U.S. patent number 3,915,164 [Application Number 05/499,554] was granted by the patent office on 1975-10-28 for ventilator.
Invention is credited to Forrest M. Bird.
United States Patent |
3,915,164 |
Bird |
October 28, 1975 |
Ventilator
Abstract
Ventilator with an inhalation phase and an exhalation phase in
its operative cycle having a servo controller with an inlet adapted
to be connected to supply gas under pressure and also having an
outlet. The controller has control valve means movable between open
and closed positions to control the flow of gas from the inlet to
the outlet of the servo controller. The control valve means is an
open position during the inhalation phase of the ventilator and in
a closed position in the exhalation phase of the ventilator. Means
is provided for supplying gases to the patient from the servo
controller until a predetermined pressure has been reached. After
the predetermined pressure is reached, means is provided to supply
an additional flow of gases to the patient to provide an
inspiratory apneustic plateau for the patient. After a
predetermined period of time, the patient is permitted to exhale
and thereafter the same cycle is repeated.
Inventors: |
Bird; Forrest M. (Palm Springs,
CA) |
Family
ID: |
23985712 |
Appl.
No.: |
05/499,554 |
Filed: |
August 22, 1974 |
Current U.S.
Class: |
128/204.25 |
Current CPC
Class: |
A61M
16/00 (20130101); A61M 16/0833 (20140204); A61M
16/0841 (20140204); Y10S 137/901 (20130101); A61M
2016/0027 (20130101); A61M 16/107 (20140204); Y10T
137/7889 (20150401); Y10T 137/789 (20150401) |
Current International
Class: |
A61M
16/00 (20060101); A61M 016/00 () |
Field of
Search: |
;128/145.8,145.5,145.6,188,203,142,142.2,142.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Recla; Henry J.
Attorney, Agent or Firm: Flehr, Hohbach, Test, Albritton
& Herbert
Claims
I claim:
1. In a ventilator having an inhalation phase and an exhalation
phase in its operative cycle, a servo controller having an inlet
adapted to be connected to a supply of gas under pressure, said
controller also having first and second outlets, control valve
means disposed in said servo controller and movable between open
and closed positions to control the flow of gas from the inlet to
the first outlet, said control valve means being in an open or on
position during the inhalation phase of the ventilator and in a
closed or off position during the exhalation phase of the
ventilator, a patient adapter, means for supplying gas from the
first outlet to the patient adapter, an exhalation valve assembly
coupled to the patient adapter and movable between open and closed
positions and in the open position permitting gases to flow from
the patient adapter to the atmosphere and in a closed position
preventing the flow of gases from the patient adapter to the
atmosphere, means for supplying gas from the second outlet to the
exhalation valve assembly to maintain the exhalation valve assembly
in a closed position during the time the gas is being supplied from
the outlet of the servo controller, means for sensing the pressure
of the gas in the means for supplying gas from the outlet of the
servo controller to the patient adapter and for switching the servo
controller from an open position to a closed position when a
predetermined pressure is reached, apneustic plateau valve means
having having an inlet and an outlet, said apneustic plateau valve
means having a valve member movable between open and closed
position to control the flow of gases from the inlet to the outlet,
means adapted to connect the inlet of the apneustic plateau valve
means to the source of gas under pressure, means connecting the
outlet of the apneustic plateau valve means to the second outlet,
diaphragm operated means for moving said valve member between open
and closed positions, means for supplying gas from the outlet of
the servo controller to the diaphragm operated means and to the
first outlet, said means for supplying gas from the outlet of the
controller to the diaphragm operated means and to the first outlet,
including valve means for controlling the rate of flow of gas from
the diaphragm operated means to the first outlet whereby after the
servo controller is switched to a closed position, an apneustic
topping flow will be supplied to the patient adapter for a period
of time determined by the time required to reduce the pressure in
the diaphragm operated means to a value to permit the valve member
of the apneustic plateau valve means to return from an open to a
closed position.
2. A ventilator as in claim 1 wherein said last named valve means
is adjustable for varying the rate of flow of fluid from the
diaphragm operated means to thereby control the period of time
during which apneustic flow is supplied to the patient.
3. A ventilator as in claim 2 together with adjustable valve means
for adjusting the rate of flow of gas from the outlet of the servo
controller to the patient adapter.
4. A ventilator as in claim 1 wherein said means for supplying gas
from the outlet of the servo controller to the exhalation valve
includes a check valve assembly.
5. A ventilator as in claim 1 wherein said means for supplying gas
from the outlet of the controller to the diaphragm operated means
and to the first outlet includes a check valve assembly.
6. A ventilator as in claim 5 wherein said check valve assembly
includes a body having a passage extending into the body generally
axially thereof and extending out of the body generally radially
thereof and a resilient sleeve on said body and normally covering
said passage extending out of the body.
7. A ventilator as in claim 1 together with fixed orifice means for
controlling the rate of flow of gas from the outlet of the
apneustic plateau valve means to the second outlet.
8. A ventilator as in claim 1 wherein said means for supplying gas
from the first outlet to the patient adapter includes a nebulizer
through which the gas must flow and wherein said means for
supplying gas from the second outlet to the exhalation valve
assembly includes means for supplying gas from the second outlet to
the nebulizer so that there is nebulization of gases after the
controller has moved to a closed position.
9. A ventilator as in claim 1 together with a venturi assembly
coupled to said first outlet for receiving the gases supplied
through the first outlet, said venturi assembly including a
venturi-like passage and means for forming a main jet of gases
passing through the venturi-like passage and means forming a
secondary jet of gases passing through said venturi-like passage
and wherein said means for forming said main jet of gases is
coupled to the second outlet of the controller and wherein the
means for forming the secondary jet of gases is connected to the
means for supplying gas from the outlet of the controller to the
diaphragm operated means and to the first outlet.
10. A ventilator as in claim 1 together with a vapor trap assembly
coupled to the exhalation valve assembly, said vapor trap assembly
having means for causing the patient to exhale against a positive
pressure.
11. A ventilator as in claim 10 wherein said vapor trap assembly
includes a valve member having a plurality of openings therein and
a gate valve normally closing said openings.
