Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1999-03-30
2001-04-03
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S204210, C128S204240, C128S205240, C601S041000
Reexamination Certificate
active
06209540
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an artificial respiration apparatus that forcibly supplies air to a patient who cannot breathe by himself/herself and that can operate so as to reduce the load on the patient when the patient spontaneously starts breathing.
2. Description of the Related Art
FIG. 5
shows a configuration of a conventional artificial respiration apparatus. Hereinafter, explanation will be given on the conventional artificial respiration apparatus with reference to FIG.
5
.
The conventional respiration apparatus
50
includes: a blower
52
for simultaneously generating a positive pressure Ap and a negative pressure An; a rotary valve mechanism
54
for alternately selecting the positive pressure Ap and the negative pressure An generated by the blower
52
and converting the positive and negative pressures into an oscillating air pressure Apn; and a diaphragm block
56
which is urged by the oscillating air pressure Apn from the rotary valve mechanism
54
, so as to supply air to a patient P. Moreover, the artificial respiration apparatus
50
includes: a diaphragm neutral position controller
60
for maintaining a neutral position of a diaphragm
561
of the diaphragm block
56
; and a respiration gas port
62
for introducing the respiration gas.
The blower
52
has a positive pressure pipe
521
and a negative pressure pipe
522
, so that air is supplied to the blower
52
through the negative pressure pipe
522
and discharges the air through the positive pressure pipe
521
. The negative pressure pipe
522
is connected to an orifice pipe
523
communicating with the open air. The positive pressure pipe
521
is connected to an orifice pipe
524
communicating with the open air.
The rotary valve mechanism
54
is constituted by a rotary valve
544
having ports
541
,
542
,
543
, and a drive block
545
for rotating the rotary valve
544
. The drive block
545
includes a motor and a reduction gear (not depicted) so as to rotate the rotary valve
544
at 900 rpm for example. While the rotary valve
544
makes a single turn, the port
541
and the port
542
are successively made to communicate with the port
543
. The port
543
is connected to an oscillating air pressure pipe
546
for transmitting the oscillating air pressure Apn to the diaphragm block
56
. A flow control valve
547
is inserted into the oscillating air pressure pipe
546
.
The diaphragm block
56
includes a diaphragm
561
formed by an expandable member serving as a partition between a pressurizing chamber
562
and a pressurized chamber
563
. The pressurizing chamber
562
is connected to the oscillating air pressure pipe
546
.
The respiration gas port
62
is constituted by a blender
621
for mixing the open air with oxygen prepared in advance; and a humidifier
622
for humidifying the gas to be sent out from the blender
521
. The humidifier
622
is connected to a respiration gas pipe
623
for supplying to the patient P the respiration gas Ai which has passed through the humidifier. The respiration gas pipe
623
communicates with the pressurized chamber
563
and has a pressure sensor
624
provided in the vicinity of the patient P.
The diaphragm neutral position controller
60
includes: a diaphragm position sensor
601
for detecting a position of the diaphragm
561
of the diaphragm block
56
; a pressure regulating valve
64
for controlling the positive pressure Ap, the negative pressure An, or the oscillating air pressure Apn; a control block
66
for controlling the pressure regulating valve
64
according to the position of the diaphragm
561
detected by the diaphragm position sensor
601
.
The pressure regulating valve
64
has a configuration similar to a rotary valve and is constituted by a main body
646
having ports
641
to
645
and an actuator
647
for rotating a part of the main body in normal and reverse directions. The actuator
647
is constituted by a motor and a reduction gear (not depicted) and can rotate a part of the main body
646
by a desired angle. The control block
66
is, for example, a microcomputer including a CPU, ROM, RAM, I/O interface, and the like.
In the artificial respiration apparatus
50
, the single blower
52
serves to generate both of the positive pressure and the negative pressure. That is, the blower
52
has a large load. On the other hand, in order to increase the ventilation amount of the artificial respiration apparatus
50
, it is most effective to increase the power of the blower
52
. However, if the power is to be increased with the single blower
52
, it becomes necessary to design a special blower having very large dimensions and weight. Such a blower is not available on market and should be prepared by a special order.
This has been preventing reduction in size and weight as well as cost of the conventional artificial respiration apparatus
50
. Moreover, such a large blower
52
requires a 200 V power source or a large current receptacle even if a 100 V power source can be used. This makes it difficult to use the artificial respiration apparatus
50
even in a small hospital.
Next, explanation will be given on the reason why the blower
52
of the artificial respiration apparatus
50
should have such a large load. A “blower” is an apparatus constituted by a motor and a fan for sucking air from the suction side and discharging the air from the discharge side. The blower
52
generates a negative pressure An by sucking air from the suction side and generates a positive pressure Ap by discharging the sucked air from the discharge side.
Here, for use of the positive pressure Ap, the rotary valve mechanism
54
makes the discharge side of the blower
52
communicate with the oscillating air pressure pipe
546
while closing the suction side of the blower
52
. Here, if the suction side is closed completely, it becomes impossible to obtain air for discharge. Accordingly, the suction side is connected to the orifice pipe
523
communicating with the open air.
On the contrary, when using the negative pressure An, the rotary valve mechanism
54
makes the discharge side of the blower
52
closed and the suction side of the blower
52
communicate with the oscillating air pressure pipe
546
. Here, if the discharge side is closed completely, the sucked air cannot be discharged. Accordingly, the discharge side is also connected to an orifice pipe
524
communicating with the open air.
Accordingly, when using the positive air Ap, the suction side takes in air via the orifice pipe
523
, whereas the discharge side discharges the air via the oscillating air pressure pipe
546
and simultaneously with this, the air leaks out via the orifice pipe
524
. On the contrary, when using the negative pressure An, the discharge side discharges air via the orifice pipe
524
, whereas the suction side sucks air via the oscillating air pressure pipe
546
and simultaneously with this, air flows in via the orifice pipe
523
. Thus, operation of the artificial respiration apparatus
50
is inevitably accompanied by useless air leak out and flow in. This significantly increases the load of the blower
52
.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an artificial respiration apparatus which can realize a small size, small weight, and low production cost and can be used in small hospitals.
The inventors of the present invention have found that the aforementioned object can be achieved by replacing the blower generating both of a positive pressure and a negative pressure by a positive pressure blower for generating only a positive pressure in combination with a negative pressure blower for generating only a negative pressure. This can significantly reduce the load (i.e., power consumption), which in turn realizes a smaller size and weight as well as a lower cost. For example, instead of a large-size blower of a special type, ordinary two blowers are used. Such an ordinary blower is small in size and weight and is available on market, and can be u
Kamada Masahiro
Nitta Kazufuku
Sugiura Yasuhito
Suzuki Katsuyoshi
Takaki Toshihisa
Greenblum & Bernstein P.L.C.
Srivastava V.
Suzuki Corporation
Weiss John G.
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