Airway Management in the Intensive Care Unit

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Chapter 34 Airway Management in the Intensive Care Unit*

The decision to instrument the airway of a patient is one of the most crucial taken; this approach to airway management, although often required in an emergency situation, requires considerable skill, experience, and knowledge of the different types of procedures available. The main reasons to instrument the airway are (1) failure of oxygenation, (2) failure of ventilation, and (3) protection of the airways.

Patients with a variety of medical and surgical diseases may require ventilatory assistance or improved airway control. Such patients include those with primary respiratory failure or with respiratory insufficiency secondary to other pathologic conditions. Implementation of respiratory support may be undertaken semielectively or on an emergency basis.

Airway instrumentation should be performed only by a skilled physician who has assessed the patient thoroughly addressing the risks and benefits for that patient. A vital step in this assessment is prediction of the ease with which intubation is likely to be possible, with identification of an appropriate alternative approach to use in case difficulties arise. An important point to remember is that patients die not because of a failure to intubate but as a result of failure to oxygenate; therefore, recurrent failed attempts to gain airway control should be avoided. Problems with ventilation can quickly lead to severe hypoxia, brain damage, or death.

Airway Assessment

Before instrumentation of the patient’s airway, a thorough assessment should be performed to ascertain the likelihood of difficulty in achieving airway control. Several specific aspects of this assessment are considered next.

Predictors of Difficult Intubation

Difficult intubation is common in the ICU population, with frequency of reported difficulty between 6.6% and 22%. A history of airway problems should be sought—for example, snoring, sleep apnea, congenital diseases (such as Down or Pierre-Robin syndrome), and previous anesthetic problems.

Examination of the patient should determine the following: ability to protrude the mandible, range of neck movement, atlantooccipital flexion and extension, interincisor distance (less than 3 cm indicates a high likelihood of difficulty), and modified Mallampati test (Figure 34-1). Other predictors of difficult intubation include thyromental distance of less than 7 cm (Patil’s test) and obesity. Further investigations when indicated could include the view of the larynx obtained at nasal endoscopy, which may predict the view at laryngoscopy; chest radiographs, which may show tracheal deviation or mediastinal masses; and CT scans, which may be useful when abnormal anatomy is suspected—for example, in association with tracheal stenosis.

Aspiration Risk

Aspiration of gastric contents can cause significant morbidity and mortality. Evidence suggests that reducing gastric volume and increasing pH of gastric contents will limit the risk of disorders associated with aspiration. Acid aspiration may lead to a chemical pneumonitis, but aspiration of food particles can result in physical obstruction of the bronchial tree with secondary bacterial pneumonia (Box 34-1 and Table 34-1).

Table 34-1 Drugs to Reduce Aspiration Risk

Drug Class Specific Agent Mechanism of Action
Histamine H2 receptor antagonists Ranitidine 50 mg IV Increases pH and decreases gastric volume
Proton pump inhibitors Omeprazole 40 mg IV Irreversibly binds H+/K+-ATPase; increases pH and decreases gastric volume
Nonparticulate antacids 0.3 M sodium citrate, 10 mL Neutralizes gastric pH but increases volume
Very effective at increasing gastric pH if given within 30 minutes
Prokinetics Metoclopramide 10 mg Reduces gastric volume

Endotracheal Intubation with Muscle Relaxation

Bag Mask Ventilation

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