the diaphragm. For purposes of describing the
prior
art, the U-shaped tube can be described as having a first limb with a distal
end, a
second limb with a distal end, and a tube between the limbs. Connected to the
tube
between the limbs is another tube (the "patient line") that delivers gas from
the U-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
shaped tube to the patient and also delivers gas from the patient to the U-
shaped
tube. The patient line rnay be connected to the patient via an endotracheal
tube. The
distal end of the first limb is placed in sealing relation to the diaphragm so
that gas
inside the U-shaped tube is caused to oscillate as the diaphragm moves back
and
forth. Gas suitable for inspiration ("inspiratory gas") is supplied at a
location on the
U-shaped tube between the diaphragm and the patient line.
Inspiratory gas passes through the first limb of the U-shaped tube, and
exhaled gas exits to the atmosphere through the second limb of the U-shaped
tube
and out of the distal end of the second limb. To prevent expired gases from
being
. drawn back into the first limb during the expiratory phase of breathing,
more
inspiratory gas than needed by the patient is provided in order to move the
expired
gas into the second limb. The inspiratory gas provided in excess of the needs
of the
patient is referred to herein as "bias flow".
To move expired gas into the second limb of the U-shaped tube, an
inspiratory gas flow rate of approximately 20 liters per minute is used when
ventilating infants, and as much as 60 to 80 liters per minute when
ventilating older
children and adults. Such large volumes of inspiratory gas would quickly
exhaust
the available supply of most transport and ambulance vehicles. Furthermore,
such
prior art devices necessitate large and costly volumes of therapeutic gases
that might
be mingled with the inspiratory gas (e.g., volatile anesthetics, nitric oxide,
vaporized
perfluorocarbons, helium/oxygen mixtures etc.). Finally, such prior art
devices are
inefficient when one considers the amount of inspiratory gas required by the
patient
and the relatively large amount of inspiratory gas supplied to the ventilator.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a device and a method of
ventilating. The object is achieved by a ventilating device having an
oscillator, such
as an oscillatory diaphragm, and gas flow circuit comprising an oscillating
line
having a first end in sealing or pneumatic relationship with the oscillator. A
gas
supply line is connected to the oscillating line, and a patient line is
connected to a
_2_
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
second end of the oscillating line. An outlet line is in pneumatic
communication
with the patient line, and an end of the outlet line distal from the patient
line is
connected to an outlet valve. The outlet valve releases gas from the outlet
line
during inhalation, and prevents the release of gas from the outlet line during
exhalation. In one embodiment of the invention, the device has an oscillating
line
with a gas supply line connected thereto, a patient line connected to the
second end
of the oscillating line, an outlet line in pneumatic communication with the
patient
line, an outlet valve connected to the outlet line, one or more GOa scrubbers
and one
or more check valves to ensure unidirectional flow of gas through the one or
more
scrubbers. This device of this embodiment can be attached to an oscillating
ventilator.
In another embodiment, the device of the present invention is adapted for
connecting to the U-type ventilator attachments of the prior art. In one
embodiment
of the invention, the device has a gas flow circuit comprising an oscillating
line
having a first end and a second end. The first end is adapted for connecting
to an
oscillating ventilator either directly or through another device such as a
conventional
U-type tube, a patient line connected to the second end of the oscillating
line, a
return line connected to the oscillating line, one or more COa scrubbers and
one or
more check valves to ensure unidirectional flow of gas. Optionally, the device
may
have an outlet valve and a gas supply line or when used in conjunction with a
conventional U-type tube, may use the outlet valve and the gas supply line of
the
conventional U-type tube.
In a method according to the present invention, a ventilation device, such as
the one described above, is provided. A patient in pneumatic communication
with
the patient line is provided and gas is supplied to the oscillating line. The
oscillator
is moved toward the oscillating line and the outlet valve is opened. Then, the
oscillator is moved away from the oscillating line and the outlet valve is
closed.
-3-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and obj ects of the invention,
reference should be made to the following description taken in conjunction
with the
accompanying drawings, in which:
Figure 1 is a schematic sectional view of a device according to the present
invention illustrating the major components of the device and utilizing a C02
scrubber;
Figures 2a and 2b are schematic sectional representations of the closed and
open positions respectively of an outlet valve according to the present
invention;
Figures 3a and 3c are each a schematic sectional representation of an
embodiment of the present invention;
Figure 3b is a schematic sectional representation of another embodiment of
the present invention;
Figures 4a and 4b are schematic sectional views of other embodiments of the
present invention having a COa scrubber;
Figure 5 is a schematic sectional representation of another embodiment of
the present invention.
