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KEY POINTS

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KEY POINTS

  1. Expiratory reserve volume (ERV) is the most sensitive indicator of the effect of obesity on pulmonary function testing.

  2. Cardiac output increases with increasing weight, leading to ventricular dilatation and hypertrophy. Obese subjects compensate by using cardiac reserve, especially in the presence of hypertension. The dilated left ventricle has a limited capacity to hypertrophy, so when left ventricular wall thickening fails to keep pace with dilatation, systolic dysfunction (“obesity cardiomyopathy”) results, with eventual biventricular failure.

  3. Gastric emptying may be delayed in obese patients because of increased abdominal mass causing antral distension, gastrin release, and a decrease in pH with parietal cell hypersecretion. Emptying has been documented to be faster with high-energy content intake, such as fat emulsions, but residual volume (RV) is increased because of the larger gastric volume (up to 75% larger). Obese patients should follow the same fasting guidelines as nonobese patients.

  4. Neck circumference has been identified as the single biggest predictor of problematic intubation in morbidly obese patients.

  5. Preoxygenation in the head-up or sitting position is more effective and provides the longest safe apnea period during induction of anesthesia in obese patients.

  6. Difficult laryngoscopy and intubation correlate well with increased age, male sex, temporomandibular joint (TMJ) pathology, Mallampati classes 3 and 4, history of obstructive sleep apnea (OSA), and abnormal upper teeth, not body mass index (BMI).

  7. The head-elevated laryngoscopy position (HELP) position significantly elevates the obese patient’s head, neck, upper body, and shoulders above the chest to a point where an imaginary horizontal line can be drawn from the sternal notch to the external ear to better improve laryngoscopy and intubation.

  8. Positive end-expiratory pressure (PEEP) is the only ventilatory parameter that has consistently been shown to improve respiratory function in obese subjects, but it may decrease venous return, cardiac output, and subsequent oxygen delivery.

  9. Regional anesthesia should be considered in the obese patient as it may help avoid airway manipulation, respiratory depression from use of systemic opioids, and the cardiopulmonary depression associated with some anesthetics. It has also been shown to be associated with significantly less blood loss and transfusion, thromboembolic events, infection, and mortality.

  10. Drugs such as dexmedetomidine and intravenous acetaminophen are well suited as adjuncts in obese patients due to their opioid-sparing effects and favorable safety profiles.

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INTRODUCTION

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The worldwide epidemic status of obesity is a key factor in the increased incidence of type 2 diabetes mellitus and cardiovascular diseases such as high blood pressure and stroke.1 Obesity is defined as an abnormally high percentage of body weight as fat. Overweight is an increase in weight relative to a standard. Approximately 69%, or 2 of every 3 adults, in the United States are overweight or obese.2

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Approximately 85% of the economic burden of obesity can be accounted for by obesity-related diseases (coronary artery disease, stroke, type 2 diabetes mellitus, hypertension, hyperlipidemia, obstructive sleep apnea [OSA]) and prescription drugs.3 The anatomic distribution ...

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