JP2003070915A - Apparatus and method for blending gas for respirator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To blend gas by a simple constitution. SOLUTION: This apparatus is composed of an air pump 3 for feeding air for inspiration to a patient by reciprocation with extension and contraction. The air pump 3 is connected to first pipelines 4a and 4b for guiding blend gas containing oxygen. At the middle position of the first pipelines 4a and 4b, a stop valve 5 for opening and disconnecting the first pipelines 4a and 4b and a pressure regulating valve 6 positioned on a downstream side of the stop valve 5 for regulating a pressure within the air pump 3, in the flowing direction of the blend gas, a second gas pipeline 7 for guiding the air gas to the first pipelines 4b is connected to the downstream side of the stop valve 5 in the flowing direction of the blend gas, and an air feeding check valve 8 for feeding air to the pump 3 is provided in the second gas pipeline 7. The blend gas and air are blended by simple constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas mixing device for a ventilator and a gas mixing method which can be suitably applied to a ventilator.

[0002]

2. Description of the Related Art In a ventilator that supports the ventilation function of the lungs of a patient who has difficulty breathing spontaneously, the oxygen concentration of the gas supplied for inhaling the patient is the oxygen concentration of the air gas which is the atmosphere. It is adjusted to a value different for each patient or depending on the condition of the patient up to a high oxygen concentration exceeding the oxygen concentration of. The adjustment of the oxygen concentration of the gas supplied for the inspiration of the patient is performed by mixing air gas and oxygen or a blend gas containing oxygen at a higher concentration than air gas.

A conventional gas mixing device for a ventilator which mixes air gas with oxygen or a blended gas is equipped with a regulator, a dedicated mixer and a flow rate adjusting valve. For example, the pressure of high pressure oxygen gas is adjusted by the regulator, and the pressure is adjusted. The adjusted oxygen gas and air gas are mixed by a dedicated mixer, the flow rate is adjusted by a flow rate adjusting valve, introduced into the air pump of the ventilator, and supplied to the patient as inspiration by the operation of the air pump.

[0004]

The conventional gas mixing device for a ventilator has the following problems. As described above, the conventional gas mixer for a ventilator requires a large number of parts such as a regulator, a dedicated mixer, and a flow rate adjusting valve, which complicates the structure and increases the number of manufacturing processes, resulting in poor productivity. And also increase the manufacturing cost.

Further, when supplying the mixed gas into the air pump of the reciprocating ventilator for inhaling the patient, the regulator and the flow rate are adjusted with high accuracy so that the internal pressure in the air pump does not unnecessarily rise. Since the valve has to be provided as a component, there is a problem that the adjusting operation becomes complicated as the manufacturing cost increases due to the expensive component price. In addition, some dedicated mixers have a bleed amount (leakage amount) of gas to be mixed, and the gas to be mixed is undesirably consumed, which causes a problem of increasing operating cost.

An object of the present invention is to provide a gas mixing device for an artificial respirator and a gas mixing device which can mix gases with a simple structure and can shorten the time for adjusting the oxygen concentration of the mixed gas to the target oxygen concentration. Is to provide a method.

[0007]

SUMMARY OF THE INVENTION The present invention comprises an air pump for delivering inspiration to a patient by reciprocating movements of extension and retraction.
A first pipe line connected to the air pump for guiding the blend gas to the air pump, an opening / closing valve for opening / closing the first pipe line provided at an intermediate position of the first pipe line, and an opening / closing valve for the first pipe line The pressure adjusting valve, which is provided on the downstream side in the flow direction of the blend gas and adjusts the pressure in the air pump, is connected to the downstream side in the flow direction of the blend gas with respect to the pressure adjusting valve of the first pipeline, and the air gas is A gas mixing device for a ventilator, comprising: a second conduit that leads to a conduit; and a supply check valve that is provided in the second conduit and supplies air gas to an air pump.

According to the present invention, the air pump for supplying inspiration to the patient is connected to the first conduit for guiding the blended gas to the air pump, and the first conduit is opened at an intermediate position of the first conduit.
An on-off valve for shutting off is provided, and a pressure adjusting valve for adjusting the pressure in the air pump is provided on the downstream side of the on-off valve of the first pipeline in the flow direction of the blend gas. Also, a second conduit for guiding the air gas to the first conduit is connected to the downstream side in the flow direction of the blended gas, and a supply check valve for supplying the air gas to the air pump is provided in the second conduit. . This makes it possible to mix the blended gas and the air gas with a simple structure that does not require a dedicated mixer and a complicated and highly accurate flow rate adjustment mechanism, and is a combination of an on-off valve, a pressure adjustment valve and an air supply check valve. Therefore, the manufacturing cost can be reduced and the device can be downsized. Further, by opening or shutting off the first conduit by the opening / closing valve, the blend gas and the air gas introduced into the air pump can be switched, so that the blending operation of the blend gas and the air gas can be easily performed. .

Further, according to the present invention, the position detecting means for detecting the position where the air pump extends and retracts, and the opening and closing of the first conduit by the opening / closing valve in response to the detection output of the position detecting means are controlled. And a control means.

According to the present invention, it becomes possible to accurately detect the distance that the air pump moves in the reciprocating direction,
The amount of blend gas and air gas introduced into the air pump can be determined by multiplying the cross-sectional area in the direction orthogonal to the reciprocating direction of the air pump by the moving distance in the reciprocating direction due to the extension of the air pump. Therefore, the amount of the blend gas and the amount of the air gas to be introduced into the air pump can be accurately determined by controlling the opening and closing of the open / close valve according to the moving distance of the air pump. The oxygen concentration of the mixed gas composed of the blend gas and the air gas can be adjusted with high accuracy.

Further, when the blend gas is introduced into the air pump, the feed gas check valve can prevent the air gas from flowing into the first pipe line, so that the blend gas may be diluted by the air gas. Absent. Therefore, since the oxygen concentration of the blend gas is kept constant, the oxygen concentration of the mixed gas of the blend gas and the air gas in the air pump can be accurately adjusted.

According to the present invention, the control means stores the result of the stroke Li obtained by the difference between the extended position and the retracted position of the air pump detected by the position detecting means sequentially for n times, and a memory. Stored in n
Read the number of strokes Li,

[Equation 2] Calculating means for calculating the average stroke La given by the control means, and the control means is responsive to the calculation result by the calculating means, so that the stroke of the air pump is equal to the sum of the average stroke La and the predetermined margin stroke Lb. It is characterized by controlling the position where the pump extends and the position where it contracts.

According to the present invention, the average stroke La is calculated by the calculating means on the basis of the stroke record of the air pump, that is, the ventilation volume record of the patient, and the air pump is reciprocated according to the calculated average stroke La. Volumes other than those used for patient ventilation can be reduced. By this, when changing the oxygen concentration of the mixed gas in the air pump that supplies the patient's inspiration, the volume occupied by the space other than the volume used for ventilation of the patient in the air pump can be reduced,
The time required to adjust the oxygen concentration of the mixed gas in the air pump to the target oxygen concentration after the change can be shortened.