Figure 6 is a schematic sectional view of another embodiment of the
invention without a COa scrubber;
Figures 7a and 7b are schematic sectional representations of the closed and
open positions respectively of another outlet valve according to the present
invention; and
Figure 8 is a flow chart showing steps of a method according to the present
invention.
-4-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
Figures 9a, 9b, 9c and 9c are schematic sectional views of an embodiment of
the invention that can be connected to a U-type oscillator tube (9a, 9b and
9c) or to
an oscillating ventilator (9d).
DETAILED DESCRIPTION OF THE INVENTION
S As used herein the term "gas" means a pure gas or a mixture of gases. Thus,
the term "gas" may refer to a mixture of 02 and N~, and may include
therapeutic
gases.
A device 10 according to the present .invention can be connected to an
oscillating machine having an oscillator 11, such as a diaphragm, like those
described in U.S. Patent No. 4,719,9I0 and No. 5,307,794. As illustrated in
Figure
1, an inspiratory gas source 5 is connected to a device 10 according to the
present
invention through supply line 8. The flow of inspiratory gas into the device
10 can
be regulated by a flow regulator 9 connected to supply line 8. Preferably, the
flow
of inspiratory gas from supply line 8 and into connecting line 18 is
essentially at a
I S constant rate. Connecting line I8 is connected to the oscillating line 14.
In the embodiment shown in Figure 1, an inbound check valve 20 is in the
oscillating line 14. The portion of the oscillating line 14 that is downstream
of the
inbound check valve 20 is referred to herein as the inbound Iine I5. The check
valve
permits the flow of gas in the direction of arrow 21 and prevents the flow of
gas
20 in the opposite direction. When the pressure on the upstream side of the
inbound
check valve 20 is higher than the pressure on the downstream side of the
inbound
check valve 20, the inbound check valve 20 opens allowing gas to flow in the
direction of arrow 21. When the pressure on the upstream side of the inbound
check
valve 20 is lower than on the downstream side, the inbound check valve 20
shuts,
2S effectively stopping the flow of gas through inbound line 15.
Further downstream of inbound check valve 20, for example along inbound
line 15 may be placed an OZ sensor 24 and a COa sensor 22 to monitor the
quality of
the gas therein. Additional modifiers and monitors like humidifiers,
nebulizers and
the like can also be installed. Inbound line 15 connects to patient line 25,
which is in
-S-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
turn connected to an endotracheal tube (not shown in Figure 1) for delivery of
gas to
the patient's airways, and ultimately to the patient's lungs.
Inbound line 15 is also connected to exhalation line 30. In exhalation line 30
may be placed a pressure monitoring device,, such as a manometer, through port
28.
Exhalation line 30 includes a scrubber line 36 and connects to recirculation
line 34.
Recirculation line 34 connects to the oscillating line 14. At the junction of
recirculation line 34 and scrubber line 36 is a two-position valve 32 which
directs
the flow of gas either toward the recirculation line 34 or toward the scrubber
line 36.
The two position valve 32 is normally positioned to direct the flow of gas to
the
scrubber line 36. Preferably, the two-position valve 32 is normally adjusted
so that
Rio gas flows through recirculation line 34.
Included in the exhalation line 30 is a scrubber canister 38, an outbound line
40, and a discharge line 16. A second scrubber 68 may also be included and
used
when the scrubber canister 38 is not being used, for example, while scrubber
canister
38 is being replaced or recharged, for example, by purging COa using a
separate
flow of gas (not shown) . The scrubber valves 70A and 70B preferably operate
together so that either scrubber canister 38 or the second scrubber 68 is in
operation.
In a preferred embodiment, the scrubber valves 70A and 70B are not two
separate
valves, but instead a slide type valve, commonly used in the medical
community,
having an outer cylindrical shell and a movable inner cylinder, each with
holes
therethrough that allow either the scrubber canister 38 or the second scrubber
68 to
be in service.
The outbound line 40 is fitted with an outbound check valve 42, which
permits the flow of gas in the direction of arrow 43 and prevents the flow of
gas in
the opposite direction. Downstream of the outbound check valve 42 is discharge
line 16 having within it a shut-off valve 44. The shut-off valve 44 is
normally set to
the open position. The shut-off valve 44 in its open position, permits the
flow of
gas, but in its closed position blocks the flow of gas. Discharge line 16
connects to
oscillating line 14.
-6-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
Oscillating line 14 connects at one end to the patient line 25, and is placed
in
sealing relationship at the other end with the oscillator 11. Preferably, the
oscillator
11 is a diaphragm of a high frequency oscillating machine. Connected to the
oscillating line 14 is an outlet line 50, which is in turn connected to outlet
valve 52.
