Abstract:
A visualization stylet suitable is provided for use with medical devices to illuminate and visualize the interior anatomy of a body cavity or organ, wherein the stylet includes a miniature camera, light source and on-board power source.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to medical devices and methods used to illuminate and visualize the interior anatomy of a body cavity or organ using a miniature camera having an on-board power source. The present invention has particular applicability to visualization of the interior of the oral cavity during endotracheal intubation.  
       BACKGROUND OF THE INVENTION  
       [0002]     In the course of providing medical care, particularly in an emergent situation or during anesthesia, it is frequently necessary to insert a tube into a patient&#39;s trachea to allow anesthesia and/or for the mechanical ventilation of the lungs of the patient. This procedure is called endotracheal intubation. It is important that the endotracheal tube be placed into the patient&#39;s trachea, rather than into the patient&#39;s esophagus (or anywhere else), otherwise air will not be delivered to the lungs. For this reason, it is important to be able to visualize the patient&#39;s glottis during endotracheal intubation. Improper endotracheal intubation is a significant cause of morbidity and mortality during anesthesia.  
         [0003]     Typically, a device called a laryngoscope is used to facilitate endotracheal intubation. This device consists of a handle and a blade. There is the straight blade (“Miller blade”), and the slightly curved blade (“Macintosh blade”). The epiglottis normally overlies the glottic opening into the larynx to prevent the passage of food into the trachea during eating; therefore, in endotracheal intubation, it is necessary to displace the epiglottis from the glottic opening to permit the endotracheal tube to be inserted into the trachea. The blade is inserted into the patient&#39;s mouth and is used to lift the patient&#39;s tongue and epiglottis out of the way so that the patient&#39;s glottis (the entrance to the trachea) may be visualized, and the endotracheal tube may be inserted successfully into the trachea.  
         [0004]     In some patients, such as obese patients or patients with atypical anatomy, the laryngoscope alone is unable to provide a clear view of the patient&#39;s glottis. So-called “blind intubation” may be attempted in such patients, but the failure rate of blind intubation is high. Blind intubation frequently leads to trauma and bleeding of the mucosa of the larynx and successful intubation often may require several attempts, slowing critical care and jeopardizing the patient&#39;s health. In such patients, therefore, it is desirable to place a visualization and/or an illumination device into the patient&#39;s pharynx to provide for a view of the glottis and allow proper insertion of the endotracheal tube.  
         [0005]     In some cases, oral intubation is not desirable or practicable and a nasal intubation must be used. Three main techniques are used for nasal intubation. One method is to use an oral laryngoscope to observe and monitor the placement of the nasal endotracheal tube. A second method is to use blind intubation, manipulating the tube and/or the patient&#39;s head and neck. A third method employs flexible fiber-optic bronchoscope to both guide and visually confirm the proper placement of the endotracheal tube. Regardless of whether oral or nasal intubation is performed, the glottis must eventually be negotiated, and so illumination and visualization are highly desirable either way.  
         [0006]     Several visualization and/or illumination devices have been produced and are in commercial use. For example, Aaron Medical Industries produces a lighted intubation guide that is essentially a thin stylet (wand) having a bright light at the tip. This stylet is placed within the endotracheal tube. As the endotracheal tube with its contained stylet is guided (blindly) through the pharynx, the operator of the tube may judge the approximate location of the tip of the endotracheal tube by observing the location of light transmitted through the patient&#39;s neck. This device provides no direct visualization of the glottis, and supplies only a small improvement over blind intubation.  
         [0007]     Volpi Corporation manufactures a stylet device that provides direct visualization of the glottis. The device is placed within the endotracheal tube and uses fiber-optic bundles to transmit visual information from the tip of the tube back to the operator of the device. This device does not have its own light source, but requires a separate light source. Another endotracheal intubation device and methods of using it is described in a paper by Hikaru Kohase “Endotracheal Intubation Device with a Charge Couple Device Camera” (Anesth. Analg. 2003: 96: 432-434). The device comprises a wand with a Charge Couple Device (CCD) camera mounted at the distal end, and includes a side tube through which a tube introducer is inserted. The introducer is positioned into the trachea through the vocal cords, and the wand is then withdrawn, leaving the introducer in place. Vitaid Airway Management Corporation sells the GlideScope™ device, which embeds a video camera and a Light Emitting Diode (LED) light source within a laryngoscopic blade. This device does not fit inside an endotracheal tube.  
         [0008]     Olympus and Pentax corporations both produce flexible fiber-optic bronchoscopes that include both image-transmitting and light-transmitting fiber-optic bundles, as well as a fully articulated and guidable tip. These devices, while originally designed for bronchoscopy (the visualization of the lung bronchi) may also be used for difficult intubations as follows. First, the distal portion of the fiber-optic bronchoscope is inserted within an endotracheal tube. Then, by looking through an eyepiece on the bronchoscope while manipulating the endotracheal tube, the operator of the device is able to directly visualize the placement of the tube within the trachea. When the endotracheal tube is successfully placed, the fiber-optic device is withdrawn from the tube. Used in this way, the fiber-optic bronchoscope is referred to as a fiber-optic laryngoscope (not to be confused with the blade-like regular laryngoscope described earlier). Use of such fiber-optic devices provides a considerable improvement over blind intubation, but these devices are very complex and expensive, and require extensive training for effective use.  
