WO2019016501A1

WO2019016501A1 - Medical gas supply system

Info

Publication number: WO2019016501A1
Application number: PCT/GB2018/051451
Authority: WO
Inventors: Gareth Sykes
Original assignee: Keymed (Medical & Industrial Equipment) Limited
Priority date: 2017-07-17
Filing date: 2018-05-29
Publication date: 2019-01-24
Also published as: GB201711450D0; GB2564651B; GB2564651A

Abstract

Apparatus (10) for supplying insufflation gas to be administered to a patient comprises a sterile chamber (12) for holding a volume of gas and a volume of liquid. A gas inlet (16) supplies pressurised gas into the chamber. A gas outlet (18) allows gas to exit the chamber. An ultrasound generator (20) is configured to apply ultrasound to liquid in the chamber to cause cavitation. An ultrasonic transmission path is located between the ultrasound generator and the liquid in the chamber. The apparatus may further comprise a wall (34) dividing the chamber into first and second volumes (36, 38) and defining an opening (40) between them. The location of the opening (40) defines a predetermined level for the liquid in the chamber (12) to achieve optimum cavitation.

Description

MEDICAL GAS SUPPLY SYSTEM

Certain medical procedures require a body cavity to be insufflated, that is to supply pressurised gas into the cavity to enlarge it so that procedures such as endoscopic inspection, laparoscopic surgery etc. can be carried out more easily. It is desirable to humidify the gas because this leads to less discomfort for the patient and faster recovery times.

The present invention provides apparatus for supplying insufflation gas to be administered to a patient, comprising a sterile chamber for holding a volume of gas and a volume of liquid, a gas inlet for supplying pressurised gas into the chamber, a gas outlet, an ultrasound generator configured to apply ultrasound to liquid in the chamber so as to cause cavitation in the liquid, and an ultrasonic transmission path located between the ultrasound generator and the liquid in the chamber.

The apparatus provides a simple, lower power way to humidify insufflation gas independently of liquid temperature to obtain a liquid vapour. The system is non-contact and therefore maintains the insufflation gas and liquid in a sterile condition.

The ultrasonic transmission path may comprise a container for holding an ultrasonically transmissive medium, such as liquid or gel, which the chamber is placed contact with, whereby ultrasound is transmitted to the chamber via the medium.

The gas inlet and the gas outlet preferably comprise tubes protruding into the chamber and the gas outlet tube protrudes a greater distance into the chamber than the gas inlet tube. This ensures the gas outlet is closer to the liquid in the chamber and thus receives gas that has been humidified.

The apparatus preferably further comprises means to indicate a level of liquid to be held in the chamber to achieve optimum cavitation, or a level control system to

automatically maintain a predetermined level of liquid. This may comprise a wall dividing the chamber into a first volume and second volume and defining an opening between the two volumes, the location of the opening defining a predetermined level for the liquid. These features improve the efficiency of the apparatus, to provide cavitation and humidification utilising minimum power for the ultrasound generator.

The apparatus may additionally comprise a liquid outlet tube for withdrawing liquid from the second volume in the chamber. Liquid may be withdrawn to use for irrigation or flushing during a medical procedure. Preferably a flow control device is also provided which is operable to selectively permit and prohibit flow of liquid from the second volume through the liquid outlet tube. In this way, although liquid in the second volume is pressurised, liquid flow through the outlet tube can be prevented until it is required.

The apparatus may further comprise a medical pump operable to supply fluid to a patient and/or to produce suction to remove fluid from a patient, and to power to the ultrasound generator. In this way an efficient and compact apparatus can be provided. The invention will now be described in detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic side view of apparatus in accordance with one embodiment of the present invention; and

Figures 2a and 2b are diagrammatic views of an alternative embodiment.

With reference to Figure 1 , the apparatus 10 comprises a container 12 defining a chamber for holding gas and liquid and which is maintained sterile. The container 12 is provided with a liquid inlet 14, a gas inlet 16 and gas outlet 18. The apparatus 10 further comprises an ultrasound generator 20, a power source 22 for powering the ultrasound generator and an ultrasound transmission medium 24.

