Cannula securement and dressing

Abstract

A cannula securement 11 for securing a winged cannula to the skin of a patient, the cannula securement comprising a skin-protecting portion 15 having a width at least equal to a wing span of the cannu

Description

TECHNOLOGICAL FIELD Examples of the disclosure relate to means for securing a cannula to skin of a patient and a multi-part dressing using the cannula securement. BACKGROUND A cannula allows medication or other substances to be delivered into the patient’s bloodstream and can be used for several days, provided it is not dislodged. It therefore avoids the need for repeatedly inserting a needle into the patient over the course of those days. However, if the cannula can move, it can create friction against both the inside of the vein or artery into which it is inserted and against skin around the insertion site. With ageing there can be increase in skin sensitivity, making even slight pressures more pronounced. This increased sensitivity can contribute to perception of discomfort. This means that a normal process of securing an intravenous (IV) cannula with an adhesive dressing can more easily cause irritation, injury, or discomfort with individuals with fragile skin. Thinner skin has less cushioning over the underlying structures, which means any pressure from an IV cannula can more directly impact sensitive tissues causing discomfort and pain. Premature babies, on the other hand, especially those born extremely early, have skin that is not fully developed which can contribute to increased sensitivity and vulnerability. For instance, skin can be friable and transparent with an underdeveloped stratum corneum (the outermost layer of the skin). This potentially can cause more discomfort compared to more mature skin. BRIEF SUMMARY According to various, but not necessarily all, examples there is provided a cannula securement for securing a winged cannula to skin of a patient, the cannula securement comprising: a skin-protecting portion, having a width at least equal to a wing span of the cannula to be secured; a first adhesive strip, extending from and foldable over a first section of the skin-protecting portion and having a length sufficient, when thusly folded, to enable adherence to skin of the patient located to a side of the skin-protecting portion which is other than that side from which it extends; and a second adhesive strip, extending from and foldable over a second section of the skin-protecting portion and having a length sufficient, when thusly folded, to enable adherence to skin of the patient located to a side of the skin-protecting portion which is other than that side from which it extends, wherein the skin-protecting portion comprises hypoallergenic padding on an opposite face of the cannula securement to an adhesive layer providing adhesive character to the first and second adhesive strips. In some but not necessarily all examples, the first and second adhesive strips are each of a length sufficient to extend at least 3 mm beyond the side of the skinprotecting portion when folded over the skin-protecting portion. In some but not necessarily all examples, the first adhesive strip is of a length sufficient, when folded over a first wing of the cannula resting on top of the first section of the skin-protecting portion, to enable adherence to skin of the patient located to a side of the skin-protecting portion which is other than the side of the skin-protecting portion from which it extends. In some but not necessarily all examples, the first and second adhesive strips each comprise a wing-adhering section proximal to the skin-protecting portion and a skinadhering section distal to the skin-protecting portion. In some but not necessarily all examples, the wing-adhering section is of length equal to a wing of the cannula to be secured and the skin-adhering section is of length of at least 3 mm. In some but not necessarily all examples, the first and second adhesive strips extend longitudinally from a transverse edge of the skin-protecting portion. In some but not necessarily all examples, the first and second adhesive strips extend in parallel and are separated by a gap. In some but not necessarily all examples, the gap is greater than an outer diameter of a hub of the cannula to be secured, or at least an outer diameter of a portion of the hub located between the wings. In some but not necessarily all examples, the adhesive layer comprises a skin-suitable / safe adhesive formulation. In some but not necessarily all examples, a thickness of the hypoallergenic padding is between 0.5 - 4 mm, at least when uncompressed. In some but not necessarily all examples, the cannula securement comprises a flexible substrate providing a base for the hypoallergenic padding and the adhesive layer. According to various, but not necessarily all, examples there is provided a multi-part cannula dressing comprising: the cannula securement; and an adhesive dressing, configured to be applied over the cannula and a portion of the surrounding skin, wherein the adhesive dressing comprises a substantially keyhole-shaped notch in one edge which is configured to enable the dressing to wrap around a hub of the cannula to be secured in order to expose a portion of the hub for access by a medical professional whilst adhering to skin under the exposed portion of the hub. In some but not necessarily all examples, at least one dimension of the adhesive dressing is greater than the wing span of the canula to be secured. In some but not necessarily all examples, the adhesive dressing comprises two reinforcing strips. In some but not necessarily all examples, the two reinforcing strips are substantially parallel. In some but not necessarily all examples, the two reinforcing strips are spaced apart by at least the outer diameter of a hub of the cannula to be secured. In some but not necessarily all