Editing Tracheal intubation (section)

==Equipment==

===Laryngoscopes===
{{Main|Laryngoscopy}}
[[File:Laryngoscopes-Miller blades.JPG|thumb|left|alt=Laryngoscope handles with an assortment of Miller blades|Laryngoscope handles with an assortment of Miller blades (large adult, small adult, child, infant and newborn)]]
[[File:Macintosh Blades.jpg|thumb|left|alt=Laryngoscope handles with an assortment of Macintosh blades|Laryngoscope handle with an assortment of [[Robert Macintosh|Macintosh]] blades (large adult, small adult, child, infant and newborn)]]
[[File:Intubación endotraqueal-8.jpg|thumb|Laryngoscopy]]
The vast majority of tracheal intubations involve the use of a [[viewing instrument]] of one type or another. The modern conventional laryngoscope consists of a handle containing batteries that power a light and a set of interchangeable [[blade]]s, which are either straight or curved. This device is designed to allow the laryngoscopist to directly view the larynx. Due to the widespread availability of such devices, the technique of blind intubation<ref name=James1950/> of the trachea is rarely practiced today, although it may still be useful in certain emergency situations, such as natural or man-made disasters.<ref name=Christod2007/> In the prehospital emergency setting, digital intubation may be necessitated if the patient is in a position that makes direct laryngoscopy impossible. For example, digital intubation may be used by a paramedic if the patient is entrapped in an inverted position in a vehicle after a motor vehicle collision with a prolonged extrication time.

The decision to use a straight or curved laryngoscope blade depends partly on the specific anatomical features of the airway, and partly on the personal experience and preference of the laryngoscopist. The Miller blade, characterized by its straight, elongated shape with a curved tip, is frequently employed in patients with challenging airway anatomy, such as those with limited mouth opening or a high larynx. Its design allows for direct visualization of the epiglottis, facilitating precise glottic exposure.<ref name="Scott2009" />
Conversely, the Macintosh blade, with its curved configuration reminiscent of the letters "C" or "J," is favored in routine intubations for patients with normal airway anatomy. Its curved design enables indirect laryngoscopy, providing enhanced visualization of the vocal cords and glottis in most adult patients.<ref name="Berry2007" />

The choice between the Miller and Macintosh blades is influenced by specific anatomical considerations and the preferences of the laryngoscopist. While the Macintosh blade is the most commonly utilized curved laryngoscope blade, the Miller blade is the preferred option for straight blade intubation. Both blades are available in various sizes, ranging from size 0 (infant) to size 4 (large adult), catering to patients of different ages and anatomies. Additionally, there exists a myriad of specialty blades with unique features, including mirrors for enhanced visualization and ports for oxygen administration, primarily utilized by anesthetists and otolaryngologists in operating room settings.<ref>{{Cite book |title=Clinical anesthesia |date=2017 |publisher=Wolters Kluwer |isbn=978-1-4963-3700-9 |editor-last=Barash |editor-first=Paul G. |edition=Eighth |location=Philadelphia Baltimore New York London Buenos Aires |editor-last2=Cullen |editor-first2=Bruce F. |editor-last3=Stoelting |editor-first3=Robert K. |editor-last4=Cahalan |editor-first4=Michael K. |editor-last5=Stock |editor-first5=M. Christine |editor-last6=Ortega |editor-first6=Rafael |editor-last7=Sharar |editor-first7=Sam R. |editor-last8=Holt |editor-first8=Natalie F.}}</ref><ref name="Scott2009" />

[[Optical fiber|Fiberoptic]] laryngoscopes have become increasingly available since the 1990s. In contrast to the conventional laryngoscope, these devices allow the laryngoscopist to indirectly view the larynx. This provides a significant advantage in situations where the operator needs to see around an acute bend in order to visualize the glottis, and deal with otherwise difficult intubations. [[Laryngoscopy#Video laryngoscope|Video laryngoscopes]] are specialized fiberoptic laryngoscopes that use a [[Digital electronics|digital]] [[active pixel sensor|video camera sensor]] to allow the operator to view the glottis and larynx on a video monitor.<ref name="Wheeler2007" /><ref name="Hansel2022" /> Other "noninvasive" devices which can be employed to assist in tracheal intubation are the [[laryngeal mask airway]]<ref name="Brain1985" /> (used as a conduit for endotracheal tube placement) and the [[Airtraq]].<ref name="Maharaj2007" />

===Stylets===
[[File:Tracheal tube stylet.JPG|thumb|alt=An endotracheal tube stylet|An endotracheal tube stylet, useful in facilitating orotracheal intubation]]

