Abstract:
The present invention relates to the field of medical devices used in the procedures of orotracheal or nasotracheal intubation. Oral or nasal endotracheal intubation procedures are commonly employed to secure a controlled airway and to deliver inhalant oxygen, anesthetic gases, and other therapeutic agents into the trachea and lungs of human and veterinary patients. Such intubation procedures carry a significant risk of dental injury resulting from contact between the laryngoscope blade used for visualization during intubation. The present invention provides an apparatus to reduce dental injury including a modified laryngoscope blade and a disposable insert which is designed to be received and retained in a single step by the modified laryngoscope blade. The disposable insert may be quickly secured by the user, and reduces both direct pressure and shear forces on the maxillary incisor teeth when the laryngoscope blade is placed in a patient&#39;s mouth during intubation.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    The present application is a divisional of U.S. patent application Ser. No. 09/911,257. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to the field of medical devices used in the procedures of orotracheal or nasotracheal intubation. More particularly, the present invention relates to a modified laryngoscope blade which is designed to receive a disposable insert which reduces both direct pressure and shear forces on the maxillary incisor teeth when the laryngoscope blade is placed in a patient&#39;s mouth during intubation.  
         BACKGROUND OF THE INVENTION  
         [0003]    Oral or nasal endotracheal intubation procedures are commonly employed to secure a controlled airway and to deliver inhalant oxygen, anesthetic gases, and other therapeutic agents into the trachea and lungs of human and veterinary patients. These clinical procedures are usually performed as a preliminary measure before surgery, thus enabling the anesthesiologist to administer anesthetic gases and other drugs while maintaining a stable delivery of oxygen to the patient&#39;s lungs throughout the surgical procedure. In other settings, intubation is used to provide a patient with a secure, direct airway when mechanical ventilation of the patient is indicated.  
           [0004]    The conventional procedure for such intubation procedures involves the visualization of the glottis and adjacent anatomic areas with a laryngoscope. A laryngoscope typically includes a handle containing a power supply and an attached blade section that serves to displace the tongue and allow direct visualization of the patient&#39;s larynx through the mouth. The technique of orotracheal or direct nasotracheal intubation involves sighting the vocal cords and the insertion of an endotracheal tube therethrough in a patient who is usually anesthetized or unconscious. The laryngoscope blade is usually introduced laterally through the right side of the mouth, and then directed medially to exclude and retract the tongue for adequate visualization of the hypopharynx.  
           [0005]    Training and experience combine to make intubation a safe, effective, and atraumatic technique. For example, a safe approach to intubation in advance of a surgical procedure involves first providing the patient with a short-acting sedative and a skeletal muscle relaxant before initiating laryngoscopy. Then, the head, neck, and shoulders of the patient must be positioned so that the oral, pharyngeal, and laryngeal axes are optimally aligned. Finally, the laryngoscope is inserted, preferably with the laryngoscopist&#39;s left hand—without regard to whether the laryngoscopist is right or left handed-laterally from the right side of the patient&#39;s mouth to avoid the incisor teeth and the tongue is deflected away from the lumen of the pharyngeal outlet by the tip of the laryngoscope blade. The epiglottis is sighted above the base of the tongue and, according to the type of laryngoscope blade used, the instrument is manipulated to expose the glottic opening. The endotracheal tube is then introduced through either the mouth or nose, and visually advanced between the vocal cords into the subglottic space. Once placement has been achieved, the laryngoscope blade is carefully removed to avoid either injury to oropharyngeal structures or unintentional displacement of the endotracheal tube.  
           [0006]    Many types of laryngoscope blades have been developed, each characterized by blade curvature or lack thereof, the point of such curvature if the blade is curved, and the flange structure of the blade. Three types of blades are most prominently used. An example of a first type of blade, characterized as a curved blade, is known in the art as the MacIntosh blade. The MacIntosh blade is advanced into the space between the base of the tongue and the pharyngeal surface of the epiglottis. Forward and upward movement of this blade stretches the hypoepiglottic ligament to cause the epiglottis to move upward to expose the glottic opening. Two other types of prominently used blades are the straight blade, known as the Jackson or Wisconsin blade, and the straight blade with a curved tip, known in the art as the Miller blade. The tip of these blades are passed beneath the laryngeal surface of the epiglottis and moved upwardly to elevate the epiglottis, thereby exposing the glottic opening.  
