WO2002074376A1

WO2002074376A1 - A device for ventilation or oxygenation of a patient

Info

Publication number: WO2002074376A1
Application number: PCT/DK2002/000186
Authority: WO
Inventors: Martin Peter Engholm
Original assignee: Rigshospitalet
Current assignee: Rigshospitalet
Priority date: 2001-03-20
Filing date: 2002-03-20
Publication date: 2002-09-26
Anticipated expiration: 2003-09-20

Abstract

The present invention relates to a device for ventilation or oxygenation of a patient and a method for operation of said device. More specifically the invention relates to the use of an inflated balloon (3) for fixation and sealing of a cannula (9) in trachea of apatient and for the control of the air pressure in the balloon (3) so as to enable the use of said cannula (9) and balloon (3) under varying external pressure. The device comprises a cannula (9) adapted for insertion into th etrachea of the patient for blowing air into the lungs, the cannula (9) being provided with a ring shaped balloon (3) having a resilient exterior engagement surface adapted for air-tight and fixating engagement with the trachea, the balloon (3) being connected with pressure providing means comprising a first liquid column (1) and a second liquid column (2), the pressure being provided by a difference between the height of the first liquid column (1) and the height of the second liquid column (2).

Description

A DEVICE FOR VENTILATION OR OXYGENATION OF A PATIENT

Field of the Invention

The present invention relates to a device for ventilation or oxygenation of a patient and a method for operation of said device. More specifically the invention relates to the use of an inflated balloon for fixation and sealing of a cannula in trachea of a patient and for the control of the air pressure in the balloon so as to enable the use of said cannula and balloon under varying external pressure.

Description of the Prior Art

Ventilation/oxygenation of patients is carried out in order to support the respiratory functions e.g. in connection with unconsciousness of the patient. In general, devices for the ventilation/oxygenation of patients wherein a cannula connected to a respiratory device is inserted into the trachea of the patient exist. The cannula is provided with a balloon attached to its distal insertion end. After insertion of the cannula, the balloon is inflated through a tiny air hose. By the selection of an adequate inflation pressure, the balloon may effectively seal the passage between the trachea and the cannula. The balloon further fixates the cannula in the trachea, thus avoiding that the cannula falls out during the ventilation/oxygenation and without causing damage to the trachea by the enlargement by the balloon.

If the surrounding external pressure changes, the pressure in the balloon relative to the external pressure may either become too low or too high. If the external pressure decreases, the size of the balloon will increase and the balloon may even be damaged, which may cause severe injuries to the patient. If the external pressure on the other hand increases, the size of the balloon will decrease and accordingly there is a risk that the passage between the cannula and trachea is not effectively sealed and in worst case, the cannula may fall out.

For the treatment of patients in hyperbaric chambers, e.g. for the treatment of divers suffering from divers disease, the pressure of the balloon will constantly have to be adjusted as the pressure of the hyperbaric chamber changes. Accordingly, the staff must constantly measure and adjust the pressure in the balloon in order to maintain a constant relative pressure. Today the problem has been solved by "inflating" the balloon with an incompressible medium such as water. Thereby the balloon will unfortunately become inflexible and may even damage the tracheal tissue.

Description of the Invention

It is an object of the present invention to provide a method and a system that allow for automatic adjustment of the pressure of the balloon so as to ensure a constant overpressure of the balloon in relation to the surrounding pressure. It is a further object to provide a system that allow easy adjustment of the pressure and that is easy to sterilise and that is so cheap and yet reliable that the system may be disposed after a single use which may be required for the treatment of sensitive patients or patients with highly infectious decreases.

Accordingly the present invention relates to a device for ventilation/oxygenation of a patient, said device comprising:

- a cannula adapted for insertion into the trachea of the patient for blowing air into the lungs, the cannula being provided with a ring shaped balloon having a resilient exterior engagement surface adapted for air-tight and fixating engagement with the trachea, the balloon being connected with

- pressure providing means adapted to provide a constant pressure differential between the pressure inside the balloon and the pressure outside the balloon.