The present invention also provides the gas mixing device for a ventilator according to any one of the above, wherein the air pump is first operated in a state in which a predetermined target oxygen concentration of inspiration to be supplied to the patient is newly set. When starting the reciprocating motion, the air pump is retracted to a predetermined position so that the length in the reciprocating direction becomes the shortest, and the on-off valve is opened to introduce the blend gas to the pressure regulating valve to extend the air pump. In this way, the blended gas is introduced into an air pump, thereby providing a gas mixing method for a respirator.

According to the present invention, when the air pump starts the first reciprocating motion with the predetermined target oxygen concentration of the inspiration to be supplied to the patient newly set, the length of the air pump in the reciprocating motion direction is increased. The blend gas is introduced into the air pump by retracting to a predetermined position so that the length becomes shortest. As a result, when changing the oxygen concentration of the mixed gas in the air pump that supplies inspiration to the patient, the volume determined by the air pump moving in the stroke, out of the inner volume of the air pump that should be replaced with the target oxygen concentration. Since the volume of the space other than the above can be minimized, the time required to adjust the oxygen concentration of the mixed gas in the air pump to the target oxygen concentration after the change can be shortened.

The present invention also provides the gas mixing device for a ventilator according to any one of the above, and sets the ventilation stroke L1 which is the difference between the extended position and the retracted position of the air pump corresponding to the ventilation volume of the patient. The oxygen concentration (C _n ) of the mixed gas obtained by mixing the blended gas and the air gas in the air pump in the reciprocating motion to be performed immediately after the air pump is determined by the air in the reciprocating motion performed immediately before the air pump. An oxygen concentration prediction formula is set based on the oxygen concentration (C _n-1 ) of the mixed gas obtained by mixing the blended gas and the air gas in the pump, and the air pump is blended based on the oxygen concentration prediction formula. Blend gas introduction step L, which is the step of guiding the gas
2 is obtained, an air gas introduction step L3 (= L1-L2) that is a step of guiding the air gas to the air pump is obtained by the obtained blend gas introduction step L2 and the ventilation step L1, and the reciprocation that the air pump should immediately perform. Ventilation stroke L1
When extending, the blend gas is introduced into the air pump according to the blend gas introduction step L2, and the air gas introduction step L
A method of mixing gas for an artificial respirator, which is characterized in that air gas is introduced into an air pump according to item 3.

According to the present invention, the blend gas and the air gas are introduced into the air pump in accordance with the blend gas introducing process L2 and the air gas introducing process L3 obtained based on the oxygen concentration predicting equation. The oxygen concentration of the mixed gas in the ventilation stroke L1 obtained by mixing the blended gas and the air gas, which is obtained based on this oxygen concentration prediction equation, is the initial value at which the air pump reciprocates after the new target oxygen concentration is set. In the period, the concentration higher than the target oxygen concentration is obtained when increasing the target oxygen concentration after the setting change, or the concentration lower than the target oxygen concentration is obtained when decreasing the target oxygen concentration after the setting change.

Therefore, when the air pump is repeatedly reciprocated after the setting is changed to change the oxygen concentration in the air pump to the target oxygen concentration, the initial reciprocating movement of the air pump is reached before the target oxygen concentration is reached after the setting is changed. During the period, a mixed gas having a higher oxygen concentration or a lower oxygen concentration than the target oxygen concentration can be introduced into the air pump, so the oxygen concentration of the mixed gas in the air pump is adjusted to the target oxygen concentration after the change. The time required for this can be shortened.

[0019]

1 is a schematic cross-sectional view showing a simplified structure of a gas mixing device 1 for an artificial respirator according to an embodiment of the present invention, and FIG. 2 is a gas for an artificial respirator shown in FIG. 1 is a system diagram showing an overall configuration of a ventilator 2 including a mixing device 1.

A gas mixing device 1 for a ventilator (hereinafter abbreviated as "gas mixing device 1"), an air pump 3 for supplying inspiration to a patient by reciprocating motion of extension and contraction, and an air pump 3
Connected to the first pipeline 4a, 4b for guiding the blend gas to the air pump 3, and an on-off valve 5 provided at an intermediate position of the first pipeline 4a, 4b for opening / closing the first pipeline 4a, 4b, A pressure adjusting valve 6 that is provided on the downstream side of the on-off valve 5 of the first pipelines 4a and 4b in the flow direction of the blend gas and that adjusts the pressure in the air pump 3, and a pressure regulating valve of the first pipelines 4a and 4b. 6
A second pipe line 7 that is connected to the downstream side of the blend gas in the flow direction and guides the air gas to the first pipe line 4b, and an air supply provided to the second pipe line 7 to supply the air gas to the air pump 3. It includes a check valve 8 and an air inlet filter 9 provided on the upstream side of the second pipeline 7 in the flow direction of the air gas.

The first pipe line 4a is made of a pressure-resistant hose or a metal pipe, and the first pipe line 4b is a tube made of synthetic resin and forms a flow path for blend gas. The first conduit 4a is
It is provided on the upstream side in the flow direction of the blend gas, and connects the supply source of the blend gas (not shown) to the on-off valve 5. The first conduit 4b is provided on the downstream side in the blend gas flow direction with respect to the first conduit 4a, and connects the pressure regulating valve 6 and the air pump 3 to each other. Here, the blended gas is a gas having an oxygen concentration higher than that of the air gas by blending oxygen gas with, for example, nitrogen gas or air gas which is the atmosphere. It should be noted that the blended gas is also included in the category of a blended gas composed of only oxygen gas.

The opening / closing valve 5 is realized by, for example, an electromagnetic valve, and can open / shut off the first conduits 4a and 4b. The on-off valve 5 is electrically connected to the control means 60, which will be described later, and responds to an output signal from the control means 60 to open / shut off the first pipelines 4a and 4b. In the present embodiment, the on-off valve 5 is a solenoid valve, but it may have a configuration in which a flow rate adjusting valve is provided instead of the solenoid valve. By restricting the flow rate adjusting valve and reducing the flow rate to zero, it is possible to operate similarly to shutting off the first pipelines 4a and 4b by the solenoid valve.

The pressure regulating valve 6 has a casing 10 made of stainless steel, for example. The casing 10 has a right cylindrical portion 11 formed in a cylindrical shape and a truncated cone portion 12 connected to the right cylindrical portion 11 and formed in a hollow substantially truncated cone shape. A suction port 13 for sucking the blended gas into the pressure regulating valve 6 is formed near the on-off valve 5 of the straight cylindrical portion 11, and the suction port 13 has a connecting pipe line for connecting the on-off valve 5 and the pressure regulating valve 6. 14
Are connected. The valve chamber 15 formed inside the straight cylindrical portion 11
The valve seat 16 on which the valve body 16 and the valve body 16 are seated and separated from each other.
And 7 are provided. The valve seat 17 is provided on an annular projecting portion 23 formed by projecting annularly toward the inside of the right cylindrical portion 11, and a valve hole 18 is formed in the valve seat 17.

The valve body 16 is integrally provided with a valve shaft 19 which rises vertically from the valve body 16 and extends in the axial direction of the valve body 16, and the free end portion of the valve shaft 19 opposite to the valve body 16 is provided. A spherical pressing member 20 is attached to the. A spring holding portion 21 is formed substantially in the middle of the valve shaft 19 in the longitudinal direction so as to project radially outward of the valve shaft 19. One end of the first spring member 22 is fixed to the spring holding portion 21, and the first spring member 22 is fixed.
The other end of is fixed to the annular protrusion 23 forming the valve seat 17. In this way, the first spring member 22 causes the valve element 16 to be seated on the valve seat 17 by its spring force.

