Title: Substance delivery apparatus
Abstract: A substance delivery apparatus for use with a system for supplying breathable gas to a human or animal includes a sensor to measure the pressure of the supplied breathable gas and to detect inhalation by the human or animal; and a reservoir, a conduit, a pump, and a diaphragm to deliver the substance to the human or animal during inhalation at a pressure higher than the supplied pressure of the breathable gas.
Patent Number: 6,990,977 Issued on 01/31/2006 to Calluaud, et al.
| Inventors:
|
Calluaud; Michel (Bayview, AU);
Yerbury; Victor (Wahroonga, AU)
|
| Assignee:
|
ResMed Limited (North Ryde, AU)
|
| Appl. No.:
|
466971 |
| Filed:
|
December 20, 1999 |
Foreign Application Priority Data
| Current U.S. Class: |
128/203.12; 128/204.21; 128/204.23 |
| Current Intern'l Class: |
A61M 15/00 (20060101) |
| Field of Search: |
128/20312,203.14,203.22,203.25,204.18,204.21,204.23,204.25,205.14
|
References Cited [Referenced By]
U.S. Patent Documents
| 2208633 | Jul., 1940 | Heidbrink.
| |
| 4127121 | Nov., 1978 | Westenskow et al.
| |
| 4141355 | Feb., 1979 | Apple.
| |
| 4155356 | May., 1979 | Venegas.
| |
| 4207887 | Jun., 1980 | Hiltebrandt et al.
| |
| 4210136 | Jul., 1980 | Apple.
| |
| 4265237 | May., 1981 | Schwanbom et al.
| |
| 4307730 | Dec., 1981 | Korn.
| |
| 4375346 | Mar., 1983 | Kraus et al.
| |
| 4538604 | Sep., 1985 | Usry et al.
| |
| 4558710 | Dec., 1985 | Eichler.
| |
| 4565194 | Jan., 1986 | Weerda et al.
| |
| 4819629 | Apr., 1989 | Jonson.
| |
| 4832014 | May., 1989 | Perkins.
| |
| 4986269 | Jan., 1991 | Hakkinen.
| |
| 5239994 | Aug., 1993 | Atkins.
| |
| 5404871 | Apr., 1995 | Goodman.
| |
| 5423313 | Jun., 1995 | Olsson et al.
| |
| 5479920 | Jan., 1996 | Piper.
| |
| 5497944 | Mar., 1996 | Weston et al.
| |
| 5503146 | Apr., 1996 | Froehlich et al.
| |
| 5540220 | Jul., 1996 | Gropper et al.
| |
| 5570682 | Nov., 1996 | Johnson.
| |
| 5572993 | Nov., 1996 | Kurome et al.
| |
| 5608647 | Mar., 1997 | Rubsamen.
| |
| 5642730 | Jul., 1997 | Baran.
| |
| 5651358 | Jul., 1997 | Briend et al.
| |
| 5655520 | Aug., 1997 | Howe.
| |
| 5666946 | Sep., 1997 | Langenback.
| |
| 5839433 | Nov., 1998 | Higenbottam.
| |
| 5845633 | Dec., 1998 | Psaros.
| |
| 5971723 | Oct., 1999 | Bolt et al.
| |
| 6029660 | Feb., 2000 | Calluaud et al.
| |
| Foreign Patent Documents |
| 3015279 | Oct., 1981 | DE.
| |
| 3537507 | Apr., 1987 | DE.
| |
| 19525557 | Oct., 1999 | DE.
| |
| 0178925 | Apr., 1986 | EP.
| |
| 2164569 | Mar., 1986 | GB.
| |
| WO 86/0696/9 | Dec., 1986 | WO.
| |
| 92/15353 | Sep., 1992 | WO.
| |
| WO 94/1675/9 | Aug., 1994 | WO.
| |
| 97/03290 | Jan., 1997 | WO.
| |
Primary Examiner: Lewis; Aaron J.
Attorney, Agent or Firm: Nixon & Vanderhye P.C.
Parent Case Text
This is a continuation of an application Ser. No. 08/989,150 filed on Dec. 12,
1997, now U.S. Pat. No. 6,029,660 which is hereby incorporated by reference in
its entirety.
Claims
We claim:
1. A substance delivery apparatus for use with a system for supplying breathable
gas pressurized above atmospheric pressure to a human or animal, the apparatus including:
means for continuously measuring the pressure of a supplied breathable gas;
means for detecting inhalation by the human or animal; and
means for delivering a substance to the human or animal during an inhalation
at a pressure that exceeds the measured pressure of a supplied pressure of the
breathable gas by a predetermined pressure difference.
2. An apparatus as claimed in claim 1, wherein the substance is a medicinal substance.
3. An apparatus as claimed in claim 1, wherein the substance is in the form of
a gas, mist, aerated suspension, jet, spray, gas mixture or the like.
4. An apparatus as claimed in claim 1, wherein the means for delivering the substance
is adapted to deliver the substance to the respiratory system of the human or animal.
5. An apparatus as claimed in claim 4, wherein the means for delivering the substance
is adapted to deliver the substance to the nasal airways of the human or animal.
