NASOPHARYNGEAL TUBES
This invention relates to nasopharyngeal tubes.
BACKGROUND
In head and neck surgeries, in order to maintain the 5 patency of the patient's airways post-operatively, it is common practice to insert an artificial airway in the form of a tube extending back into the pharynx from the mouth (oropharyngeal airway) or via the nose (nasopharyngeal airway). Note that in what follows, 10 "distal" refers to the end of the tube inserted the furthest into the patient's natural airway, while "proximal" refers to the part of the tube remaining at the outer opening of the mouth or nose. While both oropharyngeal and nasopharyngeal airways generally 15 consist of a flexible plastic tube with a flange at the proximal end, they have quite different characteristic shapes of the preformed (although flexible) tube. The flange is to prevent the tube from accidentally being pushed or sucked right into the mouth or nose. Thus, a 20 conventional oropharyngeal airway tube extends initially straight back from the front oval flange and then bends first Up and then down to fit over the back of the tongue. In contrast, a nasopharyngeal tube takes a long gentle curve all in the same direction back from the 25 proximal flange. In both tube types the distal end is smooth and bevelled so as to pass easily into the pharynx without catching.
THE INVENTION
We propose a development in nasopharyngeal tubes whose proximal flanges extend further to one side of the tube than to the opposite side, i.e. are eccentric around 5 the length axis of the tube. With a nasopharyngeal tube this feature enables the flange to be of substantial size, and project well beyond the side of the nostril so as to prevent overinsertion or sucking-in with high reliability and enable easy gripping of the tube during 10 suctioning or for withdrawal, while at the same time avoiding blocking the other nostril. The preferred construction has an eccentric flange which, while projecting radially to some extent all around the proximal end of the tube, projects at one side of the 15 tube as a substantial tab or projection of other shape, preferably projecting at least one tube diameter laterally beyond the outer surface of the main run of the tube. To project in the proper direction relative to the nose in use, the direction of projection is substantially 20 perpendicular to the plane in which the tube is curved.
A particular new proposal is to make the eccentric projection at the proximal end of the tube rotatable around the tube length axis relative to the main run of the tube. By this means the tube can be used in either 25 nostril without blocking the free nostril (not possible with a fixed eccentric flange) and furthermore can be positionally adjusted, for use of the tube in a given
nostril, to the most convenient and comfortable position for the shape of the patient's nose and face.
In a preferred construction the eccentric flange is provided as a discrete component, optionally of a stiffer 5 material than the material of the main tube, fitting around the tube as a collar and engaging behind (i.e. to the distal side of an abutment surface at the proximal end of the main tube component. This abutment surface may be provided by for example one or more 10 circumferentially localised radial projections around the proximal end of the tube, or by a general flaring or outwardly- directed notch or ledge at that end of the tube. The preferred shape of the other component is as an annular ring formed in one piece with a tab projection 15 to one side. Preferably the parts engage with a sufficiently close fit and area of surface to provide a frictional fit, so that although the lateral flange can be easily turned away from a given orientation, it will not do so spontaneously. This makes the airway easier to 20 use. Embodiments of the invention are now described with reference to the accompanying drawings, in which Fig. 1 is a side view of a nasopharyngeal tube embodying the invention; 25 Fig. 2 is a proximal end view of the same tube; Fig. 3 is a side view (on a smaller scale) showing the tube component alone with the end collar removed;
Figs. 4(a) and (b) are oblique views of the discrete collar from the distal and proximal sides respectively) Figs. 5 and 6 are proximal end views of the tube inserted into a patient's right and left nostrils 5 respectively, and Fig. 7 is a perspective view from the proximal side of a flange collar showing some optional refinements.
With reference to Figs. 1, 2 and 3, a nasopharyngeal tube embodying the invention as a main one-piece tube 10 component 1 of generally conventional form and material, e.g. PVC. The tube is of generally uniform cylindrical cross-section. It is gently curved in one plane along the main run of its length 13. At the distal end 11 it is cut off at an angle to form a bevelled leading end apt 15 for insertion through the nose and pharynx. At its proximal end 12 the tube has a slight outward flare with a somewhat conical outer surface 121 and correspondingly divergent inner surface.
In accordance with normal practice the tube may be 20 available in a range of different sizes to suit different height and sized patients. The base components of each airway may be colour coded according to size, following the colour coding system already used for suction tubes and catheters. Thus, clinicians would be able easily to 25 select the correct diameter tube or catheter to fit correctly with the internal diameter the nasopharyugeal airway. The tube's internal diameter would typically range from 5 to 10 mm. It will be noted from Figs. 1 and
2 that the tube 1 curves in a single plane. This, and the characteristic curved shape of the tube, are in themselves conventional.
A discrete flange collar 2 is fitted onto the tube 1 -
5 at its proximal end 12. The flange collar 2 is a one- = piece moulded plastics component e.g. of polyethylene, in the form of an annular collar 21 projecting at one side.
as a trapezoidal tab 22. The central opening of the -
collar 26 is a slight interference fit onto the outer 10 diameter (OD) of the tube 1, so that it can be easily s rotated around the tube's axis but will not do so spontaneously e.g. under gravity. The annular collar 21 has a recessed under-surface 25 approximately complementing the flared outer surface 121 of the tube's 15 proximal end 12. A proximal flare 12 prevents the flange collar 2 from being pulled off the end of the tube 1, so = that the collar 2 can be used as a means of gripping the tube when inserting a suction catheter into the airway or -
to pull it out of the nose when necessary.
20 The shape and dimensions of the projecting tab 22 are not critical, but they should of course be suitable 2 for the purpose in hand as a skilled person may easily determine. In this embodiment the projection FP of the -
teb 22 beyond the continuation of the main tube outer 25 diameter OD is at least as great as OD. The projection of CP of the collar 21 at other points around its = circumference is uniform and much less; not more than about half as much.
Fig. 5 shows the tube inserted into the right nostril of a patient's nose N. The collar 2 is easily swivelled around the tube 1 to leave the grip tab 22 projecting sideways beyond the side of the nose, enabling 5 easy withdrawal, preventing accidental over-insertion while not at all blocking the left nostril 30a. Fig. 6 shows how the same tube can be inserted into the left nostril leaving the right nostril 30b, simply by swivelling the collar 2 to point in the opposite 10 direction. It will of course be appreciated that the tube 1 itself cannot be rotated because its curve must be kept in the same direction relative to the patient's oropharynx. Fig. 7 shows some optional refinements. Firstly, 15 the provision of grip formations such as ribs 26 on the distal side of the grip tab 22. Secondly (and of course independently) the provision of a slot 27 through the grip tab which if wished can take a ribbon or cord for extra security. It will also provide an air passage if 20 the flange is accidentally positioned to occlude the other nostril.