Obesity describes the excess accumulation of body fat and is currently endemic in the United States, afflicting over 35% of the adult population. Although the percentage of body fat (>25% in men and >32% in women) is commonly used to describe obesity, these measurements are not readily available to most clinicians. Therefore, obesity is more commonly assessed by calculating the patient’s body mass index (BMI) or weight (kg) divided by their height in square meters (m²).¹ Using these criteria, obesity is defined as having a BMI greater than 30, and clinically severe or morbid obesity is described as a having a BMI greater than 40 or a BMI greater than 35 with severe medical comorbidities.² Using BMI criteria, more than 50% of adult Americans are overweight or obese, and approximately 5% are morbidly obese.³

Although these definitions are helpful in identifying individuals who are “at risk” for obesity-related complications, neither BMI nor percentage body fat describes the regional distribution of body fat. This is important because medical consequences of obesity are related in part to the distribution of body fat. Visceral or android obesity is more common in men and associated with insulin resistance, gastroesophageal reflux, hyperlipidemia, hypertension, obstructive sleep apnea (OSA), and metabolic syndrome.^2,4,5 Gynecoid or subcutaneous obesity describes an excess accumulation of subcutaneous fat in the gluteal or buttock area and is more commonly seen in women. Degenerative joint disease, impaired mobility, dyspnea on exertion, asthma, urinary stress incontinence, and dysfunctional uterine bleeding are common medical consequences of obesity as well. Although the metabolic consequences of subcutaneous adiposity are less than for visceral adiposity, complications related to wound healing and surgical site infections are more common with subcutaneous adiposity.^6,7,8

In 1991, the National Institutes of Health published a consensus statement, entitled “Gastrointestinal Surgery for Severe Obesity.”⁹ In this publication, they described the generally accepted criteria for surgical weight loss or “bariatric surgery.” Evaluation by a comprehensive, multidisciplinary team comprising experienced surgeons and individuals with medical, psychiatric, and nutritional expertise is recommended. The generally accepted criteria for surgical weight loss include BMI greater than 35 with severe medical comorbidities (typically type 2 diabetes or OSA) or BMI greater than 40, failure of medical weight loss, and no psychological contraindications to surgery.⁹ At this time, the most commonly performed surgical procedures were vertical banded gastroplasty (VBG) and the Roux-en-Y gastric bypass (RYGB).

Although weight loss operations have changed since 1991, the process of evaluating potential candidates for bariatric surgery remains similar. Most bariatric surgery programs offer a general information session that allows potential surgical candidates a chance to learn about the different surgical procedures; the preoperative evaluation process (nutrition counseling, psychological evaluation, medical workup); and the risks and benefits of different procedures and to ask questions and the like.^10,11 One of the most controversial criteria in evaluating candidates for bariatric surgery is ascertaining whether patients have “failed medical weight loss.” This problem is due in part to variable definitions of failure of medical weight loss by medical and nutrition specialists, bariatric surgeons, and third-party payers. Potential patients for bariatric surgery are commonly asked to describe previous attempts at weight loss (diet, exercise, behavior modification); duration of attempted weight loss; magnitude of weight loss; and successful maintenance of weight loss. The term excess body weight loss (EBWL) is commonly used to describe weight loss and is calculated using the actual and ideal body weights. Medical weight loss commonly results in 5%–10% EBWL with long-term success rates of 5% to 10%.^3,12 For a while, many insurance companies required monthly visits with a dietitian and weigh ins for 3 to 6 months with documented dietary compliance before allowing patients to be considered for surgical weight loss.^3,12 Suffice it to say, defining failure of medical weight loss remains variable in different geographic regions, by different medical specialties and different third-party payers, and among bariatric surgery programs.

It is important for patients considering surgical weight loss to understand surgery is not a “cure” for obesity; rather, it is “a tool” to help them improve their health by facilitating weight loss. For the surgery to be successful, patients need to change their eating behavior and adopt a healthier lifestyle. With that in mind, it is helpful for patients to develop some insights regarding their eating and other behaviors that contributed to their development of morbid obesity. Psychological evaluation is routinely performed by most (>80%) of bariatric surgery programs.¹³ Approximately 65% to 75% of patients presenting for surgical weight loss have some type of preexisting mood disorder.

