Note: Descriptions are shown in the official language in which they were submitted.
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~-~9544~78
ANAESTHETIST'S RESPIRATION AP~ARATUS
This invention concerns anaesthetist's respiration
apparatus and has for its object to provide a form of such
apparatus constructed so that (a) a patient, treated by use
of the apparatus, will rebreathe his deadspace gas (i.e. the
gas which has not undergone change and normally occupies the
trachea, mouth and bronchial tree); (b) it is unnecessary
. for seda lime to be incorporated therein for absorbing carbon
.` dioxide; (c) the fresh gas needed to be supplied to the
apparatus can be as low as seventy-five per cent of the pre-
dicted minute volume without build-up of carbon dioxide in
the patient; (d) in which the tidal volume as supplied to the
patient can readily be adjusted in a particularly simple
.~ manner; (e) by use of which a patient may breathe spontaneously,
: 15 be assisted, or have his respiration fully controlled; and
(f) in which all of his excess and spent gas from the apparatus
can be extracted so as not to contaminate the operating room
in which the apparatus is being used or personnel in such room.
With this object in view, the present invention
20 provides anaesthetist's respiration apparatus comprising a
. housing enclosing an expansible and contractible container, the
.,
housing defining a continuously open and unvalved fresh gas
.- supply passageway to the interior of the container, the opening
of the gas supply passageway into the container being the only
gas flow opening communicating to the container, a respiration
:` tube adapted for providing a respiration gas supply to a patient
and having a continuously open connection to the gas supply
- passageway so as to be continuously in communication with the
- interior of the housing and also being connected to the
:`
housing outside of the container by way of a nonreturn valve
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permitting flow only in the direction from the respiration ~ ~:
tube into the housing, means for adjusting the extent by
which the container may expand, and a gas flow opening through
: the housing outside of the container.
Also in accordance with the present invention there is
providea an anaesthetist's respiration apparatus which includes
an expansible and contractible container and gas flow means
associated with the container including a continuously open
: and unvalved fresh gas supply passageway to the interior of
the container, a patient respiration tube continuously open
to the interior of the container for flow of gas to and from `
. . ~ .
the container from ana to a patient, and a patient exhalation
tube connectea to the patient respiration tube remote from ~.
the container and equipped with a check valve regulating
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15 flow through the exhalation tube to flow only away from ::
~ the respiration tube, the improvement comprising a housing
: enclosing the container and defining a chamber about the
; container, the exhalation tube being connected only from ~` -:
.. the respiration tube to the chamber via the check valve, ~
~` 20 means for adjusting the extent by which the container may -
expand within the chamber, ana an unvalvea outlet through
the housing from the chamber, in which the volume of the
expanded container and of the respiration tube provides a
reservoir for an initial volume of gas exhaled by a patient, ~i:
ana in which the remaining volume of gas exhaled by the
:;- patient is applied to the chamber.
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~054478
The expansible and contractible container is con~en~
iently in the form of a bellows; the adjustment means
may then compri~e a stop provided, for example, on the
inner end of an adjustable rod extending through the wall
- 5 of the housing.
The respiration tube may, if desired, be connected
to the gas supply tube by way of a filter.
In a preferred embodiment of the apparatus of the
invention, an outlet of the housing is provided with a
valve arrangement having a connecting passageway which is
; connected to the outlet, a vacuum passageway adapted to
. be connected to suction means, a ventilator passageway
for connection to an automatic ventilator, a bag passageway
,4
.. for connecting to a self-inflating bag, and a vent passage-
way which opens to atmosphere, the valve arrangement
,~ providing for:
~ (a) increase in pressure in the bag passageway
causing such passageway to connect with the connecting
.- passageway;
. 20 (b) decrease in pressure in the bag passageway
causing such passageway to connect with the vent passageway;
:- (c) increase in pressure in the connecting passageway
.. causing such passageway to connect with the vacuum passageway;
-` (d) increase in pressure in the ventilator passageway
. 25 causing such passageway to connect with the connecting
- passageway; and
(e) decrease in pressure in the connecting passageway
.. causing such passageway to be opened to the vent passageway.