The outlet valve 52 may open and shut in response to a control pressure
provided via
control line 54. The closed and open positions of outlet valve 52 are shown in
Figures 2a and 2b respectively. The external control pressure may be provided
to
control line 54 by the oscillating machine that controls the oscillator 11. In
one
embodiment of the present invention, the control pressure provided by line 54
is
substantially stable and the oscillating pressure in line 14 caused by
movement of
the diaphragm 11 causes the outlet valve 52 to open and close. Alternatively,
operation of the outlet valve 52 may be by other means, such as a solenoid.
High frequency oscillation of the oscillator 11 facilitates movement of gas
into and out of the patient's airways. Thus, during the inspiration phase,
when the
oscillator 11 is moving toward the oscillating line 14, a pressurizing cycle
occurs,
and during the expiration phase, when the oscillator 11 is moving away from
the
oscillating line 14, a depressurizing cycle occurs. During the pressurizing
cycle, the
pressure on the upstream side of the inbound check valve 20 increases, forcing
it to
open thereby allowing gas to flow in the direction of arrow 21, and
consequently
into the patient's lungs via patient line 25. At the same time, due to the
oscillator 11
moving toward the device 10, the pressure on the downstream side of outbound
check valve 42 becomes higher than the pressure on its upstream side, which
forces
the outbound check valve 42 to close, thereby preventing the flow of gas from
discharge line 16 into the scrubber canister 38.
During the expiration phase (or depressurizing part of the cycle), the
oscillator 11 moves away from the oscillating line 14 and the pressure
differential
across the inbound check valve 20 causes the inbound check valve 20 to close.
The
exhaled gas is pushed by the patient's lungs into exhalation line 30, and into
the C02
scrubber canister 38. At the same time, the pressure differential across the
outbound
check valve 42 causes the outbound check valve 42 to open. Thus, COZ scrubbed
_7_
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
gas is returned to oscillating line 14 through the normally open shut-off
valve 44.
The gas returning to the oscillating line 14 via the discharge line 16 mixes
with the
gas in the oscillating line 14. The gas in oscillating line 14 is moved toward
the
cutlet valve 52 when the inbound check valve 20 is closed by the movement of
the
oscillator 11. Figures 2a and 2b illustrate the open and closed positions of
the
pneumatic version of the outlet valve 52. When the control pressure supplied
by
control line 54 exceeds the pressure in the oscillating line 14 (Figure 2a),
the outlet
valve 52 is in the closed position and gas from oscillating line 14 is
prevented from
escaping from the device 10. When the control pressure supplied by control
line 54
is less than the pressure in the oscillating line 14 (Figure 2b), the outlet
valve 52 is in
the open position and gas from oscillating line 14 is allowed to escape from
the
device 10. In the embodiments shov~m in Figures 1 through 5, preferably the
outlet
valve 52 is closed for at least part of the expiration phase (i.e. when the
pressure in
oscillating line 14 is decreasing due to movement of the oscillator 11 away
from the
device 10), and the outlet valve 52 is open for at least part of the
inspiration phase
(i.e. when the pressure in oscillating line 14 is increasing due to movement
of the
oscillator 11 toward the device 10).
The COa scrubber canister 38 in the device 10 of the present invention may
be used in other locations. For example, as shown in Figures 3a, 3b and 3c,
the
scrubber canister 38 may be placed at the end of patient line 25 distal from
the
inbound line 15. As shown in Figures 3a and 3c, suitable check valves 20, 42
and
return line 67 can be incorporated to assure unidirectional flow through the
scrubber
canister 38. A bypass line 66 could be provided to accommodate replacement of
the
scrubber canister 38. In a preferred embodiment of the present invention, the
second
scrubber canister 68 is provided in the bypass line 66. The second scrubber
canister
68 may be incorporated into any embodiment described herein which has a
scrubber
canister 38. The device depicted in Figures 3a, 3b and 3c could be used with
prior
art ventilator circuits.
The scrubber canister 38 contains a material that removes unwanted gas,
such as CO2. For example, the scrubber canister 38 may contain sodium
hydroxide,
_g_
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
calcium hydroxide, or barium hydroxide. Sodium hydroxide and calcium hydroxide
mixed with silica is available as Soda Lime. Another commercially available
COZ
scrubber is Baralyme~ which comprises barium hydroxide and calcium hydroxide.