The base portion 24 of the truncated cone portion 12 of the pressure regulating valve 6
A discharge port 25 for discharging the blended gas toward the first pipe line 4b is formed at, and the first pipe line 4b is connected to the discharge port 25. A bottom surface of the truncated cone portion 12 located on the opposite side of the base surface portion 24 is an opening portion, and a diaphragm 26 is provided so as to face the pressing member 20 so as to seal the opening portion. The diaphragm 26 is provided outside the diaphragm 26.
A cover member 27 for protecting the is further provided.

The pressure regulating valve 6 is opened when the gas pressure in the first pipe line 4b and the air pump 3 becomes a value smaller than the atmospheric pressure, and the blended gas is supplied to the first pipe line 4b and the air pump 3. The gas pressure in the first conduit 4b and the air pump 3 is adjusted so as to be balanced with the atmospheric pressure by introducing the gas into the inside.

When the gas pressure in the first conduit 4b and the air pump 3 becomes a negative pressure smaller than the atmospheric pressure by a predetermined pressure P1, the diaphragm 26 expands toward the inside of the truncated cone 12 by the atmospheric pressure. Set to go out. When the diaphragm 26 expands, the diaphragm 26 pushes the pressing member 20 provided at the free end of the valve shaft 19 toward the air pump 3 side. Since the valve shaft 19 and the valve body 16 are held by the annular protrusion 23 only by the first spring member 22, the diaphragm 26 is pressed by the pressing member 20.
The valve stem 19 and the valve seat 17 are pushed by pressing.
It is displaced in the direction of the arrow 28 with one point formed by and as a fulcrum 30. Therefore, the opposite side of the valve body 16 to the side forming the fulcrum 30 is separated from the valve seat 17, so that the valve hole 18 is opened and the pressure regulating valve 6 is opened.

The on-off valve 5 is open and the pressure adjusting valve 6
Is open, the blend gas is discharged from the discharge port 25 to the first conduit 4b through the valve chamber 15 and the first space 29 formed inside the truncated cone portion 12. The blended gas discharged from the discharge port 25 is introduced into the air pump 3 via the first pipe line 4b, and the inside of the air pump 3 and the first pipe line 4 are introduced.
When the gas pressure in b is in equilibrium with the atmospheric pressure, the diaphragm 26 returns to the state before the expansion.
When the diaphragm 26 returns to the state before the expansion, the valve shaft 19
Is displaced in the direction opposite to the arrow 28 direction. Diaphragm 2
When 6 returns to the state before swelling, the pressing member 20 is not pushed, so the valve body 16 is seated on the valve seat 17, the valve hole 18 is closed, the pressure adjusting valve 6 is closed, and the blend gas The introduction into the first conduit 4b is blocked.

The air supply check valve 8 includes a valve box 32 having a valve chamber 31 formed therein, an air supply port 33 formed near the air inlet filter 9 of the valve box 32, and a first valve box 32. The exhaust port 37 is formed near the first conduit 4b. The second pipeline 7 is connected to the air supply port 33 and the exhaust port 37, respectively. In the valve chamber 31, a valve seat 34, a valve body 35 that is seated on or away from the valve seat 34, and a second spring member 36 that presses the valve body 35 against the valve seat 34 are provided.

The valve box 32 of the air supply check valve 8 has a cylindrical shape and is made of, for example, plastic. Second spring member 36
Is formed by winding a metal wire into a coil around an axis extending in the direction of air gas flow. One end 38 of the second spring member 36 is fixed so as to face the exhaust port 37 of the valve box 32, and the valve body 35 is attached to the other end 39 of the second spring member 36. The valve element 35 is made of, for example, a synthetic resin and has a substantially disc shape. The spring force of the coil-shaped second spring member 36 is set such that the negative pressure in the air pump 3 and the first pipe line 4b with respect to the atmospheric pressure is a predetermined pressure P.
A spring constant having a spring constant is selected so that it is compressed when it becomes 2 or more.

As a result, the pressure in the valve chamber 31 becomes P2.
When the negative pressure of the second spring member 36 becomes
Is compressed in the axial direction and the valve element 35 is separated from the valve seat 34, so that the air supply check valve 8 is opened, and the air gas which is the atmosphere is supplied into the first conduit 4b and the air pump 3. It

The predetermined pressure P1 at which the pressure regulating valve 6 is opened is set below the predetermined pressure P2 at which the air supply check valve 8 is opened, that is, P1 <P2. . For example the pressure P1 the predetermined pressure regulating valve 6 is opened is set to 2~3cmH ₂ O,
The predetermined pressure P2 at which the supply check valve 8 is opened is 10
It is set to cmH ₂ O.

As a result, when the negative pressure in the air pump 3 is in the range of P1 to P2 and the blend gas is being introduced into the air pump 3, the air check valve 8 supplies the air gas to the first pipe. Since it can be prevented from flowing into the passage 4b,
The blend gas is not diluted with air gas. Therefore, the oxygen concentration of the blend gas introduced into the air pump 3 is kept constant, so that the oxygen concentration of the mixed gas of the blend gas and the air gas in the air pump 3 can be accurately adjusted. Air pump 3
The gas produced by mixing the blended gas and the air gas respectively introduced therein is referred to as a mixed gas here.

The air inlet filter 9 provided at the tip of the second conduit 7 which is an inlet for introducing air gas into the gas mixing device 1 is a dust-proof filter for removing dust from the air gas to be introduced into the air pump 3. is there. Air inlet filter 9
May have not only the above dust removal function but also a sterilization function by combining a hepa filter or the like.

The air pump 3 has a pump bellows 41 having a substantially right cylindrical shape. The pump bellows 41 is made of a material such as rubber, has flexibility, and can expand and contract in the direction of the axis 42. A rigid mounting member 43 is fixed to one end of the pump bellows 41 in the axial direction, and a base 44 is connected to the other end of the pump bellows 41 in the axial direction. The mounting member 43 has a disc shape and is movable in the direction of the axis 42. The base body 44 faces the mounting member 43 and is provided at a fixed position of a track member 45 provided on a base (not shown). As a result, the pump bellows 41, the mounting member 43, and the base 44
A second space 46 surrounded by and is formed. Base 4
The first pipe line 4b is connected to the gas introduction port 40 formed in the base body 44 so as to face the fourth second space 46.

A pump drive means 48 is provided for driving the pump bellows 41 to expand and contract by reciprocating motion of expansion and contraction. The pump drive means 48 comprises a screw mechanism, which comprises a ball screw 49. Ball screw 49
A screw member 50 provided outside the pump bellows 41 and extending in the direction of the axis 42, and a ball nut 51 are provided. The screw member 50 and the ball nut 51 are screwed together through a ball mounted in the ball screw groove. Screw member 50
The other end of the first end plate 5 provided at the other end of the track member 45.
It is rotatably supported by the bearings attached to 2.