12. A ventilator as in claim 10 wherein said vapor trap assembly
includes a valve member having a plurality of openings therein and
a gate valve normally closing said openings.
13. A ventilator as in claim 10 wherein said vapor trap assembly
includes a housing having an opening therein, a valve member
mounted in the housing and having at least one opening therein, a
flapper-type valve secured to said member and normally closing said
opening in said member and means mounted in the housing for
diffusing gases which are discharged through the flapper valve
assembly.
14. A ventilator as in claim 1 wherein said controller is provided
with a compound knob arrangement in which one knob is utilized for
pressure control and the other knob is utilized for sensitivity
control.
Description
BACKGROUND OF THE INVENTION
Various ventilator and respirators have been provided. However,
they have been deficient in that they have failed to provide an
adjustable post-inspiratory flow. In the past, when
post-inspiratory flow was developed by locking up the proximal
airway in a static state, many subjects developed varying degrees
of dyspnea. There is, therefore, a need for a new and improved
ventilator and method which provides an adjustable post-inspiratory
apneustic plateau flow for a period of time which does not have the
above named disadvantages.
SUMMARY OF THE INVENTION AND OBJECTS
The ventilator has an inhalation phase and an exhalation phase in
its operative cycle. A servo controller is provided having an inlet
adapted to be connected to a supply of gas under pressure. The
controller also has an outlet and control valve means disposed in
the controller and movable between open and closed positions to
control the flow of gas from the inlet to the outlet. The control
valve means is in an open position during the inhalation phase of
the ventilator and in a closed position during the exhalation phase
of the ventilator. A patient adapter is provided. Means is also
provided for supplying gas from the outlet of the servo controller
to the patient adapter. Exhalation valve means is provided which is
associated with the patient adapter and is movable between open and
closed positions to permit exhalation by the patient during the
exhalation phase. Means is provided for supplying gas from the
outlet to the exhalation means to maintain it in a closed position
during the time gas is being supplied from the outlet. Means is
provided for sensing the pressure of the gas in the means for
supplying gas from the outlet of the controller to the patient
adapter and for switching the controller from an open to a closed
position when a predetermined pressure has been reached. Apneustic
plateau valve means is provided having an inlet and an outlet. A
valve member is provided in the valve means movable between open
and closed positions to control the flow of gas from the inlet to
the outlet. Diaphragm operated means is provided for moving the
valve member between open and closed positions. Means is provided
for supplying gas from the outlet of the controller to the
diaphragm operated means and to the patient adapter. The means for
supplying gas including valve means for controlling the flow of
fluid from the diaphragm operated means whereby after the servo
controller is switched to a closed position an additonal flow of
gas is supplied to the patient adapter for a predetermined period
of time to thereby enhance the volume of gas and distribution of
gas in the patient's lungs while maintaining a graded topping-off
pressure dependent upon the pulmonary compliance of the patient's
lungs.
In general, it is an object of the present invention to provide a
ventilator and method which has means for providing an adjustable
additional flow of gas to the patient after the major portion of
the inspiration phase has been completed.
Another object of the invention is to provide a ventilator and
method of the above character in which the additional flow of gases
enhances the volume of gas and the distribution of gas in the
patient's lungs.
Another object of the invention is to provide a ventilator and
method of the above character in which a graded topping-off
pressure dependent upon the pulmonary compliance of the patient's
lungs is provided during the time of the additional flow of gas to
the patient.
Another object of the invention is to provide a ventilator of the
above character which is relatively simple in construction and
which can be readily cleaned.
Another object of the invention is to provide a ventilator of the
above character which can be readily used by a patient.
Additional objects and features of the invention will appear from
the following description in which the preferred embodiment is set
forth in detail in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a ventilator incorporating the
present invention.
FIG. 2 is a side elevational view of a portion of the ventilator
shown in FIG. 1.
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG.
2.
FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG.
3.
FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG.
3.
FIG. 6 is a partial cross-sectional view of the ventilator
particularly showing the apneustic control valve assembly and an
inlet filter.
FIG. 7 is an enlarged cross-sectional view of the servo controller
utilized in the ventilator.
FIG. 8 is a cross-sectional view taken along the line 8--8 of FIG.
7.
FIG. 9 is a cross-sectional view taken along the line 9--9 of FIG.
7.
FIG. 10 is a cross-sectional view taken along the line 10--10 of
FIG. 7.
FIG. 11 is a cross-sectional view taken along the line 11--11 of
FIG. 7.
FIG. 12 is a cross-sectional view of the normally closed apneustic
control cartridge.
FIG. 13 is a cross-sectional view taken along the line 13--13 of
FIG. 5.
FIG. 14 is a cross-sectional view taken along the line 14--14 of
FIG. 13.
FIG. 15 is a cross-sectional view taken along the line 15--15 of
FIG. 1.
FIG. 16 is a cross-sectional view taken along the line 16--16 of
FIG. 15.
FIG. 17 is a flow diagram for the ventilator.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The ventilator 20 incorporating the present invention consists of a
cabinet or case 21 which is supported in a suitable manner such as
by a stand 22. The stand 22 is of a conventional type and consists
of a base 23 which is provided with a pair of wheels 24 so that it
can be readily moved from one location to another. A fitting 26 is
mounted on the base 23 and is connected to a suitable supply of a
gas through a tube 27 for the ventilator such as a supply of oxygen
which is connected to the tube 27. The gas is supplied from the
fitting 26 through an upright tubular member 28 which is mounted
within the fitting and which has its upper end bent into a U with
the extremity of the same connected to a wing-type connector 29.
The connector 29 can be connectd to an oxygen blender (not shown)
of the type described in U.S. Pat. No. 3,727,627. Alternatively, it
can be connected directly to the ventilator 20 as shown in FIG.
1.
