Laryngoscope With Disposable Blade And Light Guide

Abstract

A laryngoscope including a wireless, disposable blade containing a relatively stiff light guide for transmitting light from a light source associated with the handle to a point substantially midway between the ends of an upper curved section of the blade. The preferred embodiment includes a blade having a straight light guide and an adaptor for connecting the blade to the handle and for mounting the light source in a position adjacent one end of the light guide.

Description

SUMMARY OF THE INVENTION

This invention relates to self-illuminating laryngoscopes generally, and more particularly to an improved reinforced disposable laryngoscope blade for use with a handle for providing a source of illumination.

BACKGROUND OF THE INVENTION

A laryngoscope is a type of device for assisting in the observation of the oral cavity, particularly the laryngeal areas. This device is frequently employed by an anaesthesiologist to aid in the placement of a tube into the larynx of a patient for the passage of anaesthetising gas. In order to obtain accurate placement, the instrument must be capable of restraining the patient's tongue while engaging the epiglottis to reveal the larynx for visual observation. The laryngoscope is also useful for general examination of the larynx. These functions are greatly aided by the use of a light source in association with the laryngoscope blade to produce localized illumination within the area to be examined. In the past, the association of a self contained light source with the conventional laryngoscope has resulted in numerous complications which among others included excessive cost due to the increased complexity and inconvenience resulting from the need for sterilization after every use. Experience with laryngoscopes having blade mounted light sources has also revealed that dependable performance is often impaired by damage to blade contained electrical circuits during blade sterilization. Furthermore, the heat generated by blade mounted light sources can possibly lead to injury of oral tissue or, at least, discomfort to the patient being examined; while, the need for strength has encouraged the use of metal blades thereby resulting in the possibility of damage to the patient's upper teeth unless protected from the hard metal surface.

Self-illumination was employed in early tongue depressors as illustrated by U.S. Pat. No. 1,246,339 to Smit. This patent discloses a tongue depressor suitable for dental and surgical work including a circular substantially straight blade of glass which allows light to be transmitted from one end of the blade to a localized area at the opposite end by means of internal reflection.

An improved illuminated tongue depressor is disclosed by U.S. Pat. No. 3,349,764 to Edinger which illustrates the use of a straight, substantially flat molded blade of transparent material which is intended to slide over an elongated light tube.

In an attempt to provide a tongue depressor of increased strength and to solve the heat problem inherent with self-illuminated depressors, U.S. Pat. No. 3,435,820 to Taub provides for a generally flat, self-illuminating tongue depressor which includes a heat shield to prevent heat transfer to the oral tissue of the patient from a light source mounted on the distal end of the depressor blade.

Unlike the tongue depressor, the peculiar requirements of the laryngoscope have led to the development of a curved blade structure, generally of metal, which possesses great strength. U.S. Pat. No. 2,289,226 to Foregger discloses a laryngoscope having a strong blade structure capable of performing the special functions required thereof. For laryngoscope applications, blades made of fragile or brittle materials would be unacceptable, due to the danger of broken pieces becoming lodged deep in the patient's throat.

The development of a laryngoscope incorporating a generally curved blade adapted to fit into the angle made by the epiglottis with the tongue is disclosed by U.S. Pat. No. 2,354,471 to MacIntosh. The strong curved blade of the MacIntosh device carries a light source and the circuitry therefor.

In U.S. Pat. No. 3,426,749 to Jephcott, a laryngoscope structure is illustrated which attempts to exploit the strength provided by the curved metal blade of the now conventional laryngoscope while minimizing the disadvantages arising from the provision of an electrical light circuit in such blade. Jephcott provides for the use of a disposable cover for a laryngoscope blade wherein the cover is formed of pre-sterilized, translucent material adapted to be pulled over the blade. By using translucent material, the light produced by a blade mounted light source is still capable of illuminating the laryngeal area.

Further advance in the art is provided by U.S. Pat. No. 3,507,272 to Laerdal which discloses a laryngoscope blade formed of soft plastic material upon which is mounted a light source near the distal end of the blade in the conventional manner.