6. An apparatus as claimed in claim 1, wherein the means for detecting inhalation
includes an airflow sensor adapted to measure a volumetric flow rate of the breathable
gas passing through a flexible conduit in fluid communication with a pressurized
gas flow generator and a mask adapted to be worn by the human or animal and being
adapted to generate a first input signal indicative of the breathable gas flow rate.
7. An apparatus as claimed in claim 6, further including an amplifier to amplify
the first input signal into a second input signal also indicative of the breathable
gas flow rate.
8. An apparatus as claimed in claim 6, further including a differentiating filter
to derive the first signal into a third input signal indicative of acceleration
or deceleration of the breathable gas to thereby indicate inhalation or exhalation respectively.
9. An apparatus as claimed in claim 6, wherein the airflow sensor is adapted
to be disposed downstream of a gas washout vent to atmosphere of the mask such
that inhalation can be detected by sensing a reversal of the direction of the breathable
gas flow through the vent.
10. An apparatus as claimed in claim 9, wherein the airflow sensor is adapted
to detect inhalation by sensing an interruption of the breathable gas flow through
the vent.
11. An apparatus as claimed in claim 1, further including means for measuring
the volume of the substance to be delivered to the human or animal.
12. An apparatus as claimed in claim 1, wherein the means for continuously measuring
the pressure is a pressure transducer adapted to be connected to a conduit in fluid
communication with a pressurized gas flow generator and a mask adapted to be worn
by the human or animal, said transducer being adapted to generate a fourth input
signal indicative of the pressure of the breathable gas in the conduit.
13. An apparatus as claimed in claim 12, including an amplifier to amplify the
fourth input signal into a fifth input signal also indicative of the breathable
gas pressure.
14. An apparatus as claimed in claim 1, wherein the means for delivering a substance
is a positive displacement pump.
15. An apparatus as claimed in claim 14, wherein the positive displacement pump
is a diaphragm pump.
16. An apparatus as claimed in claim 15, wherein the diaphragm pump is in fluid
communication with a substance reservoir via a one-way valve adapted to allow the
substance to only pass from the reservoir to the diaphragm pump.
17. An apparatus as claimed in claim 15, wherein the diaphragm pump is adapted
to be in fluid communication with the gas supply conduit via a one-way valve adapted
to allow the substance to only pass from the diaphragm pump to the conduit.
18. An apparatus as claimed in claim 15, wherein the diaphragm pump is displaced
by a linear drive.
19. An apparatus as claimed in claim 18, wherein the linear drive is an electromagnet.
20. An apparatus as claimed in claim 15, wherein the diaphragm of the diaphragm
pump is displaced by a rotary to linear converter driven by a rotary drive.
21. An apparatus as claimed in claim 20, wherein the rotary drive is one of an
electric DC motor, an electric AC motor, a stepper motor and a brushless motor.
22. An apparatus as claimed in claim 18, further including a first control system
having input means for allowing the input of a predetermined sixth input signal
indicative of the volume of the substance to be delivered and a predetermined seventh
input signal indicative of the pressure difference by which the pressure of the
delivered substance should exceed the pressure of the supplied breathable gas,
said first control system being adapted to receive the second, third, fifth, sixth
and seventh input signals and calculate and generate a first output signal indicative
of the amount of displacement of the linear drive or the rotary drive and a second
output signal indicative of the direction of the displacement required to produce
a negative or positive jumping pressure.
23. An apparatus as claimed in claim 22, wherein a negative pumping pressure
draws the substance from the substance reservoir into the pump and a positive pumping
pressure expels the substance from the pump to a flexible conduit and so to a mask
in fluid communication with the conduit and adapted to be worn by the human or animal.
24. An apparatus as claimed in claim 23, wherein the first and second output
signals are sent to a second control system adapted to convert them into third
and fourth output signals indicative of the linear drive or the rotary drive displacement
and direction respectively, the third and fourth output signals being compatible
with the linear drive or the rotary drive.
25. An apparatus as claimed in claim 24, wherein the input and output signals
can be analog and/or digital.
26. An apparatus as claimed in claim 1, further including means for storing the
substance, wherein the means for detecting inhalation also is for detecting exhalation
by the human or animal, wherein the means for storing the substance provides the
substance to the means for delivering the substance during exhalation of the human
or animal, and wherein the substance is delivered from the means for delivering
the substance to the human or animal during inhalation of the human or animal.
27. A method of delivering a substance to a human or animal being supplied with
breathable gas pressurized above atmospheric pressure, the method including:
continuously measuring the pressure of a supplied breathable gas;
detecting inhalation by the human or animal; and
delivering a substance to the human or animal during an inhalation at a pressure
that exceeds the pressure of a supplied pressure of the breathable gas by a predetermined
pressure difference.
28. A method as claimed in claim 27, wherein the substance is a medicinal substance.
29. A method as claimed in claim 28, wherein the substance is in the form of
a gas, mist, aerated suspension, jet, spray, gas mixture or the like.
30. A method as claimed in claim 27, wherein the substance is delivered to the
respiratory system of the human or animal.
31. A method as claimed in claim 30, wherein the substance is delivered to the
nasal airways of the human or animal.
32. A method as claimed in claim 27, including measuring the volumetric flow
rate of the breathable gas with an airflow sensor and generating a first input
signal indicative of the breathable gas flow rate.