The cabinet or case 21 consists of a U-shaped member 31 formed of
sheet metal which is provided with a top wall 32 and side walls 33
and 34. It also consists of a front wall or panel 36 and an
L-shaped member 37 which forms the rear wall 38 and a bottom wall
39. As can be seen, the cabinet is generally a rectangular
six-sided enclosure. A flanged boss 40 is mounted on the top wall
32 of the cabinet and is connected to the wing nut connector 29. A
fitting 41 is mounted in the flange boss 40 and is connected by a
tube 42 to one end of a filter 43. Gas is supplied from the source
at a pressure ranging from approximately 45 to 75 p.s.i. and
preferably about 50 p.s.i. A tube 44 connects the other end of the
filter 43 to a tee 46 and one end of the tee is connected by a tube
47 to the inlet of a sequencing servo cartridge or controller 48
and the other end of the tee 46 by a tube 49 to the inlet of an
apneustic plateau cartridge 51. The sequencing servo cartridge or
controller 48 is generally of the type described in United States
Letters Pat. No. 3,753,436. The filter 43 is in the form of a
cylindrical cartridge which is sealed at both ends and which has a
filter member 53 formed of a suitable filter material such as nylon
mesh which is generally cup-shaped in form and which has its lower
extremity supported by triangular supports 54 formed integral with
the cartridge.
The sequencing servo cartridge 48 consists of a housing 56 formed
of a suitable material such as plastic. The housing 56 is provided
with a circular flat bottom wall 57 which has a rim 58 formed
integral therewith and extending outwardly at right angles from the
bottom wall. The housing 56 is also provided with a cylindrical
extension 59 formed integral therewith which extends outwardly from
the flat bottom wall 57 and in a direction opposite the rim 58. The
hollow cylindrical extension 59 is provided with pairs of spaced
opposing openings 61 and 62. A hollow cylindrical control body 63
formed of a suitable material such as a transparent plastic has one
end mounted within the outer extremity of the cylindrical extension
59 and is retained therein by a metal retaining ring 64 which
slides over the outer extremity of the cylindrical extension 59
after the control body 63 is mounted therein. The control body is
provided with a wall 66 which extends diametrically across the
control body. The control body 63 is formed to provide a flow
passage 67 which serves as a pressure inlet port 68 normally in
communication with a passage 69 opening into an outlet port 71.
A master shaft 73 is slidably mounted in the housing 56. The master
shaft 73 is formed of a suitable material such as steel. A pair of
sleeve-like parts 74 and 76 formed of a suitable material such as
plastic are mounted on the master shaft 73 so that they are in
engagement with each other. The exteriors of the bushings 74 and 76
are threaded and have threadedly mounted thereon a magnetic
starting effort armature 77 and a magnetic pressure armature 78.
The plastic parts 74 and 76 are provided with teeth which engage
each other so that the two parts will not rotate with respect to
each other. The armatures 77 and 78 are adapted to be attracted by
a cylindrical magnet 79 mounted within the cylindrical extension 59
of the housing 56 between the openings 61 and 62. The starting
effort armature 77 and the pressure armature 78 can be adjusted
longitudinally of the master shaft 73 by rotating the same on the
bushings 74 and 76 to increase or decrease the force applied to
each of the armatures by the magnet 79. O-rings 80 are provided
between the armatures 77 and 78 and the bushings 74 and 76 to
provide a desired amount of friction.
The master shaft 73 extends through a hole 81 provided in the wall
66 of the control body 63. A circular servo plate 82 is mounted on
the outer extremity of one end of the master shaft 73 and is
retained in this position by snap rings 83. A fitting 84 is mounted
in the servo plate 82 adjacent the outer margin of the same and
carries a servo plunger 86. The servo plunger 86 is adapted to
engage a ball 87 that serves as a valve member which is adapted to
engage an annular valve seat 88 whereby flow passages between the
inlet port 68 and the outlet port 71 can be established or
interrupted depending upon the position of the ball 87.
An anti-rotation hub 91 which is rectangular in cross-section is
mounted upon the master shaft 73 and is mounted in an opening 92
provided in the flat bottom wall 57 to prevent rotation of the
master shaft. A metal plate 93 is mounted on the shaft and supports
the inner margin of a flexible diaphragm 94. The outer margin of
the diaphragm 94 is clamped between the rim 58 and the pressure
bell 96. The anti-rotation hub 91 prevents possible "wind up" of
the diaphragm 94 and splints the backside of the diaphragm 94. The
pressure bell 96 is frictionally retained on the housing 56 by a
cooperating ridge and groove (not shown) and is provided with a
sensing port 97. The pressure bell is provided with a cylindrical
extension or hub 98 formed integral therewith. An accessory shaft
hub 101 is threaded onto the master shaft and extends into the
extension 98 of the pressure bell 96. A pressure chamber 102 is
formed within the pressure bell and is in communication with the
sensing port 97. Yieldable means in the form of a helical spring
103 is provided within the chamber 102 which has one end engaging
the diaphragm 94 and has the other end engaging a flanged sleeve
104 slidably mounted on the accessory shaft hub 101. The flanged
sleeve 104 engages a wall 106 formed in the extension 98. An
accessory shaft 107 has one end threaded into the accessory shaft
hub 101 and extends axially of the extension 98.
An adjustable sensitivity stop member 111 is threadedly mounted
within the interior of the extension 98 and can be moved axially of
the accessory shaft 107 by rotation of the same through the
limiting screw 112 threaded into the adjustable sensitivity stop
member 111 and extends through a slot 113 provided in extension or
hub 98. The limiting screw 112 extends into a slot 114 provided in
a sensitivity control dial 116 which is used for rotating the
adjustable sensitivity stop member 111. O-ring 117 provides
friction between the member 111 and the interior of the extension
98 and with the screw 112 holding the dial 116 in place.
An index hub 121 is mounted upon the extension 98. An adjustable
pressure limiting knob 122 is mounted within the index hub 121. The
pressure limiting knob 122 is threadedly mounted on the exterior of
the extension 98. It is provided with a pin 123 extending inwardly
which is adapted to engage an abutment 124 provided on the
extension 98 to limit the rotation of the knob 122. The pressure
limiting knob 122 and the sensitivity control knob 116 serve as a
compound knob for operation of the servo cartridge 48.
A cam shaft 126 is mounted on the accessory shaft 107 and is
retained thereon by a retaining ring 127. A key 128 is formed
integral with the extension 98 and engages a wide slot 129 provided
in the index hub 121.
