WO2005002657A1

WO2005002657A1 - Artificial respiration head and artificial respiration device for new-borns

Info

Publication number: WO2005002657A1
Application number: PCT/AT2004/000228
Authority: WO
Inventors: Martin Wald
Original assignee: Martin Wald
Priority date: 2003-07-07
Filing date: 2004-06-29
Publication date: 2005-01-13
Also published as: AT412704B; ATA10402003A

Abstract

The invention relates to an atrificial respiration head (4) for an artificial respiration device for new-borns consisting of an inspiration connecting piece (3) for connecting an inspiration conduit (2), an expiration connecting piece (5) for connecting an expiration conduit (6) provided with an expiration valve (7), a tube connector (8) for connecting a tube (9) which is used for liaison with a patient's lungs (10) and a flow measuring device (11). Said invention relates to an artificial respiration device comprising such an atrificial respiration head (4). In order to reduce a dead volume while flow measurement during a new born respiration, a bypass (12) shunting the flow measuring device (11) is arranged between the inspiration connecting piece (3) and the inspiration conduit (2) connected thereto and the tube connector (8) or the tube (9) connected thereto.

Description

Ventilation head and ventilator for newborns

The invention relates to a ventilation head for a respirator for newborns, in particular for extremely small premature babies, with an inspiration port for connecting an inspiration line, an expiration port for connecting an expiration line with an expiration valve, and a tube connection for connecting a tube for connection to the patient's lung, and with a flow measuring device.

Furthermore, the invention relates to a respirator with a ventilation head described above, with a device for providing air via the inspiration line to the inspiration port of the ventilation head and with an expiration line connected to the expiration port of the ventilation head with an expiration valve and with a tube connected to the tube connection of the ventilation head Connection with the patient's lung and with a flow measuring device.

Ventilators, which are usually pneumatically / electrically driven, serve to maintain breathing artificially or to support spontaneous breathing. While artificial respirators for adults usually only produce a gas flow during inspiration, respirators for newborns work according to a different principle. Such ventilation machines for newborns deliver a continuous flow into the inspiration hose and over the ventilation head, the so-called Y-piece, into the

Expiratory hose that runs back to the ventilator, where an expiratory valve is located at the end. At the beginning of inspiration, the expiration valve is closed, which creates pressure in the ventilation system and directs the flow from the Y-piece through the tube into the patient's lung. At the beginning of the expiration, the expiration valve is opened again, which leads to a passive emptying of the lungs. To assess the ventilation of the lungs during artificial ventilation, the minute ventilation is measured. The measurement of minute ventilation during ventilation of newborns, especially of extremely small premature babies, However, due to the low tidal volumes, this is a problem. For this reason, in contrast to ventilators for adults, the flow sensor must be arranged directly behind the tube adapter of the ventilation head. Apart from the fact that particularly sensitive flow sensors are required to measure the very small tidal volumes during artificial ventilation of newborns, the so-called dead space volume is a particularly big problem when ventilating newborns. The dead space volume is an air volume that moves with every breathing cycle must, but does not contribute to gas exchange. At the end of the expiration there is used exhaled air in the tube between the Y-piece and the lung alveoli, which is pushed back into the lungs with the next inspiration. In artificial respiration for adults, this dead space volume is very small in contrast to the tidal volume and is usually negligible. In newborns, especially extremely small premature babies, the dead space volume can even be larger than the spontaneous tidal volume, which is why the dead space volume must be reduced for an exact recording of the tidal volumes in the artificial ventilation of newborns. Since excessive tidal volumes can lead to chronic lung damage in premature babies and the pressure amplitude between inspiration and expiration plays a role in the pathophysiology of chronic lung damage, care must be taken to minimize the tidal volume when ventilating premature babies. For example, a premature baby with a weight of 500 g has an average tidal volume of approx. 3 ml, the alveolar ventilation responsible for gas exchange comprising approx. 2 ml. In the case of intubation and the artificial ventilation currently customary, the dead space not involved in gas exchange increases to at least 4.2 ml, above all due to the flow sensor, and is therefore more than twice the alveolar ventilation per breath.

The main problem with ventilated premature and newborn babies is therefore that a safe measurement of the tidal volume is not possible without stressing the patient. Previous ventilation heads or flow measuring devices have an excessively large dead space volume, an excessively high flow resistance and other disadvantages. DE 40 34 176 AI describes a spirometry measuring device with particular suitability for spontaneously breathing and artificially ventilated premature babies, newborns and infants, which solves the known problems by using a measuring adapter and an automatic blow-through pressure measuring device with processing and control electronics. This enables trouble-free registration of the respiratory rate and the tidal volume to be achieved over several days. However, the design effort and thus the probability of errors is relatively high.