While the above discussion demonstrates that significant advances have been made toward the development of an optimum laryngoscope blade having a self-illuminating feature, there still remains a need for a simply designed laryngoscope blade which combines the safety and strength inherent in the metal blade with the inexpensiveness and disposability of the plastic blade and, at the same time, provides a means for directing a sufficiently intense light to the exact area under observation. More particularly, there is a need for a laryngoscope blade employing a curved configuration having sufficient strength to withstand the forces necessary for drawing back a patient's lower jaw; however, the blade must not be brittle or subject to breakage in view of the danger that a broken piece could become lodged in the patient's throat. The blade should also be somewhat pliable in order to avoid damage to the upper teeth during insertion of the blade into the patient's mouth and should be sufficiently inexpensive to be disposable after a single use. Desirably, it should also possess the capability of self-illumination and more particularly of concentrating illumination within the laryngeal area; however, the light source must not be supported in a manner which would result in injurious heat transfer to the surrounding tissue. A need, therefore, exists for a self-illuminating laryngoscope blade which, in addition to the above, does not have a blade mounted light source and associated circuitry.

SUMMARY OF THE INVENTION

It is the object of this invention to provide an improved laryngoscope of substantial strength, convenience, low cost, and safety.

Another object of this invention is to provide a light-weight disposable laryngoscope blade capable of transmitting light by means of a light guide which light guide also provides strength to the laryngoscope blade.

A further object of this invention is to provide a disposable laryngoscope blade made of a relatively soft synthetic plastic containing a relatively stiff light guide for transmitting light and for providing strength to the laryngoscope blade, said light guide allowing the light source to be mounted within the blade handle.

Another object of this invention is to provide a disposable laryngoscope blade made of a relatively soft, pliable synthetic plastic containing a relatively stiff light guide for transmitting light and for providing strength to the laryngoscope blade which blade defines a cavity near the proximal end for receiving a handle projection carrying a light source wherein the projection has an axial length substantially greater than its diameter for attaching the disposable blade to the handle.

A further object of this invention is to provide a laryngoscope blade made of soft, pliable plastic and containing a relatively stiff light guide which is inexpensive to manufacture and can therefore be disposed after a single use.

A further object of this invention is to provide a disposable laryngoscope blade made of soft, pliable synthetic plastic for containing a relatively straight stiff light guide such that the outer plastic prevents broken parts of the guide from lodging in the throat of a patient should the light guide be broken in use.

A further object of this invention is to provide a laryngoscope adaptor for connecting a disposable laryngoscope blade to a standard light battery casing.

The foregoing and other objects of the invention will become apparent upon a consideration of the following specification and appended claims, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevational view in partial cross section of a laryngoscope incorporating the disposable, light guide reinforced, plastic blade of this invention;

FIG. 2 is a side elevational view in partial cross section of a modification of the laryngoscope of FIG. 1 which incorporates a laryngoscope adaptor according to the present invention, and

FIG. 3 is a perspective view of the laryngoscope adaptor of FIG. 2 incorporating an integral reflector element according to the present invention.

The laryngoscope, shown in cross section in FIG. 1, includes a blade 2 formed of a synthetic plastic sufficiently soft and pliable to minimize the danger of injurious contact with the teeth of the upper jaw of a patient, yet rigid enough to insure that the blade maintains its generally curved shape including a lower curved surface 4 generally approximating the shape of the lower surface of the human oral cavity and extending a sufficient distance to reach the epiglottis when inserted. Examples of suitable materials would be polyvinylchloride and polyethylene. The upper surface of the blade includes a first generally planar section 6 of the proximal end and a second curved section 8 extending from the first section to the distal end of the blade, said second section having a gradually increasing radius of curvature in the direction of the distal end. Blade 2 contains a light guide 10 for transmitting light as will be discussed below. The guide preferably serves to reinforce the blade, to render the blade sufficiently strong to withstand the forces incurred in drawing the patient's lower jaw forwardly such as when "intubing" an anaesthetist tube. Light conducting rods or fibers molded in a unitary bundle and curved to match the curvature of the blade 2 are molded into the blade of FIG. 1. The light guide extends toward the distal end of the blade and emerges through the blade surface substantially midway between the ends of the curved second upper section 8 whereby it is able to concentrate a projected light beam within the laryngeal area. The emerging light guide end 12 has a smooth surface flush with the second upper section surface which combines with the smooth outer surface of the remainder of the working blade to insure that no corners or edges exist along the entire upper and lower surfaces. The other end 14 of the light guide emerges through the closed end of a cavity 16 located at the proximal end of the blade defined by generally curved side walls having a longitudinal axis extending generally perpendicular to the longitudinal axis of the blade. The cavity 16 opens on the concave side of the curved lower surface 4 of the blade.