         [0009]     The patent literature includes a number of devices for insertion into the oral cavity that provide illumination and visualization. One of the earliest examples is Smit U.S. Pat. No. 1,246,339, which discloses a tongue depressor having an internal electric light source and a glass light-conducting element that allows light to be conducted from the bulb to the tip of the instrument to aid in visualization of the oral cavity.  
         [0010]     U.S. Pat. No. 6,655,377 to Pacey describes an endotracheal intubation instrument having a camera and a light positioned near the tip of the instrument. The camera and light may be powered by a battery internal to the handle of the device. The camera is optionally a CCD or CMOS (Complementary Metal Oxide Semiconductor) camera and the light source is optionally an LED. Suction is provided near the tip of the device to cool the light source and to remove moisture that would otherwise cloud the camera lens. The visualization elements are not designed to fit within an endotracheal tube, but are mounted outside and adjacent to a tube.  
         [0011]     U.S. Pat. No. 6,652,453 to Smith describes a self-contained, light-weight laryngoscope that includes a digital camera and “light emitters” both positioned close to the distal end of the scope, powered by an internal battery. The device includes a clamp at the end that grasps the endotracheal tube to be guided into place. As above, this device is not designed to fit within an endotracheal tube.  
         [0012]     U.S. Pat. No. 6,322,498 to Gravenstein describes a tracheal imaging scope with a CCD camera and an LED light positioned at the proximal end of the instrument (near the operator) and uses fiber-optics to transmit light and images between the distal end of the instrument and the camera/light. Simple electrical and/or optical “quick-connectors” are used to link the components and the camera and light(s) are powered by an external power source. The device may include a lumen for ventilation, irrigation or suction, but is not designed to fit within an endotracheal tube.  
         [0013]     U.S. Pat. No. 5,842,973 to Bullard describes a self-contained nasal-endotracheal intubation device with an “optical channel” connected to a camera and a “light channel” connected to an internal light source. Power is supplied by an internal battery. This device may be placed within an endotracheal tube and used to guide it into place.  
         [0014]     U.S. Pat. No. 3,677,262 to Zukowski describes an illuminated endotracheal tube inserter with a light source and fiber-optic viewing bundle. This inserter device is designed to fit within an endotracheal tube.  
         [0015]     U.S. Pat. No. 5,329,940 to Adair describes a hand-held endotracheal tube insertion device that includes fiber-optic cables for transmitting light and images. The device includes a malleable “insertion section” and in use, a standard endotracheal tube is fitted over the insertion section and removably attached to the handle of the device to allow visualization and insertion of the endotracheal tube into the trachea. An inflatable cuff, of a type that is standard on most endotracheal tubes, is provided near the distal end of the device which, when in use, is inflated to seal the endotracheal tube in the trachea and properly position the tip of the tube above and between the two bronchi.  
         [0016]     U.S. Pat. No. 4,337,761 to Upsher describes a laryngoscope with a curved blade that removably grasps an endotracheal tube. The blade additionally possesses a light source and a fiber-optic viewing member to permit visualization of the epiglottis and larynx. Power is supplied by a battery in the handle. The blade can be flexible so that it may be bent into various curvatures suitable to the anatomy or a particular patient.  
         [0017]     U.S. Pat. No. 5,676,598 to Rudischhauser describes a laryngoscope with a curved spatula blade where the blade includes a waveguide for transmitting light and a separate image waveguide for transmitting images.  
         [0018]     U.S. Pat. No. 6,629,924 to Adydelotte describes an “enhanced endotracheal tube” with a fiber-optic light bundle and a reflectively coated bore used to transmit images to the user. Additionally, an air passage is provided for inflating an inflatable cuff for positioning the device.  
         [0019]     U.S. Pat. No. 6,146,402 to Munoz describes an endotracheal tube guide introducer that can be used to introduce a flexible guide tube into the trachea. Once in place, the guide tube is used to guide an endotracheal tube to its target. The device includes a fiber-optic visualization path as well as a light path for illuminating and viewing the epiglottis and larynx during use.  
         [0020]     U.S. Pat. No. 5,665,052 to Bullard is another patent that describes an endotracheal tube guide. The guide is positioned in the trachea and an endotracheal tube is advanced along the guide to the desired location. Fiber-optic cables provide transmission of light and images.  
         [0021]     U.S. Pat. No. 4,086,919 to Bullard discloses a laryngoscope for endotracheal intubation having a housing containing a working channel for containing forceps and channels containing fiber optics for lighting and viewing the internal areas of the body, and a laryngoscope blade for manipulating the epiglottis of a patient to enable viewing of a target area.  
         [0022]     U.S. Pat. No. 3,766,909 to Ozbey describes a laryngoscope with a disposable blade and light guide. The light guide is incorporated into the blade and transmits light from a bulb in the handle. The bulb is powered by a battery, also located in the handle. The blade is designed to be cheap to manufacture and to be optionally disposable.  
         [0023]     Visualization stylets, endotracheal guides and fiber-optic laryngoscopes and bronchoscopes were originally designed for bronchoscopy (visualization of the bronchi of the lungs), not for endotracheal intubation, and they generally suffer from a number of disadvantages. They often are complex and expensive to manufacture, requiring specialized parts fabrication and assembly. Due to their cost, they are generally non-disposable, which means that they have to be sterilized and carefully maintained after each use. This adds to the cost of maintaining such a device. They are generally difficult to sterilize due to the number and complexity of their sub-components and may require special procedures for cleaning and sterilization. They frequently are fragile, and fiber-optic light bundles are especially susceptible to damage. Repair is costly and takes the instrument out of use.  