33. A method as claimed in claim 32, including amplifying the first signal into
a second signal also indicative of the breathable gas flow rate.
34. A method as claimed in claim 32, including differentiating the first signal
into a third signal indicative of breathable gas acceleration or deceleration to
indicate inhalation or exhalation respectively.
35. A method as claimed in claim 27, including measuring the volume of the substance
to be delivered to the human or animal.
36. A method as claimed in claim 35, wherein the breathable gas pressure is measured
with a pressure transducer adapted to generate a fourth input signal indicative
of the breathable gas pressure.
37. A method as claimed in claim 36, including amplifying the fourth input signal
into a fifth input signal also indicative of the breathable gas pressure.
38. A method as claimed in claim 27, wherein the substance is delivered to the
human or animal using a positive displacement pump.
39. A method as claimed in claim 38, wherein the positive displacement pump is
a discharge pump.
40. A method as claimed in claim 39, wherein the diaphragm pump is in fluid communication
with a substance reservoir via a one-way valve adapted to allow the substance to
only pass from the reservoir to the diaphragm pump.
41. A method as claimed in claim 39, wherein the diaphragm pump is adapted to
be in fluid communication with the gas supply conduit via a one-way valve adapted
to allow the substance to only pass from the diaphragm pump to the conduit.
42. A method as claimed in claim 39, wherein the diaphragm pump is displaced
by a linear drive means.
43. A method as claimed in claim 42, wherein the linear drive is an electromagnet.
44. A method as claimed in claim 39, wherein the diaphragm pump is displaced
by a rotary to linear converter driven by a rotary drive.
45. A method as claimed in claim 44, wherein the rotary drive means is at least
one of an electric DC motor, an electric AC motor, a stepper motor and a brushless motor.
46. A method as claimed in claim 42, further including inputting the second,
third, fourth, fifth input signals and a predetermined sixth input signal indicative
of the volume of the substance to be delivered and a predetermined seventh input
signal indicative of the pressure difference by which the pressure of the delivered
substance should exceed the pressure of the breathable gas into a first control
means and the first control system adapted to generate a first output signal indicative
of the amount of displacement of the drive means and a second output signal indicative
of the direction of the displacement required to produce negative or positive pumping pressure.
47. A method as claimed in claim 47, further including inputting the first and
second output signals into a second control system and the second control system
converting them into third and fourth output signals indicative of drive means
displacement length and direction respectively, the third and fourth output signals
being compatible with the linear or rotary drive means.
48. A method as claimed in claim 27, further including storing the substance,
detecting exhalation by the human or animal, retrieving the substance from storage
during exhalation of the human or animal, and delivering the substance to the human
or animal during inhalation of the human or animal.
49. A system as claimed in claim 75, further including a substance reservoir
to store the substance, wherein the airflow sensor is also configured to detect
exhalation by the human or animal, wherein the substance reservoir is configured
to provide the substance to the positive displacement pump during exhalation of
the human or animal, and wherein the substance is delivered from the positive displacement
pump to the human or animal during inhalation of the human or animal.
50. A substance delivery apparatus for use with a system for supplying breathable
gas pressurized above atmospheric pressure to a human or animal, the apparatus including:
a pressure transducer to continuously measure pressure of a supplied breathable gas;
an airflow sensor to detect inhalation by the human or animal; and
a positive displacement pump to deliver a substance to the human or animal during
the inhalation at a pressure that exceeds the measured pressure of the supplied
breathable gas by a predetermined pressure difference.
51. An apparatus as claimed in claim 50, wherein the substance is a medicinal substance.
52. An apparatus as claimed in claim 50, wherein the substance is in the form
of a gas, mist, aerated suspension, jet, spray, gas mixture or the like.
53. An apparatus as claimed in claim 50, wherein the substance is delivered to
the respiratory system of the human or animal.
54. An apparatus as claimed in claim 53, wherein the substance is delivered to
the nasal airways of the human or animal.
55. An apparatus as claimed in claim 50, wherein the airflow sensor to detect
inhalation further measures a volumetric flow rate of the breathable gas passing
through a flexible conduit in fluid communication with a pressurized gas flow generator
and a mask adapted to be worn by the human or animal, and generates a first input
signal indicative of the breathable gas flow rate.
56. An apparatus as claimed in claim 55, further including an amplifier adapted
to amplify the first input signal into a second input signal also indicative of
the breathable gas flow rate.
57. An apparatus as claimed in claim 55, further including a differentiating
filter adapted to derive the first signal into a third input signal indicative
of acceleration or deceleration of the breathable gas to thereby indicate inhalation
or exhalation respectively.
58. An apparatus as claimed in claim 55, wherein the airflow sensor is disposed
downstream of a gas washout vent to atmosphere of the mask such that inhalation
can be detected by sensing a reversal of the direction of the breathable gas flow
through the vent.
59. An apparatus as claimed in claim 58, wherein inhalation is detected by sensing
an interruption of the breathable gas flow through the vent.
60. An apparatus as claimed in claim 50, further including signals indicative
of the volume of the substance to be delivered to the human or animal.
