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Wednesday, July 31, 2019

THE BULLARD LARYNGOSCOPE PROCEDURE


THE BULLARD LARYNGOSCOPE




The Bullard laryngoscope was invented by James Roger Bullard of Augusta, GA, in 1993 and was patented for use in 1995. It was a breakthrough in the area of fiberoptic medical devices for visualization and minimally invasive procedures. The Bullard laryngoscope refined manipulation and visualization in the field of laryngoscopy.

Laryngoscopy is a procedure whereby the airway and the passage into the airway (the glottis) is visualized or exposed to provide a route for the administration of anesthetic gases, introduce an endotracheal tube for securing the airway, allow a detailed examination of the larynx and its structures, or perform minor endolaryngeal procedures (eg, obtaining tissue specimens for biopsy).


In the resting human larynx, the epiglottis usually protects, and thus covers, the opening of the glottis. Therefore, it needs to be retracted out of the way when doing any of the other procedures. This retraction of the epiglottis is facilitated by laryngoscopy with the help of the blade of the laryngoscope. 

The first generation of laryngoscopes have a straight (Miller) or a curved (Mackintosh) blade, which is adequate for performing routine laryngoscopy in a patient. However, certain characteristics of a patient or a clinical situation may render laryngoscopy cumbersome or even hazardous. These scenarios may give rise to what is known as difficult intubation. In these cases, standard endotracheal intubation using a Miller or a Mackintosh blade may prove challenging and even result in failure. Alternative methods are then used, which may include the use of a Bullard laryngoscope to bypass or overcome these difficulties.



Relevant Anatomy



The larynx is located within the anterior aspect of the neck, anterior to the inferior portion of the pharynx and superior to the trachea. Its primary function is to protect the lower airway by closing abruptly upon mechanical stimulation, thereby halting respiration and preventing the entry of foreign matter into the airway. Other functions of the larynx include the production of sound (phonation), coughing, the Valsalva maneuver, and control of ventilation, and acting as a sensory organ.

The larynx is composed of 3 large, unpaired cartilages (cricoid, thyroid, epiglottis); 3 pairs of smaller cartilages (arytenoids, corniculate, cuneiform); and a number of intrinsic muscles (see the image below).




Indications



Indications for Bullard laryngoscopy include the following:


An obese or overweight patient with a thick, short neck

Breast hypertrophy

Prominent incisors, receding mandible, anterior larynx, intraoral masses, edema, secretions, scar, or bleeding

Limited mouth opening due to structural problems, such as temporomandibular joint syndrome, ankylosis, large tongue, or facial fractures

Inability to position the patient optimally for intubation, such as in disease and/or instability of the cervical spine (eg, kyphosis with barrel-chest deformity, spinal fractures)

Bullard laryngoscopy has distinct advantages in patients who are difficult to intubate, have limited or undesirable head and neck movements, have limited mouth openings, have facial fractures, or are morbidly obese. Bullard laryngoscopy causes less cervical spine movement than conventional laryngoscopy. Moreover, in patients with cervical spine disease, the Bullard laryngoscope provides quicker intubation compared with flexible fiberoptic intubation.

Other advantages include rapidity of intubation, but the time for intubation may be longer for patients with Mallampati class III scores than for patients with Mallampati class I or II scores.

With Bullard laryngoscopy, there is a low risk of failed intubation, less trauma to the lips and teeth, and less discomfort in the awake patient than other methods. The Bullard laryngoscope is sturdy and less likely to be damaged. It causes less cardiovascular instability than the Macintosh blade with conventional intubation technique.
In patients with severe maxillofacial injuries (eg, after a motor vehicle collision), awake intubation with conventional direct laryngoscopy may be unsuccessful because of distorted airway anatomy, a cervical collar, presence of excessive blood in the oropharynx, and lack of patient cooperation. Flexible fiberoptic laryngoscopy may not even be attempted because blood and secretions may be too numerous to allow adequate visualization.


