“Trauma surgery isn’t like elective orthopaedic surgery; you can’t tell the patient to lose 50 pounds before you’ll operate,” said George V. Russell, MD, of the University of Mississippi. “In my practice, the ‘normal’ patient has a body mass index (BMI) between 30 and 35; it’s culturally acceptable for people to be obese.”
According to Dr. Russell, when two key epidemics—trauma and obesity—collide, the impact can be devastating for the patient and challenging for the surgeon.
“The excess weight could act as an internal airbag, enabling that patient to survive an accident that would kill a patient of normal weight,” said Dr. Russell. “If that’s true, the problems can multiply.”
Among the issues outlined by Dr. Russell during the AAOS Now forum on “Obesity, Orthopaedics, and Outcomes,” are the following:
- Field management—Airway control, immobilization, and transport are problematic. Extricating, lifting, and transporting a 500-pound patient with equipment built to handle a maximum of 300 pounds takes additional time—and time is a valuable commodity during a trauma situation.
- Imaging—“Radiographs are often compromised, and CT or MRI scans may be impossible to obtain,” said Dr. Russell. “The current capacity of our institution’s scanner is 600 pounds, but most institutions don’t have machines that large.”
- Comorbidities—Trauma patients who are obese often have other problems as well, including high blood pressure, diabetes, pressure sores, and poor nutritional status. “Hygiene is another issue,” said Dr. Russell. “It can get pretty nasty within the folds of the skin, and the risk of infection is high.”
Once the patient is in the operating room, trauma surgeons must address other issues related to weight. “We don’t have open-frame operating tables that allow the fat to hang down when the patient is in the prone position,” said Dr. Russell. “Instead, we may put the patient on his or her side and let the panniculus hang over the side of the table.”
As a trauma surgeon, Dr. Russell frequently sees patients with acetabular fractures. He noted that accessing the joint in patients who are obese frequently results in a wide-open wound (Fig. 1). “Sometimes, we have to go through 15 cm of fat before we reach the muscle, and the bone is even farther in. The fat is slippery, and as it slides out, it provides entry for bacteria, thus increasing the risk of wound complications and infection.”
Patients who are obese and are being treated while in the prone position may experience physiologic problems, including oliguria. “I think this is due to the fact that the weight is pressing on the bladder, and backing up the low-pressure urinary system,” Dr. Russell explained. “As soon as you turn these patients on their backs, they start to urinate again.”
The amount of fat surrounding the injury also presents a problem with stabilization. Standard-sized external fixators cannot reach the bone. As a result, supplemental implants must be used. Surgery becomes more difficult and complications increase the closer the injury is to the trunk.
In one study, for example, patients with a BMI of 40 or higher had a 60 percent wound complication rate after acetabular fracture. “No elective practice would continue with that high a complication rate, but trauma surgeons don’t have a choice. We must act and assume the risk,” said Dr. Russell.
“Just as pediatric patients are not small adults, morbidly obese patients are not large adults,” explained Patrick F. Bergin, MD, of the University of Mississippi Medical Center. “They have a unique physiology and inflammatory model in trauma that should be addressed.”
Dr. Bergin noted that patients who are morbidly obese frequently experience the following:
- Higher rates of multiorgan failure and acute respiratory distress syndrome
- Higher infection rates
- Longer stays in the intensive care unit
- Longer hospital stays
- Increased costs
Possibly increased mortality
He cited several studies that showed links between obesity and multiorgan failure rates, liver and cardiac failure, and renal and lung failure. “Obesity is as damning as being older than age 55, having a higher injury severity score, and needing more than 6 units of blood,” he said.
One reason may be inflammation. Adipose (fat) tissue is an endocrine organ, and people who are obese have, as a baseline, a higher level of inflammatory cues, such as higher basal C-reactive protein rates, increased macrophage accumulation in fat tissue, and measurable levels of circulating interleukin-6 (IL-6), which is directly linked to multiorgan failure in the trauma setting.