         [0024]     One of the main problems in the use of the fiber-optic laryngoscope/bronchoscope is a reflection of one of its benefits, that is, its flexibility. Because of its flexibility and complicated controlling system, it is often difficult to control the bronchoscope as it is advanced through the patient airways to the vocal cords. The proper use of such fiber-optic devices requires significant training and it is estimated that 25 to 50 practice intubations on a mannequin followed by 50 to 100 intubations on normal patients is required before a physician should attempts what is termed “difficult airway management.” 
         [0025]     In view of the foregoing disadvantages, the financial cost of endotracheal intubation in patients who cannot be intubated solely through use of a regular laryngoscope (e.g., obese patients) is very high. In addition, significant delays in treatment may be caused by the need to locate and mobilize appropriate fiber-optic equipment. A need exists for a small, hand-held endotracheal visualization stylet that provides high quality optics and that is both easy to use and inexpensive to manufacture.  
       SUMMARY OF THE INVENTION  
       [0026]     In view of the foregoing, it is an object of the present invention to provide apparatus for visualizing a bodily cavity comprising a visualization stylet including a self-contained power source. The visualization stylet of the invention may be used for various medical procedures including endotracheal intubation or to visualize the internal features of any anatomical structure such as the colon, vagina, uterus, esophagus, nasal passages, ear passages, joints, or abdominal cavity.  
         [0027]     In a preferred embodiment, the visualization stylet of the invention is used to facilitate endotracheal intubation. The visualization stylet is shaped and sized so that it may fit inside an endotracheal tube designed for endotracheal intubation of a human or animal subject. The stylet is elongated and preferably curved, and comprises a number of elements including a thin, flexible tube-shaped body defining a lumen therethrough, having a proximal end (near the operator) and a distal end (further away from the operator). The stylet also includes an image-gathering device, such as a charged couple device (CCD) or a complementary metal oxide semiconductor (CMOS) or a very large scale integrated (VLSI) chip camera, at or near the distal tip of the body, and a light-emitting device such as an LED or plurality of LEDs, also at or near the distal tip of the body. Electronic connectors transfer power and/or data to and from the image-gathering and light-emitting devices.  
         [0028]     In use, the visualization stylet is placed within an endotracheal tube, such that the tip of the stylet is at the distal tip of the endotracheal tube, and the electronic connectors of the stylet are accessible from the proximal end of the endotracheal tube. The visualization stylet may optionally be reversibly attached in place relative to the endotracheal tube by using a standard luer-lock feature. The electronic connectors are attached to an internal or external power supply, as well as a visualization device such as a cathode ray tube (CRT) or equivalent device (e.g. an Liquid Crystal Display (LCD) monitor), thus providing a view of the patient&#39;s pharynx, glottis, and other anatomical structures during intubation. Once intubation is accomplished, the visualization stylet is withdrawn from the endotracheal tube and either sterilized for re-use, or preferably discarded.  
         [0029]     The light source may be of any acceptable type; for example, it may be an incandescent electric light or preferably a light emitting diode (LED). The light source is generally mounted at the distal end of the stylet and is preferably positioned and shielded in such a way that the illumination from the light source does not interfere with the image received by the camera. In one embodiment, the light source is positioned in front of the camera and is shielded from the camera (for example, by the rim of a collimator) so that the light projects forward from the device and not backward towards the camera. Light may optionally be supplied by a light source separate from the device, wherein the light is transmitted to the distal tip of the stylet by means of fiber-optic cables. The stylet may employ a single light source such as an LED or a plurality of LEDs. Such LEDs may optionally be arranged in a generally circular pattern about the distal tip of the stylet.  
         [0030]     The camera may be any suitable image collecting device known in the art, for example a charged couple device (CCD), complementary metal oxide semiconductor (CMOS), or other electronic camera may be used. The image received by the camera may be transmitted directly from the illuminated object or may be transmitted and focused from the illuminated object to the camera via a lens (or plurality of lenses).  
         [0031]     Additionally, an optional collimator may be positioned in front of the lens. One or more LEDs may be mounted peripherally to the collimator, so that the collimator shields the camera from the light emitted by the LEDs. The collimator both improves the optics of the system by filtering non-parallel incoming light, and shields the camera from direct illumination by the light source(s).  
         [0032]     In an alternative embodiment the stylet is provided with more than one camera. In particular, the provision of two adjacent cameras enables stereoscopic imaging. In a stereoscopic embodiment where lenses are used, the device may include a lens for each camera. Each camera may have one or more associated lenses. Each camera may optionally have its own lens(es) and its own collimator.  
         [0033]     In this disclosure the term “lens” includes any transparent cover, whether or not it can serve to focus light, and specifically includes transparent covers whose sole purpose is to protect the image-gathering device (e.g., a camera).  
         [0034]     In order to keep the front lens of the camera free of condensation, fluids, mucus or other debris, the device may also include one or more of the following. It may include a moisture-removing element such as a heating element in thermal communication with the lens to keep the lens free of moisture or a vacuum or suction device. It may include a debris-removing element to remove solid or liquid debris, such as a vacuum or suction device, or a lens-washing element or an air-jet or water-jet device, or a mechanical wiper device. These components may be activated at the will of the operator to maintain a clear view. Such devices are well-known and may be adapted for use with the invention.  