A manual override knob 131 is secured to the cam shaft 126 by a set
screw 132. The cam shaft 126 is provided with an enlarged
cylindrical portion 126a which has O-rings 133 mounted thereon that
serve as bumpers. A helical drag spring 136 is mounted within the
extension 98 and has one end engaging the adjustable sensitivity
stop member 111 and has the other end engaging an inner surface of
the knob 122. A flat washer 137 is provided between 136 spring and
122 knob to add friction to inhibit rotation of the pressure
limiting knob 122. The drag spring 136 performs two functions. One
is providing indirect friction for the starting effort dial or knob
116 and direct function for the pressure limiting knob 122. The
other is eliminating possible backlash in the coarse threads of
both travel limiting stops for the knobs 116 and 122 by maintaining
tension between the stops.
The apneustic control cartridge 51 is shown in detail in FIG. 12,
and as shown therein, consists of housing 141 which is provided
with an enlarged portion 141a. The portion 141a has a cup-shaped
cavity 142 which is in communication with a bore 143 extending
longitudinally of the housing. A flexible diaphragm 144 is disposed
within the cavity 142 and has its outer margin clamped between the
enlarged portion 141a and an end or retainer cap 146 which is
retained within the enlarged portion 141a by a retaining ring 147.
A rigid cam button 148 engages a central portion of the diaphragm
144 and extends through a seal retainer 149 threaded into the
enlarged portion 141a. A flexible sealing member 151 has its outer
margin engaged between the retainer 149 and the interior of the
housing 141. One side of the sealing ring 151 is engaged by the
button 148 and the other side engages a rigid disc or button 152.
The button 152 engages a valve stem 153 forming a part of a valve
member or puppet valve 154 which carries an O-ring 156 adapted to
make sealing engagement with a valve seat 157 formed on the
interior of the housing 141. The valve member 154 is provided with
a boss 158 in which there is mounted one end of helical coil spring
159 extending axially of the bore 143. The outer end of the spring
159 is seated in a well 161 of a fitting or mounting cap 162
threaded into the end of the housing 141.
A pressure gauge 163 is mounted on the front panel 36 by a screw
164 which is part of the gauge 163 and extends through a U-shaped
bracket 166 mounted on the front panel 36 and is secured thereto by
a nut 167. The cartridge 51 is mounted on the outer extremity of
the screw 164 by threading the mounting cap 162 upon the screw
163.
First and second fittings 171 and 172 with fitting 171 being the
inlet fitting and fitting 172 being the outlet fitting are threaded
into the body 141 and are in communication with the bore 143 on
opposite sides of the valve seat 157. A bleed hole 176 is provided
in the housing 141 and serves to prevent any build-up of pressure
against the diaphragm which could give a false indication. The end
cap 146 is provided with a servo port 177 which is in communication
with a chamber 178 provided on one side of the diaphragm 144.
The tube 47 is connected to a fitting 181 which is mounted in one
end of the means forming the flow passage 67. The other end is
closed by a plug 182. The outlet port 71 has a fitting 183 mounted
therein which is connected to a tube 184. The tube 184 is connected
to a tee 186. One end of the tee 186 is connected by tube 187 which
is connected to a fitting 188 mounted in a flow rate valve 189 of
the conventional type. The flow rate valve is provided with a
control knob 191 for adjusting the rate of flow of gas through the
flow rate control valve 189 through a fitting 192 which is mounted
in the body 193 of the valve. The fitting 192 is connected by a
tube 194 to a tee 196. One end of the tee 196 is connected by a
tube 197 to a check valve assembly 198.
As shown in FIG. 13, the check valve assembly 198 consists of a
central body 201 on which there is mounted a housing 202 both of
which are formed of a suitable material such as plastic and are
fastened together in a suitable manner such as by ultrasonic
welding to provide a bubble tight seal. The central body 201 has a
cylindrical portion 201a of reduced diameter as shown in FIG. 13.
It is also provided with a flange 203 on the end of the portion
201a of reduced diameter. A passage or bore 207 is provided in the
central body and extends longitudinally thereof through a stem-like
portion 201b of the central body. The passage 207 empties into a
passage 208 extending diametrically of the central body 201. The
passage 208 is normally closed by a sleeve 209 formed of a suitable
elastic material such as rubber which is slipped over the portion
201a and is retained thereon by the flange 203. It can be seen that
if air is entering under pressure in the passage 207 in a direction
indicated by the arrow that it can cause the elastic member 209 to
expand and to permit the gas to escape into the housing 202 and to
be discharged therefrom through a passage 211. When the air ceases
to be applied under pressure through the passage 207, the elastic
member will close the openings or passage 208 and prevent gas flow
in an opposite direction.
The passage 111 is connected by a tube 216 to a tee 217. One end of
the tube 216 is directly connected to the inspiratory power fitting
219 mounted on the front panel 36 which can be termed a second
outlet. The other end of the tee 217 is connected through a member
221 providing a restricted orifice and then through a tube 222
which is connected by an elbow 223 which is mounted in the fitting
172. (See FIG. 4)
The end of the tee 196 is connected by tube 226 to a fitting 227
mounted in a boss 228 provided on a venturi assembly 229. The boss
is provided with a main passage 231 which is centrally disposed in
the nozzle 232 to provide a main venturi jet of gases. Additional
passages 233 are provided in the nozzle 232 and are disposed around
the centrally disposed passage 231 to provide secondary venturi
jets. The passages 233 are in communication with a passage 234
provided in a boss 236. A fitting 237 is provided in the boss and
is connected to a tube 238. The nozzle 232 is disposed in a
T-shaped housing 239. One end of the housing 239 is threaded onto a
venturi housing 241 which has a venturi passage 242 therein in
communication with the jets of gas discharging from the passages
231 and 233 in the nozzle 232.
A fitting 243 is mounted in the other end of the housing 239 and is
connected by a large tube 244 to an air inlet filter 245 mounted in
the side wall 34. The venturi housing 241 is provided with first
and second spaced parallel radially extending flanges 246 and 247
which are adapted to seat within a gate valve housing 248. An
O-ring 249 is mounted in the flange 246 and establishes a seal
between the venturi housing 241 and the gate valve housing 248.
