Laryngoscopy

Source: Wikipedia, the free encyclopedia.
"Laryngoscope" redirects here. For the journal, see The Laryngoscope.
Laryngoscopy
View of the glottis as seen during laryngoscopy
View of the glottis as seen during laryngoscopy
ICD-9-CM31.42
MeSHD007828
OPS-301 code1-610
MedlinePlus007507

Laryngoscopy (

vocal folds and the glottis. Laryngoscopy may be performed to facilitate tracheal intubation during general anaesthesia or cardiopulmonary resuscitation or for surgical procedures on the larynx or other parts of the upper tracheobronchial tree
.

Direct laryngoscopy

Anatomical parts seen during laryngoscopy

Direct laryngoscopy is carried out (usually) with the patient lying on his or her back; the laryngoscope is inserted into the mouth on the right side and flipped to the left to trap and move the tongue out of the line of sight, and, depending on the type of blade used, inserted either anterior or posterior to the epiglottis and then lifted with an upwards and forward motion ("away from you and towards the roof "). This move makes a view of the glottis possible. This procedure is done in an operation theatre with full preparation for resuscitative measures to deal with respiratory distress. There are at least ten different types of laryngoscope used for this procedure, each of which has a specialized use for the otolaryngologist and medical speech pathologist. This procedure is most often employed by anaesthetists for endotracheal intubation under general anaesthesia, but also in direct diagnostic laryngoscopy with biopsy. It is extremely uncomfortable and is not typically performed on

gag reflex.[citation needed
]

Indirect laryngoscopy

Indirect laryngoscopy is performed whenever the provider visualizes the patient's vocal cords by a means other than obtaining a direct line of sight (e.g. a mirror). For the purpose of intubation, this is facilitated by fiberoptic bronchoscopes, video laryngoscopes, fiberoptic stylets and mirror or prism optically enhanced laryngoscopes.[citation needed]

History

See also: Tracheal intubation
García
, 1884

Some historians (for example,

hypopharynx.[4]

In 1854, the

light source.[5][6] Using this device, he was able to observe the function of his own glottic apparatus and the uppermost portion of his trachea. He presented his findings at the Royal Society of London in 1855.[7][8]

All previous observations of the glottis and larynx had been performed under indirect vision (using mirrors) until 23 April 1895, when Alfred Kirstein (1863–1922) of Germany first described direct visualization of the vocal cords. Kirstein performed the first direct laryngoscopy in Berlin, using an esophagoscope he had modified for this purpose; he called this device an autoscope.[9] It is believed that the death in 1888 of Emperor Frederick III[10] motivated Kirstein to develop the autoscope.[11]

In 1913, Chevalier Jackson was the first to report a high rate of success for the use of direct laryngoscopy as a means to intubate the trachea.[12] Jackson introduced a new laryngoscope blade that had a light source at the distal tip, rather than the proximal light source used by Kirstein.[13] This new blade incorporated a component that the operator could slide out to allow room for passage of an endoracheal tube or bronchoscope.[14]

That same year,

batteries within the handle, a central notch in the blade for maintaining the tracheal tube in the midline of the oropharynx during intubation, and a slight curve to the distal tip of the blade to help guide the tube through the glottis. The success of this design led to its subsequent use in other types of surgery. Janeway was thus instrumental in popularizing the widespread use of direct laryngoscopy and tracheal intubation in the practice of anesthesiology.[11]

Applications

  • Helps in intubation during the administration of general anaesthesia or for mechanical ventilation.
  • Detects causes of voice problems, such as breathing voice, hoarse voice, weak voice, or no voice.
  • Detects causes of throat and ear pain.
  • Evaluates difficulty in swallowing : a persistent sensation of lump in the throat, or mucous with blood.
  • Detects strictures or injury to the throat, or obstructive masses in the airway.

Conventional laryngoscope

neonate
)
neonate
)

The vast majority of tracheal intubations involve the use of a

light source, and a set of interchangeable blades
.

Laryngoscope blades

Early laryngoscopes used a straight

cardiac arrhythmias
to spontaneously occur in adults.

Two basic styles of laryngoscope blade are currently commercially available: the curved blade and the straight blade. The

anesthetists, most commonly in the operating room.[19]
Additionally, paramedics are trained to use direct laryngoscopy to assist with intubation in the field.

The Macintosh blade is positioned in the

fulcrum
.

Vie Scope Direct Line of Site Laryngoscope by Adroit Surgical

The Miller, Wisconsin, Wis-Hipple, and Robertshaw blades are commonly used for infants. It is easier to visualize the glottis using these blades than the Macintosh blade in infants, due to the larger size of the epiglottis relative to that of the glottis.

Blade Named for Year introduced Comments
Bainton[20] Cedric Bainton 1987 Straight tongue with distal 7 cm. tubular, designed specifically for pathologic conditions
Cranwall[citation needed] George D. Cranton and Barry L. Wall 1963 straight, no flange
Jackson Chevalier Jackson straight
Janeway Henry H. Janeway straight
Reduced Flange (RF Mac)[citation needed] George D. Cranton 1999 curved reduced flange at heel
Macintosh[21] Robert Macintosh 1943 curved
Magill[22] Ivan Magill 1921 straight
McCoy[23] 1993 Lever-tip for anterior displacement of the Epiglottic vallecula and epiglottis in difficult intubation.
Miller Robert A. Miller 1941 straight
Parrott C.M. Parrott 1951 curved
Phillips 1973 straight
Robertshaw straight
Seward straight
Siker 1956 curved, with integrated mirror
Soper R.I. Soper 1947 straight
Vie Scope N. Vasan 2016 Direct Line of Sight
Wis-Hipple straight
Wisconsin straight

Fiberoptic laryngoscopes

Besides the conventional laryngoscopes, many other devices have been developed as alternatives to direct laryngoscopy. These include a number of indirect

otolaryngology, pulmonology and anesthesia
communities.