           [0007]    During insertion of the laryngoscope, care must be taken to avoid pressure on the teeth and gums of the patient. Care must also be taken to avoid traumatizing both the oral mucosa and the epiglottis. Use of a gentle technique for inserting the laryngoscope, may lessen, but cannot totally remove the possibility of intubation trauma. However, poor dentition or suboptimal anatomy of the teeth, jaw, neck, or throat may leave the maxillary incisors at particularly significant risk during intubation by even the most experienced of technicians.  
           [0008]    When properly positioned, a laryngoscope blade may rest against the upper teeth of the maxilla, depending upon the individual patient&#39;s anatomy. Because the laryngoscope blade is necessarily formed of a hard, inflexible material, dental damage is a potential result of such intubation procedures. Such dental injury is typically aggravated when the upper teeth are used as a fulcrum during insertion procedures.  
           [0009]    Even edentulous patients may be at risk for significant injuries to their maxillary alveolar ridges during the process of endotracheal intubation. The same mechanism of injury that may fracture or dislocate teeth may contuse or fracture the maxillary alveolar ridge, resulting in post-intubation difficulties in using the patient&#39;s previous dental prostheses or dentures. Such prostheses may have to be replaced, at considerable cost. In addition, residual local pain at the site of injury may aggravate the patient&#39;s tolerance for the use of any dental prostheses following such an intubation injury.  
           [0010]    Various methods have been proposed to minimize such dental injury. Protected shields have limited advantage in preventing dental injuries during intubation. The shields cover the maxillary incisors, yet provide only limited protection for the teeth. Such shields are prone to displacement by either the laryngoscope blade or other instrumentation. Furthermore, existing shields are relatively difficult to use, requiring multiple operator steps to secure the shields for use. The multiple steps required to secure existing shields may discourage their use by significantly increasing the time and effort required to achieve the desired intubation. Moreover, the bulk of the protective shields may obstruct the user&#39;s view into the hypopharynx.  
           [0011]    U.S. Pat. No. 3,826,248 to Gobels presents a laryngoscope blade in which an elastic insert which is anchored within a mating opening in the tongue deflector by means of undercut grooves extending in cross and longitudinal directions relative to each other.  
           [0012]    U.S. Pat. No. 4,583,527 to Musicant et al. teaches the placement of an elongated layer of soft, pliable plastic material which is adhere to the upper surface of a sheath which is slidably and removably coupled to the flange or curved edge of the tongue deflector of a laryngoscope blade.  
           [0013]    U.S. Pat. No. 5,065,738 to Van Dam provides for a flexible padded sheath, which is adhered along the length of a laryngoscope blade, covering substantially its entire outer surface.  
           [0014]    U.S. Pat. No. 5,438,976 to Nash provides a self-adherent, deformable cushioning device wrapped around a laryngoscope blade along at least a portion of its length.  
           [0015]    U.S. Pat. No. 5,776,053 to Dragisic et al. provides a laryngoscope blade with a cutout or recess in the vertical portion of the tongue deflector where a resilient insert is removably coupled at its proximal and distal ends.  
           [0016]    The devices currently available do not satisfactorily address the need to protect a patient&#39;s teeth, as well as the needs of convenience and feasibility of use. Blade covers are cumbersome and slow to apply to the blade, and are therefore impractical in emergency situations. Moreover, a cushioning device should be easy to remove after use and should not leave a permanent residue on the blade or the patient&#39;s teeth or mouth. While blade covers currently available are generally used only once, a typical laryngoscope blade is reusable and is commonly sterilized in steam autoclaves between uses. Adhesives used in applying a blade cover to a blade often make it difficult to remove the blade cover and may leave a residue that is difficult to remove. Adhesive residues may become even more difficult to remove after the residue has been subjected to the heat and pressure of the sterilization process. In addition, any such residue on a reusable instrument may present a potential focus for infectious bacteria or other pathogenic organisms. Further, blade covers that surround the entire blade or entire flange occupy too much space in a patient&#39;s mouth, making manipulation of the laryngoscope blade and introduction of the endotracheal tube difficult.  