The gate valve housing 248 is provided with an interior spider 251
which forms a centrally disposed hole 252 that receives the
dish-shaped gate valve 254 which is adapted to engage the outer
extremity of the venturi housing 248. An O-ring 256 is provided on
the exterior of the venturi housing 241 to establish a good seal
between the gate valve 254 and the venturi housing. Yieldable means
is provided for urging the gate valve into engagement with the
O-ring and consists of a helical spring 257 mounted on the stem 253
and having one end engaging the spider 251 and having the other end
engaging the valve 254. The housing 248 is provided with a boss 258
which has a tee 259 mounted therein. One end of the tee 259 is
connected by a tube 261 to the pressure manometer 168. The other
end of the tee 259 is connected by a tube 262 to the sensing port
97 of the servo cartridge 48.
The gate valve housing 248 is provided with an outlet 263 which is
connected to a tee 264. One end of the tee 264 is mounted in a
breathing tube receptacle 266 which is mounted on the front panel
36 and which can be termed a first outlet. The receptacle 266 is
contained within the front panel 36 by nut 267 which is threaded
thereon. The other end of the tee 264 has a safety-blow off valve
assembly 268 mounted therein.
The valve assembly 268 consists of a generally cylindrical housing
269 with a flow passage 271 therein. An apertured wall 272 is
provided in the passage and has a valve stem 273 slidably mounted
therein. A valve member 274 is carried by the valve stem and is
adapted to engage a valve seat 276 which is formed on the housing
and surrounds the passage 271. Means is provided for yieldably
urging the valve member into engagement with the seat and consists
of a spring 277 having one end engaging the wall 272 and having the
other end engaging a nut 278 provided on the valve stem 273.
The tube 238 is connected to a fitting 281 mounted in an apneustic
plateau control valve assembly 282. The control valve assembly 282
is provided with a valve body 283 having a control knob 284 for
adjusting the flow through the valve assembly. A fitting 286 is
mounted on the valve assembly 282 and is connected to the tube 287
which is connected to a fitting (not shown) of the apneustic
control valve assembly 51. The valve assembly 282 is provided with
another fitting 288 (FIG. 6) which is connected by a tube 289 to a
check valve assembly 291. The check valve assembly 291 is similar
to the check valve assembly 198 and, therefore, will not be
described in detail. The check valve assembly 291 is connected by a
tube 292 to the tee 186.
A hanger rod 296 is slidably mounted in a fitting 297 provided in
the front panel 36.
As shown in FIG. 1, a large breathing tube 301 is adapted to be
mounted in the breathing tube receptacle 266. A small tube 302 is
mounted in the inspiratory power control fitting 219. The other end
of the large breathing tube 301 is connected to a fitting 303 which
is connected into a nebulizer 304 of the type described in U.S.
Pat. No. 3,172,406. The other end of the nebulizer 304 is connected
to a tee 306 which has a patient adapter or mouthpiece 307 mounted
in one end thereof and which has an exhaust valve assembly 308
mounted in the other end thereof. The small tube 302 is connected
to a tee 309 which has one end mounted in the nebulizer 304. The
other end of the tee 309 is connected by a tube 311 to the
exhalation valve assembly 308. The exhalation valve assembly 308 is
of a conventional type. A vapor trap assembly 312 is mounted on the
exhalation valve assembly to collect moisture which has
precipitated out of the airstream.
The vapor trap assembly 312 consists of an outer cup-like housing
313 in which there is removably mounted a gate valve and diffuser
assembly 314. The housing 313 is generally cylindrical in shape and
is provided with an upstanding cylindrical wall 316 with a bottom
wall 317 formed integral therewith. A central opening 318 is
provided in the bottom wall and is circumscribed by an upstanding
lip or flange 319 so that there is provided an annular recess 321
between the upstanding flange 319 and the upstanding cylindrical
wall 316. One end of the housing 313 is open and is adapted to
receive the gate valve and diffuser assembly 314.
The gate valve and diffuser assembly 314 consists of a hollow
cylindrical member 322 which is carried by a plurality of
upstanding circumferentially spaced ribs or posts 323. The ribs or
posts 323 are formed integral with a diffuser member 324. The
diffuser member 324 is provided with a cylindrical wall 326 which
is closed at its top by a transversely extending top wall 327. The
top wall 327 is provided with a centrally disposed upwardly
extending cone-shaped portion 327a which underlies the hollow
cylindrical member 322. As will be noted, the lower extremities of
the posts or ribs 323 extend below the bottom of the cylindrical
wall 326 and are adapted to seat within the annular recess 321a in
the housing 313. The annular rim 331 is formed integral with the
hollow cylindrical member 322 and is provided with an upstanding
flange 332 which is adapted to engage the inner surface of the
cylindrical wall 316 of the housing 313 to frictionally retain the
gate valve and diffuser assembly 314 within the housing 313. The
lower extremity of the hollow cylindrical member 322 is spaced
above the top wall 327.
A circular plate 333 is mounted within the hollow cylindrical
member 322 and is seated upon the upper extremities of the ribs
323. The plate 323 is provided with downwardly depending ears 334
which are adapted to snap over the lower extremity of the hollow
cylindrical member 322 to retain the plate 333 within the hollow
cylindrical member 322. The plate 336 is formed with a plurality of
openings 336 which are arranged in a circle. An umbrella-type
flapper valve 337 formed of a suitable material such as a flexible
plastic is provided to form a gate valve in conjunction with the
openings 336. The flapper valve 337 is provided with a centrally
disposed tit 338 which is mounted in a centrally disposed hole 339
provided in the plate 333 to retain the flapper valve 337 in
engagement with the bottom side of the plate 333 to normally close
the openings 336. The flapper valve 337 generally overlies the
cone-shaped portion 337a so that when air passes through the
openings 336 and pushes the flapper valve downwardly the air will
be diffused outwardly over the diffuser member 324 and through the
ribs and downwardly and then up and over the flange 319 and to the
atmosphere through the opening 318.