The balloon could preferably be glued onto the insertion end of the cannula or may even be integrated in the cannula. The cannula and balloon may be of the well known type e.g. a Portex Tracheal Tube or a Sheridan tube. The pressure providing means could be connected to the balloon by means of a tiny air-hose e.g. to be attached to the cannula by a glue or the air-hose being an integrated part of the cannula. The pressure providing means should preferably be adapted to maintain a reference pressure, i.e. a pressure difference between the inside of the balloon and the outside of the balloon between 0,001 bar and 0,5 bar, such as between 0,003 bar and 0,4 bar, such as between 0,005 bar and 0,3 bar, such as between 0,007 bar and 0,2 bar, such as between 0,01 bar and 0,1 bar, such as between 0,015 bar and 0,08 bar, such as between 0,02 bar and 0,06 bar, such as between 0,025 bar and 0,05 bar, such as between 0,03 bar and 0,04 bar. The pressure difference should preferably be above the over pressure provided by the lungs but still not so high that the balloon becomes inflexible compared with the flexibility of the trachea. Preferably the over pressure should be held constant within 5 pet. In an embodiment a part of the liquid in one chamber, e.g the first chamber, may be elevated to a position above the surface of the liquid of the other chamber, e.g. the second chamber, so as to establish the pressure difference between the inside of the balloon and the outside.

According to a preferred embodiment the fixating and sealing balloon could be separated from the cannula, e.g. by providing a ring shaped balloon having a resilient exterior engagement surface adapted for an air-tight and fixating engagement with the trachea and an interior engagement surface adapted for air-tight and fixating engagement with the cannula. The balloon could be connected with the pressure providing means via a thin and flexible hose which could be introduced into the trachea along with the cannula. Before the insertion of the cannula into the trachea, the cannula is prepared by fitting the balloon to the distal insertion end of the cannula. The interior engagement surface of the balloon could be provided in a soft and slightly sticking material so as to ensure that the balloon doesn't slide on the cannula.

According to a preferred embodiment of the invention the pressure providing means comprises a first liquid column and a second liquid column the two liquid columns being interconnected with a tube so as to allow the liquid to flow between the columns. The first and second liquid columns could be comprised in at least one chamber , e.g. a U-shaped tube filled with a liquid - a so called U-pipe. The liquid in the two columns will seek to level out in one level. However, the height of one of the columns may be different than the height of the other one of the columns if the columns are subjected to a different pressure. Accordingly the pressure may be provided by a difference between the height of the first liquid column and the height of the second liquid column.

The difference in height of the surfaces of the water in the two chambers may be 1 mm, such as 3 mm, such as 5 mm, such as 7 mm, such as 10 mm, such as 13 mm, such as 15 mm, such as 17 mm, such as 20 mm, such as 23 mm, such as 25 mm, such as 27 mm, such as 30 mm, such as 35 mm, such as 40 mm, such as 45 mm, such as 50 mm, such as 55 mm, such as 60 mm, such as 65 mm, such as 70 mm, such as 10 cm, such as 13 cm, such as 15 cm, such as 17 cm, such as 20 cm, such as 23 cm, such as 25 cm, such as 27 cm, such as 30 cm, such as 35 cm, such as 40 cm, such as 45 cm, such as 50 cm, such as 55 cm, such as 60 cm, such as 65 cm, such as 70 cm.

According to a preferred embodiment of the invention, the first liquid column may be comprised in a first chamber and the second liquid column may be comprised in a second chamber, the chambers being interconnected so as to allow the liquid to flow freely between the two chambers, e.g. by interconnecting the bottom part of the two chambers with an open tube. The first chamber could be connected to the balloon at a point near or at the top of the chamber so as to avoid the liquid to run into the balloon. As the height of the liquid column goes up, the liquid will press air out of the upper part of the chamber and thus change the pressure of the balloon. The height difference between the height of the liquid column in the second chamber compared with the height of the liquid column in the first chamber will provide the pressure difference between the pressure of the balloon and the surrounding pressure.

As the surrounding pressure increases, the gas or air in the balloon will be compressed and thus liquid will flow from the second chamber to the first chamber, as the first chamber is connected with the balloon. The amount of liquid in the second charnber should therefore be sufficient to compensate for the compression of the gas or air in the balloon. The compression of the gas or air in the balloon will, as it will be understood for the skilled person in the art, therefore contribute to a small but insignificant error in the over pressure of the balloon as long as the amount of liquid in the second chamber is significantly larger than the amount of liquid in the first chamber.

According to a preferred embodiment, the first chamber may be positioned in a fixed position in relation to the second chamber, e.g. by attaching the two chambers to one common frame or alternatively by providing the two chambers as one element being divided into to areas, one for each of the liquid columns (e.g. by providing the chamber as a U-shaped tube). By means of the fixed position between the chambers, the height difference between the height of the first liquid column compared with the height of the second liquid column indicates the pressure provided by the pressure providing means. The first chamber may be provided with a visual indication of the height of the liquid column in the chamber so that the user of the device easily can monitor the pressure provided. The visual indication may be provided in some pressure relative scale, e.g. in centimetres and in bars. The pressure and/or height indication may also be given via visual indication on the second chamber. The liquid of the liquid columns may be coloured in a colour different from the colour of the frame thus easing the reading of the height of the columns.

