Understanding Anesthesiology - The Global Regional Anesthesia ...

SECTION 1
Airway Management
In This Section
• Airway Anatomy
• Airway Assessment
• Airway Management
• Airway Devices and
Adjuncts
• The Difficult Airway
In order to ensure adequate oxygenation and ventilation
throughout the insults of anesthesia and
surgery, the anesthesiologist must take active
measures to maintain the patency of the airway
as well as ensuring its protection from aspiration.
A brief discussion of airway anatomy, assessment
and management is given below.
Airway Anatomy
The upper airway refers to the nasal passages,
oral cavity (teeth, tongue), pharynx (tonsils,
uvula, epiglottis) and larynx. Although the larynx
is the narrowest structure in the adult airway
and a common site of obstruction, the upper
airway can also become obstructed by the
tongue, tonsils and epiglottis.
The lower airway begins below the level of the
larynx. The lower airway is supported by numerous
cartilaginous structures. The most prominent
of these is the thyroid cartilage (Adam’s apple)
which acts as a shield for the delicate laryngeal
structures behind it. Below the larynx, at the
level of the sixth cervical vertebra (C6), the cricoid
cartilage forms the only complete circumferential
ring in the airway. Below the cricoid, many
horseshoe-shaped cartilaginous rings help maintain
the rigid, pipe-like structure of the trachea.
The trachea bifurcates at the level of the fourth
thoracic vertebra (T4) where the right mainstem
bronchus takes off at a much less acute angle
than the left.
The airway is innervated by both sensory and
motor fibres (Table 1,Figure 1, Figure 2). The purpose
of the sensory fibres is to allow detection of
foreign matter in the airway and to trigger the numerous
protective responses designed to prevent
aspiration. The swallowing mechanism is an example
of such a response whereby the larynx
moves up and under the epiglottis to ensure that
the bolus of food does not enter the laryngeal inlet.
The cough reflex is an attempt to clear the upper
or lower airway of foreign matter and is also
triggered by sensory input.
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