Operation and use of the ventilator 20 may now be briefly described
as follows. Let it be assumed that the ventilator 20 is to be
utilized by a patient who is in a comfortable supine position or
sitting erect in an armchair. The nebulizer 304 is filled with a
suitable solution which is to be utilized by the patient and as may
be prescribed by a physician. The tee 306 with the exhalation valve
assembly 308 is then mounted on the nebulizer 304 with a mouthpiece
or patient adapter 307. The water trap assembly 312 is mounted upon
the exhalation valve assembly 308. The breathing tube 301 is placed
in the breathing tube socket 266 and the tube 302 is mounted in the
expiratory power fitting 219.
The starting effort for the patient is set by utilizing the control
dial 116 which carries indicia ranging from 1 to 5. An appropriate
setting is 2 which represents -2 cm of water. Next, the inspiratory
positive pressure is set by utilizing the dial or knob 122. The
dial or knob carries indicia ranging from 15 to 60 cm H.sub.2 O and
can be set within this range. For starting it should be set to 15.
If desired a dual range can be provided with the one range of 15 to
60 p.s.i. as a therapy range and with another range of 15 to 100
p.s.i. as an intensive care range.
The flow rate is next adjusted by operating the knob 191 so that an
arrow (not shown) carried by the knob is in the twelve o'clock
position.
The manual control timer knob 131 is depressed inwardly and
thereafter, the oxygen or air supply is turned on to supply oxygen
or air or a mixture of the same through the tube 27 to the
ventilator 20. The manual timer control knob 131 is then pulled out
so that the ventilator is "on". There should be a dense flow of
aerosol from the nebulizer 304. The manual timer control knob 131
is then pushed in to the ventilator "off" position. After this for
a specific period of time (between 0.25 to 3 seconds) there should
still be a flow of aerosol from the nebulizer 304. This is the
apneustic flow time. The knob 284 is then rotated fully
counterclockwise to the minimum period (0.25 second). The
ventilator is then ready for use by the patient.
In operation of the ventilator, air from the source at suitable
pressure such as 50 p.s.i. is supplied through the filter 43 and
then through the tube 44 and the tubing 49 to the apneustic plateau
cartridge 51 and also through the tube 47 to the servo cartridge
48.
Let it be assumed that the control knob 131 is moved to the left
from the position shown in FIG. 7 to cause the master shaft 73 to
be moved to the left which, in turn, causes movement of the servo
plate 82 and the fitting 84 to the left. Movement of the fitting 84
to the left causes movement of the plunger 86 to the left to engage
the ball 87 to move it out of engagement with the seat 88. In this
position of the ball 87, source gases with flow around the ball and
through the orifice or valve seat around the plunger 86 and out the
outlet port 71. During this on or open period, the flow of the
source gas around the ball literally spins the ball 87 on the end
of the plunger 86 and serves to keep the ball free of
microcontaminations such as could be carried by water. This flow
through the port 71 can be identified as inspiratory flow gas.
Inspiratory flow gas is supplied through tube 184 and the tube 187
to the flow rate valve 189, then through the tube 194 and the tube
226 through the center venturi passage 231 of the venturi assembly
229. The jet of gases passing from the passage 231 in the nozzle
232 will pass down through the venturi 242 which will cause
aspiration of additional gases which will be drawn in through the
filter 245 and through the large bore tube 244 as shown
particularly in FIG. 6. The gases which are supplied by the venturi
passage 242 apply positive pressure to the gate valve 274 against
the yieldable force of the spring 277 to open the gate valve and to
permit the gases to be discharged through the receptacle 266 and
thence through the large tube 301 through the nebulizer 304, the
tee 306 and the mouthpiece 307 to the patient. At the same time,
inspiratory gases are being supplied by the tube 197 to a check
valve assembly 198 to the inspiratory power socket 219 provided on
the front panel 36. The small tube 302 is connected to this
inspiratory power socket and supplies inspiratory gases under
pressure to the nebulizer 304 and to the exhalation valve assembly
to maintain the same closed during the inhalation or inspiratory
phase of the ventilator. The safety blow-off valve assembly 268 is
provided to protect the patient from over-pressure as, for example,
a pressure above 67 cm of water, to prevent damaging the patient's
lungs.
As herein before pointed out, means is provided for sensing the
pressure of the gases being supplied to the patient and consists of
the manometer 168 which is connected to the outlet receptacle 266.
It also is connected through the tube 262 to the sensing port 97 of
the servo cartridge 48.
Inspiratory gas is also supplied through the tube 292 through a
check valve assembly 291 through the apneustic control valve
assembly 282 through tube 238 to the passage 234 provided in the
venturi assembly 229. The passage 234 is connected to a plurality
of passages 233 provided in the nozzle 232 to provide additional or
secondary venturi jets of gas which are directed through the throat
of the venturi assembly to augment the flow of gases through the
venturi. The gas under pressure is also supplied from the apneustic
control valve 282 through a tube 287 to the normally closed
apneustic plateau cartridge 51 to move it to the open position.
Additional inspiratory gases are supplied to the inspiratory power
socket 219 through the orifice 271 at a fixed rate as determined by
the size of the orifice 271. The orifice 271 is supplied with
inspiratory gases from the tube 222 which is fed from the open
apneustic plateau cartridge 51 which in turn is fed by the tube 49.
These additional inspiratory gases augment the flow of gases
through the nebulizer 304.
The initial flow of inspiratory gases during the inspiratory phase
of the ventilator delivers inspiratory air into the distal airway
or ducts of the patient' s lungs. Automatic nebulization occurs
during inspiratory phase because the inspiratory gases pass through
the nebulizer 304. The rate of inspiratory flow determines the
volume of inspiratory nebulization. As flow rate is increased, the
pressure behind the primary jet of gases from the nozzle 232
increases causing an increased flow into the breathing circuit. In
the present invention the basic inspiratory flow rate is
supplemented or augmented by parallel flows of inspiratory gases
one of which is through the apneustic plateau cartridge 51 and the
other of which is through the apneustic control valve 282. The flow
through the cartridge 51 which is fixed by the size of the orifice
271, continues throughout the inspiratory phase and for a period of
time after the end of the inspiratory phase as determined by the
setting of the apneustic control valve 282. Thus there is provided
a minimum flow from the nebulizer regardless of the slowing of the
inspiratory flow rate near the end of the inspiratory phase. In
this manner it is possible to effectively double the volume of
particulate delivery from the micronebulizer 304 during slow flow
techniques.
