Endotracheal intubation may be employed as a life saving measure and in this circumstance there are few absolute contraindications to its use. However, clinicians must be mindful of conditions in which intubation may provoke additional problems. This includes blunt or penetrating trauma to the larynx causing laryngeal fracture or separation of tissue layers. Traction with a laryngoscope, stylet, or endotracheal tube may cannulate a false lumen or tear the airway. When there is significant doubt as to the safety of intubation noninvasive oxygenation and ventilation are preferred until a definitive or surgical airway can be created.

Relative contraindications to intubation include patients with a difficult airway. The mnemonic LEMON (Look, Evaluate, Mallampati Class, Obstruction/Obesity, Neck mobility) can be used to stratify a difficult airway [2]. Look externally for any clear visible evidence of potential problems such as micrognathia. Evaluate using the 3-3-2 rule (Fig. 17.1) to confirm that the mouth can open to fit 3 of the patient’s fingers between upper and lower incisors, the submandibular space can fit 3 of the patient’s fingers from chin to angle of the neck, and the space between the superior aspect of thyroid cartilage and angle of the neck can fit 2 of the patient’s fingers. Mallampati class (Fig. 17.2) rates the space for oral intubation based on tongue size and degree of mouth opening from I (most open) to IV (least open). Obstruction and obesity assess any upper airway impediment caused by tumors, swelling, excess adipose tissue, or other masses. Neck mobility assesses the patient’s ability to be placed in the sniffing position in which the head is elevated and neck extended forward.

Assembly of all necessary equipment prior to starting is essential as unforeseen complications may result in critical delays (Table 17.2).

Laryngoscopes are composed of a handle, blade, and light source. The two most frequently used blades are the Macintosh which is curved and the Miller which is straight. The choice of which to use is based on experience and personal preference [4]. These and other images of essential equipment are displayed in Fig. 17.3.

When there is difficulty visualizing the glottis a bougie or tube introducer is placed in the trachea and the endotracheal tube is passed over it. Oral and nasal airways are adjuncts and can be used to prevent the tongue from obstructing the posterior pharynx.

Endotracheal tubes are measured lengthwise in centimeters and by internal diameter in millimeters and French. Assemble tubes one size greater and one size smaller than the estimated tube to be used. Most adults will need at least an 8.0 mm tube but an inappropriately small tube will increase the work of breathing and if a bronchoscopy is to be performed the tube must be sufficiently wide to allow passage of equipment.