What is claimed is
1. A nasal cannula designed for contact with the philtrum of a patient's upper lip, comprising:
2. A cannula according to claim 1 wherein the upper and lower surfaces of the lip plate are approximately circular in curvature and each describes an angle of approximately 90° of arc.
3. A nasal cannula comprising:
4. A cannula according to claim 3 wherein the upper surface of the lip plate is approximately circular in curvature and describes an angle of approximately 90° of arc, the lip plate has a gradually decreasing width from the fixed end at the point of juncture with the main tubular portion to the free end thereof, the free end having a width generally equal to the width of the patient's philtrum for limiting the amount of contact between the nasal cannula and the patient's upper lip.
5. A nasal cannula designed for contact with the philtrum of a patient's upper lip, comprising:
BACKGROUND OF THE INVENTION
The present invention relates to a nasal cannula for use in the administration of fluids such as oxygen into the nasal passages of a convalescent or a person having respiratory ailments and in particular to a cannula which is both positionable and self-positioning on the upper lip of a patient's face just below the patient's nose.
In the field of respiratory ailments and post operative convalescence a relatively new discipline known as inhalation therapy has in recent years assumed significance and importance as increased understanding and appreciation of the significance of proper and continuing administration of fluids to a patient for proper respiration has increased. This has been accomplished in a number of ways including the use of oxygen masks and catheters, both of which types of devices have been in use for a relatively long time.
Oxygen masks are used in specialized situations where the administration of the fluid is intended to take only a relatively short time. These masks are usually unsatisfactory where it is desired to administer such fluids for an indefinite period of time, for example, in supplying oxygen to a bedridden patient. One alternative when such situations have occurred in the past has been to utilize a catheter which is inserted into one of the nostrils of the patient and passed into the pharynx and the esophagus. Another has been to employ a nasal cannula.
Since the use of catheters usually has associated with it a significant amount of patient discomfort, particularly where the patient is not unconscious or under heavy sedation, nasal cannulas have usually been preferred. In their original form such devices were rigid metallic devices which were strapped in varying fashion to the patient's head and were provided with nasal extensions of varying lengths which extended from a main fluid supply tube or reservoir to a point just inside the patient's nostrils. Such devices were reusable but as can readily be appreciated rigorous sterilization was necessary after use on a given patient. As the virulence of various respiratory ailments and the limitations of sterilization have received greater recognition, it has been the increasing tendency in the field of inhalation therapy to utilize disposable fluid administration apparatus which are used in the treatment of a single patient only and immediately discarded after completion of use with no attempt being made to sterilize or reuse the apparatus on another patient. Illustrations of disposable nasal cannula devices of this type can be found in patents such as U.S. Pat. Nos. 2,693,800 and 2,931,358.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a nasal cannula comprising a hollow tubular portion open at each end, a first hollow nasal extension communicating with the interior of the tubular portion, a second hollow nasal extension spaced from and parallel to the first extension, also communicating with the interior of the tubular portion and a flexible, curved lip plate extending from the tubular portion at a location approximately centered between the nasal extensions, said plate extending generally outwardly from the tubular portion and downwardly in a direction opposite to the direction of extension of the nasal extensions whereby the cannula is caused to be balanced and positioned on a patient's upper lip so as to comfortably position the nasal extensions in the patient's nostrils.
A device is thus provided that is suitable for injection molding from a soft and flexible material such as polyvinylchloride to produce a disposable nasal cannula which is essentially non-irritating to the user. In a complete assembly the cannula has a pair of auxiliary fluid supply tubes connected to opposite ends of the tubular portion thereof which extend to an adapter-connector for an essentially fluid-tight connection to a main fluid supply tube and thence to a fluid supply device such as an oxygen humidifier. A slip loop may be optionally provided around the auxiliary oxygen supply tubes for cinching the cannula in position on the patient. Typically the auxiliary oxygen supply tubes extend from the tubular portion over the ears of a patient and then either down in front of the neck of the patient or back over the crown of the head.
