Trachea

The trachea, colloquially called the windpipe, is a cartilaginous tube that connects the pharynx and larynx to the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends from the larynx and branches into the two primary bronchi. At the top of the trachea the cricoid cartilage attaches it to the larynx. This is the only complete tracheal ring, the others being incomplete rings of reinforcing cartilage. The trachealis muscle joins the ends of the rings and these are joined vertically by bands of fibrous connective tissue – the annular ligaments of trachea. The epiglottis closes the opening to the larynx during swallowing.

The trachea develops in the second month of development. It is lined with an epithelium that has goblet cells which produce protective mucins (see Respiratory epithelium). An inflammatory condition, also involving the larynx and bronchi, called croup can result in a barking cough. A tracheotomy is often performed for ventilation in surgical operations where needed. Intubation is also carried out for the same reason by the inserting of a tube into the trachea. From 2008, operations have experimentally transplanted a windpipe grown by stem cells, and synthetic windpipes; however, a successful method for this method of transplant does not currently exist and development of such a method remains theoretically daunting.[1][2]

The word "trachea" is used to define a very different organ in invertebrates than in vertebrates. Insects have an open respiratory system made up of spiracles, tracheae, and tracheoles to transport metabolic gases to and from tissues.

Trachea
Illu conducting passages
Conducting passages.
Details
Arterytracheal branches of inferior thyroid artery
Veinbrachiocephalic vein, azygos vein accessory hemiazygos vein
Identifiers
LatinTrachea
MeSHD014132
TAA06.3.01.001
FMA7394
Anatomical terminology

Structure

Blausen 0865 TracheaAnatomy

An adult's trachea has an inner diameter of about 1.5 to 2 centimetres (0.6 to 0.8 in) and a length of about 10 to 11 centimetres (4 in.).[3] It begins at the bottom of the larynx, and ends at the carina, the point where the trachea branches into left and right main bronchi.[3] The trachea begins level with the sixth cervical vertebra and the carina is found at the level of the fifth thoracic vertebra (T5),[3] opposite the sternal angle and can be positioned up to two vertebrae lower or higher, depending on breathing.

The trachea is surrounded by rings of hyaline cartilage; these rings are incomplete and C-shaped. The cricoid cartilage is attached to the first tracheal ring at top of the trachea and acts as the bottom of the larynx. There are fifteen to twenty rings in total, separated by narrow intervals. These reinforce the front and sides of the trachea to protect and maintain the airway.

In front of the rings lies connective tissue and skin. Several other structures pass or sit over it; the jugular arch, which joins the two anterior jugular veins, sits in front of the upper part of the trachea. The sternohyoid and sternothyroid muscles stretch along its length, and the thyroid gland sits below this; with the isthmus of the gland overlying the second to fourth rings.[3]

The first tracheal ring is broader than the rest, and often divided at one end; it is connected by the cricotracheal ligament with the lower border of the cricoid cartilage, and is sometimes blended with the next cartilage down. The last cartilage is thick and broad in the middle, due to its lower border being prolonged into a triangular hook-shaped (uncinate) process, which curves downward and backward between the two bronchi. It ends on each side in an imperfect ring, which encloses the commencement of the bronchus. The cartilage above the last is somewhat broader than the others at its center.

Two or more of the cartilages often unite, partially or completely, and they are sometimes bifurcated at their extremities. The rings are generally highly elastic but they may calcify with age.

The trachealis muscle connects the ends of the incomplete rings and contracts during coughing, reducing the size of the lumen of the trachea to increase the rate of air flow.[4] The esophagus lies posteriorly to the trachea, adjoining along the tracheoesophageal stripe. Circular horizontal bands of fibrous tissue called the annular ligaments of trachea join the tracheal rings together. The cartilaginous rings are incomplete to allow the trachea to collapse slightly so that food can pass down the esophagus. A flap-like epiglottis closes the opening to the larynx during swallowing to prevent swallowed matter from entering the trachea.

