Apparatus for administering a gas to a person or an animal

An apparatus (1) for administering a gas to a person or an animal, is provided with a chamber (9) for receiving a quantity of gas to be administered. The chamber is provided with a gas line (3) for supplying gas from a source to the chamber (9) and elements for pressurizing the gas in the chamber. The chamber (9) is connected to a breathing tube (5) for supplying pressurized gas from the chamber (9) to the person or the animal, wherein the breathing tube (5) connects to a discharge channel (26), for discharging gas exhaled by the person or the animal, via a valve (11), which restricts the flow of exhaled gas from the breathing tube (5) to the discharge channel (26) in order to build up gas pressure in the breathing tube (5) during exhalation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for administering a gas to a person or an animal, provided with a chamber for receiving a quantity of gas to be administered, which chamber is provided with a gas line for supplying gas from a source to the chamber and means for pressurising the gas in the chamber, the chamber connecting to a breathing tube for supplying pressurised gas from the chamber to the person or the animal.

2. Description of the Related Art

Ventilators of the type specified in the preamble are known in the prior art. Such ventilators are used for ventilating patients. A certain quantity of gas is received in a chamber, after which the gas is brought under elevated pressure. As a result of raising the pressure, a flow channel is opened from the chamber to the breathing tube which is connected to the apparatus. The gas is administered to the patient via this breathing tube. The gas pressure in the chamber and, consequently, in the breathing tube is then lowered. The patient is given the opportunity to breathe out. The gas flow of the exhaled gas is now fed via the breathing tube to a discharge channel to discharge the gas from the apparatus.

For numerous applications it is desirable that the gas supplied to the patient remains in the patient's respiratory tract for a prolonged period. Moreover, it is desirable if this gas is kept under a certain minimum pressure in the patient's lungs. It is not possible with the aid of the apparatus according to the prior art to choose a threshold value which must be exceeded in the patient's lungs before the patient is able to exhale the inhaled air via the breathing apparatus.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide an apparatus of the type specified in the preamble with which a patient is able to exhale inhaled air only when the pressure of this air in the lungs and the breathing tube is in excess of a certain minimum.

This aim is achieved in the present invention in that the breathing tube connects to a discharge channel, for discharging gas exhaled by the person or the animal, via a valve, which valve restricts the flow of the exhaled gas from the breathing tube to the discharge channel in order to build up gas pressure in the breathing tube during exhalation.

As a result of this measure it is possible to retain inhaled air longer in the lungs and to ensure that a certain pressure build-up takes place in the lungs before the inhaled air can be exhaled again.

The apparatus according to the invention is further improved in that the apparatus contains means for adjusting the degree to which the valve shuts off the flow of gas from the breathing tube to the discharge channel. As a result of this measure it is possible to set the threshold value depending on the desired objective.

The apparatus is further improved in that the valve is constructed as a movable wall which separates the chamber from an inlet opening for the breathing tube and for the discharge channel, wherein the movable wall of the chamber is movable between a first position, in which the wall is forced against the inlet end of the breathing tube and consequently shuts off the breathing tube, and a second position, in which the wall exposes the inlet end of the breathing tube, the outlet end of the breathing tube being brought into open communication with the discharge channel, wherein the position of the wall between the first and the second position thereof is determined by the instantaneous pressure differences in the chamber and in the breathing tube, wherein one or more channels and a shut-off element are provided in the movable wall, which shut-off element is movable between a closed position, in which the shut-off element shuts off the channels in the movable wall, and an open position, in which the shut-off element exposes the channels in the movable wall, wherein the position of the shut-off element is determined by instantaneous pressure differences in the chamber and the breathing tube, wherein the shut-off element is forced into the open position thereof when the instantaneous pressure in the chamber exceeds a threshold value. Furthermore, it is possible for the apparatus to be provided with pretensioning means for forcing the movable wall into the first position.

In the apparatus according to the prior art the movable wall, and the shut-off element provided therein, is used for guiding the gas stream through the apparatus in the correct manner. At an elevated gas pressure in the chamber the communication between the outlet end of the breathing tube and the discharge channel is shut off with the aid of the movable wall. Under the influence of the elevated pressure in the chamber, the shut-off element is forced into the open position thereof, so that the gas can pass from the chamber into the breathing tube. When the patient exhales, the movable wall is moved into the second position thereof, so that there is open communication between the breathing tube and the discharge channel. The shut-off element in the movable wall is forced into the closed position thereof, so that the gas exhaled by a patient cannot flow back into the chamber. The gas exhaled by the patient is guided via the breathing tube and the discharge channel in the direction of the discharge, with the aid of which the gas is discharged from the apparatus.

According to the invention, it is furthermore possible that the pretensioning means comprise a spring. It is furthermore possible that the pretensioning force of the pretensioning means is adjustable manually with the aid of a dial.

As a result of these measures, an adjustable pretensioning force on the movable wall is provided with the aid of very simple means. Consequently the apparatus according to the invention is relatively simple to produce. This makes it possible also to use the apparatus in countries where technical development is less advanced. Furthermore, the construction of the apparatus according to the invention is relatively simple and thus inexpensive.

