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KEY CONCEPTS
Improper face mask technique can result in continued deflation of the anesthesia reservoir bag despite the adjustable pressure-limiting valve being closed, usually indicating a substantial leak around the mask. In contrast, the generation of high breathing circuit pressures with minimal chest movement and breath sounds implies an obstructed airway or obstructed tubing.
The laryngeal mask airway partially protects the larynx from pharyngeal secretions, but not gastric regurgitation.
After insertion of an endotracheal tube (ETT), the cuff is inflated with the least amount of air necessary to create a seal during positive-pressure ventilation to minimize the pressure transmitted to the tracheal mucosa.
Although the persistent detection of CO2 by a capnograph is the best confirmation of tracheal placement of an ETT, it cannot exclude bronchial intubation. The earliest evidence of bronchial intubation often is an increase in peak inspiratory pressure.
After intubation, the cuff of an ETT should not be felt above the level of the cricoid cartilage, because a prolonged intralaryngeal location may result in postoperative hoarseness and increases the risk of accidental extubation.
Unrecognized esophageal intubation can produce catastrophic results. Prevention of this complication depends on direct visualization of the tip of the ETT passing through the vocal cords, careful auscultation for the presence of bilateral breath sounds and the absence of gastric gurgling while ventilating through the ETT, analysis of exhaled gas for the presence of CO2 (the most reliable automated method), chest radiography, airway ultrasonography, or use of fiberoptic bronchoscopy.
Clues to the diagnosis of bronchial intubation include unilateral breath sounds, unexpected hypoxia with pulse oximetry (unreliable with high inspired oxygen concentrations), inability to palpate the ETT cuff in the sternal notch during cuff inflation, and decreased breathing bag compliance (high peak inspiratory pressures).
The large negative intrathoracic pressures generated by a struggling patient in laryngospasm can result in the development of negative-pressure pulmonary edema, particularly in healthy patients.
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Expert airway management is an essential skill in anesthetic practice. This chapter reviews the anatomy of the upper respiratory tract, describes necessary airway equipment, presents various management techniques, and discusses complications of laryngoscopy, intubation, and extubation. Patient safety depends on a thorough understanding of each of these topics.
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The upper airway consists of the pharynx, nose, mouth, larynx, trachea, and mainstem bronchi. The mouth and pharynx are also a part of the upper gastrointestinal tract. The laryngeal structures in part serve to prevent aspiration into the trachea.
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There are two openings to the human airway: the nose, which leads to the nasopharynx, and the mouth, which leads to the oropharynx. These passages are separated anteriorly by the palate, but they join posteriorly in the pharynx (Figure 19–1). The pharynx is a U-shaped fibromuscular structure that extends from the base of the skull to the cricoid cartilage at the entrance to the esophagus. It opens anteriorly into the nasal cavity, ...