61. An apparatus as claimed in claim 50, wherein the pressure transducer is connected
to a conduit in fluid communication with a pressurized gas flow generator and a
mask adapted to be worn by the human or animal of the system for supplying breathable
gas, said transducer being adapted to generate a fourth input signal indicative
of the pressure of the breathable gas in the conduit.
62. An apparatus as claimed in claim 61, including an amplifier to amplify the
fourth input signal into a fifth input signal also indicative of the breathable
gas pressure.
63. An apparatus as claimed in claim 50, wherein the positive displacement pump
is a diaphragm pump.
64. An apparatus as claimed in claim 63, wherein the diaphragm pump is in fluid
communication with a substance reservoir via a one-way valve adapted to allow the
substance to only pass from the reservoir to the diaphragm pump.
65. An apparatus as claimed in claim 63, wherein the diaphragm pump is adapted
to be in fluid communication with the gas supply conduit via a one-way valve adapted
to allow the substance to only pass from the diaphragm pump to the conduit.
66. An apparatus as claimed in claim 63, wherein the diaphragm pump is displaced
by a linear drive.
67. An apparatus as claimed in claim 66, wherein the linear drive is an electromagnet.
68. An apparatus as claimed in claim 63, wherein the diaphragm of the diaphragm
pump is displaced by a rotary to linear converter driven by a rotary drive.
69. An apparatus as claimed in claim 68, wherein the rotary drive is one of an
electric DC motor, an electric AC motor, a stepper motor and a brushless motor.
70. An apparatus as claimed in claim 66, further including a first control system
adapted to allow the input of a predetermined sixth input signal indicative of
the volume of the substance to be delivered and a predetermined seventh input signal
indicative of the pressure difference by which the pressure of the delivered substance
should exceed the pressure of the supplied breathable gas, said first control system
being adapted to receive the second, third, fifth, sixth and seventh input signals
and calculate and generate a first output signal indicative of the amount of displacement
of the linear drive or the rotary drive and a second output signal indicative of
the direction of the displacement required to produce a negative or positive pumping pressure.
71. An apparatus as claimed in claim 70, wherein a negative pumping pressure
draws the substance from the substance reservoir into the pump and a positive pumping
pressure expels the substance from the pump to a flexible conduit and so to a mask
in fluid communication with the conduit and adapted to be worn by the human or animal.
72. An apparatus as claimed in claim 71, wherein the first and second output
signals are sent to a second control system adapted to convert them into third
and fourth output signals indicative of the linear drive or the rotary drive displacement
and direction respectively, the third and fourth output signals being compatible
with the linear drive or the rotary drive.
73. An apparatus as claimed in claim 72, wherein the input and output signals
can be analog and/or digital.
74. An apparatus as claimed in claim 50, further including a substance reservoir
to store the substance, wherein the airflow sensor is also configured to detect
exhalation by the human or animal, wherein the substance reservoir is configured
to provide the substance to the positive displacement pump during exhalation of
the human or animal, and wherein the substance is delivered from the positive displacement
pump to the human or animal during inhalation of the human or animal.
75. A substance delivery system for supplying breathable gas pressurized above
atmospheric pressure to a human or animal, the system including:
a pressurized gas flow generator in fluid communication with a mask adapted to
be worn by the human or animal via a flexible conduit;
a pressure transducer adapted to continuously measure the pressure of a supplied
breathable gas;
an airflow sensor adapted to detect inhalation by the human or animal; and
a positive displacement pump adapted to deliver a substance to the human or animal
during the inhalation at a pressure that exceeds the measured pressure to the supplied
breathable gas by a predetermined pressure difference.
76. A system as claimed in claim 75, further including a substance reservoir
to store the substance, wherein the airflow sensor is also configured to detect
exhalation by the human or animal, wherein the substance reservoir is configured
to provide the substance to the positive displacement pump during exhalation of
the human or animal, and wherein the substance is delivered from the positive displacement
pump to the human or animal during inhalation of the human or animal.
Description
FIELD OF THE INVENTION
The present invention relates to a substance delivery apparatus for use with
a system for supplying breathable gas to a human or animal.
BACKGROUND OF THE INVENTION
Treatment of Obstructive Sleep Apnea (OSA) with Continuous Positive Airway
Pressure (CPAP) flow generator systems involves the continuous delivery of a breathable
gas (generally air) pressurised above atmospheric pressure to a patient's airways
via a conduit and a mask. CPAP pressures of 4 cm H
2O to 22 cm H
2O
are typically used for treatment of OSA, depending on patient requirements. Treatment
pressures for assisted ventilation can range of up to 32 cm H
2O and
beyond, again depending on patient requirements.
For either the treatment of OSA or the application of assisted ventilation or
similar, the pressure of the gas delivered to patients can be constant level, bi-level
(in synchronism with patient inspiration) or auto setting in level. Throughout
the specification reference to CPAP is intended to incorporate a reference to any
one of, or combination of, these forms of pressurised gas supply.
It is difficult to administer substances such as medicines to patients undergoing
CPAP treatment without interrupting the treatment by removing the gas supply mask.
It is an object of the present invention to ameliorate the above disadvantage.