The provision of a lip plate preferably formed integrally with the cannula enables the positioning of the cannula at various positions on the upper lip of the patient between the extreme of having the upper side of the tubular portion between the cannula extensions bear against the patient's septum and a position where the free ends of the nasal extensions barely enter the patient's nostrils. Regardless of where it is located along the patient's upper lip, the flexible plate provides a spring action for the cannula and enables it to assume the proper angular orientation with respect to each individual patient's nostrils so as to center the nasal extensions within the nostrils and prevent the fluid flow from being directed at too high or too low an angle into the nostrils.
The lip plate preferably has an approximately trapezoidal shape with the minor base being located at the free end thereof and its width being selected so as to approximate the width of the philtrum on the patient's upper lip. This permits mating engagement of the lip plate and this portion of the patient's anatomy so as to impede side to side shifting of the cannula once mounted on the patient and, in effect, safeguard against lateral slipping which might cause the nasal extensions to become "cocked" or to bear against and irritate the sides of the nostrils.
The lip plate provides additional advantages in that the point of support and mounting when in position on a patient is located at a point removed from and below the center of mass of the cannula permitting the cannula to be spaced slightly away from the face and to achieve a lower equilibrium position which is significantly more comfortable to the patient. It has been quite typical of prior art cannulas that complaints of the cannula riding "too high" have frequently been encountered. The lip plate also provides positive prevention of the cannula from rolling out of the patient's nostrils while at the same time riding lightly on the patient's upper lip so as to permit the patient to shift its position slightly in a vertical direction by the expedient of flexing his upper lip.
Additional advantages of the nasal cannula of the present invention include significantly less irritation to the patient because of reduced skin contact (it has been found that irritation sometimes results when skin acids react with PVC or when the cannula has been improperly sterilized). When provided with flared free ends on the nasal extensions an additional advantage is present in that the gas or fluid supplied is allowed to diffuse gently within the nostrils reducing the "gas jet" action which has been particularly characteristic of extensions having small, constricted fluid outlets.
DESCRIPTION OF THE DRAWINGS
These and other advantages of the present invention will be better understood by reference to the drawing wherein:
FIG. 1 is a front view of a cannula assembly according to the present invention in position on a patient;
FIG. 2 is a side view of the illustration shown in FIG. 1;
FIG. 3 is an enlarged plan view of a complete cannula assembly including the cannula auxiliary and main fluid supply tubes;
FIG. 4 is a sectional view taken along lines 4--4 of FIG. 3; and
FIG. 5 is an elevation view of an alternate embodiment of the present invention utilizing straight, non-flared nasal extensions.
DESCRIPTION OF A SPECIFIC EMBODIMENT
A cannula assembly 10, according to the present invention, is shown in FIGS. 1, 2 and 3 as it would be worn by a patient to whom fluids such as oxygen are to be administered. The assembly comprises the nasal cannula 12, a pair of auxiliary oxygen supply tubes 14 and 16 connected to opposite ends of cannula 12, a main oxygen supply line 18, a connector 20 for joining auxiliary tubes 14 and 16 to supply tube 18 and a slip loop 22 disposed about auxiliary tubes 14 and 16. The nasal cannula 12, the structural features of which will be discussed in more detail in conjunction with FIGS. 3 and 4, is preferably fabricated of injection molded polyvinylchloride having a durometer rating of 55. The auxiliary supply tubes 14 and 16 extend into the open ends of the main tube 30 of cannula 12 a predetermined distance and are secured in place therein by a suitable bonding agent. Connector 20, which also serves as an adapter permitting a single main line 18 to supply oxygen or other fluid to the pair of auxiliary tubes 14, 16 and to communicate therewith in a fluid-tight manner, is provided with a first half 21 for receiving the main oxygen supply tube 18. The end of tube 18 extends a predetermined distance into connector 20 and is friction fitted or bonded in place therein. The opposite half of connector 20 is provided with a pair of ports 24 and 26 for receiving the ends of the auxiliary tubes 14 and 16. The auxiliary tubes likewise extend a predetermined distance into ports 24 and 26 and are friction fitted or bonded in place therein.