Once the C02 scrubber canister 38 is depleted of its scrubbing capacity, it
can be
replaced. To replace the scrubber canister 38, the two-position valve 32 is
set to
direct the gas from the exhalation line 30 to the recirculation line 34, while
the shut-
off valve 44 is set to the closed position. Upon replacement of the scrubber
canister
38, the two-position valve 32 and the shut-off valve 44 are reset to their
normal
positions.
~ Figures 4a and 4b show two additional embodiments of the present
invention. As illustrated in Figure 4a, the scrubber canister 38 may be placed
in the
oscillating line 14 upstream of the CO2 and 02 sensors 22, 24, or as shown in
Figure
4b, downstream of the sensors 22, 24. In the embodiments shown in Figures 4a
and
4b, check valves are not required to direct the flow of inspiratory gas toward
the
patient line 25 or to direct the flow of expired gas toward the scrubber
canister 38. ~~
Normally, gas moves in both directions through the scrubber canister 38. To
replace
the scrubber canister 38, two block valves 62, 64 can be temporarily adjusted
so that
gas flows through the bypass line 66.
Figure 5 shows another embodiment of the present invention in which the
scrubber is located in the oscillating line 14, and gas flows through the
scrubber
canister 38 toward the patient line 25. Flow from the patient line 25 moves
through
the exhalation line 30 to oscillating line 14. A check valve 42 is in bypass
line 66 to
assure that flow moves through exhalation line 30 in one direction only. An
additional check valve 20 may be included in oscillating line 14 to assure
flow
through the scrubber canister 38 in one direction only.
In another embodiment of the present invention, illustrated in Figure 6,
instead of scrubbing COa from the exhaled gas, the exhaled gas is simply
allowed to
leave a device 100. The device 100 is connected to an inspiratory gas source 5
through connecting line 18. The inspiratory gas enters an oscillating line 14
and
moves toward the patient line 25 in the direction of arrow 21 via the inbound
check
-9-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
valve 20. CO~ and Oa sensors 22, 24 and pressure monitoring port 28 can be
placed
near the patient line 25. The exhaled gas is conducted by the exhalation line
30 to
another type of outlet valve 52. The outlet valve 52 shown in Figures 6, 7a
and 7b
operates based on the pressure differential between oscillating line 14 and
the
exhalation line 30. During the pressurizing cycle, outlet valve 52 is caused
to close
the end 132 of exhalation line 30 by the rising pressure in oscillating line
14.
However, during the depressurizirig phase, the pressure in the outlet Iine 50
causes
the outlet valve 52 to open the end 132 and allow gas to escape to the
atmosphere.
Preferably, for at least part of the pressurization cycle, outlet valve 52 is
closed and
there is no communication between the exhalation line 30 and the atmosphere,
and
for at least part of the depressurization cycle, outlet valve 52 is open and
there is
communication between line 30 and the atmosphere.
Figures 7a and 7b show a preferred embodiment of the outlet valve 52 shown
in Figure 6. The outlet valve 52 in Figures 7a and 7b has a first flexible
membrane
15. 300 disposed in the oscillating line 14 and a second flexible membrane 303
situated
to selectively close the end 132 of the outlet line 50. The flexible membranes
300,
303 are connected by a pressure communication line 306. The pressure
communication line 306 may be filled with a gas or a fluid. When the pressure
in
the pressure communication line 306 is above the pressure in outlet line 50,
the end
132 of the outlet line 50 is closed by the second flexible membrane 303. When
the
pressure in the outlet line 50 is above the pressure in the pressure
communication
line 306, gas is allowed to escape from the end 132 of the outlet line 50. It
will be
recognized that due to the first flexible membrane 300, the pressure in
oscillating
line 14 will change the pressure in the pressure communication line 306.
In a preferred embodiment, a control pressure line 309 is connected to the
pressure communication line 306. When the control pressure line 309 is
provided,
the pressure in the pressure communication line 306 may be changed, and
thereby,
the pressure in the outlet line 50 required to open the end 132 of the outlet
line 50
may be changed.
-10-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
In another embodiment of the invention shown in Figures 9a, 9b and 9c,
device 10 may be connected to an U-type oscillator tube (termed herein as a
connecting tube} of the prior art. The U-type tubes typically have a gas
supply line
and an outlet valve or means. In this embodiment, the device has a gas flow
circuit
comprising an oscillating line, a patient line and a return line. The first
end of the
oscillating line 14 is adapted for communication with a connector 402 of the U-
type
oscillator tube 400 as indicated by dotted lines 404. The second end of the
oscillating line 14 is connected to patient line 25. A return line 67 is
provided for
return of exhaled air. The return line at both ends is connected to the
oscillating
line. On the oscillating line between the ends of the return line is located
check
valve 20 to move the gas toward patient line 25. A CO~. scrubber 38 is located
in the
return line (Figure 9a) or in the oscillating line (Figure 9b). In a preferred
embodiment (Figure 9a), another,check valve 42.is provided in the return line.
