This invention relates to cuff inflation indicators of the kind for a tube with a sealing cuff, the interior of the sealing cuff communicating with one end of an inflation line the opposite end of which opens into a flexible enclosure of the indicator such that the enclosure is inflated by pressure from the sealing cuff via the inflation line.

Tracheal tubes are used to supply ventilation and anaesthetic gases to a patient, such as during surgery. The tracheal tube may be inserted via the mouth or nose, in the case of an endotracheal tube, or may be inserted via a surgically made tracheostomy opening in the neck, in the case of a tracheostomy tube. Most, but not all, tracheal tubes have some form of a seal on their outside, which forms a seal between the outside of the tube and the inside of the trachea so that gas flow is confined to the bore of the tube and cannot flow around the outside of the tube, between the tube and the trachea.

The most common form of seal is provided by a cuff that is inflated and deflated via a small-bore lumen extending along the tube and connected towards its rear end to an inflation line terminated by an inflation indicator, valve, and connector. These inflatable cuffs may be of the high- volume/low-pressure kind where the cuff is formed of a flexible plastics material moulded with a natural annular or doughnut shape. Such cuffs are inflated without stretching, to contact the wall of the trachea, by relatively low-pressure gas supplied via the inflation line. Alternatively, the cuff may be of the low-volume/high-pressure kind where the cuff is of an elastic material that lies close to the tube shaft when uninflated but is inflated and stretched to a larger diameter by relatively high pressure gas supplied via the inflation line. The sealing cuff may alternatively be inflated by a liquid, such as sterile water, especially when it is of the low-volume/high-pressure kind of cuff.

The inflation line usually connects with some form of inflation indicator or cuff pressure indicator externally of the patient, at the machine end of the inflation line. The purpose of the inflation indicator is to show the clinician whether the sealing cuff is correctly inflated. Most commonly this inflation indicator is in the form of a small flexible pilot balloon connected with the inflation line. Conventionally, the pilot balloon is moulded as an integral component with a relatively flat oval shape having two opposite walls, when not inflated. When the pilot balloon is inflated the two walls move apart from one another and the balloon takes a more rounded shape. It is common practice for the pilot balloon to be printed with a legend giving information about the tube, this is convenient because the pilot balloon lies outside the patient and is more accessible than the rest of the tube. In order for the printed legend to be visible, the walls of the balloon are commonly given a matt or contrasting surface. This can be a problem with tubes having a sealing cuff that is inflated with a liquid, such as water, because it becomes difficult to determine if the balloon is filled with the liquid. The preferred printing technique is laser printing but, to achieve a clear print, the wall of the balloon should be opaque and matt to enable focussing and high absorption of the laser energy.

Examples of tubes with sealing cuffs and pilot balloons are shown in W02019/008305 and GB2174303.

It is an object of the present invention to provide an alternative cuff inflation indicator and an alternative cuffed tube including a cuff inflation indicator.

According to one aspect of the present invention there is provided a cuff inflation indicator of the above-specified kind, characterised in that the flexible enclosure is formed of two opposite walls of different characteristics joined together around their edges so that inflation causes the walls to be displaced away from each other, that one of the walls is of a clear, transparent material that enables any liquid in the enclosure to be viewed externally, and that the other wall is printed with a marking and at least partially obscures a clear view of the contents of the enclosure.

The other wall is preferably printed by laser printing.

According to another aspect of the presen: invention there is provided a cuff inflation indicator of the kind for a tube with a sealing cuff, the interior of the sealing cuff communicating with one end of an inflation line the opposite end of which opens into a flexible enclosure of the indicator such that the enclosure is inflated by pressure from the sealing cuff via the inflation line, characterised in that the flexible enclosure is formed of two opposite walls of different characteristics joined together around their edges so that inflation causes the walls to be displaced away from each other, that one of the walls is clear and transparent to enable liquid in the enclosure to be viewed externally, and that the other wall has a surface at least arranged to be laser printed with a marking.

The other wall is preferably opaque and coloured. The indicator may be made by blow moulding from a co-extrusion of two different materials.

According to a further aspect of the present invention there is provided a medico- surgical tube having an inflatable sealing cuff towards its patient end, an inflation line communicating at one end with the interior of the sealing cuff, and a cuff inflation indicator according to the above one or other aspect of the present invention connected with an opposite end of the inflation line.

The sealing cuff and a cuff inflation indicator are preferably filled with a liquid.

The tube may be a tracheostomy tube.

