Abstract:
An improved laryngoscope blade for use with a conventional laryngoscope handle and conventional means of illumination. The blade tapers from the handle end to the end that is inserted in the mouth, so that the blade roughly conforms to the shape of the tongue. In addition, the sides of the blade curve upward so as to cradle the tongue. This design allows the intubator to better control the tongue and more easily view the vocal chords during insertion of an endotracheal tube. Furthermore, the ambidextrous, symmetrical design is easier for left-handed doctors and technician to use.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     N/A 
     STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     N/A 
     REFERENCE TO A MICROFICHE APPENDIX 
     N/A 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a laryngoscope, which is a device used in an endotracheal intubation procedure. In particular, this invention is an improved design for the blade of a laryngoscope. 
     2. Description of the Related Art 
     While a laryngoscope may be used for inspection of the upper airway for possible foreign body obstruction or to visualize the larynx, the primary purpose of the laryngoscope is to visualize the vocal chords prior to insertion of an endotracheal tube during intubation. The need for such intubation may arise during a controlled situation, such as pre-surgery, or in a crisis situation where the patient is unable to breathe adequately and requires advanced airway interventions. 
     In order to intubate the patient, the intubator (either a physician or trained technician) must have a clear view of the vocal chords to insure the tube enters between the chords and not down the esophagus. When the body is in the supine position and the head is in the normal anatomic position the airway is narrowed and the tongue itself may possibly become an obstructing factor. It is therefore recommended that the intubator be able to secure the tongue and visualize the vocal chords as rapidly as possible. The laryngoscope itself generally comprises a handle and a blade. The intubator will hold the handle in one hand and position the blade against the patient&#39;s tongue. The intubator will use the edge of the blade to push the tongue to one side and the tip of the blade to lift the epiglottis, exposing the vocal chords. The handle will generally contain a light source which will illuminate the vocal chords. The intubator will then use her free hand to insert the tube between the patient&#39;s vocal chords. 
     In the current state of the art, the two most widely used blades as Miller blades and Macintosh blades. A Miller blade is a substantially straight blade with a curved tip, the curve commencing approximately 2 inches from the end of the blade. A Macintosh is a blade which is curved substantially its entire length (U.S. Pat. No. 2,354,471. Issued Jul. 25, 1944). In practice, the Miller blade is inserted along the longitudinal axis of the larynx past the epiglottis to lift it enough to visualize the vocal chords and slip the endotracheal tube between the chords and into the trachea. The Macintosh blade is inserted on a combination of the axis of the oral cavity and the longitudinal axis of the larynx, the tip being placed in the vallecula, which is the shallow depression in the membranous folds of tissue between the epiglottis and the roof of the tongue. By applying upward pressure at the vallecula, the epiglottis is raised enough to visualize the vocal chords. 
     While both Miller blades and Macintosh blades are adequate for performing intubation, both types of blade designs leaves three problems unsolved. First, prior art blades are designed such that in order to visualize the vocal chords, the doctor or technician will operate the laryngoscope with one hand and intubate the patient with the other hand. Standard blades are designed for right handed people; that is, the blade is operated with the left hand and the intubation is done with the dominant right hand. Left handed people either require different blades or are required to wield the tool in their dominant hand and attempt intubation, which is a delicate procedure, with their non-dominant hand. A second problem with prior art blades is that they do not include adequate means for securing the tongue. The tongue is always wet and tends to slide off the edge of a standard laryngoscope blade. Lastly, and partially as a result of the first two design shortcomings, current state of the art blades do not provide a sufficient view of the field of work (i.e. the vocal chords), because these tools do not provide an adequate angle of address for the vocal chords and allow unsecured portions of the tongue to block the field of view. 
     While there have been efforts to improve blade design, none of the improvements, taken either singularly or in combination, adequately address the aforementioned problems. Efforts to improve the curvature of the blade are shown in U.S. Pat. No. 5,003,962, issued Apr. 2, 1991 to Choi, and U.S. Pat. No. 5,406,941 issued Apr. 18, 1995 to Roberts. Choi describes a blade having 3 straight segments, the second segment at a 20 degree angle to the first, and the third at a 30 degree angle to the second. The Roberts patent describes a flat, flexible blade, having a cam attached to one side of the blade so the curvature may be adjusted by rotating the cam. U.S. Pat. No. 3,856,001 issued to O.C. Phillips Dec., 24, 1974 describes a Jackson or straight blade having a “U” shaped cross section and a tip similar to the Miller blade, curving about 2 inches from its end. 
     Efforts to improve the tip are shown in U.S. Pat. No 4,573,451, issued Mar. 4, 1986 to Bauman, and U.S. Pat. No. 5,603,688 issued Feb. 18, 1997 to Upsher. The Bauman patent describes a blade made of plastic or metal, thinning or hinged at the tip, with a push rod and ratchet to change the angle of the tip. Upsher&#39;s patent shows a blade having a hollow tube in the side of the tip to prevent the natural curve of the endotracheal tube to leave the field of vision after exiting the hollow tube in the blade. 