One end of the screw member 50 is rotatably supported by a bearing attached to the second end plate 53 provided at one end of the track member 45. One end of the screw member 50 penetrates the second end plate 53 to project, and the pulley 54 is attached to the projecting portion. The ball nut 51 is connected to the mounting member 43 via the support member 55. On the base,
An electric motor 56, which is a drive source, is provided. A pulley 57 is attached to the shaft of the electric motor 56, and a transmission belt 58, which is a transmission means, is stretched between the pulley 54 of the screw member 50 and the pulley 57 of the shaft.

The electric motor 56 is provided with position detecting means 59 for detecting the position where the pump bellows 41 constituting the air pump 3 extends and contracts. Position detecting means 59
Is realized by, for example, an encoder. The encoder converts the number of revolutions of the electric motor 56 into a distance to obtain a moving distance with respect to a predetermined reference position, and can detect a position associated with extension and contraction of the pump bellows 41 with respect to the reference position. Position detecting means 5
The detection output of 9 is input to the control means 60, and the control means 60
Responds to the detection output of the position detecting means 59, that is, controls the operation of the opening / closing valve 5 in accordance with the position where the pump bellows 41 of the air pump 3 expands and contracts, and the first pipelines 4a, 4
Open / shut off b. In the air pump 3, since the pump bellows 41 included in the air pump 3 expands and contracts, the reciprocating position and the expressions such as expansion / contraction are referred to as the position of the pump bellows 41 and the expansion / contraction of the pump pellose 41. And so on.

The control means 60 is, for example, a CPU (Centra).
l Processing Unit) is realized by a microcomputer equipped with. The control means 60 is provided with a memory 61 for storing the results of detecting the expanded and contracted positions of the pump bellows 41, and the difference between the expanded position and the contracted position of the pump bellows 41 detected by the position detecting means 59. Calculating means 6 for calculating the stroke and the oxygen concentration based on the oxygen concentration prediction formula described later
2 and. Further, the control means 60 outputs a control signal in response to the calculation result of the calculation means 62 to output the pump bellows 4
It is possible to control the position where 1 is expanded and contracted.

Next, the operation of the air pump 3 will be described. When the electric motor 56 is driven, its rotational movement is transmitted to the screw member 50 via the transmission belt 58, and the screw member 50 is rotationally driven. The rotational movement of the screw member 50 is converted into the linear movement of the ball nut 51, and the ball nut 51 is moved to one end side or the other end side of the screw member 50 depending on the rotation direction. When the ball nut 51 is moved, the ball nut 5
1 is attached to the mounting member 43 via a supporting member 55.
Moves. When the mounting member 43 moves, the pump bellows 41 moves and expands / contracts in a direction corresponding to the rotational movement of the screw member 50.

When the pump bellows 41 extends, the inside of the air pump 3, that is, the second space 46 (hereinafter, the inside of the air pump 3 will be referred to as the second space 46) and the first conduit 4b.
Pressure drops. At this time, the negative pressure preset from the atmospheric pressure as described above is set so that the pressure adjusting valve 6 is in the open state P1 <the negative pressure P2 in which the air supply check valve 8 is open. To be done.

Therefore, as the pump bellows 41 expands and the pressure in the second space 46 decreases, only the period in which only the pressure adjusting valve 6 is open, and the pressure adjusting valve 6 and the air supply check valve 8 are opened. And both are open. That is, when the negative pressure is P1 or more and less than P2, only the pressure adjusting valve 6 is open, and when the negative pressure is P2 or more, both the pressure adjusting valve 6 and the air supply check valve 8 are open.

When only the pressure adjusting valve 6 is open, the open / close valve 5 is opened so that only the blend gas can be introduced into the second space 46. When both the pressure adjusting valve 6 and the air supply check valve 8 are in the open state, the pressure adjusting valve 6 is in the open state, but the open / close valve 5 is closed so that the second space 46 of the blended gas enters the second space 46. Since it is possible to prevent the introduction of air, only the air gas can be introduced into the second space 46.

Since the pressure in the second space 46 has a correlation with the position where the pump bellows 41 extends, the control means 60 controls the opening and closing of the on-off valve 5 in response to the output detected by the position detecting means 59, and the blend gas Only the second space 46
And a period of introducing only the air gas into the second space 46 can be determined, and the oxygen concentration of the mixed gas generated by mixing the blend gas and the air gas in the second space 46 can be adjusted. .

The gas mixing apparatus 1 of this embodiment shown in FIG.
A ventilator 2 including a gas mixing device 1 and a mounting member 71 mounted on at least one of a mouth and a nose of a patient.
And a discharge check valve 47 provided on the base body 44 of the air pump 3 provided in the gas mixing device 1 and the mounting member 71,
An intake line 72 for guiding intake from the air pump 3 to the patient,
An exhalation valve device 70 is provided at a tip end of the inhalation duct 72 branching from an intermediate position, and an expiratory duct 73 for guiding the exhalation of the patient to the exhalation valve device 70, and opening / closing in response to the detection output of the position detecting means 59 described above. The control means 60 controls the opening / closing operation of the valve 5 and controls the expiratory valve device 70 to be closed during the inspiration period of the patient.

When the pump bellows 41 contracts, the pressure in the second space 46 increases, so that the air supply check valve 8 closes.
The discharge check valve 47 opens. Further, the contraction of the pump bellows 41 is detected by the position detection means 59, the detection output is input to the control means 60, and the control means 60 closes the on-off valve 5 in response to the detection output. Therefore, the mixed gas is supplied from the mixed gas outlet 81 formed in the base body 44 to the intake pipe line 72. The mixed gas outlet 81 and the discharge check valve 4
A pump pressure detecting port 82, which is a pressure detecting port for the discharged mixed gas, is provided between the pump pressure detecting port 82 and the pump 7.

The intake pipe line 72 is a pipe line that connects the discharge check valve 47 of the air pump 3 and the mounting member 71, and guides the mixed gas supplied through the discharge check valve 47 to the patient. The intake conduit 72 is provided with an intake-side flow meter 83, first flow rate differential pressure detection ports 84a and 84b, and an intake filter 85. The intake side flow meter 83 may be omitted.

The exhalation conduit 73 is a conduit connecting the mounting member 71 and the exhalation valve device 70, and guides the exhalation of the patient to the exhalation valve device 70. An exhalation filter 86 is provided in the exhalation duct 73. An exhaust pipe line 88 that connects the exhalation valve device 70 and an exhaust port 87 that is an opening to the outside of the ventilator 2 is provided on the downstream side of the exhalation valve device 70 in the flow direction of exhalation.

From the midway position of the inspiratory line 72 to the expiratory line 73
Is branched by the branching member 91, and the inspiratory conduit 72 communicates with the expiratory conduit 73 and the mounting member 71. A patient airway pressure detection sensor 92 is provided between the branch member 91 and the mounting member 71, and the detection output of the airway pressure detection sensor 92 is input to the control means 60. The airway pressure detection sensor 92 may be configured to be provided at an appropriate position between the discharge check valve 47 and the branch member 91 of the intake conduit 72.

When the pump bellows 41 extends, the pressure in the second space 46 decreases, so that the air supply check valve 8 opens and the discharge check valve 47 closes. Further, the expansion of the pump bellows 41 is detected by the position detection means 59, the detection output is input to the control means 60, and the control means 60 controls opening / closing of the on-off valve 5 in response to the detection output. Therefore, the air gas or the blend gas is introduced into the second space 46 from the gas introduction port 40 formed in the base body 44 and connected to the first conduit 4b.