The second chamber could preferably be provided at least partially in a resilient material. In that way the chamber will simply collapse while fluid runs from the second chamber to the first chamber and vacuum in the chamber will be avoided. In that way, the fluid of the second chamber will - at least substantially - be subjected to external pressure of the device. According to a preferred embodiment, the water is hermetically enclosed in the cavity of the at least one chamber. As an example, the water may be provided in a sealed plastic container or water bag. The container or water bag may be provided with a structure so that the water is divided into two columns. Preferably the bag or container is filled with the liquid when manufactured. Immediately following the filling process, the bag or container may be sealed hermetically and optionally sterilised e.g. by radiation. The bag or container may be of either a soft or hard plastic type but a soft plastic type will automatically adjust ■ the volume of the chambers according to the heights of the liquid columns without generation of vacuum in the second chamber. A hard plastic container could though be provided either with a valve letting air in and out of the second chamber - preferably without letting the liquid out of the chamber - or with a soft rubber or latex sealing closure membrane capable of moving in and out of the second chamber according to the pressure of the chamber and in order to avoid vacuum and so that the liquid is subjected to the external pressure.

According to a preferred embodiment, the balloon is connected with the pressure providing means and with a syringe for adjusting the pressure. After the balloon has been connected to the pressure providing means, the syringe may be used for inflating the balloon to a certain pressure. The liquid columns will adjust to the pressure, in that water will be forced from the first chamber to the second chamber. The generated height difference between the fluid columns thus preserves the pressure difference. If the external pressure increases, the pressure on the second fluid column will increase, and the internal pressure in the balloon accordingly increases as well.

The connection between the balloon and the syringe may be provided with a one-way valve, allowing the air to pass in a direction from the syringe to the balloon and preventing air from passing in a direction from the balloon to the syringe.

The device may further be provided with a safety valve connected to the balloon, the safety valve being adapted to release gas from the balloon at a predetermined pressure - so as to avoid overpressure in the balloon.

According to an alternative embodiment the pressure may be provided by a closed sealed piston moving in a pressure chamber or cylinder. The piston could preferably be provided with a weight in the range of 0,1-1 kg such as 0,2-0,8 kg, such as 0,4-0,6 kg. The cylinder could be provided with a diameter in the range of 0,01-0,5 meters, such as 0,02-0,4 meters, such as 0,04-0,3 meters, such as 0,08-0,2 meters, such as 0,1-0,15 meters. The selection of the mass and the diameter should be selected so that the resulting overpressure is provided within the range of 0,01 bar and 0,1 bar such as between 0,02 bar and 0,04 bar In order to reduce wear on the sealing components, the piston may be provided in a soft resilient material such as a rubber or rubber coated material.

The piston may be detachably mounted so that pistons with various weights may be used. The pistons could thus be selected depending upon the needed differential pressure for a specific patient. The piston could also be influenced by a spring, so that one piston, without changing the weight, could be used for providing various pressure differences, based on adjustment of selection of one or more springs. Preferably such springs should be selected so as to ensure a constant pressure independently on the compression of the spring or springs.

The pressure difference may further be provided by means of a bellow influenced by a spring or influenced by gravity.

The pressure difference may even be provided by an inflated balloon, the elasticity of balloon and the extent of inflation determines the pressure difference between the inside of the balloon and the outside of the balloon and by connecting the balloon the air supplying hose and the fixating balloon, a constant pressure differential may be achieved. However, the balloon may only be adapted to provide an overpressure, whereas the liquid columns may be used also for providing a constant vacuum.

According to another aspect, the present invention relates to a method and a device for providing a constant pressure difference, e.g. an overpressure or a vacuum compared with the surrounding pressure.

Detailed description of the invention

A preferred embodiment of the invention will now be described in details with reference to the drawing in which:

Fig. 1 shows a device for the ventilation/oxygenation of a patient according to the invention,

Fig. 2 shows, an enlarged view of the second chamber and the balloon,

Fig. 3 shows a device with a sealed piston for providing the constant overpressure in the balloon, Fig. 4 shows an embodiment of the pressure providing means wherein a closed sealed piston is suspended in a mass,

Fig. 5 shows an embodiment of the invention wherein the pressure is provided by a bellow, and

Fig. 6 shows a further preferred embodiment of the invention wherein the chambers are provided in one plastic bag, by gluing the sheets constituting the plastic bag together.

