CHAPTER 20: Airway Management of a Morbidly Obese Patient Suffering from a Cardiac Arrest

CASE PRESENTATION

A 67-year-old woman presents to the emergency department (ED) by ambulance with a 3-hour history of increasing dyspnea associated with chest pain. She has a history of coronary artery disease, hypertension, and hyperlipidemia, but no known allergies. Her medications include atenolol, low-dose aspirin, atorvastatin, acetaminophen with codeine, and nitroglycerin spray as needed. Prior to notifying the emergency medical services (EMS), the patient had used three sprays of nitroglycerin every 5 to 10 minutes with no relief.

She is placed on 10 L·min⁻¹ oxygen by face mask and is transported to the hospital. On examination after the arrival at the ED, her vital signs are: heart rate 113 beats per minute and irregular, respiration rate 31 breaths per minute, blood pressure 85/45 mm Hg, and SaO₂ 86%. She appears to be in severe respiratory distress and is unable to speak more than three to four words in one breath. She is morbidly obese with an estimated weight of over 137 kg (300 pounds) and is 151 cm (5 feet) tall with a body mass index (BMI) 60 kg·m⁻². Chest auscultation reveals faint breath sounds with crackles over the entire lung fields, a significant decrease in air entry in both bases combined with mild wheezing. Other findings include 1+ bilateral ankle edema, S₄ heart sound, and a grade III/VI systolic murmur radiating to the axilla. Her jugular venous pressure (JVP) cannot be assessed because of her marked obesity and short neck. Her electrocardiogram on admission to the ED reveals a pattern consistent with an acute antero-lateral myocardial infarction. The chest x-ray shows poor inflation and is also consistent with pulmonary edema.

Following the initial assessment, it is noticed that the SaO₂ decreases to 81% and her respirations increasing to 35 to 40 breaths per minute. Pink froth appears from her mouth.

As you prepare for airway intervention, she loses consciousness. The monitor shows pulseless ventricular tachycardia.

INTRODUCTION

Define Obesity

Obesity is the presence of an excess of body fat when compared to average values for age and gender. When the percentage of body fat exceeds 15% to 18% in men, or 20% to 25% in women, the individual is considered obese. Unfortunately, measuring body fat is not practical, as it requires sophisticated techniques.

The ideal body weight (IBW) has been used frequently in clinical settings to define obesity:

$IBW ( kg ) = height ( cm ) − x$ where x is 100 for males and 105 for females.

Patients who weigh 20% above IBW are considered overweight, and they are considered morbidly obese if their weight is 200% above the calculated IBW.¹

The World Health Organization (WHO) specifies the use of BMI as the international method of classifying obesity.^2...