Given these physiological and situational differences between ICU and OR intubations, a safe approach would be to consider all ICU intubations as 'difficult airways'.

With patients in the OR, bag-mask ventilation can usually provide adequate ventilation and oxygenation.

Preoxygenation is largely ineffective in these patients and oxygen desaturation occurs rapidly on induction of anesthesia, limiting the time available to secure the airway.