DE 42 32 298 AI also describes a device for measuring flow and minute ventilation with integrated automatic calibration device, which is particularly suitable for artificial ventilation of premature babies, newborns and infants.

DE 35 39 719 AI also describes a breathing monitor with a special ventilation head, in which the dead space volume is reduced. This makes the respiration monitor particularly suitable for spontaneously breathing and artificially ventilated premature babies, newborns and infants.

In order to reduce the dead space volume, there is also a so-called dead space washout, in which the dead space is replenished with fresh air at the end of the expiration due to an additional flow. In the subsequent inspiration, only fresh air gets into the patient's lung. However, the additional flow to fill up the dead space at the end of the expiration requires its own heating and its own pump and, above all, its own safety concept so that excessive pressure does not get into the patient's lungs in the event of a tube blockage. However, due to the relatively high cost and the relatively high level of uncertainty, this concept has not yet become established.

The object of the present invention is therefore to provide a ventilation head for a ventilation machine for newborns, especially extremely small premature babies, which provides a reliable conclusion about the actual tidal volume and thus a reliable setting of the parameters of artificial respiration. The facility should be as simple and robust as possible and as little prone to failure as possible. Disadvantages of the prior art should be avoided or at least reduced.

Another task is to create a ventilator for newborns, especially extremely small premature babies, which allows reliable detection of the actual tidal volume and thus a reliable setting of the ventilation parameters and is particularly simple and inexpensive and less prone to failure.

The first object according to the invention is achieved by a respiratory head of the specified type, a bypass bridging the flow measuring device being arranged between the inspiration connector or the inspiration line connected therein and the tube connection or the tube connected to it. According to the invention, the inspiratory hose system is thus divided into two lines, the flow being measured in one line. The bridging bypass allows the dead space to be filled with fresh air at the end of the expiration. In the subsequent inspiration, essentially only fresh air enters the patient's lung. The flow measuring device located in the ventilation head is thus able to measure the flow without dead space volume, as a result of which the particularly small tidal volumes occurring during ventilation of newborns can be determined very precisely. By precisely determining the breathing parameters, optimal ventilation of the premature baby can again be achieved without the risk of chronic lung damage due to excessive tidal volumes. The solution according to the invention is characterized by particular simplicity, which means that particularly low manufacturing costs, but also a particularly low susceptibility to failure, are associated. Of course, the one end of the bypass bridging the flow measuring device can also be connected in a device for closed suction, which can be attached instead of the usual tube connection.

The bypass is advantageously connected to the inspiration tube or the inspiration line via corresponding connecting pieces and connected to the tube connection or the tube. These generally detachable connections can be made using standard connections used in medicine, such as plug-in or bayonet connections.

According to a further feature of the invention, it is provided that the bypass has a cross section, that the amount of air flowing through the bypass during the inspiration phase is 10 to 40% of the total inspired air. This means that the majority of the flow is directed through the ventilation head and the flow measuring device into the tube and only a small proportion is led through the bypass. It makes no difference to the patient whether the inspired air comes from the ventilation head or the bridging bypass. Studies have shown that the flow is very variable over the course of a breathing cycle.

The flow measuring device must be calibrated to a constant expiratory flow. In contrast to previous measurements of the tidal volume, in which the absolute flow was registered, the flow measuring device in the respiratory head according to the invention only detects a relative change in flow which makes calibration necessary. For this reason, a device for calibrating the flow measuring device is provided according to a further feature of the invention. Such a calibration device can be formed in the bypass, for example, in the form of an additional flow sensor.

Furthermore, it is possible for the bypass to be integrated in the ventilation head and, if necessary, to be produced in one piece with it.

The bypass is advantageously made of plastic. When choosing the plastic, the cleanability and sterilizability required in medicine must be taken into account.

The flow measuring device can be formed by a differential pressure meter or a heating wire anemometer or glow wire flow sensor. Of course, other measurement methods are also possible. The flow measuring device is advantageously connected via corresponding measuring connections in the ventilation head. As a result, the flow measuring device can continue to be used even when the ventilation head is replaced.

If the flow measuring device has an interface for connection to a control device, the ventilator can be controlled or regulated based on the measured breath parameters.

The second object of the invention is also achieved by a respirator with a ventilation head as described above and a device for providing air via the inspiration line to the inspiration port of the ventilation head and with an expiration line connected to the expiration port of the ventilation head with an expiration valve and with one connected to the tube connection of the ventilation head Tube for connection to the patient's lung and to a flow measuring device, in which a control device is provided which is connected to the flow measuring device, the expiration valve and the device for providing air. Thus, due to the precise recording of the breath parameters, the ventilation can also be regulated precisely in newborns without the risk of damage to the lungs from excessive breath volumes.

A heating device and a humidification device are advantageously arranged in the inspiration line.