         [0035]     Additionally, the lens may be pre-treated with a hydrophilic or hydrophobic substance in order to help manage water, blood, or other substances that may be encountered during intubation. Likewise, the lens may be constructed of a hydrophilic or hydrophobic material.  
         [0036]     In certain embodiments one or more working channels may also be included in the stylet. Such a working channel can receive a flexible guide member, which in use may be passed through the working channel and guided through the vocal chords into the trachea prior to introduction of an intubation apparatus into the subject. Alternatively, the working channel may be used to receive a catheter or may be used for suction, delivery of oxygen or other gases, or delivery of local and/or general anesthetics to the subject.  
         [0037]     In another embodiment, the distal tip of the stylet may be controllable by the operator and may be pivoted in two or three dimensions to allow additional visualization of internal structures. Methods of achieving such manipulation are known and described for instance in U.S. Pat. Nos. 5,318,008 and 5,842,973.  
         [0038]     The stylet tube of the invention may be made from any suitable material that is malleable such that it may be bent into a shape suitable for introduction into the anatomy of a particular space such as the oral cavity and larynx. Suitable materials for making the stylet tube are well known in the catheter art and include metals such as aluminum, plastics and polymers such as polyvinylchloride, polypropylene, polyethylene, polyester, polyamide and silicone. Such materials are simple to manufacture in various shapes and sizes and are easy to sterilize.  
         [0039]     In accordance with one aspect of the present invention, the stylet includes an internal power supply, such as a battery. In certain embodiments, such as when the light source and/or camera can function using very low electrical current, standard disposable dry cell batteries may be used to power both camera and lights. Batteries may be contained within the structure of the stylet, or located externally and connected via standard electrical connections. Some embodiments include a battery that may be replaceable, rechargeable, or disposable. Other embodiments may use an external power supply.  
         [0040]     In some embodiments in which the stylet contains an internal power supply, the power supply may be activated in response to certain stimuli. For example, an embodiment may contain a data cable that can be extended and coupled to a display device, such as a video cable capable of delivering a signal viewable on a television screen. In such an embodiment, removal of the video cable may activate the power supply. Likewise, another embodiment may contain a port to which a separate video cable may be coupled. In that embodiment, coupling of the video cable to the port may activate the power supply.  
         [0041]     In embodiments where power is supplied externally to the stylet, a standard electrical coupling may be used to transmit power from an external electrical source such as a battery or transformer. Visual signals are transmitted from the device&#39;s camera to a display screen, such as a liquid crystal display (LCD) or cathode ray tube (CRT), and such signals may be transmitted via a standard optical or electrical cables. Visual information may be stored in an analog or digital storage device for later retrieval.  
         [0042]     The visualization stylet of the invention displays several advantageous characteristics including the fact that it is inexpensive to manufacture because it may be constructed from standard electrical components such as LEDs, CCD or CMOS cameras, and other standard electrical components. The cost of construction may be sufficiently small such that the device may effectively be disposable. If disposable, then the device requires no sterilization, reducing the cost of operation. The visualization stylet is also rugged and, because of its relative simplicity, is less prone to malfunction and damage than presently-used devices. Ease and effectiveness of use reduces the incidence of trauma to the patient and increases intubation speed, which may be life-saving. Additionally the stylet of the invention provides high quality optics and is easy to use without specialized training. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0043]     The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:  
         [0044]      FIG. 1  is a schematic longitudinal cross-sectional representation of a general embodiment of the visualization stylet;  
         [0045]      FIG. 2  is a schematic representation of the visualization stylet fitted within an endotracheal tube;  
         [0046]      FIG. 3  is a schematic representation of a stereoscopic visualization stylet employing two separate cameras and two lenses;  
         [0047]      FIG. 4  is a schematic representation of the visualization stylet of the invention fitted with an optional collimator;  
         [0048]      FIGS. 5A and 5B  are schematic representations of the visualization stylet of the invention fitted with an annular light source and a light transmissive element, respectively;  
         [0049]      FIGS. 6A and 6B  are, respectively, perspective and schematic representations of an embodiment of a visualization stylet employing an internal battery activated by attachment of a video cable;  
         [0050]      FIGS. 7A and 7B  are, respectively, perspective and schematic representations of an embodiment of a visualization stylet employing an internal battery activated by detachment of a video cable;  
         [0051]      FIG. 8  is a schematic representation of the visualization stylet of the invention fitted with a wiper and sensors for detecting breathing;  
         [0052]      FIGS. 9A and 9B  are schematic and cross-sectional representations, respectively, of the visualization stylet of the invention fitted with manipulators in the stylet tube; and  
         [0053]      FIGS. 10A and 10B  are schematic and cross-sectional representations, respectively, of the visualization stylet of the invention incorporating electroactive polymer into the stylet tube. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0054]     Referring to  FIGS. 1 and 2 , a schematic representation of visualization stylet  14  constructed in accordance with the principles of the present invention is described. All the elements in this particular embodiment of the stylet are contained within the lumen of stylet tube  1 , although other embodiments may comprise additional features or elements in other locations. The stylet in this particular embodiment has a plurality of white LED lights  3  disposed in a circular pattern at the outside circumference of the distal tip of the stylet, surrounding central lens  2 . The lens focuses light from an image onto CMOS camera  4 . The LED lights receive power from one or more power conduits  5  that are electrically connected to power supply  8 . The power supply comprise one or more dry cell batteries contained within the body of the stylet. The camera, which may be a CMOS or CCD camera, is centered within the axis of the lumen and slightly behind the distal tip of stylet tube  1 , shielded from lights  3 . The camera receives electrical power from power supply  10  via power supply conduit  6  and transmits visual information to video display  9  via data transmission conduit  7 . The power supply to the camera and to the LED lights may be identical, depending on the voltage/power requirements of the camera and the LED lights.  
