Asleep fiberoptic intubation

Since the first use of the fiberoptic device for airway management in 1967, a variety of new airway equipment has become available. It is important for anesthesiologists to understand the role and limitations of the available equipment to make appropriate choices. An Indepth knowledge of the asleep fiberoptic intubation is valuable to every anesthesiologist. In this article, we aim to discuss the uses of the asleep fiberoptic intubation, the equipment, procedure and medications needed for the procedure.

Asleep fiberoptic intubation can be done both orally and nasally. It can be performed practically in any patient that needs intubation, however specific indications/uses may include patients with contraindication to manipulation of the neck during laryngoscopy and intubation (unstable cervical spine injury), patients at risk of teeth damage with direct laryngoscopy, confirmation of correct placement of a double lumen tube (DLT). Absolute contraindications will be patient's refusal and lack of skill by anesthesiologist.

The asleep fiberoptic intubation provides a comfortable and cooperative patient (since patient is asleep) in addition, it is easy to change to other airway devices if needed. However, there is loss of airway tone, depressed respiratory function, decreased functional residual capacity and oxygen reserves in the asleep patient.

Equipment required include a flexible fiberoptic bronchoscope, specialized intubating oral airways, an informed assistant, anti-sialagogue medication, nasal vasoconstrictor medication e.g., intranasal oxymetazoline.

During asleep fiberoptic intubation, the loss of airway tone leading to collapse of oral pharyngeal structures, the flexible fiberoptic scope which has the tendency to go off the midline all provide little to no space between the tongue and the palate through which to navigate the scope. For the above reasons, specialized oral airways are used. There is a plethora of these specialized airways, some common ones include Ovassapian, Berman and Williams. The picture attached shows a comparison of the above-mentioned intubating oral airways, their pros and cons. The flexible fiberoptic scope with a camera at the tip of the scope, a suction port and a port for oxygenation is used. Anti-sialagogue, unless contraindicated, may be used to decrease airway secretions as these secretions can obscure the view of the anesthesiologist during the procedure. The vasoconstrictor is sprayed intranasally to reduce bleeding from the turbinate, if intranasal asleep fiberoptic if being performed.

The asleep fiberoptic intubation is performed in the supine position with the patient under general anesthesia. Performing the procedure, involves oral/nasal endoscopy to obtain a view of the glottis with the flexible scope and manipulating the scope through the vocal cords into the trachea, the endotracheal tube is then advanced over the scope, placed in the appropriate position and the scope is removed. In preparation for this procedure, the endotracheal tube is placed in warm water to make it less rigid and prevent airway trauma, intranasal oxymetazoline is placed in the bilateral nostrils. The distal half to two thirds of the scope is lubricated and the endotracheal tube is mounted on the scope and advanced to the proximal part of the scope before the procedure starts.

The steps involved are outlined below.

• Patient asleep in the supine position, anesthesiologist at patient's head, the distal part of the scope is placed in the nostril of choice (if intranasal) or through the intubating oral airway if oral route is used.
• An informed assistant may help with jaw thrust or gently pull the tongue anteriorly with a 4x4in gauze. This facilitates exposure and prevents the tongue from falling back. Care should be taken to avoid injury to the tongue and other oral structures.
• Correct positioning of the scope in the oropharynx will reveal the epiglottis, slight anterior angulation of the scope will reveal the vocal cords. The scope is advanced distally through the cords.
• Advancing the scope further will reveal the trachea which can be identified by the presence of the tracheal rings. The scope is advanced to the point just above the carina.
• The endotracheal tube is then advanced over the scope with the aim of placing it just above the carina. As the endotracheal tube is being advanced, the trachea is continually being visualized through the scope. This provides confirmation that neither the scope nor the endotracheal tube has been dislodged.
• After a successful placement, proper depth is confirmed during the withdrawal of the flexible scope.

Proficiency in this procedure is essential, and can be obtained by constant practice, developing good hand-eye coordination and selecting the right patient population.