The
device may also have a gas supply line and an outlet valve. For use of this
device
directly with an oscillating ventilator 410 as indicated by dotted lines 404
(Figure
9d), a gas supply line 8 having a flow regulator 9 is connected to any
location in the
gas flow circuit through connecting line 18. An outlet valve 52 may also be
placed
at any location in the gas flow circuit. One example of a location for the
supply line
18 and outlet valve 52 is shown in Figure 9d. The scrubber canister 38 may be
placed at any location in the oscillating line or return line, but is
preferably placed in
the return line. Optionally, as shown in Figure 9c, a second C02 scrubber
canister
68 may be provided in another return line 66. Scrubber valves 70A and 70B
operate
as described above such that either scrubber canister 38 or scrubber canister
68 is in
use. Oxygen and CO~ sensors, and pressure monitoring devices can also be
placed in
the gas flow circuit as shown in Figures 1, 4a, 4b or 6.
To illustrate the concept of the present invention, mathematical relationships
were developed for the device 10 shown in Figure 1. Tables 1-10 below list
data
corresponding to these mathematical relationships. In the tables:
VO2 is the volume rate of oxygen consumed by the patient;
VI is the volume rate of inspiratory gas supplied to the device 10;
-11-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
FiOa is the mole fraction of oxygen in the inspiratory gas;
Fm02 is the mole fraction of oxygen in the mixed gas crossing inbound
check valve 20;
Fi02 =1-FiNa. where FiN2 is the mole fraction of nitrogen in the inspiratory
gas;
FmOz =1-FmN2, where FmNa is the mole fraction of nitrogen in the mixed
gas exiting the outlet valve 52;
VI = K + V02, where K = outflow volume from outlet valve;
VI x FiN2 = K x FmN2;
VI (1-FiO~) = K (1-FmO~.);
(VI=K) (1-FiOa) =1-FmOa;
FmO~ =1- ( (VI-K) (1-FiOa) ).
TABLE 1
VO~ VI FiOa Fm02 Fm02 K Vi=VOa
ml/kgl ml/kg/ = ml/kg/
min min FiOa min
5.0 6.0 0.21 -3.74 -17.81 1.0 1.2
5.0 10.0 0.21 -0.58 -2.76 5.0 2.0
5.0 20.0 0.21 -0.05 -0.25 15.0 4.0
5.0 30.0 0.21 0.05 0.25 25.0 6.0
5.0 40.0 0.21 0.10 0.46 35.0 8.0
5.0 50.0 0.21 0.12 0.58 45.4 10.0
5.0 60.0 0.21 0.14 0.66 55.0 12.0
5.0 70.0 0.21 0.15 0.71 65.0 14.0
5.0 80.0 0.21 0.16 0.75 75.0 16.0
5.0 90.0 0.21 0.16 0.78 85.0 18.0
5.0 100.0 0.21 0.17 0.80 95.0 20.0
-12-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
5.0 200.0 0.21 0.19 0.90 195.0 40.0*
5.0 500.0 0.21 0.20 0.96 495.0 100.0
5.0 1000.0 0.21 0.21 0.98 995.0 200.0
TABLE 2
VOa VI FiOa FmOz FmO~ K Vi-V02
ml/kg/ ml/kg/ = mllkg/
min min FiOa min
5.0 6.0 0.30 -3.20 -10.67 1.0 1.2
5.0 10.0 0.30 -0.40 -1.33 5.0 2.0
5.0 20.0 0.30 0.07 0.22 15.0 4.0
5.0 30.0 0.30 0.16 0.53 25.0 6.0
5.0 40.0 0.30 0.20. 0.67 35.0 8.0