From the foregoing it can be seen that a "topping low flow" is
introduced into the patient's breathing circuit during the period
of apneustic hold which is encountered after termination of the
inspiratory phase. Decreasing the apneustic flow time increases the
rate of flow of bleed down gases through the secondary venturi jets
during the apneustic plateau and conversely increasing the
apneustic flow time decreases the rate of flow of bleed down gases
through the secondary venturi jets during the apneustic plateau.
Also there is an analog tapering off of the rate of flow of the
bleed down gases near the end of the apneustic plateau which
creates a gradual pressure drop within the physiological system of
the patient to prevent an abrupt rapid expiratory flow. These
latter features are important because they make it easy to teach
the patient how to use the ventilator to provide a satisfactory
apneustic plateau.
With the present ventilator, a post-inspiratory apneustic plateau
ranging from 0.25 to 3 seconds in duration can be provided by
adjustment of the control knob 284 of the apneustic control valve
282. In this way, it is possible to further enhance the total
inspiratory distribution of respiratory gases transporting
topically active aerosols. By way of example, it has been found
that during apneustic flow approximately 200 cc of inspiratory gas
is delivered per second so that during a maximum 3 second apneustic
plateau, as much as 600 cc of dense aerosol can be delivered to the
patient's lungs. Thus, it can be seen that during the initial
inspiratory flow the humidity deficits are resolved, whereas during
apneustic flow a larger particle high volume aersol is delivered
into the tracheobronchial tree to effectively enhance the
mobilzation of retained tracheobronchial secretions.
When a certain pressure is reached in the lungs of the patient as
measured by the manometer 168 and since through the tube 262
connected to the servo cartridge, the pressure present in the
chamber 102 will cause movement of the diaphragm 94 and the master
shaft 73 to the right as viewed in FIG. 7. This movement of the
master shaft causes the plunger 86 to move to the right towards a
closed position and permits the ball 87 to approach its orifice
seat or valve seat. The size of the passage between the ball 87 and
the orifice seat decreases to increase the flow velocity of the
gases. This minimizes the tendency for the ball to fly off the seat
during low flow when the plunger is withdrawn to the off position.
To completely eliminate the possibility of a flying ball (during
expected low flow conditions) causing an incompetent switch over
(from the inspiratory to the expiratory phase), circumferentially
spaced, longitudinally extending spoiler strips (not shown) are
formed in the cylindrical walls of the passage 68. These spoiler
strips cause the ball to stall out on its orifice seat during low
flow serving to further guarantee a competent closing. Since the
plunger 86 is mechanically linked by the servo disc 82 to the
master shaft 73, the plunger 86 is pulled to permit the ball 87 to
move to a closed position and is pushed to move the ball from the
closed position.
Opening and closing of the switch of which the ball 87 forms a part
occurs at approximately the mid point of the master shaft travel.
Over-travel in both the on and off directions accomodates master
shaft travel between the magnetic on and off clutches as
described.
At the servo cartridge 48 off position, the ball valve 87 is held
in closed position by the pressure of the source gas which enters
at inlet port 67 and passes into cavity 68 and then pushes ball 87
against seat 88. The magnetic force of magnet 79 holds armature
plate 77, which through shaft 73 and servo plate 82 keeps pin 86
away from ball 87. At the servo cartridge 48 on position, the
magnet 79 holding armature plate 78, which through shaft 73 and
servo plate 82 pushes pin 86 which holds ball 87 away from seat 88.
Source gases are allowed to pass through from cavity 68 to outlet
port 71. Magnetic fields are created by the fixed ring magnet 79.
The strong front field is used to attract the large (pressure
limiting) armature 78. The weaker back field of the magnet
influences the smaller (starting effort) armature 77.
When beginning inspiratory break-away occurs within the servo
cartridge 48 by reducing the pressure in the chamber 102, the
starting effort armature 77 moves away from its magnetic field and
the pressure limiting armature moves into its magnetic field under
the influence of increasing magnetic force. The magnetic opening
force is necessary to prevent a stall (peak starting effort
sensitivity) against the piston effect created during opening of
the ball valve. This is provided in the design of the servo
cartridge by controlling the distance between the pressure limiting
armature and its magnetic field to provide sufficient
"pull-through" forces as servo plunger 86 contacts the ball during
movement to the switch on position.
As the pressure limiting armature moves towards the front field of
the magnet, the pulling force of the magnet pulls rapidly right.
The opposite is true with the starting effort armature as it moves
progressively out of the influence pf the magnetic back field.
Because of the proportionate increase and decrease of the distances
as one armature approaches and the other departs its magnetic
field, only one magnetic field can capture its armature at a time.
This establishes the positive snap on-snap off function of the
pneumatic ball valve.
The functions of the magnetically controlled valve are interfaced
with the servo sensing diaphragm 94 which is capable of applying
servoing forces to the master shaft 73 carrying the magnetic
armatures 77 and 78. The diaphragm area is of sufficient size to
override and magnetic on-off clutches at their maximum torques.
At the commencement of the inspiratory phase, the pressure inside
the airways of the lung start to drop below ambient. Thus
sub-ambient condition is transmitted through the sensing port 97 to
the back side of the diaphragm 94 so that the diaphragm will apply
force to move the master shaft 73 to the left as viewed in FIG. 7.
This movement is resisted by the magnetic (starting effort) source
supplied to the starting effort armature 77. As the physiological
diaphragm of the patient continues to descend during the initial
inspiratory phase, sub-ambient pressures acting against the servo
diaphragm 94 increase until the ON servoing force supplied by the
diaphragm 94 exceeds the opposing force supplied by the preset
commanding magnetic off force set up by the starting effort
armature 77. As soon as this occurs, the master shaft 73 will
travel to the left causing the pneumatic ball valve 87 to open.
