JP2005279218A - Inhalation anesthesia apparatus for small laboratory animal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inhalation anesthesia apparatus for a small laboratory animal which is used in any place and safely and rapidly induces anesthesia. <P>SOLUTION: The apparatus comprises: an air pump 1; a thermal flow controller 2; a vaporizing unit 3 for volatile anesthetic; a breathing circuit 4 for making gas of a set flow rate flow; an expiration valve 5 attached to the most downstream part of the breathing circuit; a pressure sensor 6 in the breathing circuit; a means which is branched from the breathing circuit and supplies a fixed flow rate of gas to the small laboratory animal when the expiration valve is closed; a means for discharging the expiration of the small laboratory animal to the air together with anesthetic gas by opening the expiration valve when pressure in the breathing circuit reaches the set pressure or a set inspiration time is terminated; a means for supplying inspiration to the small laboratory animal by closing the expiration valve when the set expiration time is terminated; a means for integrating a fixed gas flow rate value converted into an electric signal and an inspiration time and displaying a one-time ventilation amount to be supplied to the small laboratory animal; and an artificial breathing function of performing conversion into a pressure control system or a capacity control system in response to a condition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an anesthesia apparatus for performing anesthesia by inhaling an anesthetic into an animal, and more specifically, for a small experimental animal that can be used safely over a long period of time for a small experimental animal such as a mouse. The present invention relates to an inhalation anesthesia apparatus.

  Conventionally, as an inhalation anesthesia apparatus for animals, a normal inhalation anesthesia apparatus for human beings is used as it is, and the structure is mostly a combination of a rotameter type flow meter and a wick-type vaporizer. It was. (Refer nonpatent literature 1).

  In addition, as an inhalation gas, a mixture of oxygen and nitrous oxide was allowed to flow as a carrier gas, and a gas in the form of vaporized volatile anesthetic such as sevoflurane was added for inhalation.

Furthermore, it is necessary to perform artificial respiration during anesthesia, but conventionally, a rotational movement of a motor is converted into a reciprocating movement by a crank mechanism, and a piston is reciprocated to generate a certain volume of gas in the lungs of a small animal. The so-called capacity regulating method was used. (Refer nonpatent literature 2). And the ventilator existed separately as an apparatus independent of the anesthesia apparatus, and there was no thing which combined both together.
Shinano Manufacturing Co., Ltd. “Laboratory Animal Anesthesia Equipment” Catalog Shinano Manufacturing Co., Ltd. “Laboratory Animal Ventilator” Catalog

  However, since the use of a conventional animal inhalation anesthesia apparatus requires oxygen and nitrous oxide to be supplied, it can be used in a room where oxygen and nitrous oxide supply pipes are provided, or Oxygen and nitrous oxide cylinders were required to be supplied from there nearby and could not be used easily anywhere.

  In addition, in the case of small experimental animals, the flow rate of inhaled gas is extremely smaller than that in the case of humans, and it has been difficult to obtain an accurate anesthetic concentration with a conventional wick-type vaporizer.

  Furthermore, in the capacity-restricted ventilator, the inspiratory time to expiratory time ratio (I / E ratio) is usually fixed at 1: 1. There are also ventilators designed to change the I / E ratio, but the structure becomes complicated and not only costs increase, but it is difficult to change the I / E ratio almost continuously. Met. Moreover, since a predetermined volume of gas is forcibly sent to the lungs, there is a risk that excessive pressure is applied to the lungs. Furthermore, small animal ventilators may be operated at a respiration rate of 400 times / minute, and unlike a human adult respirator that is normally used at a respiration rate of 10-20 times / minute, it is movable. There was a problem in durability because the parts were worn quickly.

  Therefore, the inventor invented a ventilator for small animals based on a new concept and filed a patent application (Application No .: Japanese Patent Application No. 2004-79203), but it is difficult to integrate it with an anesthesia machine, and inhalation There was a problem that anesthesia could not be introduced safely and quickly using anesthetics.