A cuffed tracheostomy tube with an inflation line and cuff pressure indicator according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side elevation view of the tube;

Figure 2 is a perspective view of the inflation indicator showing its upper surface;

Figure 3 is a side elevation view of the inflation indicator; and

Figure 4 is a plan view of the lower surface of the inflation indicator. The tracheostomy tube 1 has a patient end 10 adapted to locate within the trachea and a machine end 11 adapted to locate outside the patient adjacent the neck surface. The tube 1 has a curved tubular shaft 12 of circular section with a bore extending along its length. The shaft 12 has a substantially patient end portion 14 and machine end portion 15 joined by a central portion 16 so that opposite ends of the shaft are inclined at about 100° to one another. The shaft 12 is extruded or moulded from a plastics material.

The tube could be of various shapes and sizes and need not be for use in the trachea but could be adapted for use in other body cavities.

Towards its patient end 10 the tube 1 has sealing means provided by an inflatable cuff 20 embracing the shaft 12. The cuff 20 is of the low- volume/high-pressure kind so that it lies close to the outer surface of the shaft 12 when deflated but, when inflated, it expands elastically to a larger diameter intended to seal with the internal diameter of the trachea. The cuff 20 is attached to the shaft 1 by two collar portions 21 and 22 at opposite ends. The cuff 20 extends over an opening 23 on the outer surface of the shaft 12 into an inflation lumen 24 extending along the shaft within its wall thickness. The inflation lumen 24 is formed along a small-bore inflation line 26 terminated by an inflation indicator 27 with a conventional valved connector 28. In the present example both the shaft 12 and the cuff 20 are made of a silicone material, and the cuff is inflated by means of a liquid, such as sterile water, since this is less prone to leakage at high pressure than an air filling. Alternative materials and sealing cuffs could be used, such as those of the high-volume/low-pressure kind.

The inflation indicator 27 is shown in more detail in Figures 2, 3 and 4 and takes the form of a flexible pilot balloon or other flexible enclosure 30. In the present example the pilot balloon 30 has a generally flat, oval shape with the connector 28 at its machine end and a tubular extension 29 at its patient end bonded onto the outside of the machine end of the inflation line 26. It can be seen that, when the sealing cuff 20 on the tube 1 is inflated, the fluid pressure in the cuff will communicate via the inflation line 26 to the pilot balloon 30 thereby also inflating this from its normal flat shape to a more rounded shape. Similarly, if the cuff pressure should fall, the pilot balloon 30 would deflate to a flatter state, thereby providing a warning indication to the clinician. The inflation indicator 27 differs from conventional indicators by not being moulded entirely of the same material, instead the indicator is moulded of two different materials, one of which forms the upper face 30U of the balloon 30 and the other of which forms the lower face 30L. The two different materials preferably continue along both the patient end extension 29 and the machine end connector 28 as well as the balloon 30 itself. The material forming the lower face 30L is clear and transparent, being sufficiently transparent to enable the presence or absence of liquid in the balloon to be seen from outside. The material forming the upper face 30U, however, is different being opaque and coloured, such as of a white material, which is better for laser printing. Laser printing is preferred over conventional pad printing because it is quicker and cheaper. The opaque white plastics material is easier to focus the laser beam onto and absorbs a high proportion of the laser energy to create a clear deep black print, which is highly visible, especially against the white colour of the background. The material for forming the upper face 30U could include an additive to enhance laser marking. Materials of different colours could be used. The marking on the upper face 30U could indicate various characteristics of the tube, such as its size, whether or not it is fenestrated, or the name of the manufacturer. The material forming the lower face 30L could also be coloured providing it was still clear and sufficiently transparent to enable liquid in the balloon to be seen. The colour of the indicator 27 could be used to indicate a characteristic of the tube, such as its size.

The inflation indicator could be made by blow moulding from a co-extrusion of two different materials and subsequently bonded onto the inflation line. Alternatively, the indicator could be over moulded onto the machine end of the inflation line using a two-shot injection moulding process.

The invention is not limited to tracheal tubes but could be used in other medical tubes with a liquid-filled cuff. A cuff according to the present invention could, instead, be used with gas, such as air, as an inflation medium. Although there would be no benefit in being able to see through the transparent wall of an air-filled indicator there could be a commercial advantage if the same pilot balloon indicator could be used across an entire range of tubes including both liquid-filled cuffs and air- filled cuffs, since it would enable an economy of scale and reduced inventory.