Tracheal intubation (commonly known as intubation) is the placement of a flexible plastic tube into the trachea in order to maintain an open airway or to serve as a conduit through which to administer oxygen or other drugs. It is commonly performed in emergency situations and critically ill or injured patients, but intubation is also used in patients who will be undergoing a lengthy surgery that requires them to be under anesthesia for a significant number of hours.
In order to intubate, the tube is usually placed through the nose or mouth and into the trachea; however, it can also be surgically placed. A cricothyrotomy is an incision on the patient’s neck through the cricoid cartilage, and is only used in emergency situations. A tracheotomy is an incision directly leading into the trachea, and is used primarily in situations when an advanced airway will be needed long-term. Because intubation in invasive and uncomfortable, it is preferred that the patient be under a local or general anesthesia. However, in emergency situations it is performed without any anesthesia. In order to ensure easy access and correct placement, the tracheal tube is usually guided by a laryngoscope or other device that allows the glottis to be viewable. Some laryngoscopes are straight while others are curved. The device used is solely dependent on the patient’s unique anatomy and physiology.
To ensure proper placement, the medical professional can watch for chest rise on the patient as well as use an endoscopic camera to view placement further. While the tube is in place within the trachea, a small balloon is inflated at the bottom of it to ensure that it remains in place and also to prevent any leaks or unwanted material coming into the tube. It is also secured on the outside of the face or neck. From the point that it exits the body, the tracheal tube is connected to a T-piece, which facilitates a connection to the bag-valve mask or ventilator.
Once the patient can protect his airway and/or there is no longer a need for ventilatory assistance, the tracheal tube is removed. If it was placed through the nose or mouth, the removal is called extubation. If the tube was placed through an incision, the removal is referred to as decannulation.
Tracheal intubation used to be performed solely via a tracheotomy and was first documented and detailed in the early 16th century. At that time though, it was looked at as a last resort because doctors were not aware of the risk of infections. Most patients during that time died from complications. However, as time went on, it became a more acceptable procedure. In the early 20th century, William Macewen documented his use of an orotracheal tube and thus sparked a trend in intubating without surgery. In 1909, Chevalier Jackson reported a high success rate of intubation using a camera to view the larynx and pharynx. Since then, new developing techniques have surfaced and intubation has become much more common.
Indications for intubation include altered level of consciousness, hypoxemia, or airway obstruction. A depressed level of consciousness prevents the patient from protecting his own airway and can eventually lead to suffocation. The tracheal tube keeps the windpipe open and clear. Also in low levels of consciousness, the body often loses its respiratory drive. Hypoxemia is a condition in which the blood does not have enough oxygen because for some reason the patient’s body is unable to sufficiently transport gases to the blood. Hypoxemia can result from many different illnesses or injuries, but regardless the reason, intubation helps to correct that condition. An airway obstruction can result from a foreign body becoming lodged in the airway, vomit or other secretions occluding the airflow, or severe trauma to the face or neck that impedes a patient’s ability to get air to the lungs.
There are some risks involved with intubation. Minor complications include sore throat, dry mouth, and broken teeth. Infection is a bigger concern, given that the tracheal tube gives a clear and direct route from the external environment into the lungs. Tracheal perforation, damage to the vocal cords, and pulmonary aspiration are other more serious complications. Finally, if the tube is placed into the esophagus instead of the stomach, serious conditions can occur due to the high amounts of oxygen being pumped into the stomach.
Image Caption: Anesthesiologist using Glidescope video laryngoscope to intubate the trachea of a morbidly obese patient with challenging airway anatomy. Credit: DiverDave/Wikipedia (CC BY 3.0)