Tracheal Intubation and Airway Management

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Chapter 14 Tracheal Intubation and Airway Management

Manuel Pardo, Jr. , MD

1 What is the airway?

The airway is the conduit through which air and oxygen must pass before reaching the lungs. It includes the anatomic structures extending from the nose and mouth to the larynx and trachea.

2 What is airway management?

Airway management is the procedure for ensuring that the airway remains patent. It is the first step in the ABCs of basic resuscitation (B = breathing, C = circulation).

3 Why does airway management generally precede management of breathing and circulation?

If the airway is completely obstructed, no oxygen can reach the lungs, and the heart and circulation will have no oxygen to distribute to the body’s vital organs. However, the 2010 American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care now recommend beginning cardiopulmonary resuscitation with 30 chest compressions before delivering two rescue breaths. Although there is no proven mortality benefit to managing the airway after the circulation, the AHA rationale is that blood flow to vital organs depends on chest compressions.

Note: In addition, the AHA recommends “hands-only” chest compressions (i.e., no rescue breathing at all) for the untrained lay rescuer of a victim in cardiac arrest.

4 Describe the ways to manage the airway

The airway may remain patent without any intervention and can be managed with or without tracheal intubation. Airway management without intubation can involve a variety of maneuvers. In unconscious patients, the tongue commonly obstructs the airway. Techniques to open the airway include the head tilt–chin lift maneuver and the jaw thrust maneuver. Placement of oral or nasal airways may also help to maintain a patent airway. The use of a face mask with a bag-valve device (e.g., Ambu bag) is the usual next step in airway management. In the majority of patients, it is possible to maintain a patent airway without tracheal intubation. If tracheal intubation is required, it can be accomplished through surgical or nonsurgical techniques.

5 What are the indications for tracheal intubation?

There are five main indications:

image Upper airway obstruction

image Inadequate oxygenation

image Inadequate ventilation

image Elevated work of breathing

image Airway protection

6 Explain why upper airway obstruction is an indication for tracheal intubation

If the upper airway is obstructed and cannot be opened with the previously described maneuvers, the trachea must be intubated to avoid life-threatening hypoxemia. Although intubation will bypass the anatomic area of obstruction, the cause should be determined to evaluate appropriate timing of extubation or need for further treatment.

7 Explain how to evaluate hypoxemia as an indication for tracheal intubation

If the patient’s oxygen saturation is consistently less than 90% despite the use of high-flow oxygen delivered through a face mask, tracheal intubation should be considered. One hundred percent oxygen can be delivered reliably only with an endotracheal tube. Other factors to consider are the adequacy of cardiac output, blood hemoglobin concentration, presence of chronic hypoxemia, and reason for the hypoxemia. For example, patients with hypoxemia due to intracardiac right-to-left shunts may have chronic hypoxemia. In these patients, the administration of 100% oxygen with an endotracheal tube may not be effective in raising the oxygen saturation level.

8 Explain how to evaluate hypoventilation as an indication for tracheal intubation

With hypoventilation, the blood PCO2 progressively rises, which also lowers the blood pH level (respiratory acidosis). With increasing CO2 levels, patients eventually become unconscious (CO2 narcosis). Low systemic pH may be associated with abnormal myocardial irritability and contractility. The exact level of pH or PCO2 that requires assisted ventilation must be determined for each patient. Chronic respiratory acidosis (e.g., in a patient with severe chronic obstructive pulmonary disease) is usually better tolerated than acute respiratory acidosis.

9 Explain how to evaluate elevated work of breathing as an indication for tracheal intubation

Normally, the respiratory muscles account for less than 5% of the total body oxygen consumption. In patients with respiratory failure, this can increase to as much as 40%. It can be difficult to assess the work of breathing by clinical examination. However, patients who have rapid shallow breathing, use of accessory respiratory muscles, or paradoxic respirations have a predictably high work of breathing. The results of an arterial blood gas analysis (i.e., pH, PCO2, and PO2) may be initially normal in such patients. Eventually, the respiratory muscles fatigue and fail, causing inadequate oxygenation and ventilation. Mechanical ventilation can sometimes be done without tracheal intubation (see Chapter 9) but is more reliably accomplished with intubation.

10 Explain airway protection as an indication for tracheal intubation

In an awake patient, protective airway reflexes normally prevent the pulmonary aspiration of gastric contents. Patients with altered mental status from a variety of causes may lose these protective reflexes, increasing the risk of aspiration pneumonia. Tracheal intubation with a cuffed tube can decrease the risk of aspiration. However, liquids can still leak around the endotracheal tube cuff, and the glottic barrier is bypassed, which plays a role in bacterial colonization of the lower airways.

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