Referring to Fig. 1, the device comprise s a first chamber 1, a second chamber 2 and a balloon 3 for the fixation and tightening of the cannula 9 in trachea of a patient. The balloon is connected to the second chamber through the tube 4 and the second chamber is connected to the first chamber through the tube 5. A liquid 6 is provided in the cavity of the first chamber and in the bottom of the second chamber and a gas 7, e.g. regular air, is provided in the cavity of the balloon and the upper part of the second chamber.

The first chamber 1 may be made from a soft resilient material such as a soft plastic or rubber material allowing the chamber to collapse while the fluid runs out of the chamber. According to one embodiment, at least a part of the chamber, e.g. a closure 8 of the chamber may be provided in a soft rubber or latex material. In that way only very limited counter pressure will occur based on the vacuum arising in the chamber when the fluid runs out. Referring to Fig. 2, the first chamber could alternatively be provided with a valve 10, letting air in and out of the chamber above the fluid level in the chamber. In that way vacuum may be avoided.

The first and/or the second chamber may be provided so that the fluid level 13 can be visually detected, e.g. by providing the chamber in a clear plastic material or at least providing an inspection window. Provision of indication marks 14 may help the user of the device inspecting the resulting pressure caused by the height of the liquid column in the chamber.

If the first chamber and the second chamber are provided in one common frame in fixed mutual heights, the difference between the fluid level in the first chamber and the fluid level in the second chamber will indicate the gas pressure generated in the second chamber and thus in the balloon.

As it will be clear, the pressure in the balloon is dependent not only on the height difference between the fluid column of the second chamber compared with the fluid column of the first chamber. The pressure is moreover dependent on the density or gravity of the fluid. Regular water may easily provide a pressure sufficient to seal and fixate the cannula in the trachea of the patient. However, by adding colour to the water, it will be easy to see the level of the water and by adding preservatives, the device can be used a number of times without having to change the water. The colouring compounds and preservatives should be selected with precaution since the balloon may rupture or similar accidents may lead to direct contact between the patient and the fluid.

Now referring to Fig. 2 the tube 4 may connect the balloon with the second chamber through a 3-way valve 11 allowing air to be blown into the cavity of the second chamber and into the tube and the balloon - e.g. by use of a syringe 12. A one-way valve 15 may be adapted so that air can pass from the syringe to the balloon but not the other way. All the connections and the 3-vay valve could be provided with the Luer-Lock™ system for interconnection of hoses for medical use.

The tube 4 may further be provided with a valve 16 preventing water from the second chamber to enter the tube or at least preventing water from entering the balloon. If the balloon were ruptured, such water would have had access to the trachea and the lungs of the patient. However, the valve should of course allow the air to pass freely both in the direction from the second chamber to the balloon and in the direction from the balloon to the second chamber.

Referring to Fig. 3 the constant relative pressure of the balloon could also be provided by means of a closed sealed piston. The pressure being provided by the gravity and the external pressure thus resulting in overpressure in the balloon the pressure being relative to the mass of the piston 18. The closed sealed piston is connected directly to the tube 4 thus providing pressure to the balloon 3. The tube 4 may be connected to a syringe enabling the system to be pumped.

The sealed piston may be provided with a cavity bound by a cylinder, the piston and a soft rubber seal 19 - e.g. a latex membrane - between the cylinder and the piston.

Referring to Fig. 4, the closed sealed piston could be suspended by a gravity or a spring, symbolised by the box 20, whereby a specific pressure can be obtained without having to change the mass of the device.

Fig. 5 shows an embodiment of the invention wherein the pressure is provided by a bellow 21. The bellow can be subjected to forces - symbolised by the arrow 22 - either from a spring or from gravity. The pressure will be transferred to the tube 4 through the opening - symbolised by the arrow 23. Fig. 6 shows a preferred embodiment of the invention. According to this embodiment, the first and second fluid columns are provided within one single plastic bag 24. Melting or gluing the two plastic foils of the plastic bag together along the dotted line 25 may simply define the two chambers 1, 2 and the interconnecting hose 5 and the tube 4. The chambers could subsequently be filled with water 26 and the bag could finally be sealed at the outlet 27 and sterilised. Prior to use, the seal is broken and the air-tube 4 is inserted into a sealing engagement with the outlet. Alternatively, the bag may be provided with a mechanical connector such as a Luer-Lock™ connector. Water level indication marks 28 may be provided in the plastic.