As is illustrated in FIGS. 1 and 2, the cannula assembly is adapted for mounting in an "over the ear" configuration. The auxiliary supply tubes 14 and 16 can then optionally be brought down along the sides of the patient's neck with a slip loop 22 being located in front of the patient as shown or they can extend to the back of the patient's head with the slip loop 22 being located beyond this point as shown in the ghosted portion of the illustration. In either case the slip loop can be moved along the longitudinal extent of the auxiliary tubes 14, 16 to "cinch" the cannula assembly 10 in position on the patient. Loosening and tightening the loop formed by the cannula and auxiliary supply tubes permits adjustment of the tension in the loop and the angle of the cannula with respect to the patient's nose to achieve maximum patient comfort.
The cannula 12 is configured so as to be positioned on the upper lip of the patient to whom the fluid is to be administered with a pair of nasal extensions 32, 34 which communicate with the hollow interior of a main tubular portion 30 of the cannula extending from the main tube into the patient's nostrils. A lip plate 36 integrally formed with the tubular portion 30 extends outwardly and downwardly from the cannula body on the side of the cannula adjacent the patient's face for providing a positioning bar to properly orient and locate the cannula with respect to the patient's nose and upper lip.
Certain additional structural details of the cannula assembly are shown in FIG. 3, a plan view of the entire cannula assembly. As shown therein, a tip 28 is provided on the end of main tube 18 opposite connector 20 for connection of the assembly to a fluid supply, for example, an oxygen humidifier. The entire assembly with the exception of the slip loop is preferably fabricated of injection molded polyvinylchloride, each of the various parts of the assembly having dimensions and physical configuration determined by its particular function. The slip loop is fabricated of a more rigid material such as high impact polystyrene.
FIGS. 3 and 4 illustrate the nasal cannula 12 of the present invention in greater detail. As shown therein, the cannula comprises a main tube 30, a first and second nasal extension 32 and 34, and a lip plate or flap 36. The main tube 30 is hollow and open at each end. The nasal extensions 32 and 34 are likewise hollow and communicate with the hollow interior of tube 30. In the embodiment of FIGS. 3 and 4, the nasal extensions have a flared configuration with the narrow ends 35 thereof being integrally formed with the main tube 30 and the free ends 37 thereof being wider, i.e., flared and ready for insertion into a patient's nostrils. In a presently preferred embodiment the wall thickness of nasal extensions 32 and 34 is approximately .020 inch with the wall thickness of the main tube being approximately .125 inch and the thickness of the lip plate being approximately .180 inch tapering to an approximate dimension of .040 inch at the free end thereof. The relatively thin walls of the nasal extensions provide additional softness and flexibility further reducing any potential for irritation to sensitive areas inside the patient's nostrils. Flaring of each nasal extension reduces the velocity of the fluid as it leaves the open end of the nasal extension permitting the fluid to more slowly diffuse into the patient's nasal passages.
The lip plate 36 is likewise integrally formed with the main tube and extends in a curved path outwardly and downwardly from the main tube. The plate 36 has a generally trapezoidal configuration with the major base 38 being located at the point of juncture with the main tube and being approximately centered with respect to the location of extensions 32 and 34. The flap then tapers down to the minor base 40 of the trapezoid which is the free end of the lip flap. The physical dimensions of the lip plate given in the preceding paragraph are those utilized in a presently preferred embodiment. Depending on the specific application for the cannula, e.g., pediatric use, the thickness of the plate can be changed and the curvature adjusted to control the angle with respect to a reference point such as a vertical plane which the nasal extensions assume when placed on a patient.
The cannula 41 of FIG. 5 illustrates an alternate embodiment for the cannula of the present invention. Where preference of the patient or therapist dictates or use is intended on a patient with relatively small nostrils, nasal extensions 42, 44 are provided without a flared free end. The extensions are hollow as before and communicate with the interior of the main tube, but in this case have the configuration of a right cylinder. A lip plate 46 is again integrally formed with the cannula body and the ends 48, 50 of the main tubular portion of the cannula are open for connection to fluid supply lines (not shown).
By selecting the proper softness for the nasal cannula material, a non-irritating, precisely positioned, disposable cannula is provided by the present invention enabling safe, noncontaminating, efficient administration of fluids to a patient.