examples, the two reinforcing strips are spaced apart by less than a sum of a circumference of the hub and the wing span of the cannula to be secured. In some but not necessarily all examples, the two reinforcing strips overlie the first and second adhesive strips of the cannula securement to further reinforce their securement of the wings of the cannula when the adhesive dressing is applied over the cannula securement. In some but not necessarily all examples, the adhesive dressing comprises further reinforcing strips configured to reinforce a perimeter of the substantially keyholeshaped notch and the edge of dressing in which the notch is provided. In some but not necessarily all examples, the adhesive dressing comprises a transparent film coated in a layer of adhesive comprising a skin-suitable / safe adhesive formulation. According to various, but not necessarily all, examples there is provided a cannula system comprising: a cannula for accessing veins or arteries of a patient, the cannula comprising a hub and wings on either side of the hub; and the multi-part cannula dressing, wherein at least a portion of each wing and at least a portion of the hub located between the wings rests on top of the skin-protecting portion of the cannula securement, wherein the first adhesive strip of the cannula securement is folded over and adhered to a first wing of the cannula and extends beyond the first wing to enable adherence to skin of the patient, wherein the second adhesive strip of the cannula securement is folded over and adhered to a second wing of the cannula and extends beyond the second wing to enable adherence to skin of the patient, wherein the adhesive dressing is applied over the cannula and cannula securement and adhered to the cannula and extends beyond the cannula to enable adherence to skin of the patient, and wherein a portion of the adhesive dressing adjacent the substantially keyholeshaped notch is adhered around the hub of the cannula to expose a portion of the hub for access by a medical professional whilst enabling adherence of the adhesive dressing to skin of the patient under the exposed portion of the hub. According to various, but not necessarily all, embodiments there is provided examples as claimed in the appended claims. While the above examples of the disclosure and optional features are described separately, it is to be understood that their provision in all possible combinations and permutations is contained within the disclosure. It is to be understood that various examples of the disclosure can comprise any or all the features described in respect of other examples of the disclosure, and vice versa. The description of a function should additionally be considered to also disclose any means suitable for performing that function. BRIEF DESCRIPTION Some examples will now be described with reference to the accompanying drawings in which: FIG 1 shows an example of a cannula secured to skin of a patient; FIGS 2A to 2C show an example of a cannula securement; FIGS 3A and 3B show another example of a cannula securement; FIGS 4A and 4B show another example of a cannula securement; FIG 5 shows another example of a cannula securement; FIG 6 shows another example of a cannula securement; FIGS 7A and 7B show an example of an adhesive dressing; and FIG 8 shows an example of a cannula system comprising a multi-part cannula dressing. The figures are not necessarily to scale. Certain features and views of the figures can be shown schematically or exaggerated in scale in the interest of clarity and conciseness. For example, the dimensions of some elements in the figures can be exaggerated relative to other elements to aid explication. Similar reference numerals are used in the figures to designate similar features. For clarity, all reference numerals are not necessarily displayed in all figures. DETAILED DESCRIPTION The figures illustrate examples of a cannula securement 11 for securing a winged cannula 1 to skin of a patient and a multi-part cannula dressing 51 comprising such a cannula securement 11. FIG 1 illustrates an example of the cannula securement 11 in use, securing a cannula 1 to skin 6 of a patient. An example of the cannula securement 11 is shown in more detail in FIGS 2A to 2C. The cannula 1 has wings 3, 4 (sometimes also referred to as flanges) on either side of a hub 2 of the cannula 1. It is therefore a winged cannula. The wings 3, 4 may have rectangular or triangular or other shape. The hub 2 is the part to which an external device, such as a syringe or tubing, can be attached and it provides a connection between this external device and a hollow tube which provides a passageway through the patient’s skin into a vein or artery via which medication or other substances can be delivered into the patient’s bloodstream. This hollow tube runs through the centre of a long, thin, flexible shaft 5 which extends from the hub 2 and is insertable into the vein or artery. The attachment of the external device to the hub 2 may be via a Luer lock (not shown) which creates a secure, leak-proof connection. The hub 2 is typically a tube of substantially greater diameter than that of the shaft 5. The term “diameter” should be understood as a straight line between opposing sides, passing through a central point and should not be understood as implying a circular cross-section for the hub 2 or shaft 5. The cannula securement 11 is configured to cooperate with the wings 3, 4 to secure the cannula 1 to the patient’s skin 6. The precise configuration of the cannula securement 11 may therefore be adapted to cooperate with the shape of the wings 3, 4. Different sizes of cannula 1 are used for different applications and with different ages (or sizes) of patient. The cannula securement 11 is sized differently for each size of cannula 1 to be secured. FIGS 2A and 2B respectively illustrate a plan and an elevation of an example of the