     Efforts to improve the illumination of the larynx and vocal chords are shown in U.S. Pat. No. 3,771,514 issued Nov. 13, 1973 to Huffman, and in U.S. Pat. No. 3,638,644 issued Feb. 1, 1972 to Reick. The Reick patent shows a light bulb in the handle with a plastic light conduit extending through the blade. The Huffman patent shows a one piece handle and blade, the blade having a prism mounted thereon for reflecting and diffusing light. 
     These inventions leave the three aforementioned problems unsolved. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, it is a principal object of this invention to provide an improved laryngoscope blade which allows better visualization of the vocal chords, ambidextrous usability, and vast improvement in control of the tongue during the procedure. 
     The present invention is a laryngoscope blade which is generally straight throughout its length but appears inverted when compared to current state of the art laryngoscope blades. In addition, the blade has upturned edges to better control the tongue, a reengineered tip to better access the vallecula, and a unique proximal angle to insure there is no contact between the laryngoscope blade and the teeth. 
     The laryngoscope blade of the present invention is tapered to better approximate the true anatomy of the tongue. This allows the intubator superior control of the tongue during an intubation procedure or during an examination of the airway. This configuration is unlike the design of conventional laryngoscope blades. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1 . Three-dimensional view of laryngoscope broken into its component parts. 
         FIG. 2 . Three-dimensional view of laryngoscope assembled. 
         FIG. 3A . Top view of laryngoscope blade without mirror base, light bar, or light bulb attached. 
         FIG. 3B . View of the proximal end of the laryngoscope blade without mirror base, light bar, or light bulb attached. 
         FIG. 3C . Side view of laryngoscope blade without mirror base, light bar, or light bulb attached. 
         FIG. 3D . View of the distal end of the laryngoscope blade without mirror base, light bar, or light bulb attached. 
         FIG. 3E . Bottom view of laryngoscope blade without mirror base, light bar, or light bulb attached. 
         FIG. 4A . View of the proximal end of the mirror base. 
         FIG. 4B . Side view of mirror base. 
         FIG. 4C . View of the distal end of the mirror base. 
         FIG. 5 . Side view of assembled laryngoscope with mirror base attached and cutaway views at locking mechanism for light bar and at mirror base. 
         FIG. 6A . Top view of light bar. 
         FIG. 6B . Side view of light bar. 
         FIG. 6C . Three-dimensional view of rubber plug used to secure light bar to laryngoscope. 
         FIG. 6D . Bottom view of rubber plug used to secure light bar to laryngoscope. 
         FIG. 6E . Side view of rubber plug used to secure light bar to laryngoscope. 
         FIG. 7A . Top view of laryngoscope with light bar attached. 
         FIG. 7B . Side view of laryngoscope with light bar attached. 
         FIG. 7C . Bottom view of laryngoscope with light bar attached. 
         FIG. 8 . Patient&#39;s head with laryngoscope blade in use. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows the disassembled components of the laryngoscope. The major components include the blade  101 , the mirror base  106 , the light bar  104 , and the light source  103 . The other major components of a laryngoscope not shown in  FIG. 1  is a handle  801 . The present invention comprises the unique designs of the blade  101 , mirror base  106 , and light bar  104 , which can operate with a wide variety of light sources  103  and handles  801  that are well known in the field of art. 
     The blade  101  is the central component of the laryngoscope. It is used to hold the tongue out of the visual path of the intubator. As depicted in  FIG. 8 , it is also used to apply pressure to the epiglottic vallecula  802  and thereby physically expose the vocal chord and trachea  803 . The blade  101  also comprises a block housing  124 . The block housing may house a light source  103 , can attach to a handle  801 , and can attach to a mirror base  106 . In addition, a light bar  104  may be attached to the base  128  of the blade  101  to improve illumination in the mouth and throat of the patient. The blade  101  and mirror base  106  are preferably made of stainless steel. The light bar  104  is preferably made of plexiglass. 
     To intubate a patient, an intubator will insert the blade  101  into the mouth of the patient. The blade may be positioned to hold the tongue out of the visual path of the intubator. The width of the blade is tapered from the distal end  126  to the proximal end  125 . The taper closely matches the anatomy of a tongue to give the intubator better control over tongue position. The angle of taper is also calculated to ensure that there is no contact between the device and the patient&#39;s teeth. In an ideal embodiment, the width of the blade at the proximal end is between 30% and 40% of the width of the blade at the distal end. Generally, the width of the proximal end will measure between 2 and 4 centimeters and the width of the distal end will measure between 6 and 10 centimeters. The thickness  127  of the base  128  of the blade  101  is uniform and the blade&#39;s upper and lower flat surfaces are smooth. The edges  112  and  113  of the base  128  of the blade  101  are raised at an angle  301  sufficient to stabilize the position of the tongue when the laryngoscope blade is in use. 