Although there is considerable variability in scope and structure, the preoperative psychological evaluation commonly includes weight history; eating behaviors; screening and assessment of eating disorders (e.g., binge eating, nighttime eating syndrome, emotional eating, or grazing); psychosocial history; an evaluation of existing or potential mood disorder(s) and whether they are adequately controlled; and a determination of cognitive function to see if the patient understands how certain behaviors have contributed to the development of morbid obesity and whether the patient has a realistic understanding of the changes he or she will need to make for surgery to be successful. An assessment of health-related behaviors, including substance use, physical activity, expectations, and knowledge of the proposed surgery and complications is frequently performed. The most commonly identified reasons for denying surgery include substance abuse, psychotic symptoms, severe mental retardation, and patient reports of overeating to deal with stress.^14,15

It is important to realize that even the most detailed and comprehensive psychological evaluation will not identify potentially problematic patients. The psychological evaluation is most helpful in identifying patients with “absolute contraindications” or “no contraindications for surgery” for bariatric surgical procedures. Unfortunately, when “relative contraindications” to surgery are identified, the multidisciplinary team is frequently left with a difficult decision in weighing the relative risks and benefits of surgery for the individual patient. In these situations, a physician-to-physician conversation between the surgeon, psychiatrist, and the patient’s primary care physician may help to develop the best course of action to take.

Any decision to proceed with surgery requires a balanced assessment of the risks and benefits of surgery for the individual patient. While many programs have developed structured preoperative medical assessments for patients considering bariatric surgery, the individual patient’s workup should be tailored based on the patient’s age, functional status, underlying medical comorbidities, and previous surgical history.¹¹ A thorough history and physical by an experienced bariatric provider are usually the first step in the process. The need for subsequent testing and consultation is usually based on the patient’s current medical diagnoses and the extent to which their “severity” and “medical control” are documented in the medical record. For example, approximately 25%–30% of patients who present for bariatric surgery have type 2 diabetes mellitus (T2DM). Many of them check their glucose levels regularly, and their hemoglobin (Hb) A_1c values are followed routinely and are well controlled (e.g., HbA_1c <7.5). It is helpful to have an assessment of T2DM control within 6 months of bariatric evaluation. This allows enough time for patients with “poorly controlled diabetes” (e.g., HBA_1c > 8%) to be referred back to their endocrinologist or primary medical doctor for adjustment of their medical regimen before surgery.

Many patients presenting for bariatric surgery have symptoms of OSA (e.g., snoring, daytime sleepiness, poor-quality sleep, witnessed apneic episodes, etc.), while some patients have no symptoms at all. Given the prevalence of sleep-disordered breathing in this population (>80%) and the potential risks of undiagnosed, untreated OSA in the perioperative period, we routinely refer most patients for sleep studies unless they have been previously tested or are currently being treated.¹⁶ The need for cardiology evaluation and stress testing is decided on a case-by-case basis depending on the patient’s cardiac risk factors and presence of potential cardiac symptoms. Associated medical comorbidities (e.g., chronic renal failure, fatty liver, underlying pulmonary disease, previous thromboembolic events such as deep venous thromboembolism, pulmonary embolism, or hypercoagulable state) are commonly encountered and have to be assessed in the context of the individual patient’s age and other medical conditions.¹⁰ Previous studies have identified age above 55 years, BMI above 55, male gender, and reoperative surgery as risk factors for increased morbidity and mortality in bariatric surgery patients.^17,18 Ultimately, the decision to proceed with bariatric surgery is based on a comprehensive review of the risks and benefits of surgery with the multidisciplinary team, the attending bariatric surgeon, the patient, and the patient’s family. There is some evidence that surgeon and hospital volume equate with improved outcomes, and that consideration should be given for “high-risk patients” to have their bariatric surgery performed at a designated Bariatric Surgery Center of Excellence.¹⁹

The concept of identifying and designating Bariatric Surgery Centers of Excellence was based on the results of several studies that demonstrated decreased mortality and length of stay when bariatric surgery was performed at “high-volume hospitals” by “high-volume surgeons.”²⁰ In an effort to decrease surgical mortality, several professional organizations (the American Society of Bariatric Surgeons and the American College of Surgeons) developed and encouraged an accreditation process for hospitals doing bariatric surgery to meet specific standards and be designated as Bariatric Surgery Centers of Excellence.

Simultaneously, the overall quality of bariatric surgery appeared to be improving. The Longitudinal Assessment of Bariatric Surgery (LABS) consortium’s first study was published in 2010 and examined 30-day outcomes for 4776 patients who had bariatric surgery from 2005 to 2007 at 10 clinical sites in the United States.²¹ In this study (LABS-1), the 30-day mortality for RYGB and laparoscopic adjustable gastric band (LAGB) was 0.3%, and all-cause major adverse events were 4.3%.²¹ A subsequent analysis of the LABS-1 data demonstrated a reduction in risk-adjusted complications after RYGB was associated with increased surgeon volumes.²² In contrast, analysis of gastric bypass surgery outcomes using the New York State inpatient database suggested risk-adjusted morbidity accounted for more than 80% of hospital variation compared with only 20% attributable to hospital and surgical volumes.²³

Collectively, these data suggest bariatric surgery can be safely performed with acceptably low morbidity and mortality rates. Given the low, but potentially serious, risks of bariatric surgery, what are the long-term health benefits that patients considering bariatric surgery might expect? Several studies have examined the impact of bariatric surgery on mortality and other health parameters.^24,25,26,27 The Swedish Obesity Study (SOS) published 10-year follow-up data on 2010 bariatric surgery patients treated by gastric bypass (RYGB), VBG, or gastric banding (GB) compared with 2037 patients receiving conventional medical therapy.²⁷ Long-term (10-year) weight loss in the SOS was 25%, 16%, and 14%, respectively, after RYGB, VBG, and GB compared with less than 2% in the control group. The SOS also demonstrated a 29% reduction in all-cause mortality in the bariatric surgery group compared with the control group.

These results are similar to those of Adams et al., who reported a 40% reduction in mortality after gastric bypass surgery (compared with severely obese, matched controls) in a retrospective cohort study from Utah.²⁴ Interestingly, the study by Adams et al. demonstrated a reduction in cardiac-, diabetes-, and cancer-related mortality in the gastric bypass group, but an increase in suicide and accidental deaths relative to the control group. Consistent with these data, a retrospective, population-based study of 66,109 bariatric surgery patients examining all-cause mortality for bariatric surgery patients after 15 years confirmed these findings.²⁶

The majority of these studies examined predominantly low-risk, female subjects. Of note, a retrospective Veterans Affairs (VA) system demonstrated a 24% reduction in all-cause mortality at the 10-year follow-up compared with a nonsurgical matched control group.²⁸ Collectively, these data suggest significant medical and long-term mortality benefits for surgical weight loss. However, additional information is needed to better understand the potential risk-benefit ratio in high-risk subsets (e.g., the predominantly male, medically complex VA population).

Because bariatric surgery is an elective procedure, most patients expect the surgery to be performed safely with minimal or no significant risks. Despite this perception, almost by definition, morbidly obese patients having bariatric surgery procedures are at increased risk for surgical complications. Although obtaining informed consent is a standard aspect of every surgical procedure, it seems appropriate to point out that certain high-risk procedures such as bariatric surgery probably deserve additional attention to the informed consent process. Patient education about the different surgical procedures as well as the potential risks and benefits is an integral aspect of preparing patients for surgery. When asked, bariatric surgery patients routinely indicate they fully understand the risks and benefits of surgery. However, in my experience, detailed follow-up questions routinely indicate significant gaps in knowledge.

For this reason, many bariatric surgery programs routinely use preoperative true/false tests to document whether patients truly understand the actual risks of surgery as part of the informed consent process. True/false statements such as “Death is a potential complication of surgery”; “Anastomotic and staple line leaks are serious complications that may be life threatening and require additional surgery”; and “I will need to take iron and vitamin B₁₂ supplements for life after surgery to prevent deficiencies” are helpful to document preoperative bariatric surgery comprehension of the potential risks related to surgery.

Many programs use clinical pathways or order sets in an effort to standardize the perioperative care of patients having bariatric surgery.²⁹ Clinical pathways help to minimize deviations in care by establishing routine guidelines for the care of patients having a common surgical procedure. In the case of bariatric surgery, standard operating procedures for routine laboratory testing; medications (antibiotics, pain medications, glycemic medications, antiemetics, etc.); diet; activity; physical and occupational therapy consultation; and management of OSA are established. Patients, nurses, surgery residents, and other members of the health care team are educated on the established plan of care and work together to minimize variations in care. Clinical pathways are commonly associated with fewer complications, reductions in resource utilization, and improved patient satisfaction.²⁹

The perioperative management of OSA is worthy of further discussion because of its high incidence in bariatric surgery patients (>80%) and the potentially significant risks related to perioperative complications in its management. Many bariatric surgery programs, including our own, routinely screen all bariatric surgery patients for the presence of OSA. If OSA is diagnosed, we prefer to have these patients started on continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) prior to scheduling surgery. This practice is endorsed by the American Society of Anesthesiologists (ASA) practice guidelines for the perioperative management of patients with OSA, especially in patients with severe OSA.³⁰

Because patients with OSA may have difficult airways, the anesthesia team should be fully prepared to deal with this potential problem. Although regional anesthesia is preferred for peripheral procedures, bariatric surgery is commonly performed under general anesthesia. Patients with OSA may demonstrate increased susceptibility to the respiratory depressant effects of inhaled anesthetics, opioids, and sedatives.^30,31 Therefore, extubation is recommended after complete reversal of neuromuscular blockade when the patient is awake and the use of upright or lateral positioning is encouraged when possible.^30,32 The data on optimal perioperative analgesia for patients with OSA is inconclusive, but support the use of regional analgesia (vs. systemic opioids) and supplemental anti-inflammatory medications to decrease systemic narcotic administration. The use of continuous opioid infusions or the administration of concurrent sedatives (e.g., benzodiazepines) is cautioned against because of the increased risks of respiratory depression.³⁰ Postoperatively, supplemental oxygen or CPAP should be used as needed.³³ Continuous electrocardiographic monitoring and oximetry should be strongly considered in high-risk patients after surgery.

There are several aspects of the operating room (OR) phase of care that are worth mentioning when caring for the bariatric surgery population. Transporting and moving patients to and from the OR may require special equipment (heavy-duty wheelchairs, stretchers, etc.) to prevent patient injury. Moving bariatric surgery patients on and off the stretcher and OR table may result in patient or staff injury. Many centers use roller or specially designed bariatric transfer devices (e.g., HoverMatt^®, AIRPAL^®, etc.) to transfer patients with a high BMI on and off the OR table to prevent injuries. In addition, many facilities have special OR tables (e.g., Skytron, Maquet, etc.) to accommodate patients with a high BMI whose body weight exceeds the weight capacity of standard OR tables (normally 350 lb). Many of these tables can be “widened” in the abdominal, buttocks, or lower extremity part of the table by clamping components to the side rails. Routine perioperative procedures like obtaining intravenous access, placing epidural catheters, endotracheal intubation, blood pressure monitoring, placing urinary catheters, and so on can be more difficult than anticipated or require special equipment.

As with any surgical procedure, it is important to pay special attention to patient positioning and padding in the bariatric surgery patient. If the arms are placed on armboards, one must be careful the armboards are properly padded and not abducted or extended excessively, which can cause brachial plexus symptoms postoperatively. The patient’s heels should be properly padded to avoid pressure sores during prolonged procedures, and the patient must be securely attached to the OR table. If the patient will be placed in reverse Trendelenburg position, one must be careful the OR strap(s) are also padded as patients can develop anterior femoral cutaneous nerve paresthesias or numbness if they are not. Special long instruments and heavy-duty, self-retaining retractors (e.g., Thompson Surgical Retractors^®) may also be required for this patient population to facilitate exposure and allow dissection and suturing in a deep operative field.