           [0017]    Common user errors during positioning of a laryngoscope, as well as the particular structure of a given blade, may cause difficulties in proper introduction of an endotracheal tube. Such errors, which include the placement of the blade at an improper depth and incomplete displacement of the tongue, may be more likely with one blade over another. For example, complete displacement of the tongue may be more difficult with blades styles wherein the flange curves back over the blade, presenting a relatively small passageway for the actual passage of an endotracheal tube.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention is directed to a modified laryngoscope blade with a removable protective insert that is designed to reduce the risk of dental injuries in the course of endotracheal intubation in patients. The inventive blade is compatible with conventional laryngoscope handles, which provide both ergonomic and power supply functions. The inventive blade may be provided in both straight and curved embodiments, and may incorporate fiberoptic carriers, a distal miniature lamp for illumination, or other ancillary features whether visually oriented or not.  
           [0019]    The modified blade corresponds to a conventional laryngoscope blade, with the addition of a cut-out area proximally with a channel sized and shaped to receive a removable protective insert. The blade portion of the present invention is substantially rigid, and is preferably constructed of a metal or metal alloy that is capable of withstanding repeated autoclave sterilizations for repeated use. Alternately, the blade may be constructed of a rigid plastic, or other material, and may be provided as a single-use, disposable unit.  
           [0020]    In a preferred embodiment, the inventive modified blade provides a standard mechanical interface for a conventional laryngoscope handle, as well as standard electrical interfaces and wiring to a distal, miniaturized lamp for illumination. Alternately, fiberoptic illumination may be employed, using fiberoptic carriers within the modified blade that may be supplied by either an external light source, or by a conventional light source contained within a laryngoscope handle, or by an internal lamp housed proximally within the modified laryngoscope blade.  
           [0021]    To minimize inadvertent displacement of the protective insert, the modified blade may also be provided with a spring-loaded pin, or other fastener that may engage a receptacle on the insert when an insert is slid into position for use. Alternately, the modified blade may incorporate such a receptacle in the path of a spring-loaded pin or other fastener located within the insert, to similarly secure the insert during use. In various embodiments of the present invention, the spring-loaded pin may be operated by a coiled spring, or by a non-coiled spring. In each of the various embodiments of the present invention, the protective insert may be quickly and easily secured in its operative position, requiring minimal additional operator time as compared with a conventional laryngoscope blade.  
           [0022]    The protective insert is preferably constructed of a resilient material, capable of compression, and yet capable of maintaining its basic structural form. Preferably, the protective insert would be supplied as a disposable, single-use item. The protective insert is preferably shaped to provide surface continuity with the inventive modified blade when the insert is secured in position for use. Furthermore, the protective insert can preferably be sized and configured to produce no greater bulk that might obstruct either the user&#39;s visual field or working access, distal to the zone of the insert during an intubation procedure. Finally, the insert preferably has a slidable blade connector to engage with a channel on the modified blade to position the insert. In addition, the insert may be provided with either a receptacle to receive a spring-loaded pin from the modified blade to lock the insert in position during use, or alternately the insert may contain such a spring-loaded pin that might engage with a receiving interface on the modified blade. The inventive design also preferably allows a limited amount of front-to-back motion within the context of the locking spring-loaded pin/receptacle system, to minimize further shear forces that might otherwise be transmitted to the patient&#39;s teeth or alveolar ridges.  
         OBJECTS OF THE INVENTION  
         [0023]    As discussed above, there remains a need to further reduce the likelihood of trauma to which all of the mouth and throat are exposed during the technique of tracheal intubation. Therefore, one object of the present invention is to provide a device to allow intubation while adequately protecting the teeth, tongue, and oral mucosa from the blade of a laryngoscope during orotracheal or direct nasotracheal intubation.  
           [0024]    As clinicians often have personal preferences as to the style of laryngoscope blade that they routinely employ for intubation, another object of the present invention is to provide a device that may be employed to protect the teeth, tongue and oral mucosa for all types of laryngoscope blades, whether the blades are curved, straight, or partially curved.  
           [0025]    Still another object of the present invention is to provide a method for carrying out the technique of intubation whereby the teeth, tongue, and oral mucosa are protected from iatrogenic trauma.  