It is also advantageous if a safety valve or the like. is arranged, by means of which the patient is protected from overpressure in the region of the inspiratory thigh, and over-inflation of the patient's lung is prevented.

The device for providing air can be formed by a pump, possibly with a reservoir. The reservoir can build up the pressure required during inspiration again during the expiratory phase.

The present invention is illustrated by the attached drawings. nations explained in more detail. Show in it

Figure 1 is a schematic principle of operation of a ventilator for newborns with continuous flow according to the prior art.

2 shows a schematic functional principle of a respiratory head according to the invention;

3a to 3c schematically the function of the ventilator according to the invention during a breathing cycle; and FIG. 4 shows an exemplary embodiment of a respiratory head according to the invention.

1 shows a schematic functional principle of a time-controlled, pressure-limited respirator with continuous flow for newborns according to the prior art. A device 1 for providing air supplies a continuous flow to the inspiratory tube 2, which is connected to the inspiratory connector 3 of the respiratory head 4. The respiratory head 4 or the so-called Y-piece has an expiratory connection 5, to which an expiratory line 6 is connected. At the end of the expiration line 6 there is a time-controlled expiration valve 7, via which the ventilation of the patient is controlled. The tube 9, which is connected to the patient's lung 10, is connected to the tube connection 8 of the ventilation head 4. At the beginning of inspiration, the expiration valve 7 is closed, as a result of which a pressure builds up in the ventilation system, which pressure is passed into the patient's lung 10 via the tube connection 8 of the ventilation head 4 or Y-piece and the tube 9. If the expiration valve 7 is now opened again at the beginning of the expiration, the patient's lung 10 is passively emptied. Mechanical ventilation with continuous flow enables the newborn to also move between the mechanical breaths, which are predetermined by the opening and closing of the expiration valve 7 to breathe spontaneously. In order to enable the device to be controlled as sensitively as possible, the flow measuring device 11 is located in the ventilation head 4 or Y-piece above the tube connection 8. Thus, the flow that flows into or out of the patient's lung 10 becomes the flow -Measuring device 11 detected. The flow measuring device 11 measures the total flow, which flows over the tube 9 towards the patient's lung 10 and out of it. At the end of the passive expiration, however, the part between the ventilation head 4 and the patient's lung 10 is filled with used exhaled air, which is pushed back into the patient's lung 10 during inspiration by the pressure in the ventilation system. This creates the so-called dead space volume, which has to be moved with every breathing cycle, but is not involved in the gas exchange in the patient's lung 10. The necessary tidal volume, which is required for adequate ventilation in the alveoli of the patient's lung 10, must therefore be increased accordingly. Since in newborns, especially premature babies, the dead space volume is not negligible compared to the tidal volume, but can even be larger than the tidal volume, it is absolutely necessary to take the dead space volume into account in the artificial ventilation of newborns. Excessive tidal volumes and the pressure amplitude that occurs between inspiration and expiration can lead to chronic lung damage in newborns and should therefore be avoided at all costs. It should be noted that heating and humidifying devices and devices for removing the condensed water are not shown in the functional diagram for the sake of simplicity.

Fig. 2 shows schematically the part of a ventilator for newborns around the so-called ventilation head 4 or the Y-piece. The respiratory head 4 has an inspiration connector 3 for connecting an inspiration hose 2 and an expiration connector 5 for connecting an expiration line 6. A tube 9, which establishes the connection to the patient's lung 10, is connected via a tube connection 8. The respiratory head 4 or the so-called Y-piece is usually made of sterilizable plastic. A flow measuring device 11 is arranged above the tube connection 8. According to the invention, a bypass 12 bridging the flow measuring device 11 is arranged between the inspiration connection 3 or the inspiration line 2 connected to it and the tube connection 8 or the tube 9 connected to it. The inspiratory flow, which is led via the inspiration line 2 to the ventilation head 4, is thus divided into two flows, namely one through the ventilation head 4 and one via the bypass 12. For inspiration, the air is pressed into the patient's lung 10 both via the ventilation head 4 and via the bypass 12 via the tube 9. During the expiration, the bypass 12 serves to wash out the dead space volume. As a result, the flow can be measured precisely using the flow measuring device 11. The bypass 12 can be connected via connecting pieces 13, 14. It is also possible for the bypass 12 to be produced in one piece with the ventilation head 4. The cross section of the bypass 12 is smaller than that of the inspiratory part of the respiratory head 4, advantageously so large that the amount of air flowing through the bypass 12 during the inspiration phase is at most between 10 and 40% of the total inspiratory air.

The function of the bypass during a breathing cycle is shown in FIGS. 3a to 3c. 3a shows artificial ventilation during the inspiration phase. At this point, the expiration valve 7 is closed, and the fresh breathing gas supplied via the inspiration line 2 passes partly via the respiratory head 4 or the Y-piece and partly via the bypass 12 to the tube connection 8 and via the tube 9 into the patient's lung 10. Die Flow measuring device 11, which is located above the tube connection 8 in the ventilation head 4, measures the inspiratory flow that flows through the ventilation head 4.