SUMMARY OF THE INVENTION
In a first aspect, the present invention provides a substance delivery apparatus
for use with a system for supplying breathable gas to a human or animal, the apparatus including:
means to measure the pressure of the supplied breathable gas;
means to detect inhalation by the human or animal; and
means to deliver the substance to the human or animal during inhalation at
a pressure higher than the supplied pressure of the breathable gas.
In a second aspect the invention provides a method of delivering a substance
to
a human or animal being supplied with breathable gas, the method includes the steps of:
measuring the pressure of the supplied breathable gas;
detecting inhalation by the human or animal; and
delivering the substance to the human or animal during inhalation at a
pressure higher than the supplied pressure of the breathable gas.
The substance is preferably a medicinal substance and, desirably, in the form
of a gas, mist, aerated suspension, jet, spray, gas mixture or the like.
The substance is preferably delivered to the respiratory system of the human
or animal and, in particular, to the nasal airways.
The supplied breathable gas is preferably pressurised above atmospheric pressure.
The system for supplying the breathable gas preferably includes a pressurized
gas flow generator in fluid communication with a mask worn by the human or animal
via a flexible conduit, and the inhalation detection means includes an airflow
sensor adapted to measure the volumetric flow rate of the breathable gas passing
through the conduit and generate a first input signal indicative of the breathable
gas flow rate. The term mask is herein understood to include facemasks, nosemasks,
mouthmasks, apenditures in the vicinity of any of these masks and the like.
The first signal is preferably amplified by a first amplifier into a second input
signal also indicative of the gas flow rate. A derivative of the first signal is
also generated by a differentiating filter to determine the acceleration or deceleration
of the gas, which is indicative of inhalation or exhalation respectively, and is
represented by a third input signal.
When the airflow sensor is disposed downstream of the mask's vent to atmosphere
then inhalation can be detected by sensing a reversal of the direction of the gas
flow through the vent. Inhalation can also be detected by sensing an interruption
of the gas flow.
The apparatus preferably also includes means to measure the volume of the substance
to be delivered to the human or animal.
The pressure measuring means is preferably a pressure transducer connected to
the conduit which is adapted to generate a fourth input signal indicative of the
pressure of the gas in the conduit. The fourth input signal is preferably amplified
by a second amplifier into a fifth input signal also indicative of the gas pressure.
The substance delivery means is preferably a positive displacement pump, most
preferably a diaphragm pump. The diaphragm pump is desirably in fluid communication
with a substance reservoir via a one-way valve adapted to allow the substance to
only pass from the reservoir to the pump. The pump is preferably also in fluid
communication with the gas supply conduit via a one-way valve adapted to allow
the substance to only pass from the pump to the conduit.
The diaphragm of the pump is desirably displaced by a linear drive means which,
in one form, may take the form of an electromagnet. In other forms, a rotary drive
means such as an electric DC motor, an electric AC motor, a stepper motor, or a
brushless motor are used with a rotary to linear converter interposed between the
rotary drive means and the diaphragm pump.
The apparatus preferably also includes a first control system adapted to receive
the second, third and fourth input signals. The control system preferably also
includes input means adapted to allow the input of a predetermined sixth input
indicative of the volume of the substance to be delivered and a predetermined seventh
input signal indicative of the amount by which the pressure of the delivered substance
should exceed the pressure of the supplied breathable gas. The first control system
is preferably adapted to receive the second, third, fifth, sixth and seventh input
signals to calculate and generate a first output signal indicative of the amount
of displacement of the linear or rotary drive means and a second output signal
indicative of the direction of the displacement required to produce negative or
positive pumping pressure.
The first and second output signals are preferably sent to a second control system
which converts them into third and fourth output signals indicative of drive means
displacement and direction respectively, the third and fourth output signals being
compatible with the linear or rotary drive means.
Preferably, the first and second output signals are sent to a second
control system adapted to convert them into third and fourth output signals indicative
of drive means displacement and direction respectively, the third and fourth output
signals being compatible with the linear or rotary drive means.
The input and output signals can be analog, digital or the like.
The described embodiments have been developed primarily for use in delivering
medicinal substances to patients using Continuous Positive Airway Pressure (CPAP)
gas delivery systems in, for example, the treatment of Obstructive Sleep Apnea
(OSA) or similar sleep disorder breathing conditions.
The invention will be described hereinafter with reference to these applications.
However, it will be appreciated that the invention is not limited to this particular
field of use. As examples, the invention may also be used in conjunction with suitable
mask and gas delivery systems for other treatments such as assisted ventilation,
assisted respiration or mechanical ventilation.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now be described, by way of
example only, with reference to the accompanying figures in which:
FIG. 1 is a schematic diagram of a substance delivery apparatus according to
a first embodiment of the invention;
FIG. 2 is a schematic diagram of a substance delivery apparatus according to
a second embodiment of the invention;
FIG. 3 is a schematic diagram of a substance delivery apparatus according to
a third embodiment of the invention;
FIG. 4 is a schematic diagram of the apparatus of FIG. 3 during inhalation;
FIG. 5 is a schematic diagram of the apparatus shown in FIG. 3 during exhalation;
FIG. 6 is a partial schematic diagram of a substance delivery apparatus according
to a fourth embodiment of the invention; and
FIGS. 7
a, 7
b and 7
c are partial schematic
diagrams of a substance delivery apparatus according to a fifth embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring firstly to FIG. 1, there is shown a first embodiment of a substance
delivery apparatus
10 according to the invention. The apparatus
10
is used with a system, indicated generally at
12, for supplying air, indicated
by arrow
14, to a human patient (not shown). The system
12 includes
a pressurised gas flow generator
16 in fluid communication with a mask
18
via conduit
20.