     Once the tongue is stabilized and out of the visual path of the intubator, she will use the tab  116  at the distal end  126  of the blade  101  to apply pressure to the epiglottal vallecula, thus raising the epiglottis and exposing the vocal chords and trachea. The tab  116  extends upward from the base&#39;s plane  302  in the same direction as the raised edges  112  and  113  at a fixed angle  303  which approximately conforms to the anatomy of a patient&#39;s mouth. To apply pressure on the vallecula, the intubator must raise the proximal end  125  of the blade, thereby lowering the tab  116  onto the vallecula. If angle  303  is too shallow, there will be insufficient room in the patient&#39;s mouth to apply ample pressure to the vallecula. If the angle  303  is too great, there may be insufficient room to fit the blade  101  and tab  116  into the rear portion of the patient&#39;s mouth. In the preferred embodiment the angle  303  is approximately 30 degrees. After additional experimentation, it may be desirable to change this angle slightly to improve the laryngoscope or to create a laryngoscope for special patients, (e.g. children). The thickness  129  of the tab may be different than the thickness  127  of the blade base  128  from which it extends. 
     The laryngoscope blade may also comprise a block housing  124  at the proximal end  125  of the blade. The block housing  124  is designed to provide several functions. First, the block housing will allow for the attachment of a handle  801 . To provide the greatest compatibility with the existing prior art laryngoscope handles, the block housing will comprise a variety of means for attaching a handle including an angled slot  111 , an angled face  130  with a hole  131 , and ball latch pins  132  and  133 . The handle may comprise a power source, such as dry cell batteries, to provide power to a light source. 
     The block housing  124  is designed to also house an industry-standard light source  103 . The light source  103  will be inserted through a hole  109  in the upper side of the block housing  124 . The contact end  123  of the light source  103  will connect to the handle  801 . The light source will be held in place by a grommet  102  at its upper end and a ridge  120  near its lower end. The illuminating end  121  fits in a hole  134  at the proximal end  125  of the base  128  of the blade  101 . 
     There are two alternative embodiments to improve illumination in the back of the patient&#39;s mouth. In one embodiment, a mirror base  106  is attached at the proximal end  125  of the base  128  of the blade  101 , as depicted in  FIG. 2  and  FIG. 5 . The mirror base may comprise holes  136  and  137  that will be used to attach the mirror base  106  to the block housing  124  in one of two alternative methods. First, the block housing may have a hole  110  at its lower end and connecting rod  108  will be inserted through hole  136 ,  110 , and  137  to hold the mirror base in place. Secondly, the block housing may have ball latch pins  138  and  135  at its lower end which will compress when the mirror base is pushed over the block housing and release when the holes  136  and  137  of the mirror base are aligned over the ball latch pins  138  and  135 . The mirror base  106  will have a sloped base at a 45-degree angle  139 . When a mirror  107  is affixed to this sloped base, the light source will be reflected from the proximal end  125  to the distal end  126  of the blade  101  (i.e. toward the rear of the patient&#39;s mouth). 
     An alternative embodiment to improve illumination uses a light bar  104  to reflect light from the light source into the mouth. The light bar  104 , as depicted in  FIG. 6 , is made of an opaque material (such as acrylic or plexiglass). It rests along the lower surface  140  of the blade  101  and is secured in place by pushing two rubber plugs  105  through two holes  117  and  118  on the light bar and two holes  114  and  115  on the base  128  of the blade. The sides  601  and  602 , bottom surface  603 , and top surface  604  of the light bar  104  are black faced so as to prevent light from passing through. There is a hole  119  on the proximal end  605  of the light bar  104  into which the illuminating end  121  of the light source will fit. The inner circumference  607  of the hole  119  is clear such that light may enter the light bar  104  through this inner surface  607 . At its distal end  606  the light bar  104  terminates in a half circle shape. The outer circumference  608  of this half circle is also clear such that light may be emitted through the outer circumference  608 . 
       FIG. 8  shows the laryngoscope in use with both mirror base  106  and light bar  104  attached. The drawing shows both the mirror base  106  and the light bar  104  only for demonstrative purposes. In practical use, either the light bar  104  or the mirror base  106 , not both, would be used. The tongue is held in place by the blade  101 . The tab  116  is used to depress the epiglottis  802 . The intubator is then able to see through the upper trachea  803  to properly intubate the patient. 
     Unlike prior art laryngoscopes, this invention does not require that the tongue be pushed aside and held while the epiglottis is raised. Instead, because of the way the blade is designed, the tongue is held in place in its natural position by the base of the blade, while the angled tab moves the epiglottis. The blade design provides an optimal view of the trachea and exposed vocal cords. The device can easily be used in either hand since the blade is symmetrically tapered and since the paired raised edges hold the tongue in place, rather than move it to one side or the other. Endotracheal intubation is sometimes done in preparation for surgery, but is often done under emergency circumstances, when time is of the essence. The present invention contains improvements which allow critical increases in the rapidity with which patients may be intubated.