“These patients are already on their way toward multiorgan failure when they’re admitted to the emergency department,” noted Dr. Bergin. “The first hit is being obese; the second hit is the injury, and the surgery is the third hit.”
Studies have also shown that, even among people who are not obese, higher BMI levels are linked to increased rates of multiorgan failure. In one study, each 1 point increase in BMI increased the patient’s risk of multiorgan failure by 9 percent and the risk of nosocomial infection by 7 percent.
However, Dr. Bergin cautioned that inflammation may not be the entire answer. Patients who are obese may have an immune dysfunction that is not yet fully understood. They may have different injury patterns or resuscitation needs. According to one study, when obese and lean patients received similar amounts of resuscitation per kilogram of body weight, no significant differences in lactate levels were found and cardiovascular outcomes were similar. However, obese patients showed persistent metabolic acidosis at 48 hours, and among those patients, 90 percent went on to experience multiorgan failure.
“We do not have adequate measures of complete resuscitation in morbidly obese patients, and we can’t just look at lactate trending down,” he noted.
Glycemic control is also important. “The glycemic control level directly relates to mortality after trauma,” said Dr. Bergin, “even though we don’t yet understand whether glycemic control is a cause of mortality or another symptom of organ failure due to trauma.
The take-home messages from these studies, said Dr. Bergin, are as follows:
- Patients who are obese have an altered immune and metabolic response to trauma.
- Resuscitation is often inadequate and cannot be based on traditional end points.
- End organ dysfunction patterns may be different in patients who are obese compared to patients of normal weight, and more attention should be paid to liver dysfunction early in trauma.
- Glycemic control is important in all trauma patients but can make the most difference in the obese patient population, which has the highest rate of poor outcomes.
The AAOS Now forum on “Obesity, Orthopaedics, and Outcomes” was held March 18, 2013. For a copy of the agenda book, including selected study abstracts, email firstname.lastname@example.org
Mary Ann Porucznik is managing editor of AAOS Now. She can be reached at email@example.com
Obesity and Trauma
- According to the Third National Health and Nutrition Examination Survey, more than 97 million people in the United States are obese.
- By 2011, more than one third of U.S. adults (36 percent) met the definition of obesity (BMI of 35 or higher).
- Patients who are obese have an altered immune and metabolic response to trauma.
- Many hospitals do not have equipment (CT scanners, operating tables) that can handle trauma patients who are morbidly obese.
- Trauma patients who are obese have increased risk of infection, multiorgan system failure, and respiratory distress.
- Porter SE, Russell GV, Dews RC, Qin Z, Woodall J Jr, Graves ML: Complications of acetabular fracture surgery in morbidly obese patients. J Orthop Trauma 2008 Oct;22(9):589-594, doi: 10.1097/BOT.0b013e318188d6c3.
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- Winfield RD, Delano MJ, Lottenberg L, et al: Traditional resuscitative practices fail to resolve metabolic acidosis in morbidly obese patients after severe blunt trauma. J Trauma. 2010;68(2):317-330, doi: 10.1097/TA.0b013e3181caab6c.
- Matheson PJ, Franklin GA, Hurt RT, Downard CD, Smith JW, Garrison RN: Direct peritoneal resuscitation improves obesity-induced hepatic dysfunction after trauma. J Am Coll Surg 2012;214(4):517-528; discussion 528–530, doi: 10.1016/j.jamcollsurg.2011.12.016. Epub 2012 Feb 17.
- Sperry JL, Frankel HL, Nathens AB, et al: Characterization of persistent hyperglycemia: What does it mean postinjury? J Trauma 2009;66(4):1076-1082, doi: 10.1097/TA.0b013e31817db0de.
- Scalea TM, Bochicchio GV, Bochicchio KM, Johnson SB, Joshi M, Pyle A. Tight glycemic control in critically injured trauma patients. Ann Surg 2007;246(4):605-610, discussion 610–612.
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