An intubating stylet is a malleable metal wire designed to be inserted into the endotracheal tube to make the tube conform better to the upper airway anatomy of the specific individual. This aid is commonly used with a difficult laryngoscopy. Just as with laryngoscope blades, there are also several types of available stylets,<ref name=Hung2007/> such as the Verathon Stylet, which is specifically designed to follow the 60° blade angle of the GlideScope video laryngoscope.<ref name=Agro2003/>

The Eschmann tracheal tube introducer (also referred to as a "gum elastic bougie") is specialized type of stylet used to facilitate difficult intubation.<ref name=Elorbany2004-1/> This flexible device is {{convert|60|cm|0|abbr=on}} in length, 15 [[French catheter scale|French]] (5&nbsp;mm diameter) with a small "hockey-stick" angle at the far end. Unlike a traditional intubating stylet, the Eschmann tracheal tube introducer is typically inserted directly into the trachea and then used as a guide over which the endotracheal tube can be passed (in a manner analogous to the [[Seldinger technique]]). As the Eschmann tracheal tube introducer is considerably less rigid than a conventional stylet, this technique is considered to be a relatively atraumatic means of tracheal intubation.<ref name=Armstrong2004/><ref name=Hodzovic2004-evaluation/>

The tracheal tube exchanger is a hollow [[catheter]], {{convert|56|to|81|cm|in|1|abbr=on}} in length, that can be used for removal and replacement of tracheal tubes without the need for laryngoscopy.<ref name=Hudson2002/> The Cook Airway Exchange Catheter (CAEC) is another example of this type of catheter; this device has a central [[Lumen (anatomy)|lumen]] (hollow channel) through which [[Insufflation (medicine)|oxygen can be administered]].<ref name=Loudermilk1997/> Airway exchange catheters are long hollow catheters which often have connectors for jet ventilation, manual ventilation, or oxygen insufflation.&nbsp;It is also possible to connect the catheter to a capnograph to perform respiratory monitoring.

The lighted stylet is a device that employs the principle of [[transillumination]] to facilitate blind orotracheal intubation (an intubation technique in which the laryngoscopist does not view the glottis).<ref name=Davis2000/>

===Tracheal tubes {{anchor|Types of tracheal tube}}===
{{Main|Tracheal tube}}
[[Image:Sondeintubation.jpg|thumb|alt=a cuffed endotracheal tube|A cuffed endotracheal tube, constructed of [[polyvinyl chloride]]]]
[[File:Carlens.jpg|thumb|alt=A Carlens double-lumen endotracheal tube|A Carlens double-lumen endotracheal tube, used for [[thoracic surgery|thoracic surgical]] operations such as [[VATS lobectomy]]]]

A tracheal tube is a catheter that is inserted into the trachea for the primary purpose of establishing and maintaining a patent (open and unobstructed) airway. Tracheal tubes are frequently used for [[airway management]] in the settings of general anesthesia, critical care, mechanical ventilation, and emergency medicine. Many different types of tracheal tubes are available, suited for different specific applications. An endotracheal tube is a specific type of tracheal tube that is nearly always inserted through the mouth (orotracheal) or nose (nasotracheal). It is a [[breathing]] conduit designed to be placed into the airway of critically injured, ill or anesthetized patients in order to perform mechanical [[positive pressure ventilation]] of the lungs and to prevent the possibility of aspiration or airway obstruction.<ref name=Adair1992/> The endotracheal tube has a fitting designed to be connected to a source of pressurized gas such as oxygen. At the other end is an orifice through which such gases are directed into the lungs and may also include a balloon (referred to as a cuff). The tip of the endotracheal tube is positioned above the [[Carina of trachea|carina]] (before the trachea divides to each lung) and sealed within the trachea so that the lungs can be ventilated equally.<ref name=Adair1992/> A tracheostomy tube is another type of tracheal tube; this {{convert|50|-|75|mm|in|adj=mid|-long}} curved metal or plastic tube is inserted into a tracheostomy [[Stoma (medicine)|stoma]] or a cricothyrotomy incision.<ref name=NatCancInst/>

Tracheal tubes can be used to ensure the adequate [[gas exchange|exchange]] of oxygen and [[carbon dioxide]], to deliver oxygen in higher concentrations than found in air, or to administer other gases such as [[helium]],<ref name=Tobias2009/> [[nitric oxide]],<ref name=Chotigeat2007/> nitrous oxide, [[xenon]],<ref name=Goto2003/> or certain volatile anesthetic agents such as [[desflurane]], [[isoflurane]], or [[sevoflurane]]. They may also be used as a route for administration of certain medications such as [[bronchodilator]]s, [[Inhaled corticosteroid#Inhaled steroids|inhaled corticosteroids]], and drugs used in treating [[cardiac arrest]] such as [[atropine]], [[epinephrine]], [[lidocaine]] and [[vasopressin]].<ref name=AHA2005-III/>