           [0026]    Still another object of the present invention is to provide a device that will permit rapid and easy protection of the teeth, tongue, and oral mucosa from the blade of a laryngoscope during intubation, while requiring minimal additional actions on the part of the user/operator.  
           [0027]    These and other objects will be better understood when the device and method of the present invention are described in the detail of the preferred embodiment and particularly pointed out and distinctly claimed in the claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    [0028]FIG. 1 shows a partially exploded view of a first embodiment of a modified laryngoscope blade and a removable protective insert according to the present invention.  
         [0029]    [0029]FIG. 2 shows the insertion of the insert of FIG. 1 into the receiving channel of the blade of FIG. 1.  
         [0030]    [0030]FIG. 3 shows the pivoting mounting of the blade assembly of FIG. 1 onto the receiving connector of a conventional laryngoscope handle.  
         [0031]    [0031]FIG. 4 shows the relationship between the blade assembly of FIG. 1 and a conventional laryngoscope handle, with the blade in a fixed and extended position for use.  
         [0032]    [0032]FIG. 5 shows a side view of the lateral surface of the blade assembly of FIG. 1.  
         [0033]    [0033]FIG. 6 shows the anterior surface of the blade assembly of FIG. 1.  
         [0034]    [0034]FIG. 7 shows a cross-sectional view of the blade assembly of FIG. 1 across the plane  7 - 7 ′ on FIG. 5.  
         [0035]    [0035]FIG. 8 shows a cross-sectional view of the blade assembly of FIG. 1 across the plane  8 - 8 ′ on FIG. 5.  
         [0036]    [0036]FIG. 9 shows an alternative embodiment of a protective insert according to the present invention in which the retention ridge on the blade interface surface is cylindrical and attached to the blade interface surface along one edge of the longitudinal axis of the retention ridge.  
         [0037]    [0037]FIG. 10 shows another alternative embodiment of a protective insert in which the retention ridge on the blade interface surface is T-shaped and attached to the blade interface surface by the vertical portion of the T-shaped ridge.  
         [0038]    [0038]FIG. 11 shows a side view of the anatomic relationship of the laryngoscope blade assembly of FIG. 1 in clinical use for intubation of a patient.  
         [0039]    [0039]FIG. 12 shows another alternative embodiment of the present invention, in which a fixed pin on the laryngoscope handle is received by a bore on the laryngoscope blade assembly, and in turn displaces a spring-loaded pin within the blade assembly to secure an attached protective insert. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0040]    An overview of a preferred embodiment of the present invention is illustrated in FIG. 1. The inventive modified laryngoscope blade assembly  100  includes a removable protective insert  10  and a modified blade structure  20 . The blade structure  20  has a recess  25  in its upper surface into which the insert  10  is received. The inventive modified laryngoscope blade assembly  100  is designed to functionally mount on a conventional laryngoscope handle  30  which serves both as a user handle and as a battery housing and power supply.  
         [0041]    [0041]FIG. 2 provides further details of the working interaction among the removable protective insert  10 , the modified blade structure  20 , and the conventional laryngoscope handle  30  of FIG. 1. The protective insert  10  has a body portion  105  and a blade portion  145 . The body portion  105  has an maxillary surface  110 , a blade interface surface  115 , a buccal surface  120 , a medial surface  125 , an anterior surface  130 , and a retention ridge  135 . The retention ridge  135  extends along the long axis of the blade interface surface  115  of the body portion  105 . The retention ridge  135  in this embodiment of the present invention is slightly wedge-shaped, with a narrower attachment to the body portion  105  and a broader base at its free edge. The buccal surface  120  may be a vertical planar component, or it may be beveled or rounded in various embodiments of the present invention.  
         [0042]    The blade portion  145  of the insert  10  consists of a vertical blade  150 , a palatal blade  155 , and a distal edge  160 .  
         [0043]    According to the present invention, the protective insert  10  is preferably constructed of a resilient, pliable material that would maintain its structural integrity, but would absorb and diffuse mechanical stress that might be imparted to the teeth or other body structures at risk with a completely rigid blade. Resilience in the context of the present invention is a quality of the construction or composition of the protective insert  10  that allows the protective insert  10  to provide a cushioning effect to adjacent structures. More preferably, the protective insert  10  according to the present invention provides a cushioning structure which is compressible when mechanical force is applied, yet capable of elastic reformation upon relaxation of the compressing force. Most preferably, the protective insert  10  according to the present invention has sufficient elasticity to provide a localized cushioning effect while possessing sufficiently firm durometer strength to substantially maintain its basic shape and form.  