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The invention will be describe~ ~urthe~, by way o~
example, with reference to the acconlpanying drawings~ in which:-
Fig. 1. is a diagrammatic cross-sectional view illustrating
a first embodiment of the respiration apparatus of the
invention in its condition corresponding to inspiration by
a patient;
Fig. 2 is a view similar to Fig. 1 but showing the
condition of the apparatus at the end of inspiration; ~ -
Fig. 3 is a view similar to Figs. 1 and 2 but showing
the condition of the apparatus during exhalation by the
patient;
Fig. 4 is a view similar to Figs. 1, 2 and 3 but
showing the apparatus at the end of exhalation;
Fig. 5 is a diagrammatic cross-sectional view illustrating
a second embodiment (which can be obtained by modification
of the embodiment of Figs. 1 to 4) of the respiration
: apparatus of the invention in its condition corresponding to
inflation of the patient's lungs in using the apparatus
for manual ventilation of the patient;
Fig. 6 is a view similar to Fig. 5 but showing the
condition of the apparatus corresponding to exhalation
in using the apparatus for manual ventilation of the patient;
Fig. 7 is a view similar to Figs. 5 and 6 but showing
the apparatus in its condition corresponding to inflation
of the patient's lungs in using the apparatus for automatic
ventilation of the patient;
: . ,
Fig. 8 is a view similar to Fig. 7 but showing the
condition of the apparatus corresponding to exhalation in
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1~3544~8
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- using the apparatus Eor automatic ~entilation of the patient;
Fig. 9 is a view similar to Figs 5 to 8, but showing
the apparatus in operation with spontaneous breathin~ of
the patient, during inhalation by the patient; and
Fig. 10 is a view similar to Fig. 9 but showing the
- apparatus during exhalation.
Referring firstly to Figs. 1 to 4 of the drawings,
the preferred embodiment of the anaesthetist's respi~ation
. apparatus conforming to the invention illustrated therein
comprises an exterior generally-cylindrical housing 10
connected by a gauge line 12 to a pressure gauge 14. The
housing 10 encloses an expansible and contractible container
in the form of a bellows 16 which is arranged substantially
axially of the housing 10 and is fixedly connected to one
end wall provided by a detachable bottom closure plate 18
of such housing 10.
Provided in the bottom closure plate 18 of the housing
.
10 is an outlet duct 22 which simply opens the interior
; of the housing 10 to atmosphere.
- 20 Set centrally in the other end wall 20 of the housing,
which end wall 20 may be integrally formed, is a gland 24
through which extends adjustment means in the form of a
rod 26 provided on its outer end with a Xnurled knob 28.
At its inner end, the rod 26 carries a stop in the form of
- 25 a disc which confronts adjacent free end 32 of the
bellows 16. As shown, the rod 26 is externally smooth and
is sealed relative to the gland 25 by sealing rings 25
which so frictionally engage the rod 26 as to ensure that
it remains in any axially-adjusted position into which it
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may be shifted. The rod 26 could , ~lternatively, be
externally threaded to engage with corresponding threads
in the gland in which case axial adjustment of the rod
26 can be achieved by rotation thereof.
A gas supply duct 34, in the bottom plate 18 connects
with the interior of the bellows 16, and is connected to
an appropriate fresh gas supply machine (not shown), by
way of an inlet 35.
A respiration tube 36 adapted for providing a respiration
gas supply to a patient (e.g. by being connected to an
- endrotracheal tube or a mask, neither of which axe shown
in the drawing) is connected by way of a fresh gas tube
: 38 with the gas supply duct 34. The fresh gas tube 38 may
` optionally incorporate a filter 40.
The respiration tube 36 is also connected with the
interior of the housing 10, outside the bellows 16, by
way of an expiration tube 42 and an expiration duct 43
in the bottom plate 18. The expiration duct 34 is fitted
with a dead-weighted non-return valve 44 which permits gas
flow only in the direction from the respiration tube 36 into
the interior of the houslng 10 outside the bellows 16 only
upon a predetermined pressure being exceeded in the
expiration duct 43.
Assuming the apparatus to be connected to a patient,
` 25 not shown, by way of the respiration tube 36 and fresh gas
~ to be supplied to the gas supply duct 34 by way of the
; inlet 35, the operation of the apparatus is as follows.
. . ~ .