Claims

1. A device for ventilation or oxygenation of a patient, said device comprising:

2. A device for fixation of a cannula in trachea of a patient, said device comprising:

- a ring shaped balloon having a resilient exterior engagement surface adapted for an air-tight and fixating engagement with the trachea and an interior engagement surface adapted for air-tight and fixating engagement with the cannula, the balloon being connected with

3. A device according to claim 1 or 2, wherein the pressure providing means comprises a first liquid column and a second liquid column, the first and second liquid columns being comprised in at least one chamber and the pressure being provided by a difference between the height of the first liquid column and the height of the second liquid column.

4. A device according to claim 3, wherein the first liquid column is comprised in a first chamber and the second liquid column is comprised in a second chamber, the chambers being interconnected so as to allow the liquid to flow freely between the two chambers.

5. A device according to claim 4, wherein the first chamber is positioned in a fixed position in relation to the second chamber.

6. A device according to any of claims 4 - 5, wherein the first chamber is provided with a visual indication of the height of the liquid column in the chamber.

7. A device according to claim 6, wherein the visual indication comprises an indicator of a reference pressure in the pressure tube.

8. A device according to any of claims 4-7, wherein the second chamber is provided with a visual indication of the height of the liquid column in the chamber.

9. A device according to any of claims 4-8, wherein the second chamber is provided at 5 least partially in a resilient material.

10. A device according to any of claims 3-9, wherein the liquid of the liquid columns is coloured in a colour different from the colour of the frame.

10 11. A device according to any of claims 3-10, wherein the water is hermetically enclosed in the cavity of the chambers.

12. A device according to any of claims 3-11, wherein the cavity of the at least one chamber is isolated from the surroundings by means of a valve, said valve allowing gas to

15 pass in and out of the cavity and preventing the liquid from passing out of the cavity.

13. A device according to any of claims 1-12, wherein the balloon is connected to a syringe.

20 14. A device according to claim 13, wherein the connection between the balloon and the syringe comprises a one-way valve, allowing the air to pass in a direction from the syringe to the balloon and preventing air from passing in a direction from the balloon to the syringe.

25 15. A device according to any of the preceding claims, further comprising a safety valve connected to the balloon, the safety valve being adapted to release gas from the balloon at a predetermined pressure.

16. A device according to any of the preceding claims, wherein the first chamber and/or 30 the second chamber may comprise at least 10 litres of liquid, such as 8 litres, such as 6 litres, such as 5 litres, such as 4 litres, such as 3,5 litres, such as 3 litres, such as 2,75 litres, such as 2,5 litres, such as 2,25 litres, such as 2 litres, such as 1,75 litres, such as 1,5 litres, such as 1,25 litres, such as 1 litre, such as 0,9 litre, such as 0,8 litres, such as 0,7 litres, such as 0,6 litres, such as 0,5 litres, such as 0,4 litres, such as 0,3 litres, such 35 as 0,2 litres, such as 0,1 litres, such as 0,05 litres, such as 0,02 litres, such as 0,01 litres, such as 0,05 litres, such as 0,04 litres, such as 0,03 litres, such as 0,02 litres, such as 0,01 litres, such as 0,005 litres.

17. A device according to claim 1, wherein the pressure providing means comprises a close-sealed piston and wherein the overpressure is provided by gravity.

18. A device according to claim 17, wherein the close-sealed piston comprises a cylinder 5 and a piston, the cylinder being provided with a weight in the range of 0,1-1 kg and the cylinder being provided with a diameter in the range of 0,05-0,1 meters.

19. A device according to claim 17 or 18, wherein the piston is provided in a soft resilient material.

10

20. A device according to any of claims 17-19, wherein the piston is detachably mounted and wherein a selection of pistons with various weights are provided thus enabling selection of a piston suitable for a specific patient.

15 21. A device according to any of the preceding claims, wherein the pressure is provided by a flexible container subjected to gravitational forces, such as a bellow.

22. A pressure providing device for generation of a constant overpressure for medical use, said device comprising a first liquid column and a second liquid column, the first and

20 second liquid columns being comprised in at least one chamber and the pressure being provided by a difference between the height of the first liquid column and the height of the second liquid column.

23. A pressure providing device for generation of a constant overpressure for medical use, 25 said device comprising a flexible container subjected to gravitational forces.

24. A method for providing a constant overpressure, said method comprising

- providing a first liquid column with a first liquid filling level, the first liquid column 30 being in hermetically sealed connection with a pressure providing outlet at a first end above the first liquid filling level and at a second end below the liquid filling level the first liquid column is being connected with a second liquid column having a second filling level, and

35 - providing a pressure differential between the external pressure and the pressure of a volume of gas confined between the first liquid level and the pressure providing outlet through the pressure providing outlet thereby causing a liquid differential between the first filling level and the second filling level, the provided pressure differential thereafter being maintained by the liquid differential.