         [0044]    A protective insert  10  according to the present invention would be capable of withstanding sterilization by irradiation, gas or chemical agents, or steam autoclave exposure without suffering structural degradation.  
         [0045]    A protective insert  10  according to the present invention may be formed of a solid structure. Alternately, a protective insert  10  according to the present invention may be formed of a laminar, foam, matrix, or partially hollow structure. In a protective insert  10  according to the present invention may be formed of a the protective insert  10  may be constructed of rubber, plastic, or other polymers. In a more preferred embodiment of a protective insert  10  according to the present invention, the insert  10  may be formed of materials selected from the group of natural or synthetic rubbers, elastomers, polyisoprenes, polyurethanes, vinyl plastisols, acrylic polyesters, polyvinylpyrrolidone-polyurethane interpolymers, butadiene rubbers, styrene-butadiene rubbers, rubber lattices, and other polymers or materials with similar resilience and pliability qualities.  
         [0046]    In a preferred embodiment of the present invention, the protective insert  10  may be fabricated by a molding process. Alternately, the protective insert  10  may be fabricated by machining the finished form of the insert  10  from a block of raw material. In a more preferred embodiment according to the present invention, the protective insert  10  may be fabricated by an extrusion molding process. Most preferably, an embodiment of the protective insert  10  may be formed by injection molding, according to the present invention. In a preferred embodiment of the present invention, the protective insert  10  may be fabricated with a surface coating to reduce water absorption and surface friction along the exposed surfaces of the insert  10 . In yet another preferred embodiment of the present invention, the protective insert  10  may be fabricated without a surface coating over the exposed surfaces of the insert  10 .  
         [0047]    In a preferred embodiment according to the present invention, the protective insert  10  would be supplied as a sterile packaged, disposable item for single use. In an alternate preferred embodiment, the protective insert  10  would be constructed to resist degradation from repeated gas, chemical, or steam autoclave sterilization exposures.  
         [0048]    The modified blade structure  20  includes a blade body portion  205  and a blade portion  305 . The blade body portion  205  includes a maxillary surface  210 , a handle interface facet  245 , a buccal surface  260 , a medial surface  265 , an anterior surface  270 , and a posterior facet. The maxillary surface  210  further contains a retention channel  215 , defined by side walls  220  and a floor  225 .  
         [0049]    As shown in FIGS.  2 - 3 , when the blade structure  20  is mounted atop the handle  30 , but not extended into a locked position for use, the protective insert  10  is freely slidable, with the retention ridge  135  of the insert  10  sized to be received by the retention channel  215  of the blade body portion  205 . However, the floor  225  of the retention channel  215  may also be provided with a vertical bore  230  that contains a retention pin  235  that protrudes from the surface of the handle interface facet  245  under tension from a spring  240  also contained within the bore  230 . As shown in FIG. 4, the retention pin  235  may be compressed into the blade body portion  205  under tension from the spring  240  when the blade assembly  100  is locked into an extended position on the handle  30 . When the lower end of the retention pin  235  is compressed into the blade body portion  205  by the locking, pivoting action of the inventive laryngoscope blade assembly  100 , the upper end of said pin  235  is pushed through the bore  230  and extended through the surface plane of the maxillary surface  210  of the blade body portion  205 , and into a pin receptacle  140  provided in the lower edge of the retention ridge  135  of the insert  10 . This has the effect of mechanically engaging and securely locking the insert  10  onto the blade assembly  20 .  
         [0050]    The action of securing the insert  10  onto the blade assembly  20  thus occurs as a result of the mechanical action of engaging the blade assembly  20  with the laryngoscope handle  30 . Therefore, in a preferred embodiment of the present invention, only the additional step of sliding the protective insert  10  onto the blade assembly  20  is required of the user, and the position of the insert  10  is automatically secured when the blade assembly  20  is engaged in an extended position on the handle  30 .  