5.0 50.0 0.30 0.22 0.74 45.0 10.0
5.0 60.0 0.30 0.24 0.79 55.0 12.0
5.0 70.0 0.30 0.25 0.82 65.0 14.0
5.0 80.0 0.30 0.25 0.84 75.0 16.0
5.0 90.0 0.30 0.26 0.86 85.0 18.0
5.0 100.0 0.30 0.26 0.88 95.0 20.0
5.0 200.0 0.30 0.28 0.94 195.0 40.0*
5.0 500.0 0.30 0.29 0.98 495.0 100.0
5.0 1000.0 0.30 0.30 0.99 995.0 200.0
TABLE 3
V02 VI FiOa Fm02 FmOa ~ Vi=VO~
ml/kg/ ml/kg/ = ml/kg/
min min FiOz min
5.0 6.0 0.40 -2.60 -6.50 1.0 1.2
5.0 10.0 0.40 -0.20 -0.50 5.0 2.0
5.0 20.0 0.40 0.20 0.50 15.0 4.0
-13-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
5.0 30.0 0.40 0.28 0.70 25.0 6.0
5.0 40.0 0.40 0.31 0.79 35.0 8.0
5.0 50.0 0.40 0.33 0.83 45.0 10.0
5.0 60.0 0.40 0.35 0.86 55.0 12.0
5.0 70.0 0.40 0.35 0.88 65.0 14.0
5.0 80.0 0.40 0.36 0.90 75.0 16.0*
5.0 90.0 0.40 0.36 0.91 85.0 18.0
5.0 100.0 0.40 0.37 0.92 95.0 20.0
5.0 200.0 0.40 0.38 0.96 195.0 40.0
5.0 500.0 0.40 0.39 0.98 495.0 100.0
5.0 1000.0 0.40 0.40 0.99 995.0 200.0
TABLE 4
V02 VI Fi02 Fm02 FmO~ ~ Vi=VOa
ml/kg/ ml/kg/ = m~~
min min ~ FiO~ m~
5.0 6.0 0.50 -2.00 -4.00 1.0 1.2
S.0 10.0 0.50 0.00 0.00 5.0 2.0
5.0 20.0 ~ 0.50 0.33 0.67 15.0 4.0
5.0 30.0 0.50 0.40 0.80 25.0 6.0
5.0 40.0 0.50 0.43 0.86 35.0 8.0
5.0 50.0 0.50 0.44 0.89 45.0 10.0
5.0 60.0 0.50 0.45 0.91 55.0 12.0*
5.0 70.0 0.50 0.46 0.92 65.0 14.0
5.0 80.0 0.50 0.47 0.93 75.0 16.0
5.0 90.0 0.50 0.47 0.94 85.0 18.0
5.0 100.0 0.50 0.47 0.95 95.0 20.0
S.0 200.0 0.50 0.49 0.97 195.0 40.0
S.0 500.0 0.50 0.49 0.99 495.0 100.0
5.0 1000.0 0.50 0.50 0.99 995.0 200.0
- 14-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
TABLE 5
V02 VI FiOa FmOa FmOa K Vi=VOa
ml/kg/ mllkg/ = m~8~
min min Fi02 min
5.0 6.0 0.60 -1.40 -2.33 1.0 1.2
5.0 10.0 0.60 0.20 0.33 5.0 2.0
5.0 20.0 0.60 0.47 0.78 15.0 4.0
5.0 30.0 0.60 0.52 0.87 25.0 6.0
.
5.0 40.0 0.60 0.54 0.90 35.0 8.0*
5.0 50.0 0.60 0.56 0.93 45.0 10.0
5.0 60.0 0.60 0.56 0.94 55.0 12.0
5.0 70.0 0.60 0.57 0.95 65.0 14.0
5.0 ~ 80.0 0.60 0.57 0.96 75.0 16.0
5.0 90.0 0.60 0.58 0.96 85.0 18.0
5.0 100.0 0.60 0.58 0.96 95.0 20.0
5.0 200.0 0.60 0.59 0.98 195.0 40.0
5.0 500.0 0.60 0.60 0.99 495.0 100.0
5.0 1000.0 0.60 0.60 1.00 995.0 200.0
TABLE 6
VOa VI Fi02 FmOa FmOa K Vi=VOa
ml/kg/ ml/kg/ = m~~
min min FiOa min
5.0 6.0 0.70 -0.80 -1.14 1.0 1.2
5.0 10.0 0.70 0.40 0.57 5.0 2.0
5.0 20.0 0.70 0.60 0.86 15.0 4.0
5.0 30.0 0.70 0.64 0.91 25.0 6.0*
5.0 40.0 0.70 0.67 0.94 35.0 8.0
5.0 50.0 0.70 0.67 0.95 45.0 10.0
5.0 60.0 0.70 0.68 0.96 55.0 12.0
-15-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
5.0 70.0 0.70 0.68 0.97 65.0 14.0
5.0 80.0 0.70 0.68 0.97 75.0 16.0
5.0 90.0 0.70 0.68 0.97 85.0 18.0
5.0 100.0 0.70 0.68 0.98 95.0 20.0
5.0 200.0 0.70 0.69 0.99 195.0 40.0
5.0 500.0 0.70 0.70 1.00 495.0 100.0
5.0 1000.0 0.70 0.70 1.00 995.0 200.0
TABLE 7