A controlled inspiratory flow of gas into the breathing circuit
occurs as hereinbefore described. As the lungs of the patient
gradually fill with the respiratory gases into the breathing circle
connected to the patient, pressures within the physiological and
mechanical ventilatory systems begin to rise. The previous pressure
drop across the servo diaphragm favoring switching to the on
position is now reversed and the pressure favoring switching to the
off position is created. When sufficient pressure is supplied to
the chamber 102 to create a force large enough to overcome the
force applied by the pressure limiting armature 78, the master
shaft 73 is shifted to the right as viewed in FIG. 7 so that the
starting effort armature comes into control of the magnetic field
supplied by the magnet 79. The servo cartridge 48 is switched to
the opposite position by movement of the plunger 86 to the right
and the ball valve 87 seats upon its valve seat to prevent further
flow of source gases through the servo cartridge 48.
By adjustment of the armature 77 on the master shaft 73, it is
possible to preselect a definite value of patient effort required
to switch the ventilator on during mechanically assisted
spontaneous breathing. In addition, it is possible to preselect a
definite positive inspiratory pressure limit by adjusting the
position of the armature 78. Positioning of the armatures 77 and 78
can be adjusted in relation to calibrated adjustable sensitivity
and pressure control knobs 116 and 122, respectively. Calibration
of the starting effort sensitivity is expressed in negative
centimeters of H.sub.2 O and is indexed counter-clockwise 1 to 5
and represents the pressure drop required in centimeters of H.sub.2
O during spontaneous inspiration to trigger the servo cartridge 48
to the on position for assisted mechanical respiration.
Pressurization of the chamber 178 occurs as soon as inspiratory
gases are supplied through the apneustic plateau control valve 282
to the servo port 177 of the apneustic plateau cartridge 51.
Diaphram 147 is urged to the left to open the pocket valve 154 from
a normally closed position. The apneustic plateau control cartridge
utilizes a diaphram seal in place of dynamic O-ring seals because
of varying frictional loads associated with decreasing surface
lubrication and service for O-ring seals.
As soon as the poppet valve 154 is moved to an open position,
source gases are supplied through the inlet fitting 171 and out
through the outlet fitting 172 through the tube 222 and then
through the restricted orifice 221 to the receptacle 219.
When the servo cartridge 48 senses that a predetermined pressure
has been reached in the patient's lungs, the servo cartridge is
shifted from on to off. This is accomplished because as the
pressure builds up in the patient's lungs, it also builds up in the
chamber 102 to cause the diaphragm 94 to apply a pressure to move
the master shaft 73 to the right as viewed in FIG. 7 to move it to
the off position in a manner hereinbefore described. As soon as
this occurs, the ball valve 88 will seat on its seat to prevent
further flow of source gas to the check valve 291 and to the
apneustic plateau control valve 282. At the same time that the
servo cartridge 48 moves to the off position, source gas under
pressure is no longer supplied to the apneustic plateau
cartridge.
At the time of sequencing of the servo cartridge 48, the apneustic
plateau cartridge will still have a certain volume of gas in the
chamber 178 which is at the pressure of the inlet source gas. This
gas must be brought out through the line 287 through the apneustic
plateau control valve 282 and through the tube 238 through the
venturi assembly 229. The time required to bleed down this chamber
178 is determined by the adjustment of the knob 284 of the
apneustic plateau control valve 282. Thus, source gas under the 50
p.s.i. pressure will be supplied through the tube 49, through the
inlet fitting 171, through the outlet fitting 172 and through the
tube 222, through the restricted orifice 221 to the receptacle 219
so that even after the servo cartridge 48 has servoed to the off
position, source gas will be supplied to the breathing tube
receptacle 219 and to the patient. At the same time, source gas
under pressure will be supplied to the inspiratory power fitting
219. Thus, after the servo cartridge 48 has switched to the off
position to end the inspiratory phase, there will still be a
diminishing topping off or a supplemental flow of source gas
through the secondary venturi jets 333 to the lungs of the patient
as hereinbefore described.
It is only after sufficient gas has been bled out of the chamber
178 to permit the spring 159 to move the valve member 154 to a
closed position that the flow of source gas to the patient ceases.
At the same time, source gas under pressure is no longer supplied
to the socket 219 and to the exhalation valve so that the
exhalation valve can open and the patient can exhale through the
exhalation valve.
The exhalation gases from the exhalation valve assembly 308 are
exhausted through the vapor trap assembly 312. These exhalation
gases must pass through the openings 336 and must urge the flapper
valve 337 away from the openings to permit the exhalation gases to
pass downwardly and outwardly over the diffuser member 324 and down
past the ribs 323 and then upwardly over the flange 319 through the
central opening 318 to the atmosphere. The flapper valve forces the
patient to breathe or exhale against a graded positive pressure as
for example 3 centimeters of water. As is well known to those
skilled in the art, the use of means requiring the patient to
exhale against a positive pressure is paticularly efficacious with
patients having obstructive pulmonary diseases. The flapper valve
is of a type which serves to retard the flow of gases very little
at peak flows of gases but does serve to retard the flow of gases
at slow rates of flow. Thus it can be seen that the vapor trap
assembly 312 does provide a retard function and in addition serves
to collect vapors from the exhalation gases within the housing 313.
The housing 313 can be readily removed from the gate valve and
diffuser assembly 314 and emptied when necessary.
As soon as the expiratory phase has been completed, the patient
will cause the sub-ambient condition to occur in the chamber 102 of
the servo cartridge 48 to switch the servo cartridge 48 to the on
position in the manner hereinbefore described to start another
cycle.
From the foregoing, it can be seen that there has been provided a
ventilator or respirator in which a topping low flow is introduced
into the pulmonary structures of the patient during the period of
apneustic hold at the end of the inspiratory phase. This topping
low flow at the post inspiratory apneustic plateau can be from 0.25
to 3 seconds in duration and is particularly useful to permit
topically active particles of aerosol to rain out in the pulmonary
structures concommitant with increased diffusion and mechanical
mixing of the expiratory gases in the lung of the patient. In
addition, it can be seen that the ventilator which has been
provided is of a construction which can be readily manufactured.
Its construction is such that it is relatively simple to operate.
It is also readily cleaned and maintained.
* * * * *