Sternohyoid muscle

The sternohyoid and sternothyroid muscles lie on top of the upper part of the trachea

Blausen 0534 Goiter

The thyroid gland also lies on top of the trachea, and lies below the cricoid cartilage. The isthmus of the thyroid, which connects both wings, lies directly in front, whereas the wings lie on the front and stretch to the side.

Development

In the fourth week of development of the human embryo as the respiratory bud grows, the trachea separates from the foregut through the formation of tracheoesophageal ridges which fuse to form the tracheoesophageal septum and this separates the future trachea from the oesophagus and divides the foregut tube into the laryngotracheal tube. Before the end of the fifth week, the trachea begins to develop from the laryngotracheal tube which develops from the laryngotracheal groove. The first part of the cephalic region of the tube forms the larynx, and the next part forms the trachea.

The trachea is no more than 4mm diameter during the first year of life, expanding to its adult diameter by late childhood. The trachea is more mobile and of more variable length, deeper, and smaller in children.[3]

Histology

Histological sample of Trachea obtained at "Instituto Nacional de Cardiología Ignacio A. Chávez"
10 X Photograph of a histological sample of a human trachea coloured with H&E stain
Gray964
Cross-section

The trachea is lined with a layer of pseudostratified ciliated columnar epithelium. The epithelium contains goblet cells, which are glandular, modified simple columnar epithelial cells that produce mucins, the main component of mucus. Mucus helps to moisten and protect the airways.[5] Mucus lines the ciliated cells of the trachea to trap inhaled foreign particles that the cilia then waft upward toward the larynx and then the pharynx where it can be either swallowed into the stomach or expelled as phlegm. This self-clearing mechanism is termed mucociliary clearance.[6]

Clinical significance

Inflammation

Inflammation of the trachea is known as tracheitis. When the trachea is inflamed as well as the larynx and bronchi, this is known as croup, which often causes a distinct, barking cough.

Intubation

Tracheal intubation refers to the insertion of a catheter down the trachea. This procedure is commonly performed during surgery, in order to ensure a person receives enough oxygen when sedated. The catheter is connected to a machine that monitors the airflow, oxygenation and several other metrics. This is often one of the responsibilities of an anesthetist during surgery. The epiglottic vallecula is an important anatomical landmark for carrying out this procedure.

In an emergency, or when tracheal intubation is deemed impossible, a tracheotomy is often performed to insert a tube for ventilation, usually when needed for particular types of surgery to be carried out so that the airway can be kept open. The provision of the opening via a tracheotomy is called a tracheostomy.[7] Another less invasive method is used when a procedure can be carried out more quickly, or in an emergency situation, and this is a cricothyrotomy.

Congenital disorders

Tracheal diverticulum
Tracheal diverticulum as seen on axial CT imaging

Tracheal agenesis,[8] is a rare birth defect in which the trachea fails to develop. The defect is usually fatal though sometimes surgical intervention has been successful.

A tracheoesophageal fistula is a congenital defect in which the trachea and esophagus are abnormally connected.

Sometimes as an anatomical variation one or more of the tracheal rings are completely formed. These O rings are smaller than the normal C-shaped and can cause narrowing of the trachea resulting in breathing difficulties. An operation called a slide tracheoplasty can be performed which opens up the rings and rejoins them as wider rings shortening the length of the trachea.[9] Slide tracheoplasty is said to be the best option in treating tracheal stenosis.[10]

Mounier-Kuhn syndrome is a very rare congenital disorder of an abnormally enlarged trachea.

Other

Other animals

Allowing for variations in the length of the neck, the trachea in other mammals is, in general, similar to that in humans. Generally, it is also similar to the reptilian trachea.[11]

Vertebrates

In birds, the trachea runs from the pharynx to the syrinx, from which the primary bronchi diverge. Swans have an unusually elongated trachea, part of which is coiled beneath the sternum; this may act as a resonator to amplify sound. In some birds, the tracheal rings are complete, and may even be ossified.[11]

In amphibians, the trachea is normally extremely short, and leads directly into the lungs, without clear primary bronchi. A longer trachea is, however, found in some long-necked salamanders, and in caecilians. While there are irregular cartilagenous nodules on the amphibian trachea, these do not form the rings found in amniotes.[11]

The only vertebrates to have lungs, but no trachea, are the lungfish and the Polypterus, in which the lungs arise directly from the pharynx.[11]

Invertebrates

Tracheal system of dissected cockroach
Tracheal system of dissected cockroach. The largest tracheae run across the width of the body of the cockroach and are horizontal in this image. Scale bar, 2 mm.
Cockroach tracheae supplying crop.tiff
The tracheal system branches into progressively smaller tubes, here supplying the crop of the cockroach. Scale bar, 2 mm.