The use of the Bullard laryngoscope, in conjunction with forceful oxygen flow through its insufflation port, may allow the practitioner to effectively clear blood and secretions in patients with maxillofacial injuries. The oxygen insufflation port of the Bullard blade is much larger in diameter than that of a conventional fiberoptic bronchoscope. This allows for more forceful delivery of oxygen through the instrument. In addition, the Bullard laryngoscope is particularly effective in trauma situations because the patient's head may be maintained in a neutral position (eg, without removing the cervical collar, if present)

The Bullard laryngoscope may be an ideal instrument for intubation of the trachea in a patient with acute epiglottitis. Traditional laryngoscopes involve pressure on an already swollen and compromised epiglottis. Fiberoptic laryngoscopes are easily deflected by the donut shape of the epiglottis. Considerable trauma can occur while blindly trying to slide the tube over the scope itself.The Bullard laryngoscope barely touches the epiglottis on insertion and provides a clear view of the vocal cords and larynx. Also, the endotracheal tube can be viewed as the tube is placed into the trachea.[

In a study of cadaver models, both with restricted and unrestricted mobility of the cervical spine, the Bullard laryngoscope was found to produce less cervical spine movement and a better view, with intubating time similar to the GlideScope, Viewmax, and Macintosh laryngoscopes.


Contraindications


No absolute contraindications exist for the use of Bullard laryngoscope. However, there is a considerable learning curve and inexperienced persons are not encouraged to use this laryngoscope in difficult situations. For example, it has been found that the video-optical intubation stylet is especially useful when a difficult tracheal intubation is anticipated or encountered, as it is simpler to execute and more effective.


Technical Considerations


Best Practices

There is a considerable learning curve for the use of Bullard laryngoscope. Inexperienced persons are not encouraged to use this laryngoscope in difficult situations. In addition, the Bullard laryngoscope is expensive and is cumbersome to clean and maintain.

Constant positioning and repositioning while changing the tip extender blade may increase the costs and risks of the surgical procedure being undertaken.

If a tracheal tube larger than 7.5 mm is used, the introducing stylet may be pushed posteriorly and thus obscure the view.


Sometimes, the orotracheal tube may hit against the right arytenoid cartilage and a large epiglottis, leading to problems.


If laser is to be used, the metallic laser tube cannot be fitted over the introducing stylet. In these cases, a standard tube has to positioned first and then the metal laser tube should be introduced using a tube exchanger.


Technique


Approach Considerations

For intubation, any of the following may be used:


Styletted tracheal tube

Bullard stylet

Tracheal tube with a directional tip

Reinforced (anode) tracheal tube

Pediatric introducing stylet

Multifunctional stylet


Equipment


The Bullard laryngoscope is specifically designed for difficult intubation and has a rigid, anatomically curved blade. On the posterior aspect of the blade, a sheath is provided for introduction of fiberoptic bundles for illumination and visualization. It is therefore a rigid and fiberoptic laryngoscope together in the same apparatus.

A viewing arm with an eyepiece is located at an angle of 45 degrees from the handle. The newer designs of the Bullard laryngoscope include an eyepiece that can be focused. Also, for operators with refractive errors, a diopter can be snapped onto the instrument when required.

The Bullard laryngoscope comes in three sizes: pediatric, pediatric long, and adult. The pediatric version is used for infants and babies. The pediatric long version can be used in small children, up to 8-10 years of age. The adult version is useful for adults and bigger children older than 8-10 years of age.

The blade on the adult version has a deeper curve than on the pediatric versions. Also, a tip extender made of plastic is available to lengthen the tip of the adult blade. This is useful for intubating male patients but is usually not required for female patients.

The handle may contain batteries and a halogen bulb and/or have an adaptor for a flexible cable that is connected to a high-intensity light source that may be halogen or xenon. Light from the source is transmitted to the distal blade through the fiberoptic bundle.

A working channel for suction and/or insufflations extends from the body of the scope to the end of the tip where the light bundles end. The end nearest the handle has two openings. The first opening is for the Luer-lock connector, which can be attached to a medication syringe. It can be used for suction, insufflation of oxygen, or for local anesthetic or saline during the procedure. The second opening has an attachment for the introducing stylet, which may be an introducing/intubating stylet or multifunctional stylet.

The introducing or intubating stylet is thin, with a curve to the left at approximately 20 degrees near the tip. This brings the end of the stylet into the field of vision and facilitates passage of the tracheal tube into the laryngeal inlet. It attaches near the base of the viewing arm with a spring-loaded, locking mechanism. Studies have shown that the use of this stylet results in fewer attempts at intubation and faster intubations than other methods.