         [0055]     The body of visualization stylet  14  preferably is formed from a hollow malleable tube. The stylet tube may be made of any suitable material that is plastic in nature, i.e., that maintains the shape into which it is bent. In a preferred embodiment the body is made out of a synthetic shape-retaining material. In general, aluminum, brass, plastic, or any other shape-retaining materials such as polyvinylchloride, polypropylene, polyethylene, polyester, polyamide, and silicone may be used.  
         [0056]     The stylet may be straight or the distal portion of the stylet may curved. In a curved embodiment, the distal portion (approximately the distal 2 to 10 inches) may be evenly curved through an angle of between 2 degrees and 45 degrees, preferably between 5 degrees and 22 degrees, or between 7 degrees and 15 degrees. The portion of the stylet that is curved may be different for different anatomies, for example, for a baby, the stylet may be curved only at the terminal  1  to 3 inch portion. The maximum diameter of the stylet is appropriate so that it fits within the lumen of the endotracheal tube. For example, in an adult endotracheal tube having a diameter of 7.5 millimeters, a preferable diameter for the stylet of the present invention is approximately 6.5 millimeters. Likewise, stylets having smaller diameters are appropriate for pediatric endotracheal tubes.  
         [0057]     Furthermore, the diameter may vary along the length of the stylet. In an embodiment with a non-uniform diameter, it is preferable to provide a stylet having a center section with a smaller diameter than the distal end in order to reduce the interaction between the exterior of the stylet and the interior of the lumen of the endotracheal tube or other device.  
         [0058]     The distal tip of visualization stylet  14  includes one or more light sources  3 . In a preferred embodiment, the light sources are disposed in a circular pattern at the outside circumference of the distal tip of the stylet. The light sources are preferably white LED lights, but may be incandescent or fluorescent lights or in another embodiment may be a non-coherent light source transmitted via a fiber-optic bundle. The light source may also comprise an annulus that either produces light, such as an LED, or transmits light from another light source. The one or more light sources project light forward from the tip of the stylet during intubation thereby illuminating the objects to be viewed. Incoming light rays reflected from the object to be viewed are focused through lens  2  onto camera  4 .  
         [0059]     In some embodiments, lens  2  or transparent facing  18  may be pretreated with a hydrophilic or hydrophobic substance to manage water, blood, or other substance that may be encountered during the intubation procedure and that may affect visibility. Other embodiments may manage these substances by use of lens  2  or transparent facing  18  formed from a hydrophilic or hydrophobic material. Some embodiments may employ mechanical devices to assist in maintaining visibility, such as a electroactive polymer (EAP) section that acts like a wiper blade on the surface of lens  2  or transparent facing  18 . Although some embodiments position lens  2  directly in front of camera  4 , other embodiments may utilize different configurations and may redirect light waves with mirrors or other known devices.  
         [0060]     The camera is preferably a CMOS or CCD of a type commonly used in digital cameras. The camera receives power via power supply conduit  5  and transmits an electrical signal via data transmission conduit  7  to video display screen  9 , such as an LCD or CRT screen. The operator views the screen to monitor the progress of the endotracheal tube through the vocal chords into the trachea.  
         [0061]     The power and data-transmission conduits run within the lumen of the stylet and project out from the proximal end of the stylet, terminating in standard video output and power input couplings which are operatively attached to the video screen and the power source, respectively. If the device contains an internal battery, then only a video output need project from the proximal end of the device, as discussed in further detail below. Depending on the voltage requirements of the camera and LEDs and any other components, a single power supply (either internal or external battery) may be used to power the camera, LEDs, and other components. In a lesser-preferred embodiment where light is transmitted via fiber optic cables, a non-coherent fiber-optic bundle runs through the stylet tube from the light source to the distal tip of the stylet.  
         [0062]     Internal battery  20  may be disposable, such as for a single-use application, or alternately may be rechargeable or replaceable, and therefore more appropriate for repeat stylet usage.  
         [0063]     Still referring to  FIG. 2 , visualization stylet  14  is disposed within the lumen of endotracheal tube  11 , with endotracheal cuff  12  deflated. The cuff is a flexible balloon toroidally attached about the outer surface of the distal end of endotracheal tube  11  and is in air/fluid communication with inflation tube  13 . In use, endotracheal cuff  12  of endotracheal tube  11  is inflated by providing a positive pressure via inflation tube  13 ; endotracheal cuff  12  serves both to hold endotracheal tube  11  in place and to prevent passage of stomach or oropharyngeal contents into the lungs. Visualization stylet  14  may be used to ensure the proper positioning of endotracheal tube  11  prior to the inflation of endotracheal cuff  12 . Visualization stylet  14  may then be removed from secured endotracheal tube  11 .  
