tracheal intubation tracheal intubation tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. it is frequently performed in critically injured, ill, or anesthetized patients to facilitate ventilation of the lungs, including mechanical ventilation, and to prevent the possibility of asphyxiation or airway obstruction. tracheal intubationanesthesiologist using the glidescope video laryngoscope to intubate the trachea of a morbidly obese elderly person with challenging airway anatomyicd-9-cm96.04meshd007442ops-301 code8-701medlineplus003449 the most widely used route is orotracheal, in which an endotracheal tube is passed through the mouth and vocal apparatus into the trachea. in a nasotracheal procedure, an endotracheal tube is passed through the nose and vocal apparatus into the trachea. other methods of intubation involve surgery and include the cricothyrotomy (used almost exclusively in emergency circumstances) and the tracheotomy, used primarily in situations where a prolonged need for airway support is anticipated. because it is an invasive and uncomfortable medical procedure, intubation is usually performed after administration of general anesthesia and a neuromuscular-blocking drug. it can, however, be performed in the awake patient with local or topical anesthesia or in an emergency without any anesthesia at all. intubation is normally facilitated by using a conventional laryngoscope, flexible fiberoptic bronchoscope, or video laryngoscope to identify the vocal cords and pass the tube between them into the trachea instead of into the esophagus. other devices and techniques may be used alternatively. after the trachea has been intubated, a balloon cuff is typically inflated just above the far end of the tube to help secure it in place, to prevent leakage of respiratory gases, and to protect the tracheobronchial tree from receiving undesirable material such as stomach acid. the tube is then secured to the face or neck and connected to a t-piece, anesthesia breathing circuit, bag valve mask device, or a mechanical ventilator. once there is no longer a need for ventilatory assistance or protection of the airway, the tracheal tube is removed; this is referred to as extubation of the trachea (or decannulation, in the case of a surgical airway such as a cricothyrotomy or a tracheotomy). for centuries, tracheotomy was considered the only reliable method for intubation of the trachea. however, because only a minority of patients survived the operation, physicians undertook tracheotomy only as a last resort, on patients who were nearly dead. it was not until the late 19th century, however, that advances in understanding of anatomy and physiology, as well an appreciation of the germ theory of disease, had improved the outcome of this operation to the point that it could be considered an acceptable treatment option. also at that time, advances in endoscopic instrumentation had improved to such a degree that direct laryngoscopy had become a viable means to secure the airway by the non-surgical orotracheal route. by the mid-20th century, the tracheotomy as well as endoscopy and non-surgical tracheal intubation had evolved from rarely employed procedures to becoming essential components of the practices of anesthesiology, critical care medicine, emergency medicine, and laryngology. tracheal intubation can be associated with complications such as broken teeth or lacerations of the tissues of the upper airway. it can also be associated with potentially fatal complications such as pulmonary aspiration of stomach contents which can result in a severe and sometimes fatal chemical aspiration pneumonitis, or unrecognized intubation of the esophagus which can lead to potentially fatal anoxia. because of this, the potential for difficulty or complications due to the presence of unusual airway anatomy or other uncontrolled variables is carefully evaluated before undertaking tracheal intubation. alternative strategies for securing the airway must always be readily available. indications tracheal intubation is indicated in a variety of situations when illness or a medical procedure prevents a person from maintaining a clear airway, breathing, and oxygenating the blood. in these circumstances, oxygen supplementation using a simple face mask is inadequate. depressed level of consciousness perhaps the most common indication for tracheal intubation is for the placement of a conduit through which nitrous oxide or volatile anesthetics may be administered. general anesthetic agents, opioids, and neuromuscular-blocking drugs may diminish or even abolish the respiratory drive. although it is not the only means to maintain a patent airway during general anesthesia, intubation of the trachea provides the most reliable means of oxygenation and ventilation and the greatest degree of protection against regurgitation and pulmonary aspiration. damage to the brain (such as from a massive stroke, non-penetrating head injury, intoxication or poisoning) may result in a depressed level of consciousness. when this becomes severe to the point of stupor or coma (defined as a score on the glasgow coma scale of less than 8), dynamic collapse of the extrinsic muscles of the airway can obstruct the airway, impeding the free flow of air into the lungs. furthermore, protective airway reflexes such as coughing and swallowing may be diminished or absent. tracheal intubation