GB2434100A

GB2434100A - A delivery device for local anaesthetic

Info

Publication number: GB2434100A
Application number: GB0515581A
Authority: GB
Inventors: Orlando Jonathan Warner
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-07-28
Filing date: 2005-07-28
Publication date: 2007-07-18
Also published as: GB0515581D0

Abstract

A device for the delivery of local anaesthetic comprises a hollow body 20 with a first inlet 22 for receiving a flow of gas, a second inlet 28 for receiving a liquid anaesthetic and an outlet 38 for delivering the liquid anaesthetic as a stream of fine particles in the flow of gas. The hollow body 20 can be a tubular structure and may narrow after the second inlet. The gas may be oxygen and the second inlet 28 includes a syringe connection 30 and may also have a one-way valve 32. The outlet may include a flexible portion 36.

Description

MEDICAL DEVICE

This invention relates to a device for the delivery of local anaesthetic.

It is common in medical practice involving surgery or procedures performed on the upper airways mucosa (including the anterior and posterior nasal space, oral cavity and naso-lacrimal duct) to apply a local anaesthetic prior to surgery or other procedure. An example of a local anaesthetic that is commonly used is a liquid local anaesthetic known as Moffat's solution, which comprises a mixture of cocaine, adrenaline and sodium bicarbonate.

Figure 1 of the accompanying drawings shows a prior art device for the delivery of liquid local anaesthetic. It comprises a flexible tube or cannula 10. At one end there is an opening 12 to which a syringe containing liquid local anaesthetic can be connected at the other end there is an atomisation valve 14. When the operator pushes the plunger of the syringe holding the liquid local anaesthetic, the liquid enters the cannula 10 and flows to the atomisation valve 14 which, when sufficient pressure is applied, emits the anaesthetic as a fine spray of liquid.

However, this device suffers from a number of problems. When the operator begins pushing the plunger of the syringe, drops of liquid local anaesthetic can drip from the nozzle of the atomisation valve 14 because insufficient pressure has built up for the valve to function properly to provide atomisation. These drops of liquid local anaesthetic are not delivered to the place intended by the operator and are essentially wasted. After the operator has generated sufficient driving pressure by pushing the plunger of the syringe such that an atomised stream of liquid local anaesthetic is being emitted from the atomisation valve 14, it is not possible conveniently to pause or interrupt the flow of anaesthetic because then the pressure drops and atomisation is not achieved unless the operator starts again and builds up sufficient driving pressure. Therefore, once delivery is started, the operator is essentially committed to delivering the entire syringe full of anaesthetic in one go. Furthermore, the atomisation valve 14 is bulky which makes it difficult to accurately direct the flow of atomised anaesthetic, particularly when inserted in a confined space such as the nasal space of a patient.

It is desirable to provide an improved device for the delivery of local anaesthetic.

According to the present invention there is provided a device for the delivery of local anaesthetic, comprising: a hollow body, said body comprising: a first inlet for receiving a flow of gas; a second inlet for receiving a liquid anaesthetic; and an outlet for delivering said liquid anaesthetic as a stream of fine particles in the flow of gas.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates a device for the delivery of local anaesthetic according to

the prior art; and

Figure 2 illustrates a device for the delivery of local anaesthetic according to an embodiment of the invention.

An example of a device embodying the present invention is illustrated in Figure 2. This device comprises a hollow body 20 which is generally elongate and tubular. At one end there is a first inlet 22 for receiving a flow of gas. The portion of the device by the first inlet 22 comprises a tapered tubing connection 24 that allows any type and gauge of gas tubing to be attached for supplying a driving gas for the device. The tapered tubing connection 24 also allows a snug fit for the gas tubing to prevent reflux of the local anaesthetic via a potential leak. However, the tapered tubing connection 24 is different from other connections, such as a Luer lock (trademark) and therefore avoids accidental connection of intravenous infusions.

The function of the driving gas will be described in more detail below.

The middle portion of the body 20 of the device comprises a wide-bore banel portion 26 which has a side port 28 provided on it. The side port 28 constitutes a second inlet of the device for receiving a liquid anaesthetic and comprises an opening with a standard connection for any size syringe and a one-way valve 32 of any suitable construction, such as a flap valve or slit valve, to prevent reflux of the local anaesthetic back into the syringe. In Figure 2 the side port 28 is shown substantially perpendicular to the length of the device. However, this is not essential, and in alternative embodiments the side port 28 can form an acute angle with the barrel portion 26 of the device.

On the opposite side of the body 20 from the side port 28 is a tab 34 which can be grasped between the index finger and thumb of the operator to aid the accurate delivery of the local anaesthetic while operating the syringe with the other hand.

At the opposite end of the device from the first inlet 22 is a narrow nose portion 36 leading to an outlet 38. Between the wide-bore barrel portion of the device 26 and the nose portion 36 the lumen of the device suddenly narrows. In a preferred embodiment of the invention, the internal diameter of the barrel portion 26 is 5mm to 6mm and the internal diameter of the nose portion 36 is 1.1mm to 1.3mm.

The length of the nose portion is typically in the range of 32mm to 45mm.