The word "trachea" is used to define a very different organ in invertebrates than in vertebrates. Insects have an open respiratory system made up of spiracles, tracheae, and tracheoles to transport metabolic gases to and from tissues.[12] The distribution of spiracles can vary greatly among the many orders of insects, but in general each segment of the body can have only one pair of spiracles, each of which connects to an atrium and has a relatively large tracheal tube behind it. The tracheae are invaginations of the cuticular exoskeleton that branch (anastomose) throughout the body with diameters from only a few micrometres up to 0.8 mm. Diffusion of oxygen and carbon dioxide takes place across the walls of the smallest tubes, called tracheoles, which penetrate tissues and even indent individual cells.[13] Gas may be conducted through the respiratory system by means of active ventilation or passive diffusion. Unlike vertebrates, insects do not generally carry oxygen in their haemolymph.[14] This is one of the factors that may limit their size.

A tracheal tube may contain ridge-like circumferential rings of taenidia in various geometries such as loops or helices. Taenidia provide strength and flexibility to the trachea. In the head, thorax, or abdomen, tracheae may also be connected to air sacs. Many insects, such as grasshoppers and bees, which actively pump the air sacs in their abdomen, are able to control the flow of air through their body. In some aquatic insects, the tracheae exchange gas through the body wall directly, in the form of a gill, or function essentially as normal, via a plastron. Note that despite being internal, the tracheae of arthropods are lined with cuticular tissue and are shed during moulting (ecdysis).[13]

Bioengineering and prosthesis

In 2008, a Colombian woman, Claudia Castillo (30), received a trachea transplant using her own stem cells.[15]

Between 2011 and 2014 Paolo Macchiarini of the Karolinska University Hospital performed eight operations in which he generated an artificial trachea from a person's stem cells; four of them at Karolinska, three in Russia, and one in Illinois.[1] In January 2016 the Swedish television station Sveriges Television broadcast a three part documentary about Macchiarini that suggested that Macchiarini did not obtain informed consent from these people, six of whom died.[1] Macchiraini had been a "media darling" and had been seen as a pioneer in the field.[1] In February 2016 Karolinska announced it would not renew his contract when it expired in November 2016 and that it would open an investigation of Macchiarini's work and publications.[1]

Several bioengineering approaches have been tested to repair and replace the trachea, indicating extraordinary difficulties in a successful graft due. A 2016 article cited the tremendous difficulties of tracheal revascularization as a major challenge to any form of tracheal replacement. The study also notes that on top of the revascularization issue, there is no evidence that using bone-marrow stem-cells on a de-cellularized native trachea or synthetic scaffold will induce airway tissue regeneration, and such a method remains hypothetical.[2]

Additional images

Larynx detailed

Trachea.

Gray622

The tracheobronchial lymph glands.

Gray954

Coronal section of larynx and upper part of trachea.

Trachea

Microscopic cross section of human trachea.

Larynx

Larynx helps in the passage of air.