At the beginning of the expiration according to FIG. 3b, the expiration valve 7 is opened, which leads to a passive emptying of the patient's lung 10. This means that the exhaled air escapes via the ventilation head 4 and the expiration line 6 via the expiration valve 7. In addition, a portion of the fresh breathing gas that has flowed in via the inspiration line 2 and the bypass 12 is likewise conducted into the expiration line 6 and the expiration valve 7 via the ventilation head 4 and the flow measuring device 11.

At the end of the expiration according to FIG. 3c, only in the area between the patient's lung 10 and the tube connection 8 of the respiratory head 4, that is to say essentially in the tube 9, is used breathing air, the respiratory head 4 including the flow measuring device 11 is completely filled with fresh breathing air, ie the dead space volume is washed out with fresh breathing gas. In the next inspiration according to FIG. 3a, essentially only fresh air enters the patient's lung, and the flow measuring device 11 measures the flow essentially without dead space volume.

4 shows an embodiment variant of a respiratory head according to the invention. A part of the ventilation head 4 is designed as a housing 15, in which the flow measuring device 11 can be arranged, for example plugged in. The flow measuring device 11 can be formed by a heating wire anemometer and has an interface 16 for connection to a control device (not shown). The housing 15 also contains the tube connection 8, via which the tube 9, which establishes the connection with the patient's lung 10, can be connected. An opening 17 for arranging one end of the bypass 12 is provided in the housing 15. The other end of the bypass 12 is led to the inspiration line 2 via a connecting piece 13. The housing 15 as part of the ventilation head 4 is advantageously made of plastic. In order to enable the housing 15 to be used several times, it consists of materials which can withstand the usual sterilization methods. Of course, the entire respiratory head 4, i.e. the housing 15 together with the Y-piece, at most with the connecting piece 13 and at most with the bypass 12 also be made in one piece.

Claims

Claims:

1. Ventilation head (4) for a ventilator for newborns, with an inspiration port (3) for connecting an inspiration line (2), an expiration port (5) for connecting an expiration line (6) with an expiration valve (7) and a tube connection (8) for connecting a tube (9) for connection to the patient's lung (10), and with a flow measuring device (11), characterized in that between the inspiration connector (3) or the inspiration line (2) connected to it and the tube connection (8) or a bypass (12) bridging the flow measuring device (11) is arranged on the tube (9) connected to it.

2. Ventilation head according to claim 1, characterized in that the bypass (12) can be connected to the inspiration tube (3) or the inspiration line (2) and the tube connection (8) or the tube (9) via corresponding connection pieces (13, 14) ,

3. Ventilation head according to claim 1 or 2, characterized in that the bypass (12) has a cross section that the amount of air flowing through the bypass (12) during the inspiration phase is 10 to 40% of the total air.

4. Respiratory head according to one of claims 1 to 3, characterized in that a device for calibrating the flow measuring device (11) is provided.

5. Ventilation head according to claim 1, characterized in that the bypass (12) is integrated in the ventilation head (4).

6. Ventilation head according to one of claims 1 to 5, characterized in that the bypass (12) is made of plastic.

7. Ventilation head according to one of claims 1 to 6, characterized in that the flow measuring device (11) is formed by a differential pressure meter.

8. Ventilation head according to one of claims 1 to 6, characterized in that the flow measuring device (11) by a Heating wire anemometer is formed.

9. Respiratory head according to one of claims 1 to 8, characterized in that the flow measuring device (11) is connected via measuring connections in the respiratory head (4).

10. Ventilation head according to one of claims 1 to 9, characterized in that the flow measuring device (11) has an interface for connection to a control device.

11. Ventilator with a respiratory head according to one of claims 1 to 10, with a device (1) for providing air via the inspiration line (2) to the inspiratory connector (3) of the respiratory head (4) and with one on the expiratory connector (5) Ventilation head (4) connected expiration line (6) with an expiration valve (7), and with a tube (9) connected to the tube connection (8) of the ventilation head (4) for connection to the patient's lung (10), and with a flow measuring device ( 11), characterized in that a control device is provided which is connected to the flow measuring device (11), the expiration valve (7) and the device (1) for providing air.

12. Ventilator according to claim 11, characterized in that a heating device is arranged in the inspiration line (2).

13. Ventilator according to claim 11 or 12, characterized in that a humidification device is arranged in the inspiration line (2).

14. Ventilator according to one of claims 11 to 13, characterized in that a safety valve or the like is arranged.

15. Ventilator according to one of claims 11 to 14, characterized in that the device (1) for providing air by a pump is at most formed with a reservoir.