Next, the adjustment of the oxygen concentration of the mixed gas produced by introducing the blend gas and the air gas into the second space 46 will be described. The oxygen concentration of the mixed gas, which is the inspiration of the patient, is not limited to the atmospheric oxygen concentration of about 21%, but is set differently for each patient or for each patient's condition within the range of the atmospheric oxygen concentration or higher. It Therefore,
The oxygen concentration of the mixed gas prepared in the second space 46 must be adjusted differently for each patient or each patient's condition.

In adjusting the oxygen concentration of the mixed gas, in order to shorten the adjustment time, the second oxygen concentration should be adjusted.
The volume of space 46 is preferably the minimum required volume equal to the ventilation of the patient. However, the reciprocating type air pump provided in a practical respirator does not have a zero internal volume even when it is most degenerated, and the distance outside the stroke of the air pump and the direction perpendicular to the reciprocating direction of the air pump are cut off. It has a volume determined by the area (hereinafter referred to as a stroke outside volume Bv). Further, in general operation of the ventilator, a volume exceeding the sum of the out-of-stroke volume Bv and the ventilation volume of the patient is set as the internal volume of the air pump. As described above, since the internal volume of the air pump includes a large volume that is unnecessary for ventilation, it takes a long time to adjust the mixed gas to the target oxygen concentration.

The gas mixing apparatus 1 can control the inner volume of the air pump 3, that is, the volume of the second space 46 to the sum of the out-of-stroke volume Bv and the ventilation volume of the patient and a predetermined marginal ventilation volume. FIG. 3 is a simplified view showing a state in which the pump bellows 41 is extended according to the ventilation volume. Figure 3
(A) shows the volume of the second space 46 when the ventilation volume of the patient is small. The result (S1 × LB) obtained by multiplying the average area S1 of the cross section of the pump bellows 41 perpendicular to the reciprocating direction by the stroke outside distance LB of the pump bellows 41 is the stroke outside volume B.
v. The result (S1 × LL) obtained by multiplying the average area S1 by the ventilation stroke LL of the air pump 3 is the ventilation volume of the patient.

Further, FIG. 3B shows the volume of the second space 46 when the ventilation volume of the patient is large. The out-of-stroke volume Bv is the same as when the patient's ventilation is small (S1 × LB),
The ventilation volume of the patient is the product of the average area S1 and the ventilation stroke LG of the pump bellows 41 (S1 × LG). In either case of low ventilation volume (S1 × LL) or high ventilation volume (S1 × LG), the gas mixing device 1 determines the volume of the second space 46 according to the actual ventilation volume of the patient. The sum of the volume and the excess ventilation and the outside stroke volume Bv is controlled.

The control in which the volume of the second space 46 is the sum of the out-of-stroke volume Bv and the ventilation volume and margin ventilation volume of the patient can be realized as follows. The position detection means 59 provided in the air pump 3 can detect the extended position and the retracted position of the pump bellows 41, and further can detect the stroke Li which is the difference between them. The track record of the stroke Li detected by the position detection means 59 is stored in the memory 61 provided in the sequential control means 60. The previous travel record stored in the memory 61 is read back n times, and the average travel La given by the equation (1) is calculated by the calculation means 62 provided in the control means 60.

[0056]

[Equation 3]

The control means 60 outputs the average stroke La, which is the calculation result of the arithmetic means 62, to the position detecting means 59 and the electric motor 56 as a control signal, and the stroke of the pump bellows 41 corresponds to the average stroke La and the above-mentioned excess ventilation volume. The position where the pump bellows 41 extends and the position where the pump bellows 41 retract are controlled so as to be the sum of the margin stroke Lb. In this way, the volume of the second space 46 is the out-of-stroke volume Bv (= S1 ×
LB) and the actual ventilation volume of the patient (S1 × La) and the marginal ventilation volume (S1 × Lb).

As a result, when the oxygen concentration of the mixed gas in the second space 46 for supplying the inspiratory air of the patient is changed, a space other than the volume used for the ventilation of the patient and the volume of the marginal ventilation is the second space 46. Since the volume occupied can be only the out-of-stroke volume Bv, the second space 46
The time required to adjust the oxygen concentration of the mixed gas to the target oxygen concentration after the change can be shortened.

FIG. 4 is a simplified view showing the pump bellows 41 in the most retracted state, and FIG. 5 is a simplified view showing the pump bellows 41 shown in FIG. 4 in the extended state. When the pump bellows 41 starts the first reciprocating movement with the target oxygen concentration of the mixed gas newly set to operate the ventilator 2, or the oxygen concentration of the mixed gas supplied to the patient is changed. Therefore, when the pump bellows 41 starts the first reciprocating motion with the target oxygen concentration newly set, as shown in FIG. 4, the pump bellows 41 is out of the stroke so that the length in the reciprocating direction becomes the shortest. It is degenerated to a position where only the distance LB is left. By contracting the pump bellows 41 to a position where only the outside stroke distance LB is left, the volume of the second space 46 becomes only the minimum outside stroke volume Bv.

As a result, when the oxygen concentration of the mixed gas in the second space 46 of the air pump 3 that supplies the patient's inhalation is changed, the pump bellows 41 of the volume of the second space 46 to be replaced with the target oxygen concentration. Since the volume of the space other than the volume determined by moving the stroke can be set to only the minimum outside stroke volume Bv, the second space 4
It is possible to further reduce the time required to adjust the oxygen concentration of the mixed gas of No. 6 to the target oxygen concentration after the change.

FIG. 6 is a schematic view showing a state where the pump bellows 41 moves in the stroke. In the gas mixing device 1, in response to the detection output of the position where the pump bellows 41 extends by the position detection means 59, the control means 60 controls the opening and closing of the first conduits 4 a, 4 b by the opening / closing valve 5. The volume ratio of the blend gas and the air gas introduced into the second space 46 is changed to adjust the oxygen concentration of the mixed gas. Since the average area S1 of the cross section perpendicular to the reciprocating direction of the pump bellows 41 is constant in the reciprocating direction of the pump bellows 41, the blend gas and air gas introduced into the pump bellows 41, and the volume ratio of the ventilation volume. Is
It can be represented by the ratio of the blend gas introduction stroke L2, the air gas introduction stroke L3, and the ventilation stroke L1 which are distances. Note that one reciprocating movement in which the air pump 3 retracts and extends is sometimes referred to as a stroke hereinafter.

When the pump bellows 41 is repeatedly reciprocated to adjust the oxygen concentration of the mixed gas to the target oxygen concentration, the oxygen concentration before the setting change is made in the initial several strokes of the reciprocation until the target oxygen concentration is reached. If the target oxygen concentration after changing the setting is higher than that, a mixed gas with an oxygen concentration exceeding the target oxygen concentration is introduced, and if the target oxygen concentration after changing the setting is lower than the oxygen concentration before changing the setting, By introducing a mixed gas having an oxygen concentration less than the target oxygen concentration, the oxygen concentration of the gas in the pump bellows 41 is set to the target oxygen concentration as compared with the adjusting method of introducing a mixed gas having an oxygen concentration equal to the target oxygen concentration all the time. The adjustment time can be shortened.