Referring firstly to Fig. 1, upon the patient breathing in,
; at least some fresh gas is inhaled by way of the fresh gas
tube 38 and the filter 40, and the resultant reduction in
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~05447~3
pressure in the fresh gas tube 38 and the bellows 16 causes
at least partial collapse of such beIlows 16. Fig~ 2 shows
the apparatus at the end of inspiration by the patient,
the bellows 16 being shown collapsed partially.
' 5 Upon the patient now exhaling, the exhaled gas prefer-entially feeds back by way of the fresh gas tube 38 and
the gas supply duct 34 to the bellows 16, because of the
presence of the dead-weighted non-return valve 44 in the
expiration duct 34. Initially, therefore, the bellows
h 10 16 expands again as has been indicated in Fig. 3 until
such time as the free end 32 of the bellows 16 encounters
and is arrested by the stop disc 30.
So soon as the free end 32 of the bellows 16 meets
the stop disc 30, further expansion of the bellows 16 is
prevented. As a result the pressure then rises in the
fresh gas tube 38, gas supply duct 34, bellows 16, expiration
tube 42 and expiration duct 34 sufficiently to open the
valve 44 which then permits exhaled gases to enter the
housing 10 outside the bellows 16 and thence to escape to
atmosphere by way of the outlet 22, as shown in Fig. 4.
If the rate of the fresh gas flow is appropriately
adjusted, it can be achieved that only the gas from the
patient's alveoli will be vented to atmosphere by way of
' the housing 10 and the outlet 22 , and dead-space gas from
the patient's trachea, mouth and bronchial tree, which has
not undergone any change in each breathing cycle, is
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- retained within the apparatus ready to be inhaled by the
patient upon his next inspiration. This dead-space gas is,
of course, equally as good as fresh gas being fed to the
apparatus. Accordingly, with the apparatus as described,
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the actual xate at which fresh gas needs to be supplied
to the apparatus will always be less than (usually about
70~ of) the thebretical or preducted minute volume of
the patient, yet the patient does not rebreathe alveolar gas.
Referring now to Figs. 5 to 10 of the drawings, these
figures illustrate a second embodiment of the apparatus of
the invention, which is obtained by modification of the
apparatus of Figs. 1 to ~. Accordingly, similar reference
numerals have been allocated to those parts of this embodiment
- 10 which are substantially identical with those already described. `~
As shown, in this embodiment, a valve assembly which
- is illustrated schematically and indicated generally by
the reference numeral 50 is connected to the outlet 22.
This valve has five passageways, namely connecting passageway
52 which is connected to the outlet 22; vacuum passageway 54
which is connected to a vacuum line (not shown); ventilator
passageway 56 which is connected to an anaesthetist's automatic
ventilator (not shown) such as that described in the spec- -
ification of my prior United Kingdom Patent No. 1,207,661; a
bag passageway 58 connected to a self-inflating bag which is
.~ . .
- illustrated diagrammatically at 60; and a vent passageway 62
which opens to atmospheric air. The vent passageway 62 may
alternatively be located in the bottom of the self-inflating bag
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~- 60 in which case it will be provided with its own automatically-
:
-operating non-return valve member. This valve assembly is set
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up to operate automatically to provide for the following
- circumstances:
(a) Upon increase in pressure in the self-inflating
bag 60 and the bag passageway 58, the latter is connected
~;~ 30
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~05~47~3
; to the connecting passageway 52, as shown in Fig. 5;
(b~ Upon decrease in pressure in the self-inflating
bag 60 and the bag passageway 58, the latter is opened to
the vent passageway 62, as shown in Fig. 6;
(c) Upon increase in pressure in the connecting
passageway 52, the latter is connect to the vacuum
passageway 54, as shown in Figs. 6, 8 and 10;
(d~ Upon increase in pressure in the ventilator
passageway 56, the latter is connected to the connecting
passageway 52, as shown in Fig. 7; and
(e) Upon decrease in pressure in the connecting
passageway 52 by application of suction thereto, such
passageway 52 is opened to the vent passageway 62, as
shown in Fig. 9.
