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KEY POINTS
The anatomy of the airway starts at either the nasopharynx or oropharynx, and continues inferiorly past the larynx into the trachea.
In an emergency when the patient cannot be intubated or ventilated, the airway can be surgically entered via the cricothyroid membrane.
Difficult ventilation is a situation in which adequate ventilation cannot be achieved.
Identifying patients with potentially difficult airways is essential due to the increased incidence of complications associated with difficult intubations.
Preoxygenation increases the safety buffer time available during the peri-intubation period.
In order to insure amnesia, analgesia, and muscle relaxation during intubation, a balanced approach utilizing multiple medications are required.
Confirmation of correct placement of the endotracheal tube can be accomplished directly by visualizing the tube passing through the vocal cords or indirectly by auscultating bilateral breath sounds, observing rise and fall of the chest wall, and by capnography.
The risk of aspiration in patients with suspected or known full stomachs can be decreased by utilizing a rapid sequence intubation technique.
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The majority of patients admitted to the intensive care unit have varying degrees of respiratory failure. The intensivist must decide whether these patients would benefit from supplemental oxygen, noninvasive positive pressure ventilation (NIPPV), or endotracheal intubation with mechanical ventilation. The ability to secure an airway with a tracheal tube is therefore a necessity for all intensivists. As can be seen in Table 17–1, there are multiple indications for intubation. In this chapter, the airway management of critically ill patients will be discussed, including the preintubation assessment, the process of intubation, and weaning to extubation.
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FUNCTIONAL ANATOMY OF THE AIRWAY
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The upper airway (Figure 17–1) includes all of the structures externally from the nares and mouth to the vocal cords. The nasal passage way is highly vascular; disruption of Kiesselbach's plexus, located in the anterior aspect of the nasal septum, is the most common cause of epistaxis. The floor of the nasal passage way slopes very gently downward. As such, nasal airways, nasogastric tubes, and endotracheal tubes (ETTs) should be directed perpendicularly or with a slightly caudad tilt in the supine patient. The nasal passages open into the nasopharynx. Laceration of the mucosa and creation of a false passage during nasotracheal intubation most commonly occurs in the region of the eustachian tubes.
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