         [0051]    In the preferred embodiment, the pin receptacle  140  may be elongate or elliptical, rather than round in shape, and oriented to allow slight front-to-back motion while the pin  235  is in position within the insert  10 . The slight motion that is thus allowed is designed to prevent shear stress from being transmitted to the patient&#39;s upper incisor teeth, and further reduces the risk of attendant dental injuries. In an alternate embodiment of the present invention, however, where slight front-to-back motion is not desired, the pin receptacle  140  may be round to exactly receive the pin  235 .  
         [0052]    The anterior surface  270  may contain a central threaded bore  275  which may be enclosed by a set screw  280 . Depending upon the mode of illumination used in the given embodiment, the threaded bore  275  provides access either to electrical conduits (not shown) which may extend to a conventional distal lamp, or the threaded bore  275  may provide access to a conventional lamp and lamp socket (also not shown) within the blade body portion  205  with a conventional fiberoptic carrier extending distally through said bore  275  from said lamp to a terminal point (not shown).  
         [0053]    [0053]FIG. 5 shows details of the buccal, or lateral side view of the inventive blade assembly  100  of FIG. 1. The insert  10  is shown fully seated into the recess  25  in the blade structure  20 . The distal edge  160  of the vertical blade portion  150  is flushly abutted with the corresponding edge of the vertical blade  325  of the blade structure  20 . Also, the maxillary or upper surface  110  of the removable protective insert  10  is substantially flush with the upper surface  330  of the modified blade structure  20 .  
         [0054]    The illumination conduit  360  extends from the blade body portion  205  of the blade structure  20  to the illumination tip  370 . Laryngoscopes require some internal means of illumination to allow vision in the recesses of the pharynx and larynx. Typically, laryngoscopes may include a miniature lamp which is located on the laryngoscope blade, or a fiberoptic carrier may be provided to transmit light from a source either within the handle or from an external light source to the distal aspect of the laryngoscope blade.  
         [0055]    In various preferred embodiments of the present invention, either a distal conventional lamp or a conventional fiberoptic carrier may be provided for illumination on the modified laryngoscope blade. As previously stated, the illumination conduit  360  may either contain electrical leads for a lamp (not shown) located in said illumination tip  370 , or the illumination conduit may contain fiberoptic carriers extending to the tip  370  from a lamp (not shown) housed within the blade body portion  205 , or from an external light source.  
         [0056]    The blade portion  205  is further provided with an engagement hook  255 , sized and positioned to engage the pivot pin of a standard laryngoscope handle  30 .  
         [0057]    Unlike the protective insert  10  which is preferably constructed of a resilient material, in a preferred embodiment according to the present invention, the blade structure  20  is substantially rigid to allow adequate physical retraction of anatomic structures for proper use. In a more preferred embodiment of the present invention, the blade structure  20  is constructed of metal or metal alloys. In another, more preferred embodiment, the blade structure  20  is constructed of rigid plastics. Most preferably, the blade structure  20  is constructed of stainless steel or aluminum. In a preferred embodiment of the present invention, a blade structure  20  might either be provided in a straight or curved configuration.  
         [0058]    [0058]FIG. 5 further shows the relationships among the vertical bore  230  for the retention pin  235  and tension spring  240  within the blade body portion  205  of the blade structure  20  of FIG. 1.  
         [0059]    [0059]FIG. 6 shows the anterior aspect of the inventive laryngoscope  100  of FIG. 1, with a tongue deflector  345  extending medially from the blade structure  20 , and with the insert  10  and the retention ridge  135  in position. The anterior surface  270  contains the set screw  280  which provides access within as described above  
         [0060]    [0060]FIG. 7 shows a cross-sectional view through the inventive laryngoscope blade assembly  100  through the plane  7 - 7 ′ on FIG. 5. This further shows the retention ridge  135  in position within the body  205  of the blade portion  20 , as well as the relationship of the bore  275  within said body  205 . At the level shown in this cross-sectional drawing, both the insert  10  and the blade structure  20  are relatively thick in their cross-sectional area, thus imparting a great deal of structural strength to this portion of the overall inventive laryngoscope blade assembly  100 . The broadness of the insert  10  at this level further diffuses any physical stress that might be imparted to the patient&#39;s teeth at the point where maximal contact between the teeth and the inventive blade assembly  100  might be expected.  