The laryngoscope shown in FIG. 1 also includes a handle body 18 including a hollow region containing dry cell batteries 20 and including a mounting disc 22 for supporting a socket and light bulb 24 within the hollow region. The batteries and light source are electrically connected by means of wire leads including an on-off switch 25. Also supported on disk 22 is a metal reflector 26 defining a center opening through which the light bulb passes. The reflector is so shaped and oriented as to cause a light beam to be projected upwardly generally along the longitudinal axis of the laryngoscope handle to the end 14 of the light guide. This beam passes through an upstanding projection 28 extending above the handle body and along the longitudinal axis of the handle. The projection has the same dimensions as cavity 16 and is adapted to fit snugly threrein. The axial length of the projection is substantially greater than the diameter and preferably equal to approximately twice the diameter. A tongue and slot and annular groove connection is provided on the projection and cavity surfaces respectively to releasably fasten the blade to the handle. However, any suitable fastening arrangement could be used such as screw threads or an annular groove and depression.

The projection length is made sustantially greater than its diameter in order to insure sufficient torque transmitting capability which in cooperation with the relative rigidity of the light guide 10 produces a laryngoscope of unusual strength.

FIG. 2 discloses a modification of the laryngoscope of FIG. 1 wherein like numerals refer to the same elements shown in FIG. 1. As can be seen, the light guide 30 is straight rather than curved as shown in FIG. 1, which configuration renders the disposable blade less expensive to manufacture. The blade 2 is molded to include an internal channel 32 which extends from the curved second upper section 8 and opens into the blade cavity 16. Light guide 30 resides in this cavity and has one end emerging substantially midway between the ends of curved section 8 and the other end emerging in the side wall of cavity 16. The blade cavity must be extended further into the blade to provide sufficient space for enclosing the light source 24 which has been mounted in projecting fashion on an adaptor 34 having a connector section 36 removably attached to the laryngoscope handle 18. The adaptor includes a cylindrical projection 37 (equivalent to the projection 28 of FIG. 1) shaped to fit snugly within cavity 16 and to be held there by means of a suitable known connection; i.e., threads, tongue and groove, etc. The projection 37 has a longitudinal length substantially greater than its diameter; the longitudinal length being preferably equal to approximately twice the diameter. The longitudinal length is such that the light source is positioned adjacent one end of the light guide. The lower end of the projection is closed and bears on electrical contact 39 which establishes an electrical connection with the batteries within the laryngoscope handle. The upper end of the projection 37 is formed to provide a socket for the bulb 24, and an electrical circuit 41 connects this socket with the contact 39.

As further shown in FIG. 2, the inside surface of the cavity 16 opposite the light guide can be coated with a reflective material 35 for forming, in combination with the light source, a light beam oriented generally along the longitudinal axis of the light guide.

FIG. 3 shows a perspective view of the adaptor of FIG. 2 which has been modified by forming an annular groove 38 about the end of the body portion 37. A semi-cylindrical reflector 40 having a radius equal to the radius of cylindrical body portion 37 is attached to the groove 38 in order to eliminate the need for reflective material 35 in the laryngoscope blade shown in FIG. 2.

The adaptor 34 is intended to permit many battery containing handles to be used with the blade 2 of FIG. 2. Thus the connector section 36 thereof may be threaded, as illustrated in FIG. 2, for attachment to a threaded handle. Here the adaptor contact 39 establishes a direct electrical circuit with the handle supported batteries.

For other handles, the connector section 36 would be varied in construction to permit the adaptor to be connected to the handle. Also, some known laryngoscope handles have a contact on the top wall thereof which provides an electrical connection to the batteries inside. For a handle of this type, the adaptor contact 39 would rest against the handle contact rather than directly against a battery terminal.

The straight light guide 30 of FIG. 2 would be molded into the blade 2, but preferably is inserted into the channel 32 in the blade after the blade is formed. This permits a straight rod of Lucite to be used as the light guide. Such a rod might prove to be both too hard and too brittle for laryngoscope blade use if it were not encased in the protective blade 2, but the rod so encased imparts rigidity and strength to the blade.

A disposable, synthetic plastic laryngoscope blade has been disclosed having unusual strength due to the reinforcement of a relatively stiff light guide which guide also provides the means for transmitting light from a source to a point near the distal end of the blade. Furthermore, even if the relatively stiff light guide should fracture during use, the soft pliable plastic of the blade would prevent the broken portion from becoming lodged in the patient's throat. In addition to these advantages, the soft plastic also prevents damage to the patient's teeth during insertion of the blade. By using a light guide, the light source may be mounted in the laryngoscope handle, simplifying and reducing the cost of the blade while at the same time allowing a light beam to be focused only on that area of the oral cavity under observation instead of being diffused throughout the entire cavity. Handle mounting of the light source within an integral projection or on an adaptor also eliminates the disadvantage of heat transfer to adjacent tissue known to be a problem in prior art laryngoscopes having blade mounted light sources and insures the dependable operation of the light source and associated circuitry because the source and circuitry do not have to be sterilized after each use as when mounted on a non-disposable blade.