cannula securement 11 in an unfolded configuration. FIG 20 illustrates the folded configuration in plan. The cannula securement 11 comprises a skin-protecting portion 15, a first adhesive strip 20, and a second adhesive strip 23. The cannula securement 11 is substantially planar, comprising two opposite faces 13, 14 which are joined to one another along each of their edges. In some examples the cannula securement 11 comprises a flexible, substantially planar substrate 12 providing a base for those elements which provide skinprotecting character to the skin-protecting portion 15 and adhesive character to the first and second adhesive strips 20, 23. The flexible, substantially planar substrate 12 is in some examples fabricated from hypoallergenic material made from a variety of materials including, but not limited to, woven or nonwoven cloth or rayon, silicon, hydrocolloid, foam substrate etc. The skin-protecting portion 15 has a width (wi) which is at least equal to a wing span of the cannula 1 to be secured. For the avoidance of doubt, “wing span” refers to the distance between the tips of the wings 3, 4 on either side of the cannula hub 2. The skin-protecting portion 15 may have sections with corresponding dimensions, and thus equivalent shape and equal size in terms of length and width, to both wings 3, 4 of the cannula 1 to be secured. Therefore, if the wings 3, 4 are rectangular, the skinprotecting portion 15 is also rectangular, as in the illustrated example. The skin-protecting portion 15 comprises hypoallergenic padding 16 provided on a first face 13 of the cannula securement 11. The skin-protecting character of the skinprotecting portion 15 is provided by the hypoallergenic padding 16. The hypoallergenic padding 16 may extend continuously or discontinuously over the first face 13 of the cannula securement 11, its extent defining the limits of the skinprotecting portion 15. In other words, the skin protecting portion 15 may extend as far as the hypoallergenic padding 16 extends, but where the hypoallergenic padding 16 comes to an end, the skin protecting portion 15 also ends. The hypoallergenic padding 16 may be made from a variety of materials including, but not limited to, woven or nonwoven cloth or rayon, silicon, hydrocolloid, foam substrate etc. The hypoallergenic padding 16 may be latex free. The thickness (h) of the hypoallergenic padding 16 would preferably be between 0.5 - 4 mm, at least when uncompressed. In some examples, an adhesive layer may be provided over the hypoallergenic padding 16 which sticks to the skin 6 beneath and stabilizes the skin protecting portion 15 to the skin 6 thus preventing relative movement there between. The skin-protecting portion 15 therefore provides a support on which to rest the wings 3,4 of a cannula 1 and at least that portion of a hub 2 of the cannula 1 which is located between the wings 3, 4. It provides, via the hypoallergenic padding 16, a soft protective shield between these parts of the cannula 1 and the patient’s skin 6, thus preventing harm, either from pressure or friction, to the skin 6. In some examples the skin-protecting portion 15 comprises an adhesive layer provided on a second (opposite to the first) face 14 of the cannula securement 11. The adhesive layer can assist in securement of a cannula 1, resting on the skin- 9 protecting portion 15, to the hypoallergenic padding 16 to prevent relative movement therebetween. The first and second adhesive strips 20, 23 each comprise an adhesive layer 26 provided on the second (opposite to the first) face 14 of the cannula securement 11. That is, the adhesive layer 26 is provided on an opposite face of the cannula securement 11 to the hypoallergenic padding 16. The adhesive character of the first and second adhesive strips 20, 23 is provided by the adhesive layer 26. The adhesive layer 26 of the first and second adhesive strips 20, 23 may be provided by a single continuous layer of adhesive, which extends also over the skin-protecting portion 15. Thus, an adhesive layer 26 may be provided over the whole second face 14 of the cannula securement 11. Alternatively, the adhesive layer 26 may be a discontinuous layer, provided only over the second face 14 of portions of the cannula securement 11 which constitute the first and second adhesive strips 20, 23. In some examples the adhesive layer 26 comprises a skin-suitable / safe adhesive formulation. The adhesive formulations may comprise, for example, a spray-on adhesive, adhesive film, polymer-based pressure sensitive adhesive. The adhesive formulation may comprise an antibacterial agent to aid in maintaining a sterile intravenous insertion site. The cannula securement 11 may be provided with one or more removable release liners covering the adhesive layer 26. Release liners may include any material or combination of materials that permit temporary bonding between release liner and adhesive layer 26. Examples of compatible materials for release liners include plastic film, paper, plastic, metal foil, plastic coated paper, wax coated paper, wax coated plastic, plastic coated foil, and wax coated foil. They can also be coated, impregnated, or layered with a release agent, an anti-microbial agent, or both. The first and second adhesive strip 20, 23 extend from the skin-protecting portion 15. The first adhesive strip 20 extends from an edge of the skin-protecting portion 15, which is on one side of the skin-protecting portion 15. The second adhesive strip 23 also extends from an edge of the skin-protecting portion 15, which is on one side of the skin-protecting portion 15. In some examples the first and second adhesive strips 20, 23 extend from the same edge of the skin-protecting portion 15. In some examples the first and second adhesive strips 20, 23 extend longitudinally away from a transverse (transversely oriented) edge 17a of the skin-protecting portion 15. They extend in