Other available fiberoptic devices include the Bullard scope,[24] UpsherScope,[25][26] and the WuScope.[27] These devices are widely employed for tracheal intubation, especially in the setting of the difficult intubation (see below).

Video laryngoscope

active pixel sensor (CMOS APS) video camera and light source are located at the point of angulation of the blade. An anesthesia machine is visible on the high resolution LCD monitor
.

The conventional direct laryngoscope uses a line of sight provided by a rigid

lens.[28] In an attempt to address some of these limitations, Jon Berall, a New York City internist and emergency medicine physician
, designed the camera screen straight video laryngoscope in 1998. The first true video laryngoscope Glidescope was produced in 1999 and a production version with 60 degree angle, an onboard heater, and a custom screen was first sold in dec 2000. The true video laryngoscope has a camera on the blade with no intervening fiberoptic components. The concept is important because it is simpler to produce and handle the resultant images from CMOS cameras. The integrated camera leads to a series of low cost variants that are not possible with the hybrid Fiberoptic units.

GlideScope

anatomy

In 2001, the GlideScope (designed by vascular and general surgeon John Allen Pacey) became the first commercially available video laryngoscope. It incorporates a high resolution digital camera, connected by a video cable to a high resolution LCD monitor. It can be used for tracheal intubation to provide controlled mechanical ventilation, as well as for removal of foreign bodies from the airway. GlideScope owes its superior results to a combination of five key factors:

  1. The steep 60-degree angulation of its blade improves the view of the glottis by reducing the requirement for anterior displacement of the tongue.
  2. The CMOS APS digital camera is located at the point of angulation of the blade (rather than at the tip). This placement allows the operator to more effectively view the field in front of the camera.
  3. The video camera is recessed for protection from blood and secretions which might otherwise obstruct the view.
  4. The video camera has a relatively wide viewing angle of 50 degrees.
  5. The heated lens innovation helps to prevent fogging of the lens, which might otherwise obscure the view.

Tracheal intubation with the GlideScope can be facilitated by the use of the Verathon Stylet, a rigid stylet that is curved to follow the 60° angulation of the blade.[29] To achieve a 99% successful rate of intubation with the GlideScope requires the operator to acquire a new skill set with this stylet.

In a 2003 study, the authors noted that the GlideScope provided adequate vision of the glottis (Cormack and Lehane grade I-II) [30][31] even when the oral, pharyngeal and laryngeal axes could not be optimally aligned due to the presence of a cervical collar. Despite this significant limitation, the average time to intubate the trachea with the GlideScope was only 38 seconds.[29] In 2005, the first major clinical study comparing the Glidescope to the conventional laryngoscope was published. In 133 patients in whom both Glidescope and conventional laryngoscopy were performed, excellent or good laryngeal exposure was obtained in 124/133 (93%) of Glidescope laryngoscopy patients, compared with only 98/133 (74%) of patients in whom conventional laryngoscopy was used. Intubation was successful in 128/133 (96%) of Glidescope laryngoscopy patients.[32] These early results suggest that this device may be a useful alternative in the management of difficult tracheal intubation.

The Verathon design team later produced the Ranger Video Laryngoscope for a United States Air Force requirement that is now rolling forward into EMS and military use. The Cobalt series of GlideScope then introduced a single-use variant that encompasses weights from 1000 grams to morbid obesity and is successful in many airway syndromes as well. The GlideScope Ranger is a variant designed for use in pre-hospital airway management including air, land, and sea applications. This device weighs 1.5 pounds, and is waterproof as well as airworthy to 20,000 feet altitude. The GlideScope Cobalt is a variant that has a reusable video camera with light-emitting core which has a disposable or single use external shell for prevention of cross infection.

In August 2009, the team at Verathon collaborated with Professor John Sakles from the University of Arizona Emergency Department in achieving the world's first tracheal intubation conducted with the assistance of

rural hospital
as they performed a tracheal intubation using the GlideScope.

Other video laryngoscopes

Several types of

cervical spine injury is possible has raised the question of whether these scopes should supersede direct laryngoscopy in routine airway management.[29] Further evidence in support of videolaryngoscopy has accumulated over the years, indicating a favourable risk profile for video laryngoscopes over direct laryngoscopes.[44]

Other noninvasive intubation devices

Other "noninvasive" devices which can be employed to assist in tracheal intubation are the laryngeal mask airway[45][46][47][48][49][50][51] (Some types of which may be used as a conduit for endotracheal tube placement), the lighted stylet,[52][53] and the AirTraq.[54] Due to the widespread availability of such devices, the technique of blind digital intubation[55] of the trachea is rarely practiced today, though it may still be useful in emergency situations under austere conditions such as natural or man-made disasters.[56]

Complications

Cases of mild or severe injury caused by rough and inexperienced use of laryngoscopes have been reported. These include minor damage to the soft tissues within the throat which causes a sore throat after the operation to major injuries to the larynx and pharynx causing permanent scarring, ulceration and abscesses if left untreated.[citation needed] Additionally, there is a risk of causing tooth damage.

Etymology and pronunciation

The word laryngoscopy uses

combining forms of laryngo- and -scopy
.

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External links

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