VOZ VI Fi02 FmOa FmOa ~ Vi=VOZ
ml/kg/ ml/kg/ = ml/kg/
min min FiOa min
5.0 6.0 0.80 -0.20 -0.25 1.0 1.2
5.0 10.0 0.80 0.60 0.75 5.0 2.0
5.0 20.0 0.80 0.73 0.92 15.0 4.0*
5.0 30.0 0.80 0.76 0.95 25.0 6.0
5.0 40.0 0.80 0.77 0.96 35.0 8.0
5.0 50.0 0.80 0.78 0.97 45.0 10.0
5.0 60.0 0.80 0.78 0.98 55.0 12.0
5.0 70.0 0.80 0.78 0.98 65.0 14.0
5.0 80.0 0.80 0.79 0.98 75.0 16.0
5.0 90.0 0.80 0.79 0.99 85.0 18.0
5.0 100.0 0.80 0.79 0.99 95.0 20.0
5.0 200.0 0.80 0.79 0.99 195.0 40.0
5.0 500.0 0.80 0.80 1.00 495.0 100.0
5.0 1000.0 0.80 0.80 1.00 995.0 200.0
TABLE 8
VOa VI FiOa FmOa Fm02 I~ Vi=VOa
=
ml/kg/ ml/kg/ FiOa m~~
-16-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
min min min
5.0 6.0 0.90 0.40 0.44 1.0 1.2
5.0 10.0 0.90 0.80 0.89 5.0 2.0
5.0 20.0 0.90 0.87 0.96 15.0 4.0*
5.0 30.0 0.90 0.88 0.98 25.0 6.0
5.0 40.0 0.90 0.89 0.98 35.0 8.0
5.0 50.0 0.90 0.89 0.99 45.0 10.0
5.0 60.0 0.90 0.89 0.99 55.0 12.0
5.0 70.0 0.90 0.89 0.99 65.0 14.0
5.0 80.0 0.90 0.89 0.99 75.0 16.0
5.0 90.0 0.90 0.89 0.99 85.0 18.0
5.0 100.0 0.90 0.89 0.99 95.0 20.0
5.0 200.0 0.90 0.90 1.00 195.0 40.0
5.0 500.0 0.90 0.90 1.00 495.0 100.0
5.0 1000.0 0.90 0.90 1.00 995.0 200.0
TABLE 9
V~a VI FiOa FmOa FmOa ~ Vi=V02
ml/kg/ ml/kg/ = m~~
min min FiOa min
5.0 6.0 1.00 1.00 1.00 1.0 1.2*
5.0 10.0 1.00 1.00 1.00 5.0 2.0
5.0 20.0 1.00 1.00 1.00 15.0 4.0
5.0 30.0 1.00 1.00 1.00 25.0 6.0
5.0 40.0 1.00 1.00 1.00 35.0 8.0
5.0 50.0 1.00 1.00 1.00 45.0 10.0
5.0 60.0 1.00 1.00 1.00 55.0 12.0
5.0 70.0 1.00 1.00 1.00 65.0 14.0
5.0 80.0 1.00 1.00 1.00 75.0 16.0
5.0 90.0 1.00 1.00 1.00 85.0 18.0
-17-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
5.0 100.0 1.00 1.00 1.00 95.0 20.0
5.0 200.0 1.00 1.00 1.00 195.0 40.0
5.0 500.0 1.00 1.00 1.00 495.0 100.0
5.0 1000.0 0.00 1.00 1.00 995.0 200.0
TABLE 10
V02 VI FiO~ Fm02 FmOa K VI: Tole-
ml/kg/ ml/kg/ . ml/kg/ V02 rance
min min FiOa m~
5.0 200.0 0.21 0.19 0.90 195.0 40.0 10%
5.0 200.0 0.30 0.28 0.94 195.0 40.0 10%
. .
5.0 80.0 0.40 0.36 0.90 75.0 16.0 10%
5.0 60.0 0.50 0.45 0.91 55.0 12.0 10%
5.0 40.0 0.60 0.54 0.90 35.0 8.0 10%
5.0 30.0 0.70 0.64 0.91 25.0 ~ 6.0 10%
5.0 20.0 0.80 0.73 0.92 15.0 4.0 10%
5.0 20.0 0.90 0.87 0.96 15.0 4.0 10%
5.0 6.0 1.00 1.00 1.00 1.0 0.83 10%
Tables 1-9 illustrate the FmO2 achieved at various inspiratory gas flow rates
(VI) assuming an oxygen consumption rate of 5 ml/kg/min. An asterisk in the
column labeled VI/VOa indicates the minimum flow rate of inspiratory gas
needed
to achieve an Fm02 that is within 10% of the corresponding FiO2. The
inspiratory
gas corresponding to Table 1 was air (21% oxygen). As seen in Table 1, an
inspiratory gas flow rate of 50 ml/kg/min results in the fraction of OZ in the
mixed
gas (mixture of inspiratory gas and scrubbed exhaled gas) to be about 0.12.