parallel in the same direction and are separated by a gap. That is, they extend from sections of the transverse edge 17a which are spaced apart by a distance in the transverse dimension. This gap I distance in the transverse dimension is greater than an outer diameter of the hub 2 of the cannula 1 to be secured, or at least an outer diameter of the portion of the hub 2 located between the wings 3, 4. It will be appreciated that the first and second adhesive strips 20, 23 may alternatively extend longitudinally in parallel but opposite directions from opposite transverse edges 17a, 17b of the skin-protecting portion 15. More generally, it will be appreciated that the first and second adhesive strips 20, 23 may extend from the same or different edges of the skin-protecting portion 15 and may, if folded along those edges, extend to the same or to different sides of the skinprotecting portion 15. The first adhesive strip 20 is foldable over a first section 18 of the skin-protecting portion 15. The first section 18 may be a section intended to underlie a first wing 3 of the cannula 1. The first section 18 may therefore have corresponding dimensions, and thus equivalent shape and equal or approximately equal size in terms of length and width, to the first wing 3 of the cannula 1 to be secured. The second adhesive strip 23 is foldable over a second section 19 of the skin-protecting portion 15. The second section 19 may be a section intended to underlie a second wing 4 of the cannula 1. The second section 19 may therefore have corresponding dimensions, and thus equivalent shape and equal or approximately equal size in terms of length and width, to the second wing 4 of the cannula 1 to be secured. The first and second adhesive strips 20, 23 may be foldable along the edge(s) of the skin-protecting portion 15 from which they extend. The edges 17a-17d of the skin-protecting portion can provide natural fold lines created by a change in the flexibility of the cannula securement 11 at this point in consequence of at least the added thickness of the hypoallergenic padding 16. In FIG 20 the folding action in respect of the first adhesive strip 20 is illustrated by arrow 27 and the folding action in respect of the second adhesive strip 23 is illustrated by arrow 28. The position of the first and second adhesive strips 20, 23 when unfolded is shown in dashed outline and designated by the reference 20’ and 23’ respectively. The first adhesive strip 20 has a length (h) sufficient, when folded over the first section 18 of the skin-protecting portion 15, to enable adherence to an area of skin of the patient which is located to another side of the skin-protecting portion 15 (i.e., to the side of another edge of the skin-protecting portion 15). That is, the first adhesive strip 20 is long enough to extend from one side of the skin-protecting portion 15 and, when folded over the first section 18 of the skin-protecting portion 15, adhere to skin located to another side of the skin-protecting portion 15. Similarly, the second adhesive strip 23 has a length (h) sufficient, when folded over the second section 19 of the skin-protecting portion 15, to enable adherence to an area of skin of the patient which is located to another side of the skin-protecting portion 15 (i.e., to the side of another edge of the skin-protecting portion 15). That is, the second adhesive strip 23 is long enough to extend from one side of the skinprotecting portion 15 and, when folded over the second section 19 of the skinprotecting portion 15, adhere to skin located to another side of the skin-protecting portion 15. In some examples the first and second adhesive strips 20, 23 are configured for adherence to skin located to an opposite side of the skin-protecting portion 15 than the side(s) from which they extend. In other examples the first and second adhesive strips 20, 23 are configured for adherence to skin located to a side of the skinprotecting portion 15 which is adjacent to, and directly-adjoining, the side(s) from which they extend. In some examples the first and second adhesive strips 20, 23 are each of a length (l2) sufficient to extend at least 3 mm to the side (beyond an edge) of the skin-protecting portion 15 when folded over the skin-protecting portion 15. This enables a suitable area of the adhesive strips 20, 23 to contact the skin for the purpose of robustly securing the cannula 1 to the skin and reduce likelihood of dislodgement. The first adhesive strip 20 is of a length (l2) sufficient, when folded over a first wing 3 resting on top of the first section 18 of the skin-protecting portion 15, to enable adherence to skin of the patient located to a side of the skin-protecting portion 15 which is other than the side of the skin-protecting portion 15 from which it extends. Similarly, the second adhesive strip 23 is also of a length (l2) sufficient, when folded over a second wing 4 resting on top of the second section 19 of the skin-protecting portion 15, to enable adherence to skin of the patient located to a side of the skinprotecting portion 15 which is other than the side of the skin-protecting portion 15 from which it extends. The first and second adhesive strips 20, 23 each comprise a wing-adhering section 21,24 proximal to the skin-protecting portion 15 and a skin-adhering section 22, 25 distal to the skin-protecting portion 15. The length (l2b) of the skin-adhering section 22, 25 is at least 3 mm. The length (l2a) of the wing-adhering section 21,24 is at least equal to a wing 3, 4 of the cannula 1 to be secured. The length (l2b) of the wingadhering section 21,24 may sufficient to enable adherence directly to the two wing edges and the upper surface of the wing section over which the adhesive strip 20, 23 is folded. The skin-protecting portion 15 has a width (wi) in a transverse dimension of at least 23 mm and a length (h) in a longitudinal dimension of at