Originally made from [[Natural rubber|latex rubber]],<ref name=Macewen18800731/> most modern endotracheal tubes today are constructed of [[polyvinyl chloride]]. Tubes constructed of [[silicone rubber]], wire-reinforced silicone rubber or [[stainless steel]] are also available for special applications. For human use, tubes range in size from {{convert|2|to|10.5|mm|in|1|abbr=on}} in internal diameter. The size is chosen based on the patient's body size, with the smaller sizes being used for infants and children. Most endotracheal tubes have an inflatable cuff to seal the tracheobronchial tree against leakage of respiratory gases and pulmonary aspiration of gastric contents, blood, secretions, and other fluids. Uncuffed tubes are also available, though their use is limited mostly to children (in small children, the [[cricoid cartilage]] is the narrowest portion of the airway and usually provides an adequate seal for mechanical ventilation).<ref name=Wheeler2007/>

In addition to cuffed or uncuffed, preformed endotracheal tubes are also available. The oral and nasal RAE tubes (named after the inventors Ring, Adair and Elwyn) are the most widely used of the preformed tubes.<ref name=Ring1975/>

There are a number of different types of [[double-lumen endo-bronchial tube]]s that have endobronchial as well as endotracheal channels (Carlens, White and Robertshaw tubes). These tubes are typically [[coaxial]], with two separate channels and two separate openings. They incorporate an endotracheal lumen which terminates in the trachea and an endobronchial lumen, the distal tip of which is positioned 1–2&nbsp;cm into the right or left mainstem bronchus. There is also the Univent tube, which has a single tracheal lumen and an integrated [[endobronchial blocker]]. These tubes enable one to ventilate both lungs, or either lung independently. Single-lung ventilation (allowing the lung on the operative side to collapse) can be useful during [[thoracic surgery]], as it can facilitate the surgeon's view and access to other relevant structures within the [[thoracic cavity]].<ref name=Sheinbaum2007/>

The "armored" endotracheal tubes are cuffed, wire-reinforced silicone rubber tubes. They are much more flexible than polyvinyl chloride tubes, yet they are difficult to compress or kink. This can make them useful for situations in which the trachea is anticipated to remain intubated for a prolonged duration, or if the neck is to remain flexed during surgery. Most armored tubes have a Magill curve, but preformed armored RAE tubes are also available. Another type of endotracheal tube has four small openings just above the inflatable cuff, which can be used for suction of the trachea or administration of intratracheal medications if necessary. Other tubes (such as the Bivona Fome-Cuf tube) are designed specifically for use in laser surgery in and around the airway.<ref name=Rosenblatt2009/>

===Methods to confirm tube placement===
[[File:ETtubeGoodPosition.png|thumb|An endotracheal tube in good position on CXR. Arrow marks the tip.]]
[[File:ETtubeToHigh.png|thumb|An endotracheal tube not deep enough. Arrow marks the tip.]]

No single method for confirming tracheal tube placement has been shown to be 100% reliable. Accordingly, the use of multiple methods for confirmation of correct tube placement is now widely considered to be the [[Standard of care#Medical standard of care|standard of care]].<ref name=Stone2000/> Such methods include direct visualization as the tip of the tube passes through the glottis, or indirect visualization of the tracheal tube within the trachea using a device such as a bronchoscope. With a properly positioned tracheal tube, equal bilateral [[Respiratory sounds|breath sounds]] will be heard upon [[auscultation|listening to]] the chest with a stethoscope, and no sound upon listening to the area [[epigastrium|over the stomach]]. Equal bilateral rise and fall of the chest wall will be evident with ventilatory excursions. A small amount of [[water vapor]] will also be evident within the lumen of the tube with each exhalation and there will be no gastric contents in the tracheal tube at any time.<ref name=Rosenblatt2009/>

Ideally, at least one of the methods utilized for confirming tracheal tube placement will be a [[measuring instrument]]. Waveform [[capnography]] has emerged as the [[gold standard (test)|gold standard]] for the confirmation of tube placement within the trachea. Other methods relying on instruments include the use of a [[Colorimetry|colorimetric]] end-tidal carbon dioxide detector, a self-inflating esophageal bulb, or an esophageal detection device.<ref name=Wolfe1998/> The distal tip of a properly positioned tracheal tube will be located in the mid-trachea, roughly {{convert|2|cm|0|abbr=on}} above the bifurcation of the carina; this can be confirmed by [[chest radiograph|chest x-ray]]. If it is inserted too far into the trachea (beyond the carina), the tip of the tracheal tube is likely to be within the [[right main bronchus]]—a situation often referred to as a "right mainstem intubation". In this situation, the left lung may be unable to participate in ventilation, which can lead to [[hypoxemia|decreased oxygen content]] due to [[Ventilation/perfusion ratio|ventilation/perfusion mismatch]].<ref name=Salem2007/>