Bariatric Issues

Educational Objectives

The goals of this program are to reduce complication rates associated with bariatric surgery and to assist physicians in in­creasing the activity levels of their pediatric patients. After hearing and assimilating this program, the clinician will be bet­ter able to:

1.   Standardize gynecologic and reproductive care given to women before bariatric surgery.

2.   Identify patients with polycystic ovary syndrome and provide counseling on the potential benefits of bariatric sur­gery.

3.   Reduce complications associated with bariatric surgery in high-risk patients.

4.   Prevent iron deficiency anemia and associated blood transfusions in patients undergoing bariatric surgery.

5.   Encourage increased levels of physical activity among pediatric patients.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the following has been disclosed: Dr. Pritzker receives funding from Actelion, Medtronic, Pfizer, St. Jude Medical, and United Therapeutics. Additionally, in his lecture, Dr. Pritzker presents information related to the off-label or investigational use of a therapy, product, or device. Drs. Barlow, La Valleur, and Vercellotti and the planning committee reported nothing to disclose.

Acknowledgments

Drs. La Valleur, Pritzker, and Vercellotti were recorded at 5th Annual Bariatric Education Day, held May 21, 2009, in Min­neapolis, MN, and sponsored by the University of Minnesota. Dr. Barlow was recorded at North American Society for Pedi­atric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) Annual Meeting and Postgraduate Course, held November 12-14, 2009, in National Harbor, MD, and sponsored by NASPGHAN. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

Preoperative and Gynecologic Evaluation

June La Valleur, MD, Associate Professor, Department of Obstetrics, Gynecology, and Women’s Health, Uni­versity of Minnesota Medical School, Minneapolis

Preoperative considerations: data scarce; all studies small

Screening for polycystic ovary syndrome (PCOS): in small study, found in »50% of patients before bariatric surgery; PCOS  —  penetration varies; symptoms typically include obesity, cysts on ovaries, increase in testosterone local­ized to ovaries, insulin resistance, and glucose intolerance; acanthosis nigricans may be visible; hyperandrogenism, menstrual function, and insulin resistance  —  after surgery, found overall decreases in hirsutism, free serum testos­terone, and fasting insulin (not observed in all patients)

Papanicolaou (Pap) testing: screen every 3 yr in patients with no new sexual partners; asking patients about sexual partners critical in establishing risk for pathologies related to human papillomavirus; women with no history of dysplasia or 3 consecutive negative Pap tests screened every 3 yr; annual screening recommended for patients with recent history of dysplasia or without history of 3 negative Pap tests

Mammography: not required in patients <40 yr of age without family history of breast cancer

Contraception: no data specific to women with morbid obesity; depot medroxyprogesterone acetate (eg, Depo-Pro­vera) contraindicated for women weighing >200 lb; women weighing >70 kg show increased failure rates with hor­monal contraception and higher rates of deep venous thrombosis (DVT) when given estrogen before surgery; higher rates of unintended pregnancy and DVT in women weighing >90 kg using transdermal contraceptives; recom­mended methods for morbidly obese women  —  abstinence; diaphragm (patients must undergo refitting after losing or gaining ³25 lb); condoms; intrauterine devices (IUDs) recommended for patients in monogamous relationships (progestin IUD may decrease elevated risk for endometrial cancer in women with morbid obesity)

Study of obstetric and gynecologic changes after surgery: »100 women; mean preoperative weight of 124 kg de­creased to 79 kg (stabilized) after surgery; incidence of abnormal cycles decreased from 40% to 4.6%; 9 of 9 pa­tients attempting conception after surgery reported success

Evaluation before bariatric surgery: vaginal probe ultrasonography  —  recommended by speaker due to evidence suggesting high rate of PCOS in women undergoing bariatric surgery; detection of ovarian masses during pelvic examination — palpating ovaries often difficult in patients with morbid obesity due to interference of abdominal pannus; establishing presence and size of ovarian cysts recommended before surgery; abnormal uterine bleeding  —between periods or with prolonged or exceptionally heavy menstruation strongly suggests need for biopsy (due to 10-fold increase in risk for endometrial cancer or hyperplasia in women with morbid obesity); incontinence  —  small studies show both urinary and rectal incontinence improve after surgery