External links

References

  1. ^ a b c d e "Karolinska Institute has 'lost confidence' in Paolo Macchiarini, says it won't renew his contract". KI. 2016-02-04. Retrieved 2016-02-07.
  2. ^ a b Delaere, P; Van Raemdonck, D (March 2016). "Tracheal replacement". Journal of Thoracic Disease. 8 (Suppl 2): S186–96. doi:10.3978/j.issn.2072-1439.2016.01.85. PMC 4775267. PMID 26981270.
  3. ^ a b c d e Gray's Anatomy 2008, p. 1000.
  4. ^ Ross, Michael. Histology a text and atlas (5th ed.). Wojciech Pawlina. p. 617.
  5. ^ Mescher AL, "Chapter 17. The Respiratory System" (Chapter). Mescher AL: Junqueira's Basic Histology: Text & Atlas, 12e: "Archived copy". Archived from the original on 3 June 2013. Retrieved 24 February 2015..
  6. ^ Antunes, MB; Cohen, NA (February 2007). "Mucociliary clearance—a critical upper airway host defense mechanism and methods of assessment". Current Opinion in Allergy and Clinical Immunology. 7 (1): 5–10. doi:10.1097/aci.0b013e3280114eef. PMID 17218804.
  7. ^ Molnar, Heather. "Types of Tracheostomy Tubes".
  8. ^ Chiu, T.; Cuevas, D.; Cuevas, L.; Monteiro, C. (1990). "Tracheal agenesis". Southern Medical Journal. 83 (8): 925–930. doi:10.1097/00007611-199008000-00018. PMID 2200137.
  9. ^ "Slide tracheoplasty". Retrieved 2 October 2015.
  10. ^ Xue, B; Liang, B; Wang, S; Zhu, L; Lu, Z; Xu, Z (January 2015). "One-stage surgical correction of congenital tracheal stenosis complicated with congenital heart disease in infants and young children". Journal of Cardiac Surgery. 30 (1): 97–103. doi:10.1111/jocs.12418. PMID 25109422.
  11. ^ a b c d Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 336–337. ISBN 978-0-03-910284-5.
  12. ^ Wasserthal, Lutz T. (1998). Chapter 25: The Open Hemolymph System of Holometabola and Its Relation to the Tracheal Space. In "Microscopic Anatomy of Invertebrates". Wiley-Liss, Inc. ISBN 0-471-15955-7.
  13. ^ a b Triplehorn, Charles (2005). Borror and DeLong's introduction to the study of insects. Johnson, Norman F., Borror, Donald J. (7th ed.). Belmont, CA: Thompson Brooks/Cole. pp. 28–29. ISBN 978-0030968358. OCLC 55793895.
  14. ^ Westneat, Mark W.; Betz, Oliver; Blob, Richard W.; Fezzaa, Kamel; Cooper, James W.; Lee, Wah-Keat (January 2003). "Tracheal Respiration in Insects Visualized with Synchrotron X-ray Imaging". Science. 299 (5606): 558–560. doi:10.1126/science.1078008. PMID 12543973.
  15. ^ "The top health stories of 2008 - CNN.com". CNN. 2008-12-26. Retrieved 2010-05-27.
Books
  • editor-in-chief, Susan Standring ; section editors, Neil R. Borley; et al. (2008). Gray's anatomy : the anatomical basis of clinical practice (40th ed.). London: Churchill Livingstone. ISBN 978-0-8089-2371-8.
  • Britton, the editors Nicki R. Colledge, Brian R. Walker, Stuart H. Ralston ; illustrated by Robert (2010). Davidson's principles and practice of medicine (21st ed.). Edinburgh: Churchill Livingstone/Elsevier. ISBN 978-0-7020-3085-7.

Ligaments

Bronchus

A bronchus is a passage of airway in the respiratory system that conducts air into the lungs. The first bronchi to branch from the trachea are the right main bronchus and the left main bronchus. These are the widest and enter the lungs at each hilum, where they branch into narrower secondary bronchi known as lobar bronchi, and these branch into narrower tertiary bronchi known as segmental bronchi. Further divisions of the segmental bronchi are known as 4th order, 5th order, and 6th order segmental bronchi, or grouped together as subsegmental bronchi.

The bronchi when too narrow to be supported by cartilage are known as bronchioles. No gas exchange takes place in the bronchi.

Carina of trachea

In anatomy, the carina is a ridge of cartilage in the trachea that occurs between the division of the two main bronchi. This occurs at the lower end of the trachea (usually at the level of the 4th thoracic vertebra, which is in line with the sternal angle, but may raise or descend up to two vertebrae higher or lower with breathing). This ridge lies to the left of the midline, and runs antero-posteriorly (front to back). Foreign bodies that fall down the trachea are more likely to enter the right bronchus.

