The obesity rate increased from 30.5% in 1999-2000 to 42.4% in 2017-2018.1 Ambulatory surgery centers (ASCs) can expect to see more of these patients. As more complex procedures can be performed in ASCs, leaders should learn about comorbidities among obese patients and the risk factors associated with performing complicated surgery on this group.

Research suggests that although obese patients may not be at a higher risk of 90-day medical complications after outpatient joint arthroplasty, morbid obesity makes it more likely that an orthopedic patient undergoing outpatient surgery ends up with an overnight stay.2,3

In a recent paper on identifying high-risk patients for ambulatory surgery, the author pointed to increased longevity and rising prevalence of obesity as factors that result in surgery patients with a wide variety of comorbidities who need to undergo complex ambulatory procedures.4

“The goal is to identify these patients ahead of time and to have a pathway in place that fits your surgery center,” says Niraja Rajan, MBBS, associate professor in the department of anesthesiology and perioperative medicine at Penn State University. “Obesity is one of those comorbidities that would be listed when surgeons see patients in their clinic. If the BMI [body mass index] is over the cutoff, then they are not eligible for ambulatory surgery. If it’s under the cutoff, then there are graduations of risk.”

Most ambulatory surgery centers will use a BMI of 50 kg/m2 as the cutoff, often based on the capacity of their equipment. But patients with a BMI between 40 kg/m2 and 50 kg/m2 also are at higher risk of postoperative complications. Before scheduling a procedure, ask if these patients have been tested for obstructive sleep apnea. If patients have been diagnosed with the condition, ask whether they use a continuous positive airway pressure device. If patients are hypertensive, are they controlling the condition with medication regularly? If they are diabetic, is the condition properly managed?

Rajan notes patients with these comorbidities who are not managing the conditions are at risk for postoperative problems. These patients could be left off the surgical schedule until those conditions are better managed. Rajan suggests basing actions on the individual patient and procedure.

ASCs should review their policies and procedures for handling obese patients, including reviewing guidance from professional associations.

To start, administrators could review the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP), a national accreditation standard created by the American College of Surgeons and the American Society for Metabolic and Bariatric Surgery (ASMBS). “These guidelines outline the equipment, process, and structure requirements for bariatric accreditation,” says Shanu N. Kothari, MD, FACS, FASMBS, president-elect of the ASMBS. “Currently, we have over 750 accredited programs in the U.S. There is also a MBSAQIP ambulatory surgery center accreditation that can be earned for outpatient centers.”

Administrators may need to purchase certain equipment to treat obese patients. Staff must be trained to use this equipment, which includes bariatric gurneys and other machinery for moving heavy patients. Many surgery centers might already own a device called the laryngeal mask airway (LMA).

Meredith Joyner, MSNA, CRNA, owner of Anesthesia Solutions, PLLC in Richmond, VA, has used LMAs. Recently, she worked with colleagues to study whether these devices are safe for obese patients.5

They assessed 1,004 general anesthesia cases performed in a freestanding urology center, comparing the incidence of various problems in obese patients and healthy-weight patients.

Joyner and colleagues found there was no difference between these two groups in the incidence of aspiration, laryngospasm, and inadequate ventilation leading to intraoperative changes in airway management.5

“It’s less invasive, a softer tube, and it doesn’t go through the vocal cords,” Joyner says LMAs. “It’s easy to put in. When you put in a tracheal tube, the standard of care is to use a paralytic. In this case [using the LMA], you don’t have to use a paralytic.”

When surgeons do not have to use a paralytic, that helps staff better manage patients’ sedation. Specifically, if a patient is not on a paralytic, then a member of the surgical team may notice a patient’s finger or toe moving during a procedure. This indicates the patient may not be entirely sedated.

Using endotracheal tubes is a more invasive method of airway management, says Joel Gill, DNAP, CRNA, staff anesthetist at Virginia Commonwealth University Health in Richmond.

“Each method for airway management has positives and negatives,” Gill explains. “Endotracheal tubes are appropriate for a lot of settings, but for this setting, [using LMAs] has more pluses than minuses compared to the endotracheal tube.” Still, Gill notes the LMA may not be best for all obese patients. “Do your homework. If you select the right patients, you can make their surgical experience a little easier and avoid complications,” he says.

Before a procedure, surgeons could schedule obese patients into prehabilitation to help build strength, lose some weight, and possibly reduce the chance for postoperative problems.

Kothari notes multidisciplinary, team-based weight loss goals are different from mandated weight loss programs and goals set by insurance plans. He argues insurance program goals are not based on evidence and are barriers to care.

“Some people can lose 40 to 50 pounds over three months if they have that much time before the procedure,” Rajan reports. “It’s all the more reason why we have a really nice decision-making algorithm in place to identify, prehabilitate, and to know when to say ‘no’ in patient in selection.”

Surgery centers also should be prepared for the times when obese patients need to be admitted to a hospital.

“Be thoughtful in your patient selection, [employ] experienced providers who know how to deal with any consequences, and have a contingency plan if things go badly,” Joyner says.

“Outpatient surgery centers should have a transfer agreement with hospitals and health systems that can accommodate patients on the rare occasion there needs to be an escalation of care,” Kothari adds. “This provides peace of mind for both patients and providers and seamless care for patients.”


  1. Centers for Disease Control and Prevention. Overweight & obesity.
  2. Crawford DA, Adams JB, Berend KR, Lombardi AV Jr. Low complication rates in outpatient total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 2020;28:1458-1464.
  3. Crawford DA, Hurst JM, Morris MJ, et al. Impact of morbid obesity on overnight stay and early complications with outpatient arthroplasty. J Arthroplasty 2020;35:2418-2422.
  4. Rajan N. The high-risk patient for ambulatory surgery. Curr Opin Anaesthesiol 2020;33:724-731.
  5. Gill J, Wood NL, Joyner M. Changes in airway management and adverse events related to laryngeal mask airway use in obese patients in the ambulatory surgical setting. AANA J 2020;88:439-444.