The apparatus
10 includes a means to measure the pressure of the air
14
and to detect patient inhalation, in the form of an air flow sensor
22.
The sensor
22 is interposed in the conduit
20 between the mask
18
and the pressurised gas flow generator
16. The airflow sensor
22,
in the form of a fixed orifice, is connected to an electronic flow transducer
24.
A variable orifice, venturi tube, Pitot tube or tubes bundle can also be used to
sense airflow. The transducer
24 generates a first electrical input signal
26 indicative of the flow rate of the air
14 passing through the
conduit
20 which is sent to a first flow signal processing amplifier and
differentiating filter
28 which in turn generates second and third input
signals
30 and
32 respectively.
The second input signal
30 is an amplified version of the first input
signal
26. The third input signal
32 is the derivative of the first
signal
26, with acceleration and deceleration being respectively indicative
of inhalation or exhalation. When a patient inhales they apply suction to the air
being delivered thus causing acceleration. Upon exhalation the air being delivered
is obstructed by the exhaled air flowing in the opposite direction thus causing deceleration.
An air pressure transducer
34 is also connected to the conduit
20
and generates a fourth electrical input signal
36 indicative of the pressure
in the conduit. The fourth signal
36 is delivered to an air pressure processing
amplifier
38 which generates a fifth input signal
40 also indicative
of the pressure in the conduit
20.
The second, third and fifth signals
30,
32 and
40 are fed
to a first control system
42. The first control system
42 also receives
sixth and seventh predetermined input signals
44 and
46 from manual
inputs
48 and
50 in the form of potentiometers accessible by a system
operator. Variable resistors can also be used as the manual inputs. The sixth input
signal
44 is indicative of the volume of substance to be delivered to the
mask during each inhalation cycle of the patient. The seventh signal
46
is indicative of the amount by which the delivery pressure of the substance is
to exceed the measured pressure of the air
14 in the conduit
20.
The means to deliver a substance
52 to the mask
18 includes a substance
reservoir
54 connected by conduit
56 to diaphragm pump
58
having a flexible diaphragm
60. A one way valve
62 is interposed
between the reservoir
54 and pump
58 and permits the substance
52
to only enter the pump
58. The pump
58 is in fluid communication
with the conduit
20 by virtue by conduit branch
64 and one way valve
66 which allows the substance
52 to pass from the pump
58
to the conduit
20.
The stroke of the diaphragm
60 is controlled by an electromagnet drive
means
68, in the form of a magnet
70 connected to the centre of the
diaphragm
60 and surrounded by electrical windings
72. The drive
means
68 are controlled by a second control system
74.
In response to receiving the second, third, fifth, sixth and seventh input signals,
the first control system
42 generates first and second output signals
76
and
78, respectively indicative of the electromagnet displacement magnitude
and direction. Displacement in the direction of arrow
80 draws the substance
52 into the pump
58. Displacement in the direction of arrow
82
causes the substance
52 to be pumped into the conduit branch
64 and
thereafter the conduit
20. The output signals
76 and
78 are
received by the second control system
74 which issues third and fourth output
signals
84 and
86 respectively, which are compatible with the drive
means
68. The third output signal
84 is indicative of the amount
of displacement of the electromagnet
68 and the fourth signal
86
is indicative of the displacement direction.
In use, when the system is switched on, breathable air
14 is supplied
by
the gas flow generator
16 to the mask
18 via the conduit
20
so the patient may breathe.
As the patient inhales, an analogue to digital converter (not shown) in the control
system
42 samples the air flow information of the first input signal
30
over a few breaths and stores it in a memory (not shown). The stored values are
integrated with respect to the time of the inhalation portion of their respective
breathing cycle. The integrated value is the tidal volume of each breath and is
also stored in the memory. The stored values of the tidal volume are averaged over
a small number of breaths to provide an average value of the tidal volume.
From the average value of the tidal volume and the setting of the manual input
48 the volume of the substance
52 (ie. the drug or gas) to be delivered
for each breath is calculated. The control system
52 also calculates the
magnitude of the current to be applied to the windings
72 of the diaphragm
pump
58.
When the third input signal
32 indicates exhalation, the control systems
42 and
74 calculate and issue the third and fourth output signals
84 and
86 to the windings
72. The direction of the current
applied to the windings
72 causes the magnet
70 and the diaphragm
60 to be displaced in the direction of the arrow
80 to the position
shown by phantom line
87. This movement of the diaphragm
60 draws
the substance
52 past the one way valve
63 and into the pump
58.
The magnitude of the current applied to windings
72 is proportional to the
displacement of the diaphragm
60 and also therefore the volume of gas drawn
into the pump
58 which is delivered to the patient during the next inhalation
cycle. At the end of the patient exhalation cycle the current applied to the windings
72 remains constant and the magnet
70 and diaphragm
60 remain
as indicated by line
87.