  The present invention has been obtained as a result of earnest study in view of the above-described problems. That is, the present invention includes an air pump for supplying air, a thermal mass flow controller for flowing air at a set flow rate, a vaporizing unit for vaporizing a volatile anesthetic, and an anesthetic gas at a set constant flow rate. A breathing circuit through which the breathing circuit flows, an exhalation valve attached to the most downstream of the breathing circuit, a pressure sensor for measuring the pressure in the breathing circuit, and branching from the breathing circuit and connected to the trachea of a small animal, Means for delivering a constant flow of gas to the small animal as inhalation when closed, the expiratory valve opens when the pressure in the breathing circuit reaches a set pressure or when the set inspiratory time expires The expiratory air is exhausted to the atmosphere together with a constant flow of gas, the expiratory valve is closed at the end of the set expiratory time, and the inhalation is sent to the small animal again. Means for calculating and displaying the tidal volume delivered to the small animal by integrating the constant gas flow rate value and the inspiratory time, and depending on the use conditions, either the pressure regulation system or the capacity regulation system However, the present invention relates to an inhalation anesthesia apparatus for small experimental animals characterized by having an artificial respiration function that can be freely converted.

  In the inhalation anesthesia apparatus for small experimental animals, the present invention calculates the amount of volatile anesthetic necessary for the air flow rate controlled by the thermal mass flow controller when the concentration of the volatile anesthetic is set, and injects the anesthetic. The pump is equipped with a vaporizer unit that draws the calculated volume from the anesthetic bottle and drops it into the vaporization chamber.

  Further, the present invention is the above-described inhalation anesthesia apparatus for small experimental animals, comprising means for heating the vaporization chamber in order to increase the vaporization efficiency of the vaporization chamber.

  In the inhalation anesthesia apparatus for small experimental animals according to the present invention, a flow path switching valve is provided on the inhalation side of the breathing circuit, and means for flowing anesthesia gas into the anesthesia introduction box is provided.

  Furthermore, the present invention is the above-described inhalation anesthesia apparatus for small laboratory animals, wherein an adsorption column for adsorbing a volatile anesthetic is provided at the exhalation valve outlet and the anesthetic introduction box exhaust port.

  The inhalation anesthesia apparatus for small experimental animals according to the present invention does not require oxygen and nitrous oxide as carrier gases, and can be easily used everywhere because an anesthesia can be carried out independently by a built-in air pump. In addition, since a thermal mass flow controller is used, the flow rate of air as the carrier gas can be accurately defined, and a small amount of volatile anesthetic is accurately dropped into the vaporization chamber by a liquid infusion pump at about 40 ° C. Since it is heated and vaporized, a highly accurate anesthetic concentration can be obtained.

  Furthermore, the inhalation anesthesia apparatus for small experimental animals of the present invention is integrated with a ventilator function that is activated by the flow of the anesthetic gas itself, such as a mouse with a large number of breaths and a small tidal volume. For small animals, safety is high, and if you set the number of breaths, the ratio of inspiratory time to expiratory time, and the maximum inspiratory pressure, just adjust the respiratory gas flow and use it as either a volume regulation method or a pressure regulation method It is possible, and it is possible to freely convert to either while taking advantage of the advantages of both types.

  Then, the anesthesia gas is caused to flow into the anesthesia introduction box by the flow path switching valve, so that the small animal can be safely and rapidly introduced into the anesthesia box.

  Further, by adding an adsorption column for adsorbing an anesthetic to the exhalation valve and the exhaust port of the anesthesia introduction box, the anesthetic can be safely performed without exhausting the anesthetic to the outside air. As described above, the inhalation anesthesia apparatus for small experimental animals of the present invention has extremely significant effects and is highly practical.

  Embodiments of an inhalation anesthesia apparatus for small experimental animals according to the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is a piping system diagram for explaining an embodiment of an inhalation anesthesia apparatus for small experimental animals according to the present invention, and FIG. 2 is a piping system diagram when a switching valve and an anesthetic introduction box are incorporated. FIG. 3 is a piping system diagram when an adsorption column for adsorbing a volatile anesthetic is provided at the exhalation valve outlet and the anesthetic introduction box exhaust port, and FIG. 4 shows the configuration of the vaporizer unit. FIG. 5 shows the pressure in the expiratory circuit and the operation timing of each solenoid valve.

