Hidden Health Risks of the Extremely Obese Pediatric Patient
Robert D. Murray, MD, Director, Center for Healthy Weight & Nutrition
Marc P. Michalsky, MD, Surgical Director, Center for Healthy Weight & Nutrition
Stephen C. Cook, MD, Director, Non-Invasive Imaging and Research for the Adolescent and Adult Congenital Heart Disease Program at The Heart Center
Erin Teeple, MD, Fellow, Adolescent Bariatric Surgery Nationwide Children's Hospital
Every clinician working in critical care needs to know this: irrespective of outward appearances, obese and extremely obese children and teens are high risk patients. Even among health care professionals, bias can cloud a thorough assessment of the overweight patient. Serious medical conditions are commonly present, yet often unappreciated, among even morbidly obese patients because it is thought that their youth protects them from serious co-morbidities.
Initial Assessments/Complications
Obesity affects every tissue of the body. Fat cells secrete a wide variety of chemical factors that will:
- stimulate inflammation,
- raise blood pressure,
- result in liver dysfunction,
- cause insulin resistance
- and alter metabolism.
Obesity is a body mass index (BMI) of 30 kg/ m2 or more, which corresponds to approximately 30 pounds over a person’s ideal weight. Among children and teens, a BMI percentile above the 95th percentile line for age and gender, signifies obesity. Extreme obesity is defined as a BMI greater than 35 kg/ m2 or roughly 100 lbs over ideal for adults or, above the 99th percentile in children and teens (see Table 1). While about one in three of America’s youth are thought to be obese, 6 percent are considered extremely obese and this number is rapidly rising. In fact, extreme obesity has climbed to 15 percent among high-risk African-American and Hispanic populations.
Table 1: 99th Percentile Cutpoints for BMI for Males and Females ages 5 to 19 years.
Researchers from the Department of Surgery at Nationwide Children’s Hospital have discovered that children ages 6 to 20 years, presenting with traumatic injury, had unique risks when they were obese. The obese patients were younger, had more extremity fractures requiring orthopedic surgery and presented with higher systolic blood pressures than their non-obese peers. They also had unique complications, such as decubitus ulcers and deep vein thrombosis. One type of injury that they were less prone toward, however, was abdominal injury, possibly due to the protection of greater abdominal fat.
Extremely obese teens referred to the Center for Healthy Weight and Nutrition for bariatric surgery show a shockingly poor state of health and fitness. In those undergoing surgery, multiple co-morbidities including dyslipidemia, hypertension, insulin resistance, diabetes, obstructive sleep apnea, asthma, and hepatic involvement, are common. Orthopedic problems of the back, hips, knees, ankles and feet also are typical among these patients. But the extent of cardiovascular risk has remained largely underappreciated until now.
Cardiovascular Disease
Application of newer technology to the pre-surgical assessment has demonstrated an alarming degree of structural and functional deterioration of the cardiovascular system, even among young teens. Previous studies had shown that EKG assessment of cardiac status was inappropriately interpreted as “normal” in most cases. Even the addition of echocardiography has been shown to fail to demonstrate and predict cardiac risk accurately, due to the fact that in these cases chest wall fat substantially obscured the cardiac image. For example, consider Figures 1a & 1b and Figures 2a & 2b which compares the image shown by a transthoracic echocardiography with that from a cardiovascularac MR examination (CMRI).
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Figure 1: Despite the range of obese adolescents evaluated, each patient tolerated the complete cardiac examination protocol despite limitations in body habitus. Axial (1a) and sagittal (1b) black blood images demonstratesevere adiposity in a 20 year-old female with a body mass index=40kg/m2. |
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Figure 2: A parasternal long-axis view (2a) obtained from a transthoracic echocardiogram of a 19 year-old undergoing preoperative clearance for bariatric surgery. Body mass index=65.7kg/m2. Cardiovascular magnetic resonance image (2b) accurately delineates the myocardium. |
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Figure 3: Adenosine stress (top row) and rest (bottom row) perfusion images demonstrate subendocardial ischemia (arrows) in a 20 year-old female undergoing preoperative evaluation prior to bariatric surgery; BMI=40kg/m2. |
Researchers at Nationwide Children’s Hospital and Ohio State University have compared the two techniques, finding that CMRI provides a more comprehensive measure of left ventricular volume and function, valvular disease, epicardial fat, myocardial perfusion subendocardial ischemia and myocardial fibrosis. Using these techniques on 10 bariatric surgery candidates, left ventricular end-diastolic volume was more than 20 mL higher than normal values in 40 percent of the patients. Similarly, LV mass was much higher than published controls in 90 percent of patients. Although the average myocardial perfusion reserve index (MPRI) quantified by the ratio of myocardial blood flow during stress perfusion:rest, three out of 10 patients had MPRI values < 1.0 suggesting the presence of perfusion abnormalities. Adenosine stress perfusion images revealed additional defects in myocardial functional response that suggest vascular insufficiency (see Figure 3). Three of the 10 patients had myocardial perfusion reserve index (MPRI) values < 1.0, suggesting very poor perfusion response when stressed.
Reversing Co-morbidities
Last year a consortium of adolescent bariatric surgery programs conducting the NIH-funded TEEN LABS trials reported rapid reversal of diabetes and elimination of the need for medication following gastric bypass surgery. A recent paper published on Australian adolescents treated with gastric banding showed a substantial correction of metabolic derangements and elimination of co-morbidities following the procedure. Of importance, these changes appeared to be durable over time. Now, studies done independently by teams at Nationwide Children’s Hospital, at the Ohio State University Medical Center and Cincinnati Children’s Medical Center have shown that bariatric surgery also can quickly reverse the anatomic and functional cardiac abnormalities associated with extreme obesity. This may be a distinct advantage of using bariatric surgery in teen years compared with middle-aged or senior adults.
As research on the depth and breadth of the obesity epidemic among children continues to grow, the enormous health burden borne by these patients becomes more evident. For health professionals involved in critical care and trauma, an awareness and appreciation of this potential risk is crucial to providing optimal care in the field, the emergency room and in the hospital.