The mucous membrane of the carina is the most sensitive area of the trachea and larynx for triggering a cough reflex. Widening and distortion of the carina is a serious sign because it usually indicates carcinoma of the lymph nodes around the region where the trachea divides.

Tracheobronchial injury, an injury to the airways, occurs within 2.5 cm of the carina 60% of the time.

Chondrolaryngoplasty

Chondrolaryngoplasty (commonly called tracheal shave) is a surgical procedure in which the thyroid cartilage is reduced in size by shaving down the cartilage through an incision in the throat, generally to aid those who are uncomfortable with the girth of their Adam's apple.

Cilicia

In antiquity, Cilicia () was the south coastal region of Asia Minor and existed as a political entity from Hittite times into the Armenian Kingdom of Cilicia during the late Byzantine Empire. Extending inland from the southeastern coast of modern Turkey, Cilicia is due north and northeast of the island of Cyprus and corresponds to the modern region of Çukurova in Turkey.

Gapeworm

A gapeworm (Syngamus trachea), also known as a red worm and forked worm, is a parasitic nematode worm that infects the tracheas of certain birds. The resulting disease, known as "gape" or "the gapes", occurs when the worms clog and obstruct the airway. The worms are also known as "red worms" or "forked worms" due to their red color and the permanent procreative conjunction of males and females. Gapeworms are common in young, domesticated chickens and turkeys.

When the female gapeworm lays her eggs in the trachea of an infected bird, the eggs are coughed up, swallowed, then defecated. Birds are infected with the parasite when they consume the eggs found in the feces, or by consuming an intermediate host such as earthworms, snails (Planorbarius corneus, Bithynia tentaculata and others), or slugs.

The drug ivermectin is often used to control gapeworm infection in birds.

Larynx

The larynx (), commonly called the voice box, is an organ in the top of the neck of tetrapods involved in breathing, producing sound, and protecting the trachea against food aspiration. The larynx houses the vocal folds, and manipulates pitch and volume, which is essential for phonation. It is situated just below where the tract of the pharynx splits into the trachea and the esophagus. The word larynx (plural larynges) comes from a similar Ancient Greek word (λάρυγξ lárynx).

Neck

The neck is the part of the body, on many vertebrates, that separates the head from the torso. It contains blood vessels and nerves that supply structures in the head to the body. These in humans include part of the esophagus, the larynx, trachea, and thyroid gland, major blood vessels including the carotid arteries and jugular veins, and the top part of the spinal cord.

In anatomy, the neck is also called by its Latin names, cervix or collum, although when used alone, in context, the word cervix more often refers to the uterine cervix, the neck of the uterus. Thus the adjective cervical may refer either to the neck (as in cervical vertebrae or cervical lymph nodes) or to the uterine cervix (as in cervical cap or cervical cancer).

Paolo Macchiarini

Paolo Macchiarini (born August 22, 1958) is a Swiss-born Italian thoracic surgeon and a former researcher on regenerative medicine, who became known for research fraud.Previously he was considered a pioneer in the field of regenerative medicine using both biological and synthetic scaffolds seeded with patients' own stem cells as trachea transplants, and he was a visiting researcher on a temporary contract at Karolinska Institutet in Sweden from 2010. Macchiarini has been accused of research misconduct and unethically performing experimental surgeries, even on relatively healthy patients. Seven of the eight patients who received one of his synthetic trachea transplants have died. Also, an article in Vanity Fair suggested that Macchiarini had falsified some of his academic credentials on résumés. Similar accusations have been published in the Swedish newspaper Aftonbladet according to which Macchiarini's claim to have been a professor at universities in Hannover and Barcelona has turned out to be false.The secretary of the Nobel Committee for Physiology or Medicine, Urban Lendahl, resigned in February 2016, owing to his involvement in recruiting Macchiarini to Karolinska Institutet in 2010.