The apparatus according to the invention is further improved in that the chamber is provided with a safety valve which exposes a passage between the chamber and a discharge from the apparatus as soon as the pressure in the chamber exceeds a threshold value. In this context it is possible for the safety valve to be provided with pretensioning means, the pretensioning of which is adjustable manually by means of an adjusting knob.

The presence of the safety valve prevents gas from the chamber being supplied at too high a pressure to the patient. As a result of the fact that the pretensioning force on the safety valve is adjustable, the maximum pressure in the chamber can be adjusted per patient. The fact that the adjustment force can be adjusted manually makes the apparatus simple to operate, even by less highly trained personnel.

Furthermore, it is possible according to the invention for the apparatus to be provided with a measurement channel, which connects to the breathing tube, a connection for a pressure gauge being provided in the measurement channel.

According to the invention it is possible that the means for pressurising the gas in the chamber comprise an element that is compressible by hand, such as a balloon. The user provides for pressure build-up by squeezing the balloon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus1according to the invention is shown in FIG.1. The apparatus1comprises a housing2in which a chamber for receiving gas is delimited (see FIG.2). The housing2is provided with a gas line3, which can be connected to a source (not shown) for supplying gas to the housing2. The apparatus1further comprises a balloon4. This balloon4can be compressed by hand (in the direction of the arrows shown in the figure) to pressurise gas that has been received in the housing2. Gas can be discharged from the housing2via the breathing tube5. In use, this breathing tube5is fed to a patient who has to be ventilated with the aid of the apparatus1. When a patient exhales gas this gas is fed back to the housing2via the breathing tube5. As a result of the presence of discharge channels (explained with reference toFIG. 2et seq.), exhaled gas is fed via a discharge channel26to a discharge6, which discharges said exhaled gas from the apparatus1.

Furthermore, the apparatus is provided with an adjusting knob7, with the aid of which a pretensioning force can be set on a safety valve30. The apparatus further comprises a dial8, with the aid of which the pressure which a patient must overcome to be able to exhale gas via the apparatus is set. The functioning of the adjusting knob7and the dial8is explained in detail with reference to FIG.2.

FIG. 2shows a cross-section of the apparatus according toFIG. 1. Achamber9, in which a quantity of gas to be administered can be received, is delimited in the housing2. The chamber9is in open communication with the balloon4(not shown) via a line10. Via the line10gas can be forced from the balloon4under elevated pressure into the chamber9. The chamber9is provided at the bottom thereof with a movably mounted wall11. The wall11is movable between two extreme positions which are shown inFIGS. 3 and 4, respectively. The inlet16of the breathing tube5is located underneath the movable wall11. The inlet16is separated from the chamber9by the wall11. A discharge channel26, for discharging exhaled air in the direction of the discharge6, is also located underneath the movable wall11. One or more channels15have been made in the movable wall11itself, which channels can be shut off by means of a shut-off element12.

When building up gas pressure in the chamber9the movable wall11is forced, with the aid of the spring17, against the inlet16of the breathing tube5. In this position the communication between the breathing tube5and the discharge channel26is shut off. When the pressure in the chamber is then raised the shut-off element12will move down. As a result the channels15in the movable wall11are exposed, so that gas transport can take place from the chamber9in the direction of the breathing tube5. This position is shown in FIG.3. It can be seen inFIG. 3that the wall11is in contact with the inlet16of the breathing tube5. The shut-off element12has moved down and the shut-off element12is held in the position shown because a ridge14is in contact with a projecting section of the wall11. In the position shown the shut-off face13of the shut-off element12is free from the channels15in the wall11. Consequently fluid transport can take place through the wall11in the direction of the breathing tube5. Opening of the channels15can be promoted by making the shut-off face13of the shut-off element12of a relatively flexible material, such as rubber. In this case the outermost edges of the shut-off face13are able to bend, so that the channels are exposed to a considerable extent. Since the movable wall11is in contact with the inlet16of the breathing tube5, the open connection between the breathing tube5and the discharge channel26is shut off. As a result air from chamber9is prevented from passing into the discharge channel26. The shut-off element12is connected to a spring27. With the aid of this spring the movable wall11can be placed under a certain pretension. The shut-off element12exposes the channels15in the movable wall11only at a point in time when a specific threshold value is exceeded.

FIG. 4shows the case where the movable wall11has moved into the second position thereof. The movable wall11can assume this position when the pressure in the breathing tube becomes higher than that in the chamber9. This position is assumed when the patient exhales. A patient cannot get the wall11into the position shown inFIG. 4simply by exhaling. In order to be able to move the wall into this position a certain threshold value must be exceeded, which is determined by the pretensioning force that is exerted on the wall11by means of the difference between springs17-27. The higher the pretensioning force of the spring17on the wall11, the higher must be the pressure in the breathing tube in order to be able to move the wall into the position shown. It can be seen fromFIG. 4that in the position shown there is a free passage between the outlet end16of the breathing tube5and the discharge channel26. This means that the patient can blow out the exhaled air via the breathing tube5and the discharge channel26connected thereto in the direction of the discharge6of the apparatus (see FIG.2). It can also be seen inFIG. 2that the shut-off element12shuts off the channels15in the movable wall11. This means that the exhaled air cannot pass into the chamber9. The shut-off face13of the shut-off element12is in contact with the openings of the channels15and so prevents fluid transport from the breathing tube5in the direction of the chamber9. The extreme position of the movable wall11is delimited by ridges25which project from the wall of the chamber9.