Claims

I claim:

1. A disposable laryngoscope blade adapted at the proximal end thereof to be mounted on a handle having a light source and adapted to transmit light from the light source to the distal end of the blade, comprising

a. a blade element having a first curved surface generally approximating the shape of the upper surface of the human tongue and extending sufficiently to reach the epiglottis when the blade is inserted into the oral cavity said blade element being formed of a relatively pliable plastic material sufficiently soft to avoid the danger of injurious contact with the teeth of a patient;

b. connection means for removably connecting the proximal end of the blade to the handle; and

c. light guide means for transmitting light from a point adjacent the proximal end of the blade to a point adjacent the distal end and for stiffening said blade element, said light guide means including a light conducting rod in contact with and encased by the blade element along the entire longitudinal external surface of the light conducting rod and being relatively more rigid than said blade element to stiffen said blade element.

2. The disposable laryngoscope blade of claim 1 wherein said blade element includes a first surface having a curved section terminating at the distal end of the blade, said curved section having a gradually increasing radius of curvature in the direction of the distal end and wherein one end of said light guide means emerges substantially midway between the ends of said curved section, said one end being flush with the surface of said curved section.

3. The disposable laryngoscope blade according to claim 1 wherein said connecting means includes a generally curved side wall and one closed end wall defining a cavity in the proximal end of the blade element, the longitudinal axis of said curved wall is perpendicular to the longitudinal axis of said blade element, said curved wall defines an opening opposite the closed end, said opening is on the concave side of said first curved surface.

4. The laryngoscope blade according to claim 3 wherein said light guide means is straight and one end of said light guide means emerges through said curved wall of said cavity.

5. The laryngoscope blade according to claim 3 wherein said light guide means is curved and one end of said light guide means emerges through said closed end wall of said cavity.

6. A self-illuminating laryngoscope for examining the laryngeal area of a human, comprising

a. a disposable blade element formed of pliable plastic including

1. a first curved surface generally approximating the shape of the upper surface of the human tongue and extending sufficiently to reach the epiglottis when the blade element is inserted into the oral cavity;

2. a second surface including a curved section terminating at the distal end of the blade, said curved section having a gradually increasing radius of curvature in the direction of the distal end;

b. handle means for supporting said blade, said handle means including

1. a handle body,

2. a cylindrical projection at one end of said handle body, and

3. a light source mounted on the outer end of said cylindrical projection;

c. connecting means for removably connecting said blade element to said handle means, said connecting means including a cavity contained within the proximal end of said blade element, said cavity having a longitudinal axis perpendicular to the longitudinal axis of said blade element and having an open end on the concave side of said first curved surface, said cavity further having a diameter approximately equal to the diameter of said cylindrical projection of said handle means to permit said blade element to be fitted snugly over said cylindrical projection; and

d. light guide means for transmitting light from said light source to the distal end of said blade and for stiffening said blade element, said light guide means including a straight rod surrounded by and in contact with said blade element along the entire longitudinal exterior surface of said rod, said rod emerging at one end into said cavity at a point adjacent said light source when said blade element is mounted on said handle means and emerging at the other end at a point substantially midway between the ends of said curved section of said blade element, said rod being relatively more rigid than said blade element to stiffen said blade element.

7. The self-illuminating laryngoscope according to claim 6 wherein said cavity includes a reflective coating opposite said one end of said rod.

8. The self-illuminating laryngoscope according to claim 6 wherein said cylindrical projection includes a reflector extending axially from said outer end of said cylindrical projection, said reflector being positioned opposite said one end of said rod when said blade element is mounted on said handle means.

9. A self-illuminating laryngoscope according to claim 6 wherein said handle means includes a standard sized battery case and connector means for removably attaching said projection to said battery case.

10. A self-illuminating laryngoscope according to claim 9 wherein said handle means further includes

a socket mounted at one end of said projection for receiving said light source;

a contact mounted at the other end of said cylindrical projection; and

an electrical circuit for establishing an electrical connection from said contact to said light source.