Shortly afterwards the vice chancellor, Anders Hamsten, who in 2015 had cleared Macchiarini of scientific misconduct also resigned. In 2013 Karolinska terminated its clinical relationship with Macchiarini but allowed him to continue as a researcher; in February 2016 Karolinska announced that it would not renew Macchiarini's research contract, which was due to expire in November, and the next month Karolinska terminated the contract. After being dismissed from Karolinska, he worked at the Kazan (Volga region) Federal University in Russia, until the university terminated his project in April 2017, effectively firing him. Since June 2016, Macchiarini was under legal investigation by the public prosecutor's office on a suspicion for manslaughter and grievous bodily harm based on the material leading to death of the three patients operated on in Sweden released from the scientific inquiry.After a one-year medico-legal investigation, the attorney general's office announced in October 2017 that Macchiarini had been negligent in the four of the five cases investigated due to the use of devices and procedures not supported by evidence, but that a crime could not be proven because the patients might have died under any other treatment given. Also in October, Sweden's national scientific review board found scientific misconduct by Macchiarini and his co-authors in six papers about the procedures, and called for them to be retracted.

Respiratory tract

In humans, the respiratory tract is the part of the anatomy of the respiratory system involved with the process of respiration. Air is breathed in through the nose or the mouth. In the nasal cavity, a layer of mucous membrane acts as a filter and traps pollutants and other harmful substances found in the air. Next, air moves into the pharynx, a passage that contains the intersection between the esophagus and the larynx. The opening of the larynx has a special flap of cartilage, the epiglottis, that opens to allow air to pass through but closes to prevent food from moving into the airway.

From the larynx, air moves into the trachea and down to the intersection that branches to form the right and left primary (main) bronchi. Each of these bronchi branch into secondary (lobar) bronchi that branch into tertiary (segmental) bronchi that branch into smaller airways called bronchioles that eventually connect with tiny specialized structures called alveoli that function in gas exchange.

The lungs which are located in the thoracic cavity, are protected from physical damage by the rib cage. At the base of the lungs is a sheet of skeletal muscle called the diaphragm. The diaphragm separates the lungs from the stomach and intestines. The diaphragm is also the main muscle of respiration involved in breathing, and is controlled by the sympathetic nervous system.

The lungs are encased in a serous membrane that folds in on itself to form the pleurae – a two-layered protective barrier. The inner visceral pleura covers the surface of the lungs, and the outer parietal pleura is attached to the inner surface of the thoracic cavity. The pleurae enclose a cavity called the pleural cavity that contains pleural fluid. This fluid is used to decrease the amount of friction that lungs experience during breathing.

Silifke

Silifke (Greek: Σελεύκεια, Seleukeia, Latin: Seleucia ad Calycadnum) is a town and district in south-central Mersin Province, Turkey, 80 km (50 mi) west of the city of Mersin, on the west end of Çukurova.

Silifke is near the Mediterranean coast, on the banks of the Göksu River, which flows from the nearby Taurus Mountains, surrounded by attractive countryside along the river banks.

Syrinx (bird anatomy)

The syrinx (Greek σύριγξ for pan pipes) is the vocal organ of birds. Located at the base of a bird's trachea, it produces sounds without the vocal folds of mammals. The sound is produced by vibrations of some or all of the membrana tympaniformis (the walls of the syrinx) and the pessulus, caused by air flowing through the syrinx. This sets up a self-oscillating system that modulates the airflow creating the sound. The muscles modulate the sound shape by changing the tension of the membranes and the bronchial openings. The syrinx enables some species of birds (such as parrots, crows, and mynas) to mimic human speech. Unlike the larynx of mammals, the syrinx is located where the trachea forks into the lungs. Thus, lateralization of bird song is possible and some songbirds can produce more than one sound at a time. Some species of birds, such as New World vultures, lack a syrinx and communicate through throaty hisses.