With such an arrangement, when the self-inflicting
bag 60 is manually squeezed, as shown in Fig.5, gas therefrom
flows into the housing 10 into the space between the latter
and the bellows 16, thereby ensuring that the non-return
valve 44 remains closed and causing at least partial
collapse of the bellows 16. Accordingly, fresh gas from the
gas supply duct 34 passes by way of the filter 40, the fresh
gas tube 38 and the respiration tubs 36 to the patient to
inflate his lungs.
~hen the patient now breathes out, firstly the bellows
16 expands until arrested by the stop disc 30, and therearter
the non-return valve 44 opens to permit expired changed gas
to pass via outlet 22 and the vacuum passage 54 to the vacuum
line which may, for example, be part of a vacuum system ~not
` illustrated) which serves to eliminate free anaesthetic gases
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~ 30 from the atmospheric area in which the apparatus is being used.
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This is illustrated in Fig. 6 from which it will be seen that
whilst the patient is exhaling, the self-inflating bag 60 is
drawing in fresh atmospheric air by way of the vent passageway 62.
. Accordingly, it will be understood that by providing
the valve arrangement 50 fitted with the self-inflating bag 60,
one converts the embodiment of respiration apparatus of Figs.
1 to 4 in a very simple manner to enable it to be controlled
manually, with the patient's lungs being expanded upon squeezing
of the self-inflating bag 60, and exhalation occurring upon
10 subsequent release of the bag 60. In this use of the apparatus,
the ventilator, connected to the ventilator passageway 56, is
not employed. Accordingly, it will be understood that the
presence of such ventilator is optional, and it can be omitted
if desired, according to the intended use of the apparatus.
15 Conversely, if the ventilator is present and made use
of,the self-inflating bag 60 is not employed, so that the latter, : ;
too, is optional.
.~ Referring now to Figs. 7 and 8, these illustrate the
apparatus being operated with gas under pressure supplied by
the ventilator which may conform substantially to those des-
cribed in the specification of my aforementioned Patent No.
1,207,661. The breathing connection of the ventilator is
-~ connected to the ventilator passageway 56, and the gas inlet
~ connection of the ventilator is continuously suppled with gas
:;; 25 under pressure. Accordingly, the operation of such ventilator
- is such as to provide, at regular intervals, momentary opening
- of its breathing connection with its gas supply, thereby to
provide a momentary increase in pressure in the housing 10
~ of the apparatus of the invention, as shown in Fig. 7 in the
r,~ 30 drawings, with consequential compression or partial collapse
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~05~478
of the bellows 16 and inflation of the patient's lungs; upon
the ventilator subsequently shutting off its breathing connection
from the gas supply, the condition of Fig. 8 is obtained and
gas exhaled by the patient firstly passes into the bellows
16 and then the excess expelled by way of the housing to the
vacuum connection 54. Accordingly, the action of the apparatus
when the ventilator is employed is substantially the same as
- when the self-inflating bag 60 is employed, save that with the
latter the lung inflation and exhalation is controlled manually,
whilst with the former it is controlled automatically in
conformity with the operation of the ventilator and at a rate
dependent upon the adjustment of the ventilator.
- Figs. 9 and 10 show the operation of the apparatus
with the patient breathing spontaneously, so that no use is
made of either the bag 60 or the ventilator. As shown in
Fig. 9, upon the patient inhaling, the bellows 16 collapses
and air is drawn into the housing 10 by way of the connecting
passageway 52 and the air passageway 62. Upon exhalation, as
previousIy described, excess gas from the housing 10 leaves
the latter by way of the connecting passageway 52 and the
- vacuum passageway 54.
The inventi~n is not confined to the precise details
of the foregoing examples and variations may be made thereto.
Thus, for instance, the expansible container does not have to
be in the form of a bellows, but could comprise an inflatable
-~ bag or a piston/cylinder arrangement, and the disposition
thereof does not have to be such that expansion results in
upward movement, it being possible for the arrangement to be
such that horizontal or downway movement is obtained. The
non-return valve 44 can, if desired, alternatively be a
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1~544713
spring-loaded valve, or a mechanically, pneumatically,
hydraulically or electrically-operated valve; furthermore it need
not be positioned actually within the base plate of the
housing as shown but could be remotely disposed, provided it has
an appropriable operating mechanism associated therewith. The
tubing employed in the apparatus may be of rubber or plastics,
either disposable or re-usable, and may incorporate appropriate
bacteriological filters as desired.
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