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Airway control is one of the most critical actions taken during an emergency response. It is not always straightforward and can present with many variations, creating challenges for the Emergency Physician. Many factors contribute to a difficult airway, with obesity becoming one of the most prevalent in the United States.1 The negative effects of obesity are seen in nearly every organ system through anatomic, physiologic, and metabolic changes. The Emergency Physician must take these changes into account when attempting an endotracheal intubation in an obese patient, including a thorough understanding of the anatomy, physiology, equipment necessary, and complications. This chapter will aid in providing a better understanding of what many consider the most daunting challenge to an Emergency Physician.
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ANATOMY AND PATHOPHYSIOLOGY
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We will discuss the important variances seen in obesity and how they affect management. There is an overall increase in fat deposition within soft tissue structures in the oropharynx in a morbidly obese patient. These fat depositions can lead to enlarged lateral pharyngeal walls and a soft palate, a decrease in the caliber of the upper airway, and an increase risk of airway collapse.2 Neck circumference > 40 cm, a short neck, decreased mobility of the cervical spine, and a Mallampati class of III or IV are the best predictors of difficult ventilation with a mask and difficult intubation.3-6 A study performed by Stanford University showed that neck circumferences of 40 cm and 60 cm were associated with 5% and 35% probabilities of difficult intubation, respectively.7 A large neck circumference does not indicate where fat is distributed along specific areas of the anterior neck. More fat is deposited around collapsible pharyngeal segments in patients with obstructive sleep apnea (OSA) syndrome (Table 15-1).8-11 Obesity is a clear risk factor for developing OSA.12-14 Further investigation is needed to clarify the conflicting evidence associating OSA with difficult intubations. Positioning plays a key role in alleviating the difficulties provided by anatomic variations and soft tissue distributions.1
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