Throat

In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the pharynx and larynx. An important section of it is the epiglottis, which is a flap separating the esophagus from the trachea (windpipe) preventing food and drink being inhaled into the lungs. The throat contains various blood vessels, pharyngeal muscles, the nasopharyngeal tonsil, the tonsils, the palatine uvula, the trachea, the esophagus, and the vocal cords. Mammal throats consist of two bones, the hyoid bone and the clavicle. The "throat" is sometimes thought to be synonymous for the isthmus of the fauces.It works with the mouth, ears and nose, as well as a number of other parts of the body. Its pharynx is connected to the mouth, allowing speech to occur, and food and liquid to pass down the throat. It is joined to the nose by the nasopharynx at the top of the throat, and to ear by its Eustachian tube. The throat's trachea carries inhaled air to the bronchi of the lungs. The esophagus carries food through the throat to the stomach. Adenoids and tonsils help prevent infection and are composed of lymph tissue. The larynx contains vocal cords, the epiglottis (preventing food/liquid inhalation), and an area known as the subglottic larynx—the narrowest section of the upper part of the throat. In the larynx, the vocal cords consist of two membranes that act according to the pressure of the air.

Thyroid cartilage

The thyroid cartilage is the largest of the nine cartilages that make up the laryngeal skeleton, the cartilage structure in and around the trachea that contains the larynx. It does not completely encircle the larynx; only the cricoid cartilage does.

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.

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 and/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 minor 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.

Tracheal tube

A tracheal tube is a catheter that is inserted into the trachea for the primary purpose of establishing and maintaining a patent airway and to ensure the adequate exchange of oxygen and carbon dioxide.

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).

A tracheostomy tube is another type of tracheal tube; this 2–3-inch-long (51–76 mm) curved metal or plastic tube may be inserted into a tracheostomy stoma (following a tracheotomy) to maintain a patent lumen.

A tracheal button is a rigid plastic cannula about 1 inch in length that can be placed into the tracheostomy after removal of a tracheostomy tube to maintain patency of the lumen.

Tracheitis

Tracheitis is an inflammation of the trachea.

Although the trachea is usually considered part of the lower respiratory tract, in ICD-10 tracheitis is classified under "acute upper respiratory infections".

Tracheobronchial injury

Tracheobronchial injury (TBI) is damage to the tracheobronchial tree (the airway structure involving the trachea and bronchi). It can result from blunt or penetrating trauma to the neck or chest, inhalation of harmful fumes or smoke, or aspiration of liquids or objects.Though rare, TBI is a serious condition; it may cause obstruction of the airway with resulting life-threatening respiratory insufficiency. Other injuries accompany TBI in about half of cases. Of those people with TBI who die, most do so before receiving emergency care, either from airway obstruction, exsanguination, or from injuries to other vital organs. Of those who do reach a hospital, the mortality rate may be as high as 30%.TBI is frequently difficult to diagnose and treat. Early diagnosis is important to prevent complications, which include stenosis (narrowing) of the airway, respiratory tract infection, and damage to the lung tissue. Diagnosis involves procedures such as bronchoscopy, radiography, and x-ray computed tomography to visualize the tracheobronchial tree. Signs and symptoms vary based on the location and severity of the injury; they commonly include dyspnea (difficulty breathing), dysphonia (a condition where the voice can be hoarse, weak, or excessively breathy), coughing, and abnormal breath sounds. In the emergency setting, tracheal intubation can be used to ensure that the airway remains open. In severe cases, surgery may be necessary to repair a TBI.

Tracheomalacia

Tracheomalacia is a condition where the cartilage that keeps the airway (trachea) open is soft such that the trachea partly collapses especially during increased airflow. The usual symptom is stridor when a person breathes out.

The trachea normally opens slightly during breathing in and narrows slightly during breathing out. These processes are exaggerated in tracheomalacia, leading to airway collapse on breathing out.

If the condition extends further to the large airways (bronchi) (if there is also bronchomalacia), it is termed tracheobronchomalacia. The same condition can also affect the larynx, which is called laryngomalacia. The term is from trachea and the Greek μαλακία, softening

Tracheotomy

Tracheotomy (, UK also ), or tracheostomy, is a surgical procedure which consists of making an incision (cut) on the anterior aspect of the neck and opening a direct airway through an incision in the trachea (windpipe). The resulting stoma (hole) can serve independently as an airway or as a site for a tracheal tube or tracheostomy tube to be inserted; this tube allows a person to breathe without the use of the nose or mouth.

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