  In FIG. 1, 1 is an air pump, 2 is a thermal mass flow controller, 3 is a vaporizer unit, 4 is a breathing circuit, 5 is an electromagnetic valve functioning as an exhalation valve, and 6 is a pressure sensor. 7 is an electromagnetic valve for zero calibration of the pressure sensor, 8 is an electromagnetic valve for releasing excess pressure, 9 is a tracheal connection tube connected to a small animal, and a tracheal tube or tracheostomy tube It is connected to the trachea of a small animal via (not shown).

  Next, an operation method of the inhalation anesthesia apparatus for small experimental animals according to the present invention will be described. The air pump 1 is for supplying clean air to a small animal. For example, a diaphragm-type pump such as a diaphragm pump has a quiet operation sound and is preferably oil-less. By operating the air pump 1, air is sent out, and the thermal mass flow controller 2 accurately adjusts the air flow rate sent to the small animal to the set flow rate, and at the flow rate value output from the thermal mass flow controller 2. By integrating the intake time, the tidal volume is calculated. The set constant flow of air is flowed to the vaporizer unit 3, and a volatile anesthetic such as sevoflurane is vaporized and added to the flow of air in the vaporizer unit 3. It flows to 5.

  The exhalation-valve 5 is preferably a three-way solenoid valve that is open when not in operation, and has a fast operation time and excellent durability. When the exhalation valve 5 is activated and closed, the anesthetic gas flows toward the trachea of the small animal and the pressure in the breathing circuit increases.

  The breathing circuit 4 branches before the exhalation valve 5 and is connected to the pressure sensor 6 through the zero calibration electromagnetic valve 7, and the pressure in the breathing circuit is constantly measured by the pressure sensor 6. The zero-calibration solenoid valve 7 is open when not in operation, and the breathing circuit 4 and the pressure sensor 6 communicate with each other, but when in the actuated state, the breathing circuit 4 is closed and the pressure sensor 6 is in the atmosphere. And zero calibration will be performed. Normally, zero calibration is automatically performed when the power is turned on and thereafter once every four hours.

  The breathing circuit 4 branches near the supply gas connection port and is connected to an overpressure relief valve 8. The overpressure relief valve 8 is a two-way electromagnetic valve that is in a closed state when not in operation, and is opened when the pressure in the breathing circuit becomes excessive, and serves as a safety valve that releases pressure.

  In this small experimental animal inhalation anesthesia apparatus, the number of breaths and the I / E ratio are set, and the inspiratory time and expiratory time are calculated from both. In the artificial respirator incorporated in the inhalation anesthesia apparatus for small experimental animals, the maximum inspiratory pressure is set. At the time of inhalation, the exhalation valve 5 is closed, and the respiratory gas is transmitted to the respiratory circuit 4 and the trachea. While being sent to the trachea of a small animal via the connection tube 9, the expiratory valve 5 is opened when the pressure in the breathing circuit reaches the set maximum inspiratory pressure or when the set inspiratory time ends, and the expiratory gas is Together with the gas flowing through the breathing circuit 4, it is discharged to the atmosphere.

Setting the maximum intake air pressure, for example setpoint + 2 cmH ₂ limit alarm value O, low alarm value is set to the setting value -2cmH ₂ O. When the breathing circuit internal pressure exceeds the upper limit alarm value, the high pressure alarm is activated and the overpressure relief valve 6 is opened. When the breathing circuit internal pressure falls below the lower limit alarm value, the low pressure alarm is activated. The upper / lower limit alarm setting value should be set to ± ₂ cmH ₂ O or more according to the situation.

  By integrating the flow rate value converted into an electrical signal obtained from a gas supply source supplied at a constant flow rate and the inspiratory time, the tidal volume delivered to the small animal is calculated and displayed. If the inspiration ends when the pressure in the breathing circuit reaches the set maximum inspiratory pressure, the actual inspiratory time is reduced regardless of the inspiratory time calculated from the number of breaths and the I / E ratio setting. Used for calculation.

本発明による小実験動物用吸入麻酔装置に組み込まれている人工呼吸器は、最大吸気圧力を設定し、呼吸回路内圧が設定された最大吸気圧力に達すると吸気が終了して呼気に切換わるので、基本的には圧力規定方式をとっているが、定常流量値に吸気時間を積算することにより、１回換気量が計算され表示されており、設定された吸気時間中に呼吸回路内圧が最大吸気圧力に達しない場合は、１回換気量が一定に保たれることになり、容量規定方式となる。Ventilators are broadly classified into volume regulation methods that regulate the amount of inhalation and pressure regulation methods that regulate the pressure applied to the airway, and each has advantages and disadvantages as shown in the table below.

The artificial respirator incorporated in the inhalation anesthesia apparatus for small experimental animals according to the present invention sets the maximum inspiratory pressure, and when the inspiratory circuit pressure reaches the set maximum inspiratory pressure, the inspiration is terminated and switched to exhalation. Basically, the pressure regulation method is adopted, but the tidal volume is calculated and displayed by adding the inspiratory time to the steady flow rate value, and the respiratory circuit internal pressure is maximized during the set inspiratory time. When the intake pressure is not reached, the tidal volume is kept constant, which is a capacity defining method.

  In the normal pressure regulation method, generally, when the pressure in the breathing circuit reaches the set maximum inspiratory pressure, the pressure is maintained as it is, and when the set inspiratory time ends, the breath is switched to exhalation. . For this purpose, it is necessary to use an electropneumatic valve capable of continuously adjusting the opening rather than an electromagnetic valve that simply opens and closes as an exhalation valve, and the electropneumatic valve is very expensive. In order to maintain the pressure, an automatic feedback control means is necessary. However, the ventilator according to the present invention is limited to small animals and is normally used in the range of 60 to 200 breaths / minute, so the inspiratory time is 0.5 seconds or less, Does not make sense to maintain the maximum intake pressure. In view of this situation, as soon as the breathing circuit internal pressure reaches the set maximum inspiratory pressure, the inspiration is terminated and switched to exhalation, so that an inexpensive solenoid valve can be used and a steady flow rate value can be obtained. It was possible to obtain the merit that the tidal volume can be calculated by integrating the intake time. In the conventional pressure regulation system, a part of the breathing gas is leaked from the exhalation valve in order to maintain the breathing circuit internal pressure at the maximum inspiratory pressure, so that an accurate tidal volume is shown even if the inspiratory time is multiplied by the steady flow rate value. I can't.

In actual use, settings are made in the following procedure.
(1) The distal end of the tracheal connection tube 9 is closed.
(2) Set the number of breaths and the I / E ratio.
(3) Set the maximum intake pressure.
(4) If the high pressure alarm is activated, reduce the steady flow rate. When the low pressure alarm is activated, the steady flow rate is increased.
(5) Confirm that the breathing circuit internal pressure is within the maximum inspiratory pressure ± ₂ cmH ₂ O and confirm that the value of the tidal volume display is appropriate.
(6) The tracheal connection tube 9 is connected to a small animal via a tracheal tube or the like.
(7) If the high pressure alarm is activated, reduce the steady flow rate. When the low pressure alarm is activated, the steady flow rate is increased.
(8) Confirm that the breathing circuit internal pressure is within the maximum inspiratory pressure ± ₂ cmH ₂ O and confirm that the value of the tidal volume display is appropriate.
(9) When changing to the capacity regulation system when operating in the pressure regulation system, reduce the steady flow rate or increase the maximum intake pressure setting.
(10) To change to the pressure regulation system when operating in the capacity regulation system, increase the steady flow rate or lower the maximum intake pressure setting.

  If the breathing circuit internal pressure does not reach the set maximum inspiratory pressure, a constant tidal volume is delivered unless the lung compliance changes, so this is a capacity regulating method. In addition, when the breathing circuit internal pressure reaches the set maximum inspiratory pressure and switches from inspiration to expiration, the pressure regulation method is used, but even in this case, the calculated value of the tidal volume is displayed. Even when operating in the volume regulation method, when the state of the lungs of the small animal changes and the compliance becomes smaller, the pressure in the respiratory circuit reaches the set maximum inspiratory pressure and is converted to the pressure regulation method. At this time, the maximum intake pressure can be set higher or the steady flow rate can be reduced to return to the capacity regulating method.

  In FIG. 2, a flow path switching valve 10 is provided between the point branching to the overpressure relief valve 8 of the breathing circuit 4 and the point branching to the tracheal connection tube 9 to flow anesthesia gas to the anesthesia introduction box 11. It is a piping system isometric view when it is made possible. Portions common to FIG. 1 are given the same numbers.