When the third input signal
32 indicates inhalation, the control systems
42 and
74 reverse the current flowing into the windings
72,
thereby displacing the magnet
70 and the diaphragm
60 in the direction
indicated by the arrow
82 to the position shown by phantom line
89.
This movement forces the substance
52 from the pump
58 through the
one way valve
68 and conduit branch
64 into the mask
18.
The air pressure of the gas
14 in the conduit
20 is executed by
the pressure of the substance pumped through conduit branch
64. The supply
pressure of the substance
52 is calculated by the control system
42
and is the sum of the pressure measured by pressure transducer
34 in conduit
20 and the pressure increment set by manual input
48. The substance
52 is then delivered to the patient via the conduit
64 and the mask
18.
A second embodiment of the present invention is shown in FIG. 2, in which like
reference numerals are used to indicate like features.
The first control system
42 of the second embodiment incorporates a microcontroller
92 and a linear position transducer
94 connected to the magnet
70
to provide a feedback signal
96 indicative of the position of the magnet
70 and the diaphragm
60, to which it is connected.
The two manual inputs
48 and
50 are replaced by a digital control
panel
98 with: a three digit digital display
100; three push buttons:
Mode
102, "+"
104, "-"
106; and three LEDs to indicate the
mode selected: Volume
108, Delivery Pressure
110 and Run
112.
The operation of this system is generally similar to the description above except
where indicated below.
Successive depression of the Mode push button
102 cycles through
the three modes of operation: Volume, Delivery Pressure and Run.
When Volume or Delivery Pressure is selected, the digital display
100
indicates the current setting of that parameter. This value may be modified if
required by operating either of the two push buttons "+"
104 or "-"
106.
When Run is selected, the parameters stored in the memory of the microcontroller
90 calculate the desired position of the magnet
70. This is then
compared with the actual magnet position indicated by the linear position transducer
94. Any difference produces an error signal that is used to correct the
position of the magnet
70 to the desired position.
A third embodiment of the present invention is shown in FIGS. 3 to 5, in which
like reference numerals are again used to indicate like features. In this embodiment,
the flow processing amplifier and differentiating filter
28 again detects
the onset of inhalation by sensing a change in the range of flow (ie. the acceleration
or deceleration) of the gas flowing past the sensor
22.
The output signal
120 from the amplifier filter
28 of this embodiment
is active when the onset of inhalation is detected and remains active for the duration
of the inhalation portion of the breathing cycle. The output signal
120
from the amplifier filter
28 is not active for the exhalation portion of
the breathing cycle.
The output signal
120 is supplied to a driver stage
122 and an
inverter stage
124.
When the output signal
120 is active, during inhalation, the driver stage
122 is active and applies power to an electromagnetic winding
126
through a connection
128. When the output signal
120 is inactive,
during exhalation, the inverter stage
124 supplies a drive signal
130
to a driver stage
132. The driver stage
132 is activated and supplies
power to an electromagnetic winding
134 through a connection
136.
A magnetic core
138 is located within the electromagnetic winding
126.
Similarly, a magnetic core
140 is located within the electromagnetic winding
134.
The magnetic core
138 and the magnetic core
140 are connected by
a connecting rod
142 which is also connected to a sliding spool valve
144.
When the winding
126 is energised through the connection
128 the
magnetic core
138 is displaced in the direction of arrow
150 and
pulls with it the spool valve
144 and core
140.
When winding
134 is energised through connection
136 the magnetic
core
140 is displaced in the direction of arrow
152 and pulls with
it the spool valve
144 and core
138.
The body
154 of the spool valve
144 is connected to the gas flow
generator
16 through a branch conduit
156 connected to the conduit
20.
A diaphragm motor
157 is comprised of housing halves
158 and
160
separated by a diaphragm
162 which defines cavities
164 and
166.
A diaphragm pump
168 is comprised of housing halves
170 and
172
separated by a diaphragm
174 which defines cavities
176 and
178.
The cavity
164 is connected to the spool valve body
154 by a conduit
182. The cavity
166 is connected to the spool valve body
154
by a conduit
184. The cavity
176 is open to atmosphere. The cavity
178 is connected to the source
54 of the substance
52 to be
delivered by the conduit
56 and the one-way valve
62. The cavity
178 is also connected to the mask
18 by the conduit
64 and
the one-way valve
66.
The motor diaphragm
162 and the pump diaphragm
174 are connected
by a connecting rod
186. The connecting rod
186 passes through an
air sealed bearing (not shown) between cavities
166 and
176.
An adjusting screw
188 is located on the top of housing halve
158.
With reference to FIG. 4, the operation of the apparatus will be described during
the inhalation portion of the breathing cycle.
As the patient start to inhale, the second output signal
120 from the
flow
processing amplifier
28 is set to active and activates the driver stage
122. The inverter stage
124 is inactive and magnetic core
140
is free to move. The driver stage
122 supplies power to the electromagnetic
winding
126 through connection
128. The magnetic core
138
is forced in the direction of the arrow
150 and with it the spool valve
144. The air
14 now flows from the branch conduit
156 into
the spool valve body
154 and is diverted by the spool valve
144 through
the conduit
182 and into the cavity
164. The pressure of the air
entering the cavity
164 forces the motor diaphragm
162 in the direction
of arrow
190 and with it the pump diaphragm
174. The cavity
178
is already filled with the substance
52 to be delivered to the mask
18.