is often required to restore patency (the relative absence of blockage) of the airway and protect the tracheobronchial tree from pulmonary aspiration of gastric contents. hypoxemia intubation may be necessary for a patient with decreased oxygen content and oxygen saturation of the blood caused when their breathing is inadequate (hypoventilation), suspended (apnea), or when the lungs are unable to sufficiently transfer gasses to the blood. such patients, who may be awake and alert, are typically critically ill with a multisystem disease or multiple severe injuries. examples of such conditions include cervical spine injury, multiple rib fractures, severe pneumonia, acute respiratory distress syndrome (ards), or near-drowning. specifically, intubation is considered if the arterial partial pressure of oxygen (pao2) is less than 60 millimeters of mercury (mm hg) while breathing an inspired o2 concentration (fio2) of 50% or greater. in patients with elevated arterial carbon dioxide, an arterial partial pressure of co2 (paco2) greater than 45 mm hg in the setting of acidemia would prompt intubation, especially if a series of measurements demonstrate a worsening respiratory acidosis. regardless of the laboratory values, these guidelines are always interpreted in the clinical context. airway obstruction actual or impending airway obstruction is a common indication for intubation of the trachea. life-threatening airway obstruction may occur when a foreign body becomes lodged in the airway; this is especially common in infants and toddlers. severe blunt or penetrating injury to the face or neck may be accompanied by swelling and an expanding hematoma, or injury to the larynx, trachea or bronchi. airway obstruction is also common in people who have suffered smoke inhalation or burns within or near the airway or epiglottitis. sustained generalized seizure activity and angioedema are other common causes of life-threatening airway obstruction which may require tracheal intubation to secure the airway. manipulation of the airway diagnostic or therapeutic manipulation of the airway (such as bronchoscopy, laser therapy or stenting of the bronchi) may intermittently interfere with the ability to breathe; intubation may be necessary in such situations. newborns syndromes such as respiratory distress syndrome, congenital heart disease, pneumothorax, and shock may lead to breathing problems in newborn infants that require endotracheal intubation and mechanically assisted breathing (mechanical ventilation). newborn infants may also require endotracheal intubation during surgery while under general anaesthesia. equipment laryngoscopes main article: laryngoscopy laryngoscope handles with an assortment of miller blades (large adult, small adult, child, infant and newborn) laryngoscope handle with an assortment of macintosh blades (large adult, small adult, child, infant and newborn) 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 blades, 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 of the trachea is rarely practiced today, although it may still be useful in certain emergency situations, such as natural or man-made disasters. 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 macintosh blade is the most widely used curved laryngoscope blade, while the miller blade is the most popular style of straight blade. both miller and macintosh laryngoscope blades are available in sizes 0 (infant) through 4 (large adult). there are many other styles of straight and curved blades, with accessories such as mirrors for enlarging the field of view and even ports for the administration of oxygen. these specialty blades are primarily designed for use by anesthetists and otolaryngologists, most commonly in the operating room. 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. video laryngoscopes are specialized fiberoptic laryngoscopes that use a digital video camera sensor to allow the operator to view the glottis and larynx on a video monitor. other "noninvasive" devices which can be employed to assist in tracheal intubation are the laryngeal mask airway (used as a conduit for endotracheal tube placement) and the airtraq. stylets 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, such as the verathon stylet, which is specifically designed to follow the 60° blade angle of the glidescope video laryngoscope. the eschmann tracheal tube introducer (also referred to as a "gum elastic bougie") is specialized type of stylet used to facilitate difficult intubation. this flexible device is 60 cm (24 in) in length, 15 french (5 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. the tracheal tube exchanger is a hollow catheter, 56 to 81 cm (22.0 to 31.9 in) in length, that can be used for removal and replacement of tracheal tubes without the need for laryngoscopy. the cook airway exchange catheter (caec) is another example of this type of catheter; this device has a central lumen (hollow channel) through which oxygen can be administered. airway exchange catheters are long hollow catheters which often have connectors for jet ventilation, manual ventilation, or oxygen insufflation. 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). tracheal tubes main article: tracheal tube a cuffed endotracheal tube, constructed of polyvinyl chloride a carlens double-lumen endotracheal tube, used for 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)