After the oxygen concentration is newly set, in the initial several strokes in which the pump bellows 41 reciprocates,
The oxygen concentration of the mixed gas that is higher or lower than the target oxygen concentration and should be introduced into the second space 46 is set based on the oxygen concentration prediction formula. Here, the oxygen concentration prediction formula is such that the predicted oxygen concentration C _n of the mixed gas in the stroke that the pump bellows 41 should immediately perform is the oxygen concentration C _n of the mixed gas in the stroke immediately before the pump bellows 41.
It is obtained using _n-1 . As an example, when a gas having an oxygen concentration of 100%, that is, an oxygen gas is used as the blend gas, the oxygen concentration prediction formula is given by the following formula (2). C _n (%) = 100 × [L1 × {100α + Cair × (1-α)} + (L0-L1) × C _n-1 ] / L0 (2) where L0 is the reciprocating direction of the pump bellows. Length (c
m) L1: Ventilation stroke (cm) Cair: Oxygen concentration in the atmosphere (%) Cn _-1 : Oxygen concentration in the mixed gas of the previous stroke (%)

The mixing ratio α, which is the ratio of the oxygen gas introduction amount to the ventilation amount, is given by the equation (3). α = L2 / L1 (3) where L1: Ventilation process (cm) L2: Oxygen gas (blend gas) introduction process (cm)

Although the pump bellows 41 has an out-of-stroke distance, the volume that can be replaced by the stroke of the pump bellows 41 is the ventilation volume determined by the ventilation stroke L1, so the pump bellows 41 internal volume other than the ventilation volume {S
1 × (L0-L1)} is assumed to be zero, and the pump bellows 4
The predicted oxygen concentration C _n is obtained by using the mixing ratio αbase (hereinafter referred to as the mixing ratio reference value αbase) in a state where the oxygen concentration of the mixed gas within 1 has reached the target oxygen concentration Cset. The mixture ratio reference value αbase is given by equation (4). αbase = (Cset−Cair) / (100−Cair) (4) where Cset: target oxygen concentration (%) Cair: atmospheric oxygen concentration (%)

When calculating the predicted oxygen concentration C _n , the values of the ventilation stroke L1 and the like can be obtained as follows. For the ventilation stroke L1, for example, the immediately preceding degenerate distance Li can be used. Length L of pump bellows 41 in the reciprocating direction
0, the target oxygen concentration Cset and the atmospheric oxygen concentration Cair are
Since it is a predetermined value, it can be given in advance to the control means 60 by input means such as a keyboard (not shown).

Oxygen concentration C _n-1 of the mixed gas in the previous stroke
Can be detected, for example, by providing an oxygen concentration detector in the air pump 3, and the detection output of the oxygen concentration detector can be input to the control means 60 and used for calculation. Using the value thus obtained, the control means 6
The predicted oxygen concentration C _n can be calculated by the calculation means 62 provided in 0. The calculation of the predicted oxygen concentration C _n is not limited to the calculation means 62 provided in the control means 60. It is also possible to prepare a desk calculator or the like in which an arithmetic expression is programmed in advance and input the data necessary for the arithmetic operation for calculation.

The mixture ratio reference value αbase given by the equation (4) is substituted into the oxygen concentration prediction equation (2) to obtain the predicted oxygen concentration C _n when the target oxygen concentration Cset is achieved at least in the ventilation volume. Next, exemplifying a case where the target oxygen concentration set in the mixed gas is changed to be high, the predicted oxygen concentration C _n is the maximum value of the allowable variation range of the target oxygen concentration Cset in the entire volume of the second space 46. The following is obtained, that is, the maximum mixing ratio αmax that satisfies (C _n ≦ Cset + a) is determined. Here, when the maximum mixing ratio αmax exceeds 1, the maximum mixing ratio αmax is set to 1. The obtained maximum mixing ratio αmax is substituted into the equation (4) to obtain the oxygen gas introduction process L2.

Oxygen gas and air gas are supplied to the second space 46 in accordance with the oxygen gas introduction stroke L2 thus obtained and the air gas introduction stroke L3 (= L1-L2) obtained based on the oxygen gas introduction stroke L2. Each is introduced to produce a mixed gas. The oxygen concentration of the mixed gas thus generated is higher than the target oxygen concentration, that is, in the ventilation stroke L1, in the initial several strokes of the reciprocating movement of the pump bellows 41 after the target oxygen concentration is newly set. A stroke in which the proportion of the oxygen gas introduction process L2 is high is performed.

On the contrary, when the target oxygen concentration set in the mixed gas is changed to be low, the predicted oxygen concentration C _n is the allowable range of variation of the target oxygen concentration Cset in the entire volume of the second space 46. Or more, that is, the minimum mixing ratio αmin that satisfies (C _n ≧ Cset−a) is obtained. Here, when the minimum mixing ratio αmin is less than 0, the minimum mixing ratio αmin is set to 0. The obtained minimum mixing ratio αmin is substituted into the equation (4) to obtain the oxygen gas introduction process L2.

Similarly to the case where the target oxygen concentration is increased, oxygen gas and air gas are introduced into the second space 46 according to the oxygen gas introduction process L2 and the air gas introduction process L3, respectively, to generate a mixed gas. The oxygen concentration of the mixed gas thus generated is lower than the target oxygen concentration, that is, occupies the ventilation stroke L1 in the initial several strokes of the reciprocating movement of the pump bellows 41 after the target oxygen concentration is newly set. A stroke in which the proportion of the oxygen gas introduction process L2 is low is performed.

FIG. 7 is a flow chart for explaining the operation of adjusting the oxygen concentration of the gas in the second space 46 based on the oxygen concentration prediction formula. In step a1, the mixture ratio reference value α
The predicted oxygen concentration C _n is calculated by substituting base into the oxygen concentration prediction formula (2). In step a2, it is determined whether or not the predicted oxygen concentration C _n , which is the calculation result, is within a concentration range of plus or minus a% with respect to the target oxygen concentration Cset. When this determination result is affirmative, the process proceeds to step a3. In step a3, the mixture ratio reference value αbase is set to the mixture ratio α.
And the blend gas introduction stroke L2 is calculated, and the air gas introduction stroke L3 (L1-L2) is calculated based on the blend gas introduction stroke L2.

When the determination result in step a2 is negative, the process proceeds to step a4. In step a4, the predicted oxygen concentration C _n is not more than (Cset + a) which is the maximum value of the allowable variation range of the target oxygen concentration Cset, that is, (C _n ≤Cse).
The maximum mixing ratio αmax that satisfies t + a) is calculated. In step a5, the mixture ratio αmax is set to the mixture ratio α, and the formula (3) is used.
To calculate the blend gas introduction stroke L2, and based on the blend gas introduction stroke L2, the air gas introduction stroke L3.
Calculate (L1-L2).

At step a6, the expansion of the pump bellows 41 is started. In step a7, the pump bellows 4
The position detecting means 59 detects that 1 is at the extension start position of the blend gas introduction stroke L2, and the position detecting means 5
In response to the detection signal of 9, the control means 60 opens the on-off valve 5 and opens the first pipelines 4a and 4b. At step a8, the pump bellows 41 moves to step a3 or step a5.
By extending the blend gas introduction stroke L2 which is the calculation result of the
It is introduced into the second space 46 via the conduit 4b.