  It is not easy to introduce inhalation anesthesia to small animals. In the case of a human, an anesthetic can be injected into a vein, or anesthesia can be introduced by inhaling anesthetic gas using a mask, but both methods are difficult for small animals. Therefore, an anesthesia-introducing box was provided, and the small animal was placed in a nearly sealed state so that anesthesia gas could flow into this box. . That is, when the flow path switching valve 10 is provided between the point branching to the overpressure relief valve 8 of the breathing circuit 4 and the point branching to the tracheal connection tube 9 and the flow path switching switch is set to “artificial respiration”. The anesthetic gas flows toward the exhalation valve 5 and performs an artificial respiration function. When the flow path switch is set to “introduction of anesthesia”, the anesthetic gas flows toward the anesthesia introduction box 11. The anesthesia introduction box is a small experimental animal placed inside to allow anesthesia gas to be sucked in. It is equipped with an anesthetic gas inlet and exhaust port, and transparent plastic so that the state of the small experimental animal can be visually observed. It is preferable that it is manufactured.

  FIG. 3 is a piping system diagram in the case where adsorption columns 12 and 13 for adsorbing volatile anesthetics are provided at the outlet of the exhalation valve 5 and the exhaust port of the anesthesia introduction box 11. Portions common to FIG. 2 are assigned the same numbers. In the case of small experimental animals, since the minute ventilation is small, the leakage of anesthetic gas is not so great, but if the place where the device is used is poorly ventilated or if it is used for a long time, sevoflurane etc. Volatile anesthetics need to be removed. In this small laboratory animal inhalation anesthesia apparatus, anesthesia gas is thrown away into the outside air from the outlet of the exhalation valve 5 and the exhaust port of the anesthesia introduction box 11, so it is necessary to attach an adsorption column to each. The adsorption column is usually filled with activated carbon, but any other adsorbent that can remove anesthetics may be used.

  FIG. 4 shows an example of the vaporizer unit 3, which is located downstream of the thermal mass flow controller 2, vaporizes a volatile anesthetic such as sevoflurane, turns it into a gaseous state, and sends it to a small animal together with air. Thus, artificial respiration can be performed while anesthesia is performed. 3a is an anesthetic bottle, 3b is an anesthetic injection pump, 3c is a vaporizing chamber, 3d is an anesthetic gas concentration monitor, 3e is a vaporizer unit inlet, and 3f is a vaporizer unit outlet. .

  When the concentration of volatile anesthetics such as sevoflurane is set, the amount of volatile anesthetics to be injected with respect to the air flow controlled by the thermal mass flow controller 2 can be calculated. The pump 3b sucks the calculated amount from the anesthetic drug bottle 3a and drops it into the vaporizing chamber 3c. Since vaporization is performed in the vaporization chamber 3c, it is necessary to be made of a metal material having good heat conductivity in order to prevent the vaporization heat from lowering the temperature and lowering the vaporization efficiency, and further heating to about 40 ° C. with a heater. It is desirable to do. Further, for example, it is possible to confirm whether or not the anesthetic concentration is correctly maintained by the infrared absorption type anesthetic gas concentration monitor 3d, but this is not always necessary.

  Conventionally, oxygen and nitrous oxide have been used as carrier gases. However, the inhalation anesthesia device for small experimental animals uses a thermal mass flow controller, so that the flow rate can be accurately defined and a small amount of volatilization can be achieved. Sexual anesthetics are accurately dropped into the vaporizing chamber with a liquid infusion pump and heated and vaporized at about 40 ° C., so that an anesthetic concentration with extremely high accuracy can be obtained. In addition, by realizing an artificial respiration function that can safely and reliably perform artificial respiration of small animals with small tidal volume and high respiratory rate, nitrous oxide with auxiliary anesthetic effect and low oxygen due to insufficient ventilation Since it no longer needed oxygen to make up for the situation, it became possible to use air as the carrier gas.

  FIG. 5 shows the relationship between the open / close state of the solenoid valve and the internal pressure of the breathing circuit. The horizontal axis represents time, Ti represents inspiration time, Te represents expiration time, Ti + Te represents one breathing time, and the number of breaths is RR (times / minute), which is represented by 60 / RR. The vertical axis represents the pressure in the breathing circuit, and the maximum inspiratory pressure indicates the set maximum inspiratory pressure.