         [0061]    [0061]FIG. 8 shows a cross-sectional view through the inventive laryngoscope blade assembly  100  through the plane  8 - 8 ′ on FIG. 5. This shows the seamless junction of the vertical blade  150  of the insert  10  and the vertical blade  325  of the blade structure  20 . It should be noted that both the vertical blade  150  of the insert  10  and the vertical blade  325  of the blade structure  20  are relatively thin at this level, minimizing both mechanical and visual obstruction for the user who must both inspect the larynx distal to this level and be able to pass an endotracheal tube or other instrumentation around the inventive laryngoscope blade  100  at or below the level shown. However, despite the thin structure, the palatal blade  155  of the insert  10  provides a broad, resilient surface to reduce the injury potential along the course of the device which might contact the delicate palate or oropharyngeal mucosal surfaces.  
         [0062]    FIGS.  9 - 10  show alternate embodiments of the inventive insert  10 ′ and  10 ″ components, in which the retention ridges  135 ′ and  135 ″ might be provided in a rounded (FIG. 9) or T-shaped (FIG. 10) configuration, with corresponding changes in the retention channels of the blade body portions in such embodiments (not shown). Such embodiments would preserve the slidably removable quality of the inserts  10 ′ and  10 ″, as well as their interactions with the blade assemblies  20 .  
         [0063]    [0063]FIG. 11 shows a cross-sectional view of the anatomic relationships of the inventive laryngoscope blade  100  of FIG. 1 in use to visualize a patient&#39;s larynx. The user is typically working from a position above the head of a supine patient. For a right-handed user, the handle  30  is usually held vertically in the left hand, with the laryngoscope blade  100  oriented downwards and away from the user. The blade  100  is introduced into the patient&#39;s mouth, and the distal tip  270  is advanced into the pharynx, displacing the tongue anteriorly and to the left. The larynx is visualized off the medial side of the laryngoscope blade  100 , and the endotracheal tube or other instruments are introduced along the medial side of said blade  100 . In the course of insertion, or in the position of use, the laryngoscope blade  100  may contact or nearly contact the patient&#39;s upper incisor teeth at the point indicated as X on FIG. 11. This point of contact is within the insert  10  portion of the blade  100 , and is away from the rigid blade structure  20 , thus protecting the patient&#39;s teeth and other delicate oral structures from inadvertent injury during the procedure.  
         [0064]    As can be seen in FIGS. 3, 5, and  1 , when the insert  10  is positioned within the recess  25  in the modified blade structure  20 , the upper or maxillary surface  110  of the insert  10  and the upper surface  330  of the modified blade structure  20  form a substantially continuous upper surface. That is, the upper or maxillary surface  110  does not project above the adjacent upper surface  330  of the blade structure  20 . The insert  10  thus does not increase the profile of the laryngoscope system and therefore does not interfere with the intubation process any more than a conventional laryngoscope.  
         [0065]    [0065]FIG. 12 shows a side view of yet another alternative embodiment of the present invention, in which the laryngoscope handle  30 ′ is provided with a fixed pin  35 ′ which may be received by an appropriately-sized bore  247 ′ in the handle interface facet  245 ′ of the blade structure  20 ′. In this embodiment, the entry of the fixed pin  35 ′ into bore  247 ′ acts to mechanically displace the retention pin  235 ′ that is enclosed under tension of a spring  240 ′ within a vertical bore  230 ′ that is located within the blade body portion  205 ′, and is continuous therein with bore  247 ′. The displacement of the retention pin  235 ′ by the fixed pin  35 ′ as described serves to extend the opposite end of said retention pin  235 ′ into a pin receptacle  140 ′ provided in the lower edge of the retention ridge  135 ′ of the protective insert  10 ′″. This has the effect of securely locking the insert  10 ′″ into the blade assembly  20 ′. As discussed previously, the pin receptacle  140 ′ may be elongated or elliptical, rather than round in shape, and oriented to allow slight front-to-back motion while the retention pin  235 ′ is in position within the insert  10 ′″.  
         [0066]    Although the foregoing embodiments of the present invention have been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be apparent to those skilled in the art that certain changes and modifications may be practiced within the spirit and scope of the present invention. Therefore, the description and examples presented herein should not be construed to limit the scope of the present invention, the essential features of which are set forth in the appended claims.