A difficult intubation can occur because of anatomical abnormalities or situational factors like airway inflammation that make it hard to secure access to the trachea. Endotracheal intubation is necessary for general anesthesia and other settings where there are concerns about a patient's ability to breathe independently. When a patient's airway proves difficult, it can increase the risk of trauma during the intubation and may also expose the patient to the risk of low oxygen saturation caused by inadequate air supply.
One common cause of difficult intubation is the structure of the patient's airway. If a patient has anomalies in the airway, these could make it tighter and hard to work with. Patients who have trouble opening their mouths or extending their necks can also be hard to work with. While patients are usually sedated or unconscious during intubation, the residual stiffness and limited range of motion can be difficult to overcome.
The situation can also be a contributing factor. If the airway is filled with blood, vomitus, mucus, or other materials, it can make for a difficult intubation. Care providers may suction the airway to clear it, but it may fill again quickly. Patients with a recent history of trauma can also be challenging to intubate, as can patients with airway restriction caused by inflammation. Asthma patients and other people with chronic airway inflammation can also present a difficult intubation because of strictures and scarring.
Pregnancy appears to increase the difficulty of intubation, as does underlying spinal disease. If a patient has a spinal cord injury, the anesthesiologist may need to be especially careful to avoid jarring and injuring the patient. Patients with inadequate sedation are also challenging to intubate, as they typically fight the tube and can be very aggressive. Another complicating factor can be lack of experience; the only way to learn to handle difficult intubations is to do them, but it can be hard to intubate without very much experience.
Anesthesiologists can use some assessments to predict the level of intubation difficulty and plan ahead. They may examine the patient's airways to determine how open they are and to check for signs of obstructions and other problems. If a difficult intubation seems likely and a patient is not very stable, the care team may call for someone with a great deal of experience to reduce the risk of a failed intubation.