The whole device is manufactured from latex-free plastics materials. The barrel portion 26, side port 28, tubing connection 24 and tab 34 are made of a rigid plastics material. The nose portion 36 of the device is made from softened plastics material which allows some degree of flexibility, but is sufficiently rigid to support its own weight such that it does not bend under gravity. Essentially the operator can bend the nose portion to accurately direct the outlet 38. The entire device is steriuisable and is provided in a sterile packet prior to use, but is typically made as a single-use, disposable device for hygiene reasons.

The operation of the device will now be described.

The tapered tubing connection 24 is connected to tubing from a supply of a driving gas. Oxygen is typically used as the driving gas because it is readily available from cylinders that sit on the patient's trolley or from a walled oxygen supply within the anaesthetic room. However, another suitable gas such as compressed air may also be used. The driving gas is regulated to be delivered at a flow rate in the range of from 1700 to 2300 ml/min, for example 2000 ml/min. If the flow rate is too high it is uncomfortable for the awake patient and also the back-pressure in the device can tend to force the tubing off the end of the connection 24.

With the driving gas flowing through the device from the first inlet 22 to the outlet 38 and a syringe of liquid local anaesthetic, such as Moffat's solution, connected to the opening 30 of the side port 28, the plunger of the syringe (not shown) is pushed to feed the liquid local anaesthetic into the gas flow through the one-way (non-return) valve 32. The liquid local anaesthetic is picked up by the fast moving gas, and the barrel portion 26 allows a smooth pick up of the local anaesthetic without refluxing of the liquid back towards the first inlet 22.

When the gas flow encounters the narrowing of the lumen on entering the nose portion 36 of the device the gas is accelerated and the pressure within it drops (according to the Bernoulli principle, as the speed of a gas accelerates, the pressure within it falls). This acceleration and reduction in pressure atomises the liquid local anaesthetic such that it is carried as a stream of fine particles in the flow of gas. The stream of fine particles may also be referred to as a fine spray or mist or aerosol. The verb "nebulise" is also sometimes equivalently used to the verb "atomise". Thus the device atomises the liquid local anaesthetic without the need for a complex atomising valve.

The stream of fine particles of anaesthetic in the flow of gas is emitted from the outlet 38 which can be accurately directed wherever the operator of the device chooses. The anaesthetic can be delivered to the upper airways mucosa, such as the anterior nasal space, the posterior nasal space, the oral cavity (oropharynx) and the naso-lacrimal duct. The device allows very accurate placement of the local anaesthetic into desired ones of these specific anatomical areas. Furthermore, the operator can accurately control the administration of the local anaesthetic, not only in terms of exact anatomical placement, but also in the timing of delivery. The depression of the syringe plunger can be started and stopped at will, and it is not necessary to build-up a particular pressure with the syringe because the liquid local anaesthetic will always be entrained in the gas flow.

Claims

CLAIMS

1. A device for the delivery of local anaesthetic, comprising: a hollow body, said body comprising: a first inlet for receiving a flow of gas; a second inlet for receiving a liquid anaesthetic; and an outlet for delivering said liquid anaesthetic as a stream of fine particles in the flow of gas.

2. A device according to claim 1, wherein said body is an elongate tubular structure.

3. A device according to claim 1 or 2, wherein the hollow body has a lumen, and in the direction of gas flow from the first inlet to the outlet, the lumen undergoes a narrowing after the second inlet.

4. A device according to claim 1, 2 or 3, wherein the diameter of the lumen upstream of the constriction is in the range of from 4 to 7 mm.

5. A device according to any one of the preceding claims, wherein the diameter of the lumen downstream of the constriction is in the range of from 0.5 to 3 mm.

6. A device according to any one of the preceding claims, adapted for use with a gas flow rate in the range of from 1700 to 2300 ml/min.

7. A device according to any one of the preceding claims, adapted for use with a flow of oxygen gas.

8. A device according to any one of the preceding claims, wherein said first inlet comprises a tapered tubing connection.

9. A device according to any one of the preceding claims, wherein said second inlet is provided in the side of the body, between the first inlet and the outlet.

10. A device according to any one of the preceding claims, wherein said second inlet comprises a syringe connection.

11. A device according to any one of the preceding claims, wherein said second inlet comprises a one-way valve to prevent reverse flow out of the second inlet.

12. A device according to any one of the preceding claims, further comprising a tubular nose portion leading to the outlet.

13. A device according to claim 12, wherein the nose portion is flexible.

14. A device according to claim 12 or 13, wherein the length of the nose portion of the device is in the range of from 25 to 50mm.

15. A device according to claim 12, 13 or 14, wherein the nose portion extends from a narrowing in the lumen of the body to the outlet.

16. A device according to any one of the preceding claims, wherein the body further comprises a tab for being held by the user of the device.

17. A device according to any one of the preceding claims, adapted for delivering local anaesthetic to the upper airways mucosa.

17. A device according to any one of the preceding claims, adapted for delivering local anaesthetic to at least one selected from the group consisting of: the anterior nasal space, the posterior nasal space, the oral cavity and the naso-lacrimal duct.

18. A device for the delivery of local anaesthetic substantially as described herein with reference to Figure 2 of the accompanying drawings.