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  1. In the intensive care unit (ICU), endotracheal intubation is usually marked by an urgent need in face of cardiorespiratory instability, poor physiologic reserve, and an unknown airway history.

  2. The incidence of difficult intubation and complications during intubation in the ICU are considerably higher than reported in operating room settings.

  3. Preoxygenation should take place prior to any airway intervention.

  4. Flexing the neck and extending the head at the atlantooccipital joint, called the “sniffing” position is probably the best starting position for direct laryngoscopy.

  5. In recent years, the use of bladed indirect laryngoscopes (eg, Glidescope, C-MAC, McGrath) has increased in the operating room, the emergency department, and the ICU.


Endotracheal intubation in the ICU differs significantly from when performed by anesthesiologists in the operating room, with availability of special airway equipment, and trained staff support.1 In addition, ICU endotracheal intubation is usually marked by an urgent need in face of cardiorespiratory instability, poor physiologic reserve, and an unknown airway history.2

The incidence of difficult intubation in the ICU is 12% to 22%, considerably higher than reported in operating room settings.3,4,5 The rate of severe complications is very high, including severe hypoxemia (26%), hemodynamic collapse (25%), cardiac arrest (1.6%), and death (0.8%).2 The Fourth National Audit Project Report (NAP4), a review of major airway-related events occurring in the United Kingdom over a period of a year, revealed that 61% of the airway events that occurred in the ICU resulted in death or brain damage. More concerning is that after qualitative analysis of the events, reviewers assessed airway management as good in only 11%.3


Airway assessment must be performed before any procedure. The purpose of this evaluation is to identify possible difficulty with bag-mask ventilation, intubation, supraglottic device placement, or cricothyroidotomy/tracheostomy. Even in the ICU, where most intubations are performed emergently, an abbreviated assessment is warranted.6,7,8

Predicting Difficult Bag-Mask Ventilation

If endotracheal intubation is difficult or impossible, ventilation with a bag-mask will maintain oxygenation until the airway is secured. Difficult ventilation is a serious problem, and every effort should be made to anticipate this complication.9 Five independent predictors have been identified: age greater than 55, body mass index greater than 26 kg/m2, lack of teeth, history of snoring, male gender, and presence of beard.7,9

Predicting Difficult Direct Laryngoscopy

Indicators of potentially difficult direct laryngoscopy include inability to prognath (move the lower teeth in front of the upper teeth), high Mallampati-Samsoon classification score (Figure 97–1), interincisor distance of less than 4 cm (~2 fingerbreadths), short thyromental distance (< 6.5 cm or 3 fingerbreadths) measured from the top of the thyroid cartilage to the anterior border of the mandible with the head in full extension, range of neck extension less than 35°, and previous history of a difficult intubation.7,8,9,10,11

Figure 97–1

The Mallampati-Samsoon classification attempts to correlate the ...

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