Thus,
the ratio of Fm02 to Fi02 is about 0.58. To achieve the fraction of oxygen in
the
mixed gas (Fm02) to be within 10% of the Fi02, a flow rate of inspiratory gas
of
200 mllmin is needed.
-18-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
Tables 2-9 illustrate the flow rate of inspiratory gas required for FiOa
values
of 0.3 (30% oxygen) to 1.0 (pure oxygen). With a higher percentage of oxygen
in
the inspiratory gas, a lower flow of inspiratory gas is needed to achieve the
same
ratio of Fm02 to Fi02, For example to achieve an Fm02 value that is within 10%
of
Fi02, for gas containing 21 % oxygen (air) an inspiratory gas flow rate of 200
ml/min is required, whereas for inspiratory gas containing 80% oxygen, a 10
times
lower inspiratory gas flow rate (20 ml/kg/min) is required (Table 7). Table 10
presents a composite of inspiratory gas flow rates for various concentrations
of
oxygen in the inspiratory gas to achieve an FmOa value that is within 10% of
the
Fi02 (10% tolerance level). As seen in Table 10, to deliver a desired
concentration
of oxygen to the patient line 25, one could adjust the inspiratory gas flow
keeping
the FiOa constant, or one could adjust the FiOa keeping the inspiratory gas
flow rate
constant.
The data presented in these tables illustrates that by using the device of the
1 S present invention, inspiratory gas flow rates can be reduced to 6 to 200
mllkg/min.
This compares to an inspiratory gas flow rate of approximately 1000 to 2000
ml/kg/min required with currently available high frequency oscillatory
ventilators.
Figure 8 shows steps of a method according to the present invention. In the
method, a ventilating device, such as the device 10 described above, is
provided
(step 200). In addition, a patient connected to the patient line is provided
(step 203)
and gas is supplied with the gas supply line to the oscillating line (step
206). The
oscillator is moved toward the oscillating line and the outlet valve is opened
(step
209). Then, the oscillator is moved away from the oscillating line and the
outlet
valve is closed (step 212). Preferably, the gas is supplied to the oscillating
line at
approximately a constant flow rate.
Devices and methods according to the present invention are more efficient
than currently available high frequency oscillating ventilators primarily
because the
present invention substantially reduces the need for bias flow. This reduction
in bias
flow enables smaller ventilation systems. It is now clear the device and
method of
the present invention reduces the volume of bias flow required for safe
ventilation.
-19-
CA 02474428 2004-07-30
WO 03/063751 PCT/US03/03069
By using the present device, it is believed the volume of inspiratory gas
delivered to
the ventilator can be reduced from 20,000 to 80,000 ml/min to as little as 20
to 800
ml/min.
Another advantage of the present invention may be to counter the loss of
mean lung volume associated with prolonged oscillatory ventilation, which is
believed to be a problem with this form of mechanical ventilation. It is
currently
believed by some that this problem might be intensified by reductions in
inspiratory
gas flow. One approach to this problem that may counter a tendency to lose
mean
lung volume and thus preserve lung expansion involves redirection of some or
all of
the inspiratory gas flow to a small channel adapted to the endotracheal tube
to allow
delivery of some or all of the bias flow directly to the trachea. While
potentially
hazardous at high (conventional) inspiratory gas flow rates, it is believed
that this
would be safe at the lower inspiratory gas flow rates envisioned for this
invention.
Moreover, it is recognized that there might be some advantage to redirecting
some
or all of the inspiratory gas flow to the distal trachea (closer to the lungs)
even when
practicing oscillation using conventional high flow rates of inspiratory gas.
Redirection of some or all of the inspiratory gas to the trachea would trap
inspiratory
gas in the lung during the inspiratory phase of the cycle, and release it to
the device
10 at lower pressure during the expiratory phase. This should aid in the
expansion
of an atelectatic or de-recruited lung.
Although embodiments of the invention have been described herein, the
invention is not limited to such embodiments. The claims which follow are
directed
to the invention, and are intended to further describe the invention, but are
not
intended to limit the scope of the invention.
-20-