The displacement of the pump diaphragm
174 into the cavity
178
increases the substance pressure, closes the one-way valve
62, opens the
one-way valve
66, and forces the substance
52 into the conduit
64.
The conduit
64 is in fluid communication with the conduit
20 and
the mask
18 and the substance
52 is thereby delivered to the mask
18 and the patient.
With reference to FIG. 5, the operation of the apparatus will be described during
the exhalation portion of the breathing cycle.
As the patient start to exhale, the second output signal
120 from the
flow
processing amplifier
28 is set to inactive. The driver stage
122
is not activated and power is not supplied to the electromagnetic winding
126
through connection
128. The magnetic core
138 is therefore free to
move. As the output signal
120 from the flow processing amplifier
28
is now inactive, the inverter stage
124 turns its output signal
130
to active and activates the driver stage
132. The driver stage
132
supplies power to the electromagnetic winding
134 through the connection
136 and the magnetic core
140 is forced in the direction of the arrow
152 and with it the spool valve
144. The air flows from the branch
conduit
156 into the spool valve body
154 and is diverted by the
spool valve
144 through the conduit
184 into the cavity
166.
The pressure of the air in the cavity
166 forces the motor diaphragm
162
in the direction of arrow
192 and with it the pump diaphragm
174.
The displacement of pump diaphragm
174 into cavity
176 produces a
vacuum in cavity
178, closes the one-way valve
66, opens the one-way
valve
62, and draws the substance
52 through the conduit
56
into the cavity
178.
The movement of the motor diaphragm
162 and pump diaphragm
174
is limited by the adjusting screw
188. The setting of the screw
188
governs the maximum displacement of the motor diaphragm
162 and pump diaphragm
174 in direction of the arrow
192, therefore controlling the volume
of the substance
52 able to be drawn into the cavity
178 for delivery
to the patient during the next inhalation.
The pump diaphragm
174 is smaller in area than the motor diaphragm
162.
Accordingly, a given pressure supplied to motor diaphragm
162 will produce
a greater pressure from the pump diaphragm
174. Therefore, the pressure
delivered by the pump diaphragm
174 into the conduit
64 and the patient
mask
18 will always exceed the pressure of the gas in the conduit
20.
The ratio between the pressure in the conduit
20 and the conduit
64
is proportional to the ratio between the area of the diaphragms
174 and
162.
In another embodiment (not shown) the motor diaphragm
157 is replaced
by
an electric motor, such as a stepper motor, controlled by a control system to provide
more accurate delivery of the substance
52.
A fourth embodiment of the present invention is shown in FIG. 6, in which like
reference numerals are again used to indicate like features. This embodiment is
for use in conjunction with a bi-level CPAP flow generator (not shown) that delivers
breathable gas at a relatively high treatment pressure to the mask during patient
inhalation and at a relatively low treatment pressure during exhalation. The applicant
markets such a bi-level system under the trade mark VPAP.
This embodiment includes a motor cylinder
200 having a slidable piston
202 which defines cavities
204 and
206. A pump cylinder
208
is also provided having a slidable piston
210 which defines cavities
212
and
214. The pistons
202 and
210 are connected by a connecting
rod
216 which passes through an air sealed bearing
218.
The cavity
204 is connected to the conduit
20 by the branch conduit
156. The cavities
206 and
212 are open to atmosphere. The
cavity
214 is connected to the source
54 of the substance
52
by the conduit
56 via the one-way valve
62. The cavity
214
is also connected to the mask
18 by the conduit
64 and the one-way
valve
66.
The pistons are biased in the direction of arrow
220 by a spring
222.
The operation of the apparatus shown in FIG. 6 will now be described. During
exhalation, relatively low pressure gas is passing through conduit
20 which
generates only a small amount of force on the piston
202. The spring
222
overcomes this force and drives the pistons
202 and
210 in the direction
of the arrow
202 thereby creating a vacuum in cavity
214. The vacuum
draws the substance
52 past the one-way valve
62 and into the cavity
214.
During exhalation, relatively high pressure gas is passing through the conduit
20 which generates enough force on the piston
202 to overcome the
spring
222 and drive the pistons
202 and
210 in the direction
of arrow
224. This forces the substance in the cavity
214 past the
one-way valve
66 and into the mask
18 via the conduit
64.
The surface area of the piston
202 is larger than that of the piston
210
and the pressure generated by the piston
210 will therefore exceed that
applied to the piston
202. Accordingly, the substance delivery pressure
will always exceed the pressure produced by the flow generator during the inhalation
phase of the breathing cycle. The ratio between the surface areas of the pistons
202 and
210 is proportional to the ratio between the breathable gas
pressure and the substance delivery pressure.
A fifth embodiment of the present invention is shown in FIGS. 7
a, 7b
and
7c. The fifth embodiment is essentially a modification of
the fourth embodiment so it will work with a constant pressure flow generator.
The fifth embodiment includes a control valve
230 i