In step a9, the pump bellows 41 is at the start position of the air gas introduction process L3 after the extension of the blend gas introduction process L2, and the extension position of the pump bellows 41 is detected by the position detector 59, and the position detecting means is used. In response to the detection signal from 59, the control means 60 closes the on-off valve 5 to shut off the first pipelines 4a and 4b. At step a10, the pump bellows 41 extends the air gas introduction stroke L3. At this time, since the on-off valve 5 is closed as described above, the blended gas is not introduced into the second space 46, and the air supply check valve 8 is opened, so that the air gas is discharged into the second space 4.
Introduced in 6.

At step a11, the pump bellows 41
Ends the extension of the ventilation stroke L1 (= L2 + L3), the introduction of the air gas is stopped, and the mixing of the blended gas and the air gas in the second space 46 is ended. At step a12, the pump bellows 41 starts to contract, and the second space 46
The mixed gas is supplied from the discharge check valve 47 to the intake pipe line 72. After the contraction of the pump bellows 41 is started, the process returns to step a1 and the subsequent steps are repeated. In addition,
When lowering the target oxygen concentration, in step a4 (C
Instead of the _n ≦ Cset + a) the maximum mixing ratio αmax which _{satisfies, (C n ≧ Cset-a} ) become minimum mixing ratio αmin is selected.

FIG. 8 shows the second method for increasing the target oxygen concentration.
It is a figure which shows the relationship between the mixed gas oxygen concentration of space 46, and time. FIG. 9 shows the 2nd space 4 when making target oxygen concentration low.
It is a figure which shows the relationship between the mixed gas oxygen concentration of 6 and time.

The first line 95 in FIG. 8A is used to increase the target oxygen concentration of the mixed gas in the pump bellows 41 supplied as the patient's inspiratory air when the pump bellows 41 is increased.
Of the mixed gas oxygen concentration and time when the mixed gas having the oxygen concentration higher than the target oxygen concentration generated as described above is introduced into the second space 46 in the initial several strokes of the reciprocating motion of Indicates. The second line 96 in FIG. 8B shows the relationship between the oxygen concentration in the mixed gas and the time when the mixed gas having the target oxygen concentration is introduced into the second space 46 during the reciprocating movement of the pump bellows 41. Compared to the second line 96 in the case of introducing the mixed gas having the target oxygen concentration from beginning to end, the first line 95 in the case of introducing the mixed gas having an oxygen concentration higher than the target oxygen concentration has the second space in a shorter time. The gas of 46 can be adjusted to the set concentration which is the target oxygen concentration.

A third line 97 in FIG. 9 (a) indicates several initial strokes in the reciprocating motion of the pump bellows 41 when the target oxygen concentration of the mixed gas in the second space 46 supplied as the inspiration of the patient is lowered. 3 shows the relationship between the oxygen concentration of mixed gas and time when the mixed gas having the oxygen concentration lower than the target oxygen concentration generated as described above is introduced into the second space 46. A fourth line 98 in FIG. 9B shows the relationship between the mixed gas oxygen concentration and the time when the mixed gas having the target oxygen concentration is introduced into the second space 46 during the reciprocating movement of the pump bellows 41. Compared with the fourth line 98 when the mixed gas having the target oxygen concentration is constantly introduced, the third line 97 when the mixed gas having the oxygen concentration lower than the target oxygen concentration is introduced has a shorter time in the pump bellows 41. The gas inside can be adjusted to a target oxygen concentration, which is a set concentration.

As described above, in the embodiment of the present invention, the gas mixing device 1 is configured to include the position detecting means 59 and the control means 60, but the position is not limited to this, and the position detecting means 59 and the control means 60 are not limited thereto. The configuration may not include the detection unit 59 and the control unit 60.

[0081]

According to the present invention, the air pump for supplying inspiration to the patient is connected to the first conduit for guiding the blend gas to the air pump, and the first conduit is provided at an intermediate position of the first conduit. An opening / closing valve for opening / closing is provided, and a pressure adjusting valve for adjusting the pressure in the air pump is provided on the downstream side of the opening / closing valve of the first pipeline in the flow direction of the blend gas, and the pressure adjustment of the first pipeline is provided. A second pipe line that guides the air gas to the first pipe line is connected to the downstream side of the valve in the flow direction of the blend gas, and a supply check valve that supplies the air gas to the air pump is connected to the second pipe line. It is provided.
This makes it possible to mix the blended gas and the air gas with a simple structure that does not require a dedicated mixer and a complicated and highly accurate flow rate adjustment mechanism, and is a combination of an on-off valve, a pressure adjustment valve and an air supply check valve. Therefore, the manufacturing cost can be reduced and the device can be downsized.
Also, by opening or shutting off the first conduit with the on-off valve,
Since the blend gas and the air gas introduced into the air pump can be switched, the blending operation of the blend gas and the air gas can be easily performed.

Further, according to the present invention, it is possible to accurately detect the distance that the air pump moves in the reciprocating direction, and the reciprocating movement of the air pump due to the extension of the air pump is carried out in the cross-sectional area in the direction orthogonal to the reciprocating direction of the air pump. The amount of blend gas and air gas introduced into the air pump can be determined by multiplying the moving distance in the moving direction. Therefore,
By controlling the opening and closing of the on-off valve according to the movement distance of the air pump, the amount of the blend gas to be introduced into the air pump and the amount of the air gas can be accurately determined. It is possible to accurately adjust the oxygen concentration of a mixed gas composed of gas and air gas.

When the blended gas is introduced into the air pump, the feed gas check valve can prevent the air gas from flowing into the first pipe line, so that the blended gas may be diluted with the air gas. Absent. Therefore, since the oxygen concentration of the blend gas is kept constant, the oxygen concentration of the mixed gas of the blend gas and the air gas in the air pump can be accurately adjusted.

Further, according to the present invention, the average stroke La is calculated by the calculating means based on the stroke record of the air pump, that is, the ventilation volume record of the patient, and the air pump is reciprocated according to the calculated average stroke La. It is possible to reduce the volume of the internal volume other than the volume used for ventilation of the patient. As a result, when changing the oxygen concentration of the mixed gas in the air pump that supplies the patient's inspiration, the volume occupied by the space other than the volume used for ventilation of the patient in the air pump can be reduced, so that the air pump It is possible to shorten the time required to adjust the oxygen concentration of the mixed gas inside the target oxygen concentration after the change.

Further, according to the present invention, when the air pump starts the first reciprocating motion in the state where the predetermined target oxygen concentration of the inspiration to be supplied to the patient is newly set, the air pump moves in the reciprocating motion direction. The blend gas is introduced into an air pump by retracting to a predetermined position so that the length becomes the shortest. By this, when changing the oxygen concentration of the mixed gas in the air pump that supplies the inspiration of the patient,
Of the internal volume of the air pump to be replaced with the target oxygen concentration, the volume of the space other than the volume determined by the movement of the air pump can be minimized, so the oxygen concentration of the mixed gas in the air pump can be reduced. The time required to adjust to the changed target oxygen concentration can be shortened.