  In FIG. 5, the leftmost pressure waveform is the case where the pressure in the breathing circuit does not reach the maximum inspiratory pressure set during the inspiratory time, and the ventilator is operating in a capacity defining manner. The next pressure waveform is when the pressure in the breathing circuit reaches the maximum inspiratory pressure set during the inspiratory time and the exhalation valve opens, and the ventilator is operating in a pressure regulating manner. The next pressure waveform shows a case where the pressure in the breathing circuit becomes equal to or higher than the maximum inspiratory pressure set during the inspiratory time, reaches the set maximum inspiratory pressure +2 cmH2O which is the upper limit alarm value, and the safety valve is opened. At this time, the high pressure alarm is activated. The rightmost pressure waveform is a case where the pressure in the breathing circuit does not reach the set maximum inspiratory pressure −2 cmH 2 O which is the lower limit alarm value during the inhalation time, and at this time, the low pressure alarm is activated.

  The inhalation anesthesia machine for small laboratory animals of the present invention can safely anesthetize small laboratory animals such as mice over a long period of time, and further anesthesia while performing artificial respiration with an integrated ventilator. Can be suitably used as an inhalation anesthesia apparatus capable of performing the above.

  It is a piping system diagram for demonstrating embodiment of the inhalation anesthesia machine for small experiment animals of this invention.   It is a piping system figure at the time of incorporating a flow-path switching valve and an anesthesia introduction box.   It is a piping system diagram at the time of incorporating an adsorption column for making a volatile anesthetic adsorb in an exhalation-valve exit and an anesthesia introduction box exhaust port.   The structure of a vaporizer unit is shown.   The pressure in the expiration circuit and the operation timing of each solenoid valve are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air pump 2 Thermal mass flow controller 3 Vaporization unit 3a Anesthetic agent bottle 3b Anesthetic injection pump 3c Vaporization chamber 3d Anesthetic gas concentration monitor 3e Vaporizer unit inlet 3f Vaporizer unit outlet 4 Breathing circuit 5 Expiratory valve 6 Pressure sensor 7 For zero calibration Solenoid valve 8 Overpressure relief valve 9 Tracheal connection tube 10 Flow rate switching valve 11 Anesthesia introduction box 12 Adsorption column 13 Adsorption column

Claims (5)

An air pump for supplying air, a thermal mass flow controller for flowing air at a set air flow rate, a vaporizing unit for vaporizing a volatile anesthetic, and a breathing circuit through which a set constant flow of anesthetic gas flows An exhalation valve attached to the most downstream of the breathing circuit, a pressure sensor for measuring the pressure in the breathing circuit, a branch from the breathing circuit, connected to the trachea of a small animal, and constant when the exhalation valve is closed Means for injecting the gas at a flow rate as small inhalation to the small animal, when the pressure in the breathing circuit reaches a set pressure or when the set inspiratory time ends, the exhalation valve opens and the exhalation of the small animal is at a constant flow rate. Means for exhausting to the atmosphere together with gas, means for closing the exhalation valve when the set expiration time has expired, and sending the inhalation to the small animal again, and the one converted into an electric signal It has a means to calculate and display the tidal volume sent to small animals by multiplying the gas flow rate value and the inspiratory time, and it can be freely converted to either the pressure regulation system or the capacity regulation system depending on the use conditions An inhalation anesthesia apparatus for small experimental animals characterized by providing an artificial respiration function. Setting the volatile anesthetic concentration calculates the required volatile anesthetic volume for the air flow controlled by the thermal mass flow controller, and the anesthetic infusion pump draws the calculated volume from the anesthetic bottle. The inhalation anesthesia apparatus for a small experimental animal according to claim 1, further comprising a vaporizer unit that drops into the vaporization chamber. The inhalation anesthesia apparatus for small experimental animals according to claim 2, wherein the vaporizing chamber is heated in order to increase the vaporizing efficiency of the vaporizing chamber. The inhalation anesthesia apparatus for small experimental animals according to claim 1, further comprising means for providing a flow path switching valve on the inhalation side of the breathing circuit and flowing anesthesia gas to the anesthesia introduction box. The inhalation anesthesia apparatus for a small experimental animal according to claim 4, wherein an adsorption column for adsorbing a volatile anesthetic is provided at an exhalation valve outlet and an anesthetic introduction box exhaust port.

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