The High-Risk Patient

Marc R. Pritzker, MD, Professor, Department of Medicine and Surgery, Director of Cardiovascular Education and Fellowship Training, Director of Pulmonary Vascular Disease Section, Division of Cardiology, Department of Medicine, University of Minnesota, Minneapolis

Complications and risk factors: study of long-term cardiovascular mortality after bariatric surgery  —  rate 0.68% (compared to 6.17% in unoperated patients); surgery substantially prolongs life in most high-risk patients (those with advanced cardiovascular disease or pulmonary disease, pulmonary artery hypertension [PAH], or right heart failure)

Reducing risks: modify activity of adverse cytokines elaborated by adipocytes; complications often related to patient’s maxi­mal oxygen uptake (patients with extremely low functional capacity after walking 4 blocks show high complication rates); even slight increases in patient’s mobility may substantially reduce morbidity and mortality; statins  —speaker recommends initiating therapy several months before surgery (reduces inflammatory mediators); statins improve prognosis if patients de­velop sepsis or intraperitoneal leakage after surgery; obstructive sleep apnea (OSA)  —patients should receive re-evaluation before surgery; 35% to 50% of patients require readjustment of treatment device; correcting OSA improves pulmonary ar­tery pressure and may lower right atrial pressure (reduces bleeding during surgery); diet  —  speaker reports excellent results after providing nutrition journals to patients; blood pressure (BP) and blood glucose  —  significantly affect outcomes; phos­phodiesterase-5 inhibitors  —  eg, sildenafil; potentially reduce risk by improving abnormal endothelial function and reducing inflammatory mediators; muscle conditioning  —  patients typically show impaired inspiratory muscle strength; treatment should start several months before surgery (with goal of strengthening diaphragm); speaker suggests use of underwater treadmills (provide excellent support and rapid resistance-based muscle conditioning)

Noninvasive preoperative testing: imaging for coronary artery disease (CAD), right heart failure, and PAH not recom­mended due to high rate of false-positive and false-negative results seen in patients undergoing bariatric surgery; PAH  —  in speaker’s experience, 25% of referred patients showed either dramatically increased arterial pressures or pressures read as normal on echocardiography; right heart catheterization allows localization of pathology (differentiation between eg, diastolic dysfunction, PAH due to chronic thromboembolic disease, chronic hypoxia, ventilatory restriction); attenua­tion in imaging studies  —  frequent occurrence in patients undergoing bariatric surgery (due to larger quantity of tissue separating imaging from radioactive tracers in heart); transesophageal echocardiography with dobutamine stimulation  —  passage of tube down throat may cause hypoventilation and necessitate sedation; positron emission tomography  —  recommended by speaker; shows superior accuracy due to higher doses of radiation and increased resolution

Invasive preoperative testing: passage of small catheters through radial artery allows necessary imaging; complica­tion rate <1%; uncoated metal stents  —  patients must receive aspirin and clopidogrel (Plavix) for 2 mo (suspended before procedure); drug-eluting stents  —  patients must receive aspirin or clopidogrel for 1 yr (suspended before procedure); aspirin or clopidogrel should be resumed on second postoperative day (patients typically hypercoagula­ble with unfavorable cytokine profile)

Bariatric surgery in patients with manifest CAD: Mayo clinic study  —  no deaths reported among patients with his­tory of coronary revascularization, coronary artery stenosis >30% in ³1 major artery, inducible ischemia, or myo­cardial infarction (MI); extremely low incidence of nontransmural MI, unstable angina, pulmonary edema, pulmonary embolism (major complication of bariatric surgery); after surgery, low-density lipoprotein levels de­creased to 70 mg/dL; type 2 diabetes cured in 80% of patients; Pittsburgh study  —  bariatric surgery found to signif­icantly improve ejection fractions and reduce size of left ventricle