least 5 mm. The first and second adhesive strips 20, 23 each have a length (l2) in the longitudinal dimension of at least 11 mm and a width (w2) in the transverse dimension of at least 7 mm. These minimum dimensions may be suitable for use with a 24G cannula. Smaller gauge cannulas have larger dimensions and will use wings having a greater span. The cannula securement 11, sized differently, is suitable for securing at least cannulas between 14G and 26G. It should be appreciated that modifications to the cannula securement 11 given can be made without departing from the scope of the claims. For example, FIGS 3A and 3B illustrate an example of a cannula securement 11 in an unfolded and a folded configuration respectively. In this example the first and second adhesive strips 20, 23 extend from opposite longitudinal (longitudinally oriented) edges 17c, 17d of the skin-protecting portion 15. The first and second adhesive strips 20, 23 are foldable along the longitudinal edges 17c, 17d of the skinprotecting portion 15 from which they extend, over first and second sections 18, 19 of the skin-protecting portion 15 respectively, and, when thusly folded, extend over and beyond a transverse edge 17a of the skin-protecting portion 15 to enable adherence to skin located to the side (in a longitudinal dimension) of this transverse edge 17a. FIGS 4A and 4B illustrate another example of a cannula securement 11 in an unfolded and a folded configuration respectively. In this example the first and second adhesive strips 20, 23 extend transversely away from edges 17e, 17f of the skinprotecting portion 15. These edges 17e, 17f have both longitudinal and transverse components. They are diagonally oriented and thus may be particularly suitable for use with cannulas having triangular wings. The first and second adhesive strips 20, 23 are foldable along the diagonally oriented edges 17e, 17f of the skin-protecting portion 15 from which they extend, over first and second sections 18, 19 of the skinprotecting portion 15 respectively, and, when thusly folded, extend over and beyond a transverse edge 17a of the skin-protecting portion 15 to enable adherence to skin located to the side (in a longitudinal dimension) of this transverse edge 17a. FIGS 5 and 6 illustrates other examples of a cannula securement 11 in unfolded configurations wherein a section 29 of the skin-protecting portion 15 which lies between the first and second sections 18, 19, over which the adhesive strips 20, 23 are to be folded, is extended in a longitudinal dimension. This central section 29 is extended so as to be able to underlie more of the hub 2 than only that portion of the hub 2 lying directly between the first and second wings 3, 4. This central section 29 may be extended so as to be able to underlie all of the hub 2. The extension is shown in dashed lines in FIGS 5 and 6. In the example of FIG 5, this central section 29 of the skin protecting portion 15 extends longitudinally in an opposite direction from the first and second adhesive strips 20, 23 in the unfolded configuration. The central section 29 extends into the same direction as these adhesive strips 20, 23 are intended to be folded. The folding of these adhesive strips 20, 23 over the wings 3, 4 of the cannula 1 and adhering of these to skin may exert a pitching moment on the cannula 1. This can result in the hub 2 being pressed more strongly against the skin on that side of the wings 3, 4 to which the adhesive strips 20, 23 are folded and adhered. In the example of FIG 5, the central section 29 is extended underneath the portion of the hub 2 which may be more strongly pressed against the skin and thus provides enhanced skin protection. In the example of FIG 6, this the central section 29 of the skin protecting portion 15 extends longitudinally into the gap between the first and second adhesive strips 20, 23. Those parts of this longitudinally extended central section 29 which are adjacent the adhesive strips 20, 23 are separated from the adhesive strips 20, 23 by slot or slit or may be separable from the adhesive strips 20, 23 along, for example, a line of perforations provided to facilitate the separation. It is to be appreciated that rather than extending exclusively in one longitudinal direction, this central section 29 may be extended in both longitudinal directions. Thus, rather than being T-shaped as in FIGS 5 and 6, the skin-protecting portion may be cross-shaped (e.g., + -shaped). Though the examples of the cannula securement 11 in FIGS 5 and 6 are shown with adhesive strips 20, 23 which extend from the skin-protecting portion 15 in the manner of the example of FIGS 2A to 2C, it is to be appreciated that the extending of a central section 29 of the skin-protection portion 15 in a longitudinal dimension may also be implemented with the examples of FIGS 3A and 3B and FIGS 4A and 4B. In some examples the cannula securement 11 is used in combination with an adhesive dressing 31 to provide a two-part, or more generally multi-part, cannula dressing 51. FIGS 7A and 7B illustrate an example of the adhesive dressing 31. An elevation is shown in FIG 7A and a plan is shown in FIG 7B. FIG 8 illustrates the multi-part cannula dressing 51 in use in a cannula system 61. The adhesive dressing 31 is substantially planar, comprising two opposite faces 32, 33 which may be joined to one another along each of their edges. It may be rectangular, in some examples with rounded corners. The adhesive dressing 31 is configured to be applied over the cannula 1 to be secured and a portion of the skin surrounding the cannula 1. Therefore, at least in the transverse dimension, the adhesive dressing 31 is larger than the cannula 1 to be secured, specifically larger than the wing span of the cannula 1 to be secured. In some examples, the adhesive dressing 31 is sized to be larger than the planform of the cannula 1 to be secured. Preferably, though not necessarily, the adhesive dressing 31 is larger, in both longitudinal and transverse dimensions, than the cannula securement 11 or at least the cannula securement 11 in its folded configuration. The transverse dimension of the adhesive dressing 31 is defined by the orientation of an edge 34 which comprises a substantially keyhole-shaped notch 35. That is, the adhesive dressing 31 comprises a substantially keyhole-shaped notch 35 in one transverse edge 34. The substantially keyhole-shaped notch 35 comprises a slit or a slot 35a extending from the transverse edge 34 to an aperture 35b inset from the edge 34. The aperture 35b is of larger diameter than the width of the slit or slot 35a. The narrowest diameter of the aperture 35b (shortest cord passing through a centre of the aperture 35b) corresponds to the outer diameter of the hub 2 of the cannula 1 to be secured. The substantially keyhole-shaped notch 35 is configured to enable the dressing 31 to wrap around the hub 2 of the cannula 1 to be secured in order to expose a portion 2a of the hub 2, for example for access by a medical professional such as to enable attachment or detachment of the external device, whilst adhering to skin under the exposed portion 2a of the hub 2. That is, the shape of the notch 35 enables the adhesive dressing 31 to wrap underneath the exposed portion 2a of the hub 2 and adhere to the skin under the exposed portion 2a of the hub 2 via those portions of the dressing 31 adjacent to the slot or slit 35a. The portion adjacent the notch 35b may be configured to adhere to the hub 2. The adhesive character of the adhesive dressing 31 is provided by an adhesive layer 36. The adhesive layer 36 may be provided by a single continuous layer of adhesive provided completely over one face 32 of the dressing 31. Alternatively, the adhesive layer may be a discontinuous layer, provided only over certain areas of that face 32, including at least marginal areas adjacent the perimeter of the dressing 31. In some examples the adhesive layer 36 comprises a skin-suitable / safe adhesive formulation. The adhesive formulations may comprise, for example, a spray-on adhesive, adhesive film, polymer-based pressure sensitive adhesive. The adhesive formulation may comprise an antibacterial agent to aid in maintaining a sterile intravenous insertion site. The adhesive dressing 31 may be provided with one or more removable release liners covering the adhesive layer 36. Release liners may include any material or combination of materials that permit temporary bonding between release liner and adhesive layer 36. Examples of compatible materials for release liners include plastic film, paper, plastic, metal foil, plastic coated paper, wax coated paper, wax coated plastic, plastic coated foil, and wax coated foil. They can also be coated, impregnated, or layered with a release agent, an anti-microbial agent, or both. In some examples the adhesive dressing 31 comprises two reinforcing strips 37, 38, oriented longitudinally. The two reinforcing strips 37, 38 may be spaced apart in a manner corresponding to the spacing of the first and second sections 18, 19 of the skin-protecting portion 15 of the cannula securement 11. That is, the two reinforcing strips 37, 38 may be spaced apart in a manner corresponding to the spacing of the first and second adhesive strips 20, 23 of the cannula securement 11, particularly when they are folded over the skin-protecting portion 15 in the intended, afore-described manner. A purpose of the two reinforcing strips 37, 38 is to overlie the wings 3, 4 of the cannula 1 to be secured to reinforce the securement thereof. The two reinforcing strips 37, 38 overlie the first and second adhesive strips 20, 23 of the cannula securement 11 to reinforce their securement of the wings 3, 4 of the cannula 1 to the patient’s skin 6. Accordingly, when the adhesive dressing 31 is flat, the two reinforcing strips 37, 38 may be spaced apart by more than the wing span of the cannula 1 to be secured and thus also the width (wi) of the skin-protecting portion 15 of the cannula securement 11 or the gap between the first and second adhesive strips 20, 23 thereof because account needs to be taken of the manner in which the adhesive dressing 31 will be wrapped over the hub 2 of the cannula 1 when it is applied. The two reinforcing strips 37, 38 are spaced apart by at least the outer diameter of a hub 2 of the cannula 1 to be secured and by less than a sum of an outer circumference of the hub 2 and the wing span of the cannula 1 to be secured. In some examples the two reinforcing strips 37, 38 are parallel. In others they may be convergent or divergent towards either or both transverse edges of the adhesive dressing 31. In some examples the adhesive dressing 31 comprises further reinforcing strips 39-41 configured to reinforce a perimeter of the substantially keyhole-shaped notch 35 and at least the transverse edge 34 of the dressing 31 in which the notch 35 is provided. The reinforcing strips 37-41 may be made from porous, nonwoven material. In some examples this porous, nonwoven material may be hypoallergenic and / or adhesive. In some examples the adhesive dressing 31 comprises a transparent film 42 coated in the layer of adhesive 36. The transparent film 42 can be formed from polyurethane. The transparent film 42 can be moisture vapor permeable. The transparent film 42 can be water resistant to provide a barrier to contamination by bacteria or liquids. In some examples the reinforcing strips 37-41 are embedded in the transparent film 42. Although not shown, the multi-part cannula dressing 51 can comprise further parts besides the cannula securement 11 and the adhesive dressing 31 described in the foregoing. For example, further adhesive strips for wrapping over the hub 2 of the cannula 1 to be secured may be provided. The multi-part cannula dressing 51 may be provided in a protective sealed wrapper made of, e.g., a coated paper and / or plastic and / or aluminium. Turning finally to FIG 8, a cannula system 61 is shown which comprises a cannula 1 for accessing veins or arteries of a patient and the multi-part dressing 51 described in the foregoing. The cannula comprises a hub 2 and wings 3, 4 on either side of the hub 2. At least a portion of each wing 3, 4 and at least a portion of the hub 2 located between the wings 3, 4 rest on top of the skin-protecting portion 15 of the cannula securement 11. The first adhesive strip 20 of the cannula securement 11 is folded over and adhered to a first wing 3 of the cannula 1 and extends beyond the first wing 3 to enable adherence to skin of the patient. Likewise, the second adhesive strip 23 of the cannula securement 11 is folded over and adhered to a second wing 4 of the cannula 1 and extends beyond the second wing 4 to enable adherence to skin of the patient. The adhesive dressing 31 is applied over the cannula 1 and cannula securement 11 and adhered to the cannula 1 and extends beyond the cannula 1 to enable adherence to skin of the patient. In some examples it is adhered to whichever parts of the cannula 1 it is brought into contact with. It will also be adhered to the cannula securement 11. The portion of the adhesive dressing 31 adjacent the substantially keyhole-shaped notch 35 is adhered around the hub 2 of the cannula 1 to expose a portion 2a of the hub 2 for access by a medical professional whilst enabling adherence of the adhesive dressing 31 to skin of the patient under the exposed portion 2a of the hub 2. The cannula system 61 may assembled into the form described in the foregoing and then be applied to the patient. Applying it to the patient may first involve cleaning and preparing the cannulation site, inserting the shaft 5 of the cannula 1 through the skin 6 of the patient into a vein or artery and then pressing the exposed adhesive areas of the multi-part cannula dressing 51 onto the patient’s skin 6. Alternatively, it may be applied piecewise by first cleaning and preparing the cannulation site and then inserting the shaft 5 of the cannula 1 through the skin 6 of the patient into a vein or artery. The multi-part cannula dressing 51 may be applied to secure an inserted cannula 1 to the skin 6 of the patient in which it is inserted by: placing the skin-protecting portion 15 of the cannula securement 11 beneath the cannula 1 with the hypoallergenic padding 16 in contact with the skin 6, in some examples exposing an adhesive layer on the opposite face 14 of the skin-protecting portion 15 first in order to secure the cannula 1 to this portion 15; exposing the adhesive layer 26 covering the first and second adhesive strips 20, 23 and folding these over the wings 3, 4 of the cannula 1 so that they adhere thereto and then also to the skin 6 beyond the wings 3, 4; and exposing the adhesive layer 36 covering the adhesive dressing 31 and applying it over the cannula 1 and cannula securement 11 so that it adheres to both, and preferably tightly around the hub 2 using the notch 35, and adheres also to a portion of the surrounding skin 6. Where a structural feature has been described, it may be replaced by means for performing one or more of the functions of the structural feature whether that function or those functions are explicitly or implicitly described. The term ‘comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use ‘comprise’ with an exclusive meaning then it will be made clear in the context by referring to “comprising only one...” or by using “consisting”. In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term ‘example’ or ‘for example’ or ‘can’ or ‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus ‘example’, ‘for example’, ‘can’ or ‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be used in that other example. Although examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims. Features described in the preceding description may be used in combinations other than the combinations explicitly described above. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not. The term ‘a’, ‘an’ or ‘the’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a / an / the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use ‘a’, ‘an’ or ‘the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of ‘at least one’ or ‘one or more’ may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning. The presence of a feature (or combination of features) in a claim is a reference to that feature or (combination of features) itself and also to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The equivalent features include, for example, features that perform substantially the same function, in substantially the same way to achieve substantially the same result. In this description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described. The above description describes some examples of the present disclosure however those of ordinary skill in the art will be aware of possible alternative structures and method features which offer equivalent functionality to the specific examples of such structures and features described herein above and which for the sake of brevity and clarity have been omitted from the above description. Nonetheless, the above description should be read as implicitly including reference to such alternative structures and method features which provide equivalent functionality unless such alternative structures or method features are explicitly excluded in the above description of the examples of the present disclosure. Whilst endeavoring in the foregoing specification to draw attention to those features believed to be of importance it should be understood that the Applicant may seek protection via the claims in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not emphasis has been placed thereon. l / we claim:

Claims

1. A cannula securement for securing a winged cannula to skin of a patient, the cannula securement comprising:a skin-protecting portion, having a width at least equal to a wing span of the cannula to be secured;a first adhesive strip, extending from and foldable over a first section of the skin-protecting portion and having a length sufficient, when thusly folded, to enable adherence to skin of the patient located to a side of the skin-protecting portion which is other than that side from which it extends; anda second adhesive strip, extending from and foldable over a second section of the skin-protecting portion and having a length sufficient, when thusly folded, to enable adherence to skin of the patient located to a side of the skin-protecting portion which is other than that side from which it extends,wherein the skin-protecting portion comprises hypoallergenic padding on an opposite face of the cannula securement to an adhesive layer providing adhesive character to the first and second adhesive strips.

2. The cannula securement of any preceding claim, wherein the first and second adhesive strips are each of a length sufficient to extend at least 3 mm beyond the side of the skin-protecting portion when folded over the skin-protecting portion.

3. The cannula securement of any preceding claim, wherein the first adhesive strip is of a length sufficient, when folded over a first wing of the cannula resting on top of the first section of the skin-protecting portion, to enable adherence to skin of the patient located to a side of the skin-protecting portion which is other than the side of the skin-protecting portion from which it extends.

4. The cannula securement of claim 3, wherein the first and second adhesive strips each comprise a wing-adhering section proximal to the skin-protecting portion and a skin-adhering section distal to the skin-protecting portion.

5. The cannula securement of claim 4, wherein the wing-adhering section is of length equal to a wing of the cannula to be secured and the skin-adhering section is of length of at least 3 mm.

6. The cannula securement of any preceding claim, wherein the first and second adhesive strips extend longitudinally from a transverse edge of the skin-protecting portion.

7. The cannula securement of claim 6, wherein the first and second adhesive strips extend in parallel and are separated by a gap.

8. The cannula securement of claim 7, wherein the gap is greater than an outer diameter of a hub of the cannula to be secured, or at least an outer diameter of a portion of the hub located between the wings.

9. The cannula securement of any preceding claim, wherein the adhesive layer comprises a skin-suitable / safe adhesive formulation.

10. The cannula securement of any preceding claim, wherein a thickness of the hypoallergenic padding is between 0.5 - 4 mm, at least when uncompressed.

11. The cannula securement of any preceding claim, comprising a flexible substrate providing a base for the hypoallergenic padding and the adhesive layer.

12. A multi-part cannula dressing comprising:the cannula securement of any preceding claim; andan adhesive dressing, configured to be applied over the cannula and a portion of the surrounding skin,wherein the adhesive dressing comprises a substantially keyhole-shaped notch in one edge which is configured to enable the dressing to wrap around a hub of the cannula to be secured in order to expose a portion of the hub for access by a medical professional whilst adhering to skin under the exposed portion of the hub.

13. The multi-part cannula dressing of claim 12, wherein at least one dimension of the adhesive dressing is greater than the wing span of the canula to be secured.

14. The multi-part cannula dressing of claim 12 or claim 13, wherein the adhesive dressing comprises two reinforcing strips.

15. The multi-part cannula dressing of claim 14, wherein the two reinforcing strips are substantially parallel.

16. The multi-part cannula dressing of claim 14 or claim 15, wherein the two reinforcing strips are spaced apart by at least the outer diameter of a hub of the cannula to be secured.

17. The multi-part cannula dressing of any of claims 14 to 16, wherein the two reinforcing strips are spaced apart by less than a sum of a circumference of the hub and the wing span of the cannula to be secured.

18. The multi-part cannula dressing of any of claims 14 to 17, wherein the two reinforcing strips overlie the first and second adhesive strips of the cannula securement to further reinforce their securement of the wings of the cannula when the adhesive dressing is applied over the cannula securement.

19. The multi-part cannula dressing of any of claims 12 to 18, wherein the adhesive dressing comprises further reinforcing strips configured to reinforce a perimeter of the substantially keyhole-shaped notch and the edge of dressing in which the notch is provided.

20. The multi-part cannula dressing of any of claims 12 to 19, wherein the adhesive dressing comprises a transparent film coated in a layer of adhesive comprising a skin-suitable / safe adhesive formulation.

21. A cannula system comprising:a cannula for accessing veins or arteries of a patient, the cannula comprising a hub and wings on either side of the hub; andthe multi-part cannula dressing of any of claims 12 to 20,wherein at least a portion of each wing and at least a portion of the hub located between the wings rests on top of the skin-protecting portion of the cannula securement,wherein the first adhesive strip of the cannula securement is folded over and adhered to a first wing of the cannula and extends beyond the first wing to enable adherence to skin of the patient,wherein the second adhesive strip of the cannula securement is folded over and adhered to a second wing of the cannula and extends beyond the second wing to enable adherence to skin of the patient,wherein the adhesive dressing is applied over the cannula and cannula securement and adhered to the cannula and extends beyond the cannula to enable adherence to skin of the patient, andwherein a portion of the adhesive dressing adjacent the substantially keyholeshaped notch is adhered around the hub of the cannula to expose a portion of the hub for access by a medical professional whilst enabling adherence of the adhesive dressing to skin of the patient under the exposed portion of the hub.A

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