The container 12 may be a conventional saline bottle as commonly used in medical procedures such as endoscopies. This includes an opening with a lid 26 with apertures through which inlet and outlet tubes 28, 30 can pass. The lid 26 and the inlet and outlet tubes 28,30 can be removed in order to supply a volume of sterile liquid such as water or saline into the container 12. The opening thus serves as the liquid inlet 14. The lid 26 can then be replaced and seals against the rim of the opening. The inlet tube 28 protrudes a short distance into the container 12 and the outlet tube 30 protrudes a greater distance into the container 12. Pressurised gas is supplied into the container 12 through the inlet tube 28 and gas exits via the outlet tube 30.

The ultrasound generator 20 is connected to a power source 22. This may be a medical pump which also supplies the pressurised gas into the container 12 and which may also be used for supplying irrigation liquid to a medical instrument and/or suction to a medical instrument. The ultrasound generator 20 may be built-in and integral with the power source 22, or it may be a separate accessory which can be connected to the power source 22 as required.

Ultrasound produced by the ultrasound generator 20 is transmitted to liquid in the container 12 by a suitable transmission medium 24. In this embodiment, the container 12 sits in a shallow bath 32 of liquid and the ultrasound generator 20 is mounted in contact with liquid in the bath. The bath 32 may be a receptacle attached to or integral with the power source 22, for example, a tray clamped onto the side of the medical pump.

Ultrasound generated is passed through liquid in the bath 32 to liquid in the container 12.

The frequency and power of the ultrasonic waves are selected to cause cavitation in the liquid within the container 12. Bubbles created by the cavitation burst at the surface of the liquid, creating a liquid vapour and humidifying the pressurised gas above the liquid in the container 12. Since the gas inlet tube 28 provides gas under pressure, humidified gas then passes through the outlet tube 30 for delivery to a medical instrument and into a patient. Since the outlet tube 30 protrudes a greater distance into the container 12, it is closer to the surface of the liquid in order to receive as much humidified gas as possible.

The depth d of the liquid in the container 12 is critical to effective cavitation and the optimum degree of humidification. By way of example only, for a frequency of

approximately 1.6MHz and power of approximately 9.5 Watts, a depth d = approximately 10 mm has been found to be optimum. In tests, this has been found to deliver a humidity of in excess of 90% at the end of outlet tube 30.

The ultrasound transmission medium 24 may be in a different form from the liquid bath 32 shown in Figure 1. For example, the container 12 may be placed with its base in direct contact with one side of a coupling medium such as a fluid viscous gel pad and the ultrasound generator 20 in contact with the other side of the pad. As noted above, the depth of liquid in the container 12 is critical for optimum cavitation and humidification. Therefore, the container 12 may be provided with a level mark to show a user how much liquid to add. In another embodiment shown in Figure 2a and 2b, the container 12 is modified so that the level of filling is not important and a barrier system ensures that an area of fluid in contact with the pressurised gas is maintained at the desired depth d.

In this example, the container 12 is provided with a dividing wall 34 physically separating the interior into a first pressurised volume 36 and a second venting volume 38. The dividing wall 34 is sealed to the walls of the container 12 to separate the two volumes, except for an opening 40 in the wall 34 between the first volume 36 and the second volume 38, which is provided at the bottom of the container 12 at a location defining the desired depth d of liquid desired for effective cavitation. Liquid inlet 14 is used to fill the container 12 with liquid when open, and sealed when closed to force gas flow through gas outlet 18.

The gas inlet 16 communicates with the first volume 36 and the gas outlet 18 communicates with the second volume 38. When the container 12 is filled with liquid and before pressurised gas is supplied, the liquid initially equalises in both the first volume 36 and the second volume 38, via opening 40, as shown in Figure 2a. When pressurised gas is supplied into the container 12 via the gas inlet 16, the gas pressure displaces liquid in the now pressurised first volume 36 into the second venting volume 38 through the opening 40. Gas supplied through inlet 16 continues to displace liquid from the first pressurised volume 36 until the liquid level is reduced to the height of the opening 40 which

corresponds to the desired depth d. The gas then bubbles through the liquid, passes through the opening 40 into the venting volume 38. Humidified gas bubbles burst at the surface of the liquid in the second volume 38 and humidified gas exits the container 12 through the gas outlet 18. No further liquid is displaced from the pressurised volume 36 to the venting volume 38 and desired liquid depth d is maintained for as long as pressurised gas is applied to gas inlet 16. The gas pressure required to displace liquid from the first volume 36 to the second volume 38 and maintain it at the desired depth d in the first volume 36 will depend on the depth of excess liquid to be displaced. Therefore, depending on the gas pressure available in the system, the quantity of liquid added to the container 12 will be chosen accordingly. An ultrasound generator 20 is provided beneath the container 12 via a suitable ultrasonic transmission medium 24 as before. The ultrasound generator 20 is preferably located beneath the first volume 36. Figure 2b also shows an optional additional feature of a liquid outlet tube 42 which passes into the second volume 38 and is arranged to extend below the surface of liquid displaced into the second volume 38. Liquid can be withdrawn via the liquid outlet tube 42 for procedural purposes such as irrigation during a medical procedure. Preferably, a flow control device 44 is provided on the liquid outlet tube 42 which selectively permits or prevents flow through the tube 42. Therefore, although liquid in the second volume 38 is under pressure it will only exit the chamber via the liquid outlet tube 42 if the flow control device 44 permits.

The flow control device 44 may be a pump, such a peristaltic pump which prevents liquid flow when it is not in operation and actively pumps liquid through the tube 42 when it is operated. Alternatively, or in addition, a valve may be provided to control flow through the tube 42.

The precise configuration of the first and second volumes 36, 38, the dividing wall 34 and the opening 40 are not limited to the example shown and a person skilled in the art will appreciate that the arrangement can be configured in various different ways.

Thus, the present invention provides a simple, low cost apparatus for humidifying insufflation gas, resulting in less discomfort and quicker recovery times for the patient. No heating is required in order to achieve humidification, reducing the power required by the system, and the apparatus can be provided as part of an overall fluid supply system used for supplying gas, irrigation liquid and suction for a medical procedure. The system is non- contact so that the insufflation gas and humidification liquid can be maintained in a sterile condition.

Claims

CLAIMS:

1. Apparatus for supplying insufflation gas to be administered to a patient, comprising a sterile chamber for holding a volume of gas and a volume of liquid, a gas inlet for supplying pressurised gas into the chamber, a gas outlet, an ultrasound generator configured to apply ultrasound to liquid in the chamber so as to cause cavitation in the liquid, and an ultrasonic transmission path located between the ultrasound generator and the liquid in the chamber.

2. Apparatus as claimed in claim 1 , wherein the ultrasonic transmission path comprises a container for holding a quantity of liquid in which the chamber is placed, whereby ultrasound is transmitted to the chamber via the liquid in the container.

3. Apparatus as claimed in claim 1 or claim 2, wherein the ultrasonic transmission path comprises a gel pad in contact with the ultrasound generator and the chamber.

4. Apparatus as claimed in any preceding claim, wherein the gas inlet and the gas outlet comprise tubes protruding into the chamber and wherein the gas outlet tube protrudes a greater distance into the chamber than the gas inlet tube.

5. Apparatus as claimed in any preceding claim, further comprising means to indicate a level of liquid to be held in the chamber to achieve optimum cavitation.

6. Apparatus as claimed in any preceding claim, further comprising a wall dividing the chamber into a first volume and a second volume and defining an opening between the first volume and the second volume, the location of the opening defining a predetermined level for the liquid.

7. Apparatus as claimed in claim 6, further comprising a liquid outlet tube for withdrawing liquid from the second volume in use.

8. Apparatus as claimed in claim 7, further comprising a flow control device operable to selectively permit and prohibit flow of liquid from the second volume through the liquid outlet tube.

9. Apparatus as claimed in any preceding claim, further comprising a medical pump operable to supply fluid to a patient and/or to produce suction to remove fluid from a patient, and to power to the ultrasound generator.