Further, according to the present invention, the blend gas and the air gas are introduced into the air pump in accordance with the blend gas introducing process L2 and the air gas introducing process L3 obtained based on the oxygen concentration predicting equation. The oxygen concentration of the mixed gas in the ventilation stroke L1 obtained by mixing the blended gas and the air gas, which is obtained based on this oxygen concentration prediction equation, is the initial value at which the air pump reciprocates after the new target oxygen concentration is set. In the period, the concentration higher than the target oxygen concentration is obtained when increasing the target oxygen concentration after the setting change, or the concentration lower than the target oxygen concentration is obtained when decreasing the target oxygen concentration after the setting change.

Therefore, when the air pump is repeatedly reciprocated after the setting is changed to change the oxygen concentration in the air pump to the target oxygen concentration, the initial reciprocating motion of the air pump is reached until the target oxygen concentration is reached after the setting is changed. During the period, a mixed gas having a higher oxygen concentration or a lower oxygen concentration than the target oxygen concentration can be introduced into the air pump, so the oxygen concentration of the mixed gas in the air pump is adjusted to the target oxygen concentration after the change. The time required for this can be shortened.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a simplified configuration of a gas mixing device for a ventilator 1 according to an embodiment of the present invention.

FIG. 2 is a system diagram showing the overall configuration of a ventilator 2 including the gas mixing device 1 for ventilator shown in FIG.

FIG. 3 is a schematic view showing a state in which a pump bellows 41 is extended according to a ventilation amount.

FIG. 4 is a schematic view showing a state in which a pump bellows 41 is most retracted.

5 is a simplified view showing a state where the pump bellows 41 shown in FIG. 4 is extended.

FIG. 6 is a schematic view showing a state where the pump bellows 41 moves in a stroke.

FIG. 7 is a flowchart illustrating an operation of adjusting the oxygen concentration of the gas in the second space 46 based on the oxygen concentration prediction formula.

FIG. 8 is a diagram showing the relationship between the oxygen concentration of mixed gas in the second space 46 and time when the target oxygen concentration is increased.

FIG. 9 is a diagram showing the relationship between the oxygen concentration of mixed gas in the second space 46 and time when the target oxygen concentration is lowered.

[Explanation of symbols]

1 gas mixing device 2 ventilator 3 air pump 4a, 4b 1st pipeline 5 on-off valve 6 Pressure control valve 7 Second pipeline 8 Air check valve 59 Position control means 60 control means 61 memory 62 computing means

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 28, 2001 (2001.11.
28)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction content]

After the oxygen concentration is newly set, in the initial several strokes in which the pump bellows 41 reciprocates,
The oxygen concentration of the mixed gas that is higher or lower than the target oxygen concentration and should be introduced into the second space 46 is set based on the oxygen concentration prediction formula. Here, the oxygen concentration prediction formula is such that the predicted oxygen concentration C _n of the mixed gas in the stroke that the pump bellows 41 should immediately perform is the oxygen concentration C _n of the mixed gas in the stroke immediately before the pump bellows 41.
It is obtained using _n-1 . As an example, when a gas having an oxygen concentration of 100%, that is, an oxygen gas is used as the blend gas, the oxygen concentration prediction formula is given by the following formula (2). C _n (%) = [L1 × {100α + Cair × (1-α)} + (L0-L1) × C _n-1 ] / L0 (2) where L0 is the length of the pump bellows in the reciprocating direction. (C
m) L1: Ventilation stroke (cm) Cair: Oxygen concentration in the atmosphere (%) Cn _-1 : Oxygen concentration in the mixed gas of the previous stroke (%)

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinya Yonezawa             16-2, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kawaju Disaster Prevention Industry Co., Ltd.Kobe Head Office / Head Office Factory             Within (72) Inventor Kazutoshi Soga             16-2, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kawaju Disaster Prevention Industry Co., Ltd.Kobe Head Office / Head Office Factory             Within (72) Inventor Koichi Ishii             16-2, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kawaju Disaster Prevention Industry Co., Ltd.Kobe Head Office / Head Office Factory             Within (72) Inventor Haruhiko Nakata             16-2, Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kawaju Disaster Prevention Industry Co., Ltd.Kobe Head Office / Head Office Factory             Within

Claims (5)

[Claims] 1. An air pump for supplying inspiration to a patient by reciprocating motion of extension and contraction, a first conduit connected to the air pump for guiding a blend gas to the air pump, and provided at an intermediate position of the first conduit. An opening / closing valve for opening / closing the first pipe line, a pressure adjusting valve provided downstream of the opening / closing valve for the first pipe line in the flow direction of the blend gas, and for adjusting the pressure in the air pump; A second pipe line that is connected to the downstream side of the pressure control valve in the flow direction of the blend gas and guides the air gas to the first pipe line, and a supply pipe that is provided in the second pipe line and supplies the air gas to the air pump. A gas mixing device for a ventilator, comprising a gas check valve. 2. A position detecting means for detecting a position where the air pump expands and contracts, and a control means which responds to a detection output of the position detecting means to control opening and closing of the first pipeline by the opening / closing valve. The gas mixing device for a ventilator according to claim 1, further comprising: 3. The control means stores the result of the stroke Li obtained by the difference between the extended position and the retracted position of the air pump detected by the position detecting means, sequentially for n times, and a memory that stores the results. Read n strokes Li, and Calculating means for calculating the average stroke La given by the control means, and the control means responds to the calculation result by the calculating means, and sets the stroke of the air pump to the average stroke La and a margin stroke Lb which is predetermined.
The position where the air pump extends and the position where the air pump retracts are controlled so as to be the sum of the following.
A gas mixing device for the ventilator described. 4. A gas mixing device for a ventilator according to any one of claims 1 to 3 is prepared, and an air pump is set in a state where a predetermined target oxygen concentration of inspiration to be supplied to a patient is newly set. When starting the first reciprocating motion, retract the air pump to a predetermined position so that the length in the reciprocating direction is the shortest, open the on-off valve to guide the blend gas to the pressure regulating valve, and turn on the air pump. A method for mixing gases for a respirator, which comprises extending the blended gas to an air pump by stretching. 5. The ventilator gas mixing device according to claim 2 or 3 is prepared, and a ventilation stroke L1 corresponding to the ventilation volume of the patient, which is the difference between the extending position and the retracting position of the air pump, is determined. The oxygen concentration (C _n ) of the mixed gas formed by mixing the blended gas and the air gas in the air pump in the reciprocating motion to be performed immediately after the air pump is the air pump in the reciprocating motion performed immediately before the air pump. The oxygen concentration prediction formula is set based on the oxygen concentration (C _n-1 ) of the mixed gas obtained by mixing the blend gas and the air gas therein, and the blend gas is supplied to the air pump based on the oxygen concentration prediction formula. A blend gas introduction step L2 that is a step that guides the air flow is performed, and an air gas introduction step L3 that is a step that guides the air gas to the air pump by the obtained blend gas introduction step L2 and the ventilation step L1. (= L1−L2) is calculated, and the ventilation stroke L
When extending 1, the blend gas is introduced into the air pump according to the blend gas introduction step L2, and the air gas is introduced into the air pump according to the air gas introduction step L3.