Speaker’s data and recommendations: high-risk patient series  —  6 patients with mean body mass index (BMI) of 48 (330-600 lb) and ejection fraction of 22%; 1 patient required prolonged intubation; no deaths occurred; all pa­tients admitted to coronary care unit for right heart catheterization (with optimization of cardiac output and filling pressures using milrinone or sodium nitroprusside and diuretics); patients with transpulmonary gradient >15 mm Hg received intravenous (IV) prostacyclin or sildenafil and had evaluation for correction of PAH; all patients re­ceived statins and preoperative inspiratory muscle training at home; central venous pressure therapeutically manipu­lated to 12 mm Hg (minimizes bleeding); overnight recording oximetry performed; blood glucose corrected to <150 mg/dL during hospital admission (directly before surgery)

Iron Storage and Bariatric Surgery

Gregory M. Vercellotti, MD, Professor, Department of Medicine, Division of Hematology, Oncology, and Transplantation, University of Minnesota, Minneapolis

Background on iron storage and obesity: iron storage issues should be monitored and corrected before and after surgery; obesity and iron deficiency  —  obesity presents as inflammatory disease; chronic inflammation associated with obesity may cause anemia; significant increases in iron deficiency seen among adolescents, teenagers, and adults with obesity; inflammation  —  high-fat diets may activate Toll-like receptors (ie, induce inflammatory response); anemia  —  all patients anemic before surgery must undergo work-up for bleeding (iron supplementation alone insufficient); rule out infections, gallbladder disease, and protein malnutrition; patients with diabetes and even mild renal insufficiency (eg, creatinine lev­els of 1.2-1.8 mg/dL) may present with anemia caused by decreased erythropoietin (EPO); folate deficiency often causes anemia in patients with obesity and frequent alcohol consumption; iron replacement  —recommended before sur­gery (to minimize transfusions; may improve outcomes); patients anemic only after depletion of stored iron

Iron absorption: occurs primarily in duodenum; after reduction, iron must cross enterocytes and pass through ferro­portin before uptake by transferrin (carries iron to final destination and controls ferroportin); negatively affected by inflammation associated with obesity (due to increased levels of hepcidin)

Screening for iron deficiency: symptoms  —  reduced exercise tolerance and fatigue (may affect diaphragm); compulsion to ingest ice or cornstarch; blood smears appear hypochromic and microcytic (pencil-shaped cells present); screening  —review blood smears; routinely check serum iron, total iron binding capacity, soluble transferrin recep­tors, and serum ferritin; check bone marrow if other diagnostics fail; serum ferritin test shows highest sensitivity and specificity

Treatment: in speaker’s hematology clinic, patients receiving iron supplementation checked for elevations in reticulocyte counts and hemoglobin; treatment response  —  iron deficiency anemia should correct after 4 to 6 wk (in responsive patients); however, repletion of iron stores requires 6 mo of supplementation (patients often discontinue against medical advice shortly after bariatric surgery); failure to correct iron deficiency may cause bleeding; iron supplementation  —  compliance poor; may exacerbate irritable bowel symptoms and constipation; best given as ferrous iron; ascorbate helps reduce iron and enhance absorption; gastrointestinal intolerance relates to quantity of elemental iron present; new formulations of chelates (eg, Rep­liva) often better tolerated; heme iron polypeptide  —  recommended by speaker for patients with gastric bypass (eg, Proferrin-Forte); shows superior absorption; parenteral  —  recommended by speaker; iron dextran  —  intramuscular injections not rec­ommended; IV dosing effective, but carries risk for anaphylaxis; only low-molecular-weight iron dextran currently utilized (high-molecular-weight formulation associated with serum sickness); speaker recommends limiting doses to 1000 mg (after test dose); ferric gluconate and iron sucrose  —  produce fewer allergic reactions; however, higher dosages may overwhelm transferrin, leading to chest and back pain caused by oxidative stress; speaker recommends giving 125 mg over 2 hