FDA/MedSun Interested in Safety Issues in the Obese Patient Population
MedSun: Newsletter #16, July 2007

By Dolores Miranda,* Biomedical Engineer and Lead, FDA/CDRH Bariatric Workgroup

The prevalence of obesity has become a major health concern in the United States. Since 1960, the number of overweight and obese Americans has increased dramatically. Results from the 2003–2004 National Health and Nutrition Examination Survey indicated that 66.3 percent of adults in the United States were overweight, with 32.2 percent of these classified as obese, and 4.8 percent as morbidly, or extremely, obese.1

For adults, the National Institutes of Health defines overweight as a body mass index (BMI) of 25 to 29.9 kg/m2, obesity as a BMI of greater than or equal to 30 kg/m2, and morbid obesity as a BMI of greater than or equal to 40 kg/m2.2

According to the Healthcare Cost and Utilization Project, 126,240 patients were hospitalized for obesity as the principal diagnosis, and approximately 1.6 million were hospitalized for obesity as a coexisting condition in 2004. When obesity was the main diagnosis for hospital stays, 99.6 percent of the patients were morbidly obese. In contrast, when obesity was a secondary condition, only 33 percent had a diagnosis of morbid obesity.3

This patient population has unique characteristics and comorbidities that often make any medical procedure or surgery more complicated. Various medical or surgical interventions also may require use of medical devices exclusively designed for this population. Health care facilities are challenged by the dearth of specialized devices. For instance, obtaining diagnostic images in morbidly obese patients is difficult because many MRI and CT scanners have weight and size limits, and access to larger scanners may be limited. The quality of radiographic images is sometimes decreased due to the thickness the X-ray beam must penetrate.4 Additionally, managing morbidly obese patients places health care professionals at risk of injury.5 MedSun, the Medical Product Safety Network, has received several reports describing adverse events in the obese patient population. The following are summaries of three reports:

•The patient had a heart catheterization (cath) with a percutaneous transluminal coronary angioplasty/stent. The cath procedure was lengthy and difficult due to the patient’s obesity and the intervention required. The lengthy cath required the patient to experience prolonged radiation exposure. At the time of discharge, the patient had no complaint of skin irritation. Approximately 6 months later, the patient was seen at another hospital for a rectangular wound on his mid-thoracic back. This hospital reported a suspected radiation burn to the patient, possibly secondary to the catheterization that had been performed at the first hospital. The calculated radiation dose was estimated to be greater due to the patient’s weight and large chest, and the difficult location of the lesion (at the bifurcation site).

•While trying to position a transfer and repositioning mattress under a morbidly obese patient, two nurses held the device by the attached straps while four others attempted to move the patient with a draw sheet. During this activity, one of the straps broke, resulting in the patient’s falling backward to the floor and sliding into the wall. This event also caused the nurse’s head to collide with the wall.

•A patient in excess of 300 pounds was placed on a bedside commode. The patient attempted to rise from the commode but became entrapped. It took several staff to separate the patient from the commode. The patient sustained an 8-cm abrasion on the left-lateral thigh. This is the fourth instance in which an overweight patient was placed on a commode and the device broke or the patient became stuck and sustained minor injuries upon extraction.

These Bariatric Workgroup members also contributed to this article: Binita Ashar,* M.D., M.B.A.; Donna Engleman,** MedSun Program Manager; Diana Kaufman,* M.P.H.; Jill Marion,* Biomedical Engineer; and Suzanne Rich,* Senior Project Manager, R.N., M.A., CT.
*Center for Devices and Radiological Health (CDRH), Food and Drug Administration (FDA), U.S.
Department of Health and Human Services
**Social & Scientific Systems, Inc.

These adverse event reports submitted by MedSun’s facilities—along with reports from manufacturers and consumers, and the clinical community’s recognition of the challenges surrounding the care of morbidly obese patients—have prompted the Food and Drug Administration (FDA) to investigate current problems associated with the use of medical devices in the obese population. MedSun hopes to identify and characterize the adverse event reports received.

FDA analysts are interested in the following type of information in medical device reports:
•Could the patient’s size have caused or contributed to the adverse event? Is the patient overweight or extremely obese? If so, please describe the relationship of the patient’s obesity to the adverse event.
•Could the size of the device have caused or contributed to the adverse event?
•Could the patient’s size have affected the strength or durability of the device, possibly leading to failure of the device?
•Was the device selection limited due to the patient’s size?
•What are the patient’s weight and height?

We look forward to working with our MedSun hospitals to gain a better understanding of adverse events that occur in the obese population.

1 Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. Prevalence of overweight and obesity in the United States, 1999–2004. JAMA, 2006. 295:1549–1555.
2 National Institutes of Health National Heart, Lung, and Blood Institute in cooperation with the National Institute of Diabetes and Digestive and Kidney Diseases. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults. NIH Publication No. 98-4083. September 1998.
3 Elixhauser A, and Steiner C. Obese patients in U.S. hospitals, 2004. HCUP Statistical Brief #20.
December 2006. Agency for Healthcare Research and Quality. Rockville, MD.
4 Uppot RN, Sahani DV, Hahn PF, Gervais D, Mueller PR. Impact of obesity on medical imaging and imageguided intervention. AJR, 2007. 188:433–440.
5 Nguyen NT, Moore C, Stevens CM, Chalifoux S, Mavandadi S, Wilson SE. The practice of bariatric
surgery at academic medical centers. J Gastrointest Surg. 2004 Nov;8(7):856–60.

MedSun Newsletters are available at www.fda.gov/cdrh/medsun