The function of the spring17is described with reference toFIGS. 3 and 4. It can be seen inFIG. 2that the pretensioning force on the spring17is adjustable with the aid of a dial8. This dial can be turned by hand, so that a stop face18, against which the end of the spring17bears, can be moved relative to the wall11. Depending on the desired objective and depending on the expiration force (pressure that can be built up by a patient) of a patient, a certain pretension can be applied to the spring17. Because the pretensioning force on the spring17is adjustable by hand, the apparatus1according to the invention is easy to use. A correct setting can, for example, be guaranteed by providing a scale on the apparatus and/or on the dial8.

It can also be seen inFIG. 2that the top wall of the chamber9comprises a hollow body19. This hollow body19is closed off at the top by means of a valve30. This valve30serves as a safety valve. If the pressure in the chamber9becomes too high the safety valve30is forced upwards so that free communication is produced between the chamber9and openings21-22which have been made in the rotary body that is connected to the dial8. The air can escape from the chamber9via these openings22and be fed to the discharge6. This prevents gas under too high a pressure being supplied to a patient via the breathing tube5. The maximum pressure that can be reached in the chamber9can be set by adjusting the pretension on the valve30. This pretension is achieved with the aid of a spring20. The pretension of the spring20can be adjusted by means of a rotary knob7. This knob7can also be operated by hand.

A further embodiment of the ventilator according to the invention is shown in FIG.5. According toFIG. 5a hose40is arranged between the housing2and the balloon4. As a result of the presence of the hose40, a user is able to exert manual force on the balloon4whilst the balloon4is some distance away from the housing2. This increases the ease of use of the apparatus according to the invention. Medical staff can, for example, operate the balloon4from the side of the patient's bed. According toFIG. 5the gas line3is located at the end of the hose40, that is to say some distance away from the housing2. This too offers the option of coupling the gas supply to the apparatus according to the invention some distance away from the patient's mouth. The gas supply will usually have to be coupled to the gas line3from anaesthesia equipment or an anaesthesia wall set.

FIG. 5furthermore shows the case where the hose40has an inner line41which connects the balloon4to the housing2. The line41is used to supply fresh gas in the direction of the housing. The line41is enclosed by a second line42. This line42is used as discharge line. The line42terminates in a discharge opening43. As a result of the coaxial construction of the supply line for the gas and the discharge line for the gas, only one hose has to be fed from equipment in the direction of the patient. This application further increases the ease of use of the apparatus according to the invention.

Instead of the balloon shown inFIGS. 1 and 5, use can also be made of the so-called “rigid balloon”. A rigid balloon is a balloon which is provided with a valve. After the force for squeezing the balloon is removed, the balloon will assume its original shape again. During this movement the valve in the rigid balloon will be opened to draw in a quantity of fresh gas (ambient air).

For the sake of clarity it is pointed out that the apparatus shown in the figures can be produced in various sizes. For instance, a system can be made with smaller dimensions which is especially suitable for children or neonates. In this case the lines will also be made smaller.

With the aid of the adjustable force on the safety valve30it is possible to set a maximum pressure in the chamber9of, for example, 20-60 cm H2O. The maximum pressure which a patient must overcome in order to be able to blow air out of the apparatus1can be set, for example, from 0 to 20 cm H2O. In order to make the apparatus according to the invention also suitable for children, the aim is to keep the dead volume in the apparatus as small as possible. By means of the construction as is shown inFIGS. 1to4it is possible to achieve a dead volume of typically at most 7 ml.

The connection of the balloon to the apparatus1via the line10can, for example, be made using a so-called balloon cone with an external diameter of 22 mm.

The discharge6can be constructed as an evacuation cone of 19 mm.

The breathing tube5can be constructed as a cone of 22/15 mm.

The apparatus according to the invention is provided with a self-closing24measurement channel23which connects to the breathing tube5. A pressure gauge can be fitted in this measurement channel in order to be able to measure the instantaneous pressure in the breathing tube5. The pressure gauge can be constructed as a manometer or as an electronic measuring device. Furthermore, it is possible to fill the chamber9with the aid of a pump, for example a time-controlled pump, instead of a balloon. In this way a constant flow from the chamber to the breathing tube can be guaranteed while a patient is inhaling.

The movable wall11can be made of various types of materials. As an alternative, the moveable wall can also be constructed as a flexible plate clamped in place. In this case the moveable wall forms a membrane that is movable to and fro.