Patient selection takes into consideration the extent of surgical stress, anesthetic concerns [10], and post-operative recovery. The procedure should have nominal expectant blood loss and minimal derangements in physiology. The American Society of Anesthesia (ASA) patient stratification score is often used when selecting patients for elective procedures in remote settings. ASA class 1 and 2 are considered safe to be performed, while class 3 is relatively safe if comorbid systemic diseases are well controlled. If at all possible, performing procedures on ASA classification four and five patients should be done in a well-equipped environment such as the OR. Unfortunately, the clinical decision-making is not always that simple. Clinical judgment must be exercised as the patient may require an urgent procedure in and out of OR setting. For example, you are asked to perform a bedside Esophagogastroduodenoscopy (EGD), and Colonoscopy in the Critical Care Unit for a patient with a BMI of 56 kg/m². Of note, his past medical history includes ischemic cardiomyopathy and he is status post a biventricular assist device 8 years ago. He now presents with hematochezia and hemoglobin of 6.4 g/dl. At the time of his BiVAD placement his BMI was 42 kg/m², meeting inclusion criteria. There are numerous challenges in this anesthetic. Is it safe to perform this bedside, outside of the operating room given associated risks with his obesity, and comorbidities? Should this patient receive a general anesthetic with an assisted airway in order to avoid obstruction, and hypoxemia? If over sedated bedside, are resources available to treat the expected drop in systemic vascular resistance and subsequent reduced pulse index on his BiVAD? There are numerous ways to perform this anesthetic, but it’s important to identify such concerns in this high-risk patient population. Although obesity alone is not this patient’s most concerning medical problem; the physiologic differences in this patient, compared to the normal BMI patient make him more susceptible to anesthetic induced morbidity.

The basic requirements of equipment and personnel resources, as defined by the ASA practice guidelines [11] for out of operating room anesthesia must be met for every procedure. The position of the patient should allow for quick access to the patient, have adequate lighting, sufficient power sources (and back up sources), gas supply, oxygen cylinders and hand resuscitation bags capable of 90 % oxygen delivery. Access to emergency drugs and more personnel should be readily available. Monitoring should at minimum include oxygenation, ventilation, circulation and temperature. Airway equipment, suction, and emergency drugs should be readily available. Trained staff under the supervision of an Anesthesiologist should provide post anesthesia management.

It is well established that excess adipose tissue increases the risk of metabolic syndrome (MetS), diabetes, cardiovascular disease, cancer, and premature death [12–16]. The presence of metabolic syndrome is implicated in the increased all-cause mortality seen in morbidly obese patients [17]. Broadly, MetS is characterized by an imbalance between glucose and insulin homeostasis, dyslipidemia, obesity (in particular abdominal fat distribution), and hypertension. The postulated pathogenesis of this condition takes into account possible genetic susceptibility, however living a sedentary lifestyle and obesity is widely accepted as the predominant contributing factors [18, 19]. Studies have identified a direct correlation between waist size and incidence of coronary artery disease, independent of morbid obesity. That is to say, a male that has a BMI of <30, with a waist of greater than 40 in. also is at risk of coronary artery disease (CAD). Body fat content, not BMI, is the primary determinant that leads to the cascade of physiologic changes commonly present in the morbidly obese population [20]. The high vascularity of fat creates an elevation in both cardiovascular and metabolic demand. Adipose tissue also serves as a powerhouse for numerous endocrine and paracrine cytokines that trigger physiologic change [21, 22]. Accelerated atherosclerosis, insulin resistance, alterations in lipid levels, coagulation, and elevation c-reactive protein (CRP) is all seen secondary to the various bioactive markers present in adipose tissue [23–25]. Many of these processes are reversible with optimization of diet, and weight loss. Given the physiologic changes that result from an elevated body fat content in combination with the limited mobility owing to an increase in musculoskeletal disorders [26], surgical intervention is often explored by these patients for weight loss.

As with any good anesthetic, it is crucial to obtain an in depth history and focused physical examination. If available, it is helpful to review past anesthetic records, as any concerning information gathered may lead to an alteration in the planned anesthetic. A detailed history must include an assessment of obstructive sleep apnea, cardiopulmonary and other common systemic diseased associated with morbid obesity (Table 27.3).

When providing sedation in an out of OR setting, the guidelines for monitoring must be adhered to as outlined earlier. The depth of unconsciousness required varies by the procedure being performed. The patient should be kept spontaneously breathing, as entering deep sedation or general anesthesia without a protected airway increases the risk of complications resulting from hypoxia. The spectrum of sedation to general anesthesia is best examined by assessing patient response to verbal or painful stimuli, need for assistance with airway, ability to ventilate, and cardiovascular stability (Table 27.4).