         [0064]     Referring now to  FIG. 3 , an alternative embodiment is described in which two cameras are mounted side by side to provide a stereoscopic image. In certain stereoscopic embodiments, lenses may be used to focus the light from objects into the cameras. The number of lenses will generally equal the number of cameras. In the embodiment of  FIG. 3 , there are two cameras and two lenses. In some embodiments, transparent windows may be provided in addition to, or in lieu of, the lenses to help prevent fluid and other matter from fouling the camera or other underlying components. Such a window may be made of glass or any other biocompatible suitable transparent material. In yet other embodiments, no lens or window is provided. Images are transmitted via the cameras and may be displayed on a screen using differential color imaging. Images also may be viewed by the operator using 3-D goggles to give the effect of a three-dimensional image.  
         [0065]     Alternatively, the separate images may be processed by a computer to produce a three dimensional image that may be displayed and perceived without the need for special 3-D glasses. In another embodiment, a stereoscopic image may be provided without the need for a second camera. This may be done by splitting the single image into two images using an optical path separator and conducting each image to a separate camera. Such an embodiment may employ, for example, a single glass or plastic optical rod element to capture the initial single image, a prismatic optical path separator mounted behind the rod lens, and dual CCD OR CMOS elements to capture stereoscopic images. Video images can be processed electronically to convey images to a head-mounted display. See, e.g., Eguchi et al. “Stereoscopic Ophthalmic Microendoscope System,” Arch.  Ophthalmol.  115:1336-1338, 1997 and  Neurosurgical Focus  6 (4): Article 12, 1999, which are hereby incorporated by reference.  
         [0066]     With respect to  FIG. 4 , an alternative embodiment is described that employs a collimator to shield the camera from being directly illuminated by the light sources. The collimator in the figure is somewhat exaggerated and need only be of a size and shape sufficient to shield the camera. In the example shown, the collimator is a hollow tube that projects from the distal tip of the stylet. The light sources (LEDs) are mounted circumferentially about the collimator, while the camera is positioned slightly back from the tip of the stylet and within the central lumen of the stylet tube. In other embodiments, separate collimators may be positioned over and around the individual light sources, forming a tube around the light that restricts the peripheral dispersion of the light so that only the desired target is illuminated.  
         [0067]     Referring now to  FIG. 5 , alternative configurations for one or more light sources are described for the stylet in accordance with the present invention. In  FIG. 5A , light source  3  comprises an annulus or hoop-like structure disposed at the distal end of visualization stylet  14 . Light source may comprise LEDs or other light emitting elements known in the art. Lens  2  is disposed within the interior portion of light source&#39;s  3  annulus. In this embodiment, lens  2  is formed from a hydrophilic or hydrophobic material to help manage water, blood, or other substances that may be encountered during the intubation procedure and that may affect visibility.  
         [0068]     Light source  3  receives power from power supply for light  8 , which is transmitted through power supply conduit for light source  5 . Upon activation, annular light source  3  illuminates, thereby providing evenly-distributed light rays that may be reflected from the surrounding environment before entering lens  2  disposed within the central portion of light source  3 . Advantageously, use of an annular light source  3  may allow for a reduction in the diameter of stylet  14 , as the stylet&#39;s  14  distal tip may require less material for housing light sources  3  and other components.  
         [0069]     Referring now to  FIG. 5B , an alternative configuration for one or more light sources is shown. Here, light source  3  preferably comprises LEDs, but may also comprise fiber optics, incandescent light, fluorescent light, or other light source. In the embodiment shown in  FIG. 5B , two light sources  3  are shown, although other embodiments may have more or less light sources.  
         [0070]     Light source  3  is mounted adjacent to a light-transmissive annulus  24 , such that activation of light source  3  illuminates light-transmissive annulus  24 . Light-transmissive annulus  24  may comprise small non-coherent fiber optic bundles arranged in a ring shape or other known light-transmissive structures similarly arranged. Upon activation, stylet  14  operates as described above, in that the light is distributed substantially evenly around lens  2 , which can then direct the reflected light rays to camera  4 .  
         [0071]     In use, visualization stylet  14  of the above-described embodiments is inserted into standard endotracheal tube  11  such that the tip of the stylet is at or near the distal tip of the endotracheal tube. Power supply conduit  5  (if both the camera and LEDs are powered by the same supply, which is preferable) or conduits  6  (if the camera and LEDs require a separate supply) and data transmission conduit  7  project from the proximal end of the endotracheal tube. The power supply conduit or conduits are operatively attached to appropriate power supplies (either internal battery, or external) and the data transmission conduit is communicably attached to a screen (e.g., LCD or CRT), thus providing a view of the patient&#39;s pharynx, glottis, and other anatomical structures during intubation. Once intubation is accomplished, the visualization stylet is withdrawn from the endotracheal tube and either sterilized for re-use, or preferably discarded.  
         [0072]     Referring now to  FIG. 6 , another embodiment of the present invention is described. Here, visualization stylet  14  is configured to activate an internal power source when attached to an external display source. In particular, visualization stylet  14  contains internal battery  20  that serves as power supply for light  8  and power supply for camera  10 . Internal battery  20  is in communication with light source  3  and camera  4  via power supply conduits  5  and  6 , which may coexist along at least a portion of their lengths, as shown in  FIG. 6 .  
         [0073]     This embodiment further comprises stylet tube  1  that houses internal battery  20 . In a stylet for use with adults, the overall length of stylet  14  is preferably about 40 cm, whereas pediatric stylets  14  are shorter. In this regard, when sized properly, stylet  14  should fit inside the lumen of an endotracheal tube (or other device), with a relatively small portion protruding from the endotracheal tube&#39;s (or other device&#39;s) proximal end.  
         [0074]     In some embodiments, stylet tube  1 , which preferably does not exceed a diameter of 6.5 mm, surrounds core  19 , power supply conduits  5  and  6 , and data transmission conduit  7 . Core comprises a deformable structure, such as a thin metallic rod or similarly plastically deformable material, that may be manipulated into a variety of shapes by the user. Other embodiments may not have core  19 . Camera  4 , light source  3 , lens  2 , transparent facing  18 , and collimator  17  are disposed near the distal end of stylet tube  1 . In some embodiments, the exterior of transparent facing  18  or lens  2  may be covered with coating  28  to help manage water, blood, or other substances that may be encountered during the intubation procedure and that may affect visibility. Coating  28  may be a hydrophilic or hydrophobic substance. Yet other embodiments comprise transparent facing  18  or lens  2  formed of a hydrophilic or hydrophobic material.  
         [0075]     Switch  23  is located along the communication path between internal battery  20  and powered components, here light source  3  and camera  4 . In a preferred embodiment, switch  23  is biased in an open position until a user interacts with the device. In the embodiment depicted in  FIG. 6 , switch  23  comprises an element that moves when video cable male connector  22  is coupled with video cable female connector  24 . Movement of switch  23  completes the electrical connection and allows light source  3  and camera  4  to receive electrical power. Other embodiments may comprise different known switching mechanisms. These mechanisms may be switchable between on and off positions, or may be one-way toggle switches that prevent unintentional deactivation by maintaining an “on” position after activation.  
         [0076]     In the embodiment of  FIG. 6 , video cable  21  is attached to visualization stylet  14  using male connector  22  located at the distal end and female connector  24  located at the proximal end. The proximal end of video cable  21  is used as a source feed for video display  9 . Preferably, male connector  22  and female connector  24  are commonly available connectors, such as RCA plugs and RCA jacks. The data output from stylet  14  preferably is in a format that may be directly delivered to video display  9 , such as NTSC, PAL, or SECAM analog video signals.  
         [0077]     The embodiment of  FIG. 6  advantageously permits the physician to activate the device simply by connecting visualization stylet  14  to video cable  21  using the connectors. Preferably, the device is equipped with a 3 V or 5 V battery, such as a lithium coin battery, and provides approximately ten minutes of operating time prior to losing effectiveness. Similar embodiments also may employ various configurations of switches  23 . For example, switch  23  may toggle the electrical connection by use of mechanical movement, magnetism, or other methods.  
         [0078]     Referring now to  FIG. 7 , another alternative embodiment of the present invention is described. Here, the device is similar to the embodiment described above and in  FIG. 6 , but is shown in a configuration adapted to activate an internal power source when integrated video cable  21  is at least partially removed from visualization stylet  14 . Likewise, whereas the embodiment described above and in  FIG. 6  has coating  28  on the exterior of transparent facing  18 , this embodiment comprises transparent facing  18  formed from a hydrophilic or hydrophobic material. Visualization stylet  14  contains internal battery  20  which serves as power supply for light  8  and power supply for camera  10 . As discussed above, internal battery  20  may be disposable, replaceable, or rechargeable. Internal battery  20  is in communication with light source  3  and camera  4  via conduits  5  and  6 , which may coexist along at least a portion of their lengths.  
         [0079]     Switch  23  is located along the communication path between internal battery  20  and powered components, here light source  3  and camera  4 . In a preferred embodiment, switch  23  is stable in a closed position, but is held in the open position until the user interacts with the device. As depicted in  FIG. 7 , switch  23  comprises an element that moves when male connector  22  is detached from stylet  14 . Movement of switch  23  completes the electrical connection and allows light source  3  and camera  4  to receive electrical power. Switch  23  may be switchable between on and off positions, or may be a one-way toggle switch that prevents unintentional deactivation by maintaining an “on” position after activation.  
         [0080]     In  FIG. 7 , video cable  21  is integrated into visualization stylet  14  and is configured to attach directly to a separate device having female connector  24 . Preferably, male connector  22  and female connector  24  are commonly available connectors, such as RCA plugs and RCA jacks. The data output from stylet  14  preferably is in a format that may be directly delivered to video display  9 , such as NTSC, PAL, or SECAM analog video signals.  
         [0081]     This embodiment advantageously permits the physician to activate the device simply by pulling out male connector  24  and attaching visualization stylet  14  directly to a separate receiver with video display  9 . Preferably, visualization stylet  14  contains approximately one meter of video cable  21  that may be extended from a compartment within the stylet. Preferably, the device is equipped with a  3 V or  5 V battery, such as a lithium coin battery, and provides approximately ten minutes of operating time prior to losing effectiveness. Similar embodiments also may employ various configurations of switches  23 . For example, switch  23  may toggle the electrical connection by use of mechanical movement, magnetism, or other methods.  
         [0082]     A preferred method of using visualization stylet  14  as depicted in  FIG. 6  or  7  is now described. First, visualization stylet  14  is activated by either attaching video cable connector  22 , such as for the embodiment of  FIG. 6 , or by removing video cable connector  22 , such as for the embodiment shown in  FIG. 7 . Once visualization stylet  14  is activated, it may be inserted into standard endotracheal tube  11  such that the distal tip of the stylet is at or near the distal tip of the endotracheal tube. The power supply conduit or conduits are operatively attached to internal battery  20  and the data transmission conduit is communicably attached to video display  9 , thus providing a view of the patient&#39;s pharynx, glottis, and other anatomical structures during intubation. Once intubation is accomplished, the visualization stylet is withdrawn from the endotracheal tube and preferably discarded.  
         [0083]     Referring to  FIG. 8 , a schematic representation of another embodiment of the visualization stylet of the present invention is described. In this embodiment, stylet tube  1  has a non-uniform diameter, a majority of which is smaller than the diameter at the distal end. Additionally, wiper  25  is provided to help reduce obstructions on lens  2 . Here, conduit  6  connects camera  4  to power supply for camera  10 , and output from the camera is communicated through data transmission conduit for camera  7  to video display  9 . Light sources  3  receive their power from power supply for light  8 , which is communicated through power supply conduits for light source  5 .  
         [0084]     Stylet tube  1  of  FIG. 8  includes a non-uniform diameter along its length. In particular, the distal end of stylet tube  1  encircles lens  2 , camera  4 , and light sources  3 . Proximal to this section, stylet tube  1  has a slightly narrower diameter than the distal end. Advantageously, this non-uniform design may reduce friction and the resistance encountered when moving visualization stylet  14  through a lumen of an endotracheal tube or similar device. Preferably, the reduced diameter portion is sufficiently rigid to allow visualization stylet  14  to be pushably advanced through a lumen without undesired kinking or flexing.  
         [0085]     Another feature shown in the embodiment of  FIG. 8  is wiper  25 . Wiper  25  comprises a mechanical device to assist in maintaining visibility. For example, wiper  25  may comprise an electroactive polymer that moves across lens  2  or transparent facing  18  upon receipt of power sent from power supply for wiper  26  and communicated through conduit  27 . Other wiper designs may include polymer blades or rotating surfaces.  
         [0086]     The visualization stylet  14  also may comprise sensors that may be used to detect breathing. Two types of such sensors are illustratively shown in  FIG. 8 . First, carbon dioxide sensor  28  may be disposed at or near the distal end of stylet  14 . Carbon dioxide sensor  28  is in communication with display  30  via CO2 sensor conduit  29 . Display  30  may be integrated into stylet  14  or may be external. Alternatively, output from carbon dioxide sensor  28  may be delivered to video display  9 . In this alternative embodiment, the output from carbon dioxide sensor  28  may be displayed in conjunction with the output from camera  4 , or the video display may be switchable to selectively view the output from camera  4  or carbon dioxide sensor  28 .  
         [0087]     Alternatively, breathing may be detected using microphone  31  disposed at the distal end of stylet  14  and connected to speaker  33  via audio transmission conduit  32 . Speaker  33  may be integrated as part of stylet  14  or may be external.  
         [0088]      FIG. 9  depict an alternative embodiment of the stylet of the present invention. Here, stylet tube  1  comprises one or more lumens  34  through wall  35 . Manipulator  36  passes through the lumen  34  and is affixed at the distal end. The application of force to the manipulator causes stylet tube  1  to deflect, thereby allowing steerage of the device without the need for removal and reinsertion.  
         [0089]     Manipulator  36  preferably consists of wire, string, twine, or other flexible member capable of transmitting tensile force. Stylet tube  1  preferably comprises a polymer having sufficient flexibility such that tension applied to a manipulator causes deformation, yet sufficiently elastic such that stylet tube  1  may substantially return to an undeformed configuration in the absence of any outside forces.  
         [0090]     Proximal end of manipulator  36  is configured to facilitate operation by the user, such as being attached to handle  37 , lever, or other device. It should be appreciated that in some applications, such as an endotracheal tube, it is sufficient to allow manipulation in a single plane, such as simple up and down motion of the distal tip. Likewise, multidirectional motion may be desirable for other applications, in which stylet  14  may be moved through multiple planes.  
         [0091]      FIG. 10  depict an alternative embodiment of a stylet with a selectively deformable tube, in accordance with the principles of the present invention. In this embodiment, stylet tube  1  comprises electroactive polymer  38 , activated by controller  40  through conduit  39 . Accordingly, activation of electroactive polymer  38  by the user causes deformation of stylet tube  1 , which may be used to steer the device without the need for removal and reinsertion.  
         [0092]     In use, the embodiments shown in  FIG. 9  or  10  are inserted into an endotracheal tube or other instrument and then the combination of devices is inserted into a patient. If the user determines that the feedback of the stylet  14  indicate that repositioning is desired, the user can then selectively deform stylet tube  1 , such as by applying tension to a manipulator  36  or activating electroactive polymer  38 . The user may then observe the output from stylet  14  to reevaluate the position if the devices, and continue to deform stylet tube  1  until the endotracheal tube or other surrounding instrument is in place.  
         [0093]     Although preferred illustrative embodiments of the present invention are described above, it will be evident to one skilled in the art that various changes and modifications may be made without departing from the invention. It is intended in the appended claims to cover all such changes and modifications that fall within the true spirit and scope of the invention.