The multifunctional stylet consists of a long, hollow tube affixed to and extending generally parallel to the laryngoscope body. It is curved at the tip to direct the tube into the field of vision. It may attach to the viewing arm using a screw clamp. Its hollow core can serve as a guide by threading a flexible fiberscope, tracheal tube exchanger, or a small catheter through it. It is more difficult to maneuver than the introducing stylet. The multifunctional intubating stylet was patented in 1997.

In addition to the Bullard laryngoscope, the standard equipment for difficult intubation includes the following:

Fiberscope

Fiberoptic light source

Video head

Videocassette recorder

Defogging solution

Swivel fiberoptic adaptors

Local anesthetic spray

Patil-Syracuse endoscopic mask

Fiberoptic intubation airways

Fiberoptic stylet laryngoscope

Lighted intubation stylet

Special laryngoscope

Pediatric Bullard laryngoscope

Bougies

Flexible suction catheters

Yankauer suction tips

Laryngeal mask airways

Cricothyrotomy device

Device for tracheal tube ventilation

Combitubes

Retrograde intubation kit

Tracheostomy kit

Binasal airway


General Approach



Insert the blade of the Bullard laryngoscope into the oral cavity. Rotate it from horizontal to vertical, which will allow the blade to move around the tongue. With the laryngoscope fully vertical, allow the blade to drop momentarily to the patient’s posterior pharynx.

Next, elevate the blade against the tongue’s dorsal surface. Upward movement along the axis of the handle should be minimal and results in the blade of the laryngoscope lifting the epiglottis. The glottis opening is now fully visible.

In some patients it may be necessary to remove the laryngoscope, mount a blade tip extender, and then reinsert the laryngoscope to achieve an effective blade length because the location of the glottis and epiglottis differs from patient to patient.

Jet ventilation may be used or oxygen may be delivered from the working channel on the side. If needed, apply suction through the working channel to clear secretions. Oxygen administration also helps to clear secretions and prevent fogging.

If using a pediatric or multifunctional stylet, disengage the tracheal tube connector and backload it over the stylet. Position pediatric and multipurpose stylets near the tip of the tracheal tube but not protruding through the end.

Apply a small amount of lubricant to the stylet and tube before placing the tracheal tube over the stylet. Thread the adult tracheal tube over the lubricated stylet so that the stylet tip protrudes through the Murphy eye.

Alternatively, an endotracheal tube can be mounted on the exterior of the stylet. Pass a guide member through the interior of the stylet and advance it through the patient's vocal cords into the trachea. Then advance the endotracheal tube along the guide member until it is in a desired location in the patient's trachea to permit ventilation.

Fasten the stylet-tracheal tube combination to the laryngoscope, which brings the vertical part of the stylet behind and to the right side of the laryngoscope in the groove formed by the blade anteriorly and by the lens housing in the middle. When properly loaded, the tip of the introducing stylet should be visible at the four-o'clock position through the eyepiece or video camera. The tip of the multipurpose stylet is usually not visible.


Oral Intubation


For oral intubation, insert the blade midline into the oral cavity, with the handle horizontal, either by manually opening the mouth or with the aid of a tongue blade. The handle sometimes impinges upon the chest during insertion, especially in obese patients. In these cases, remove it prior to insertion and reconnect after the laryngoscope is positioned in the pharynx.

As the blade is advanced, rotate the handle to the vertical position so that the blade slides over the tongue. Once the blade has been rotated around the tongue, exert upward movement along the axis of the handle to visualize the larynx. If properly placed, either the epiglottis or glottis should come into view through the eyepiece. Occasionally, slight displacement of the blade posteriorly followed by use of the blade (directly or indirectly) to lift the epiglottis vertically may be necessary to optimize visualization.

In some cases, the tip of the tracheal tube will impact on the right arytenoid. If this occurs, reposition the laryngoscope and the stylet to the left. If this does not work, consider one of the following approaches:

The tube may be rotated 180 degrees on the stylet

The end of the bevel can be positioned near the blade

The tip of the stylet may be allowed to protrude through the central opening of the tracheal tube

If the tube passes through the vocal cords but cannot be advanced past the level of the cricoid cartilage, angle the laryngoscope slightly forward.

The Bullard laryngoscope can also be used for oral intubation without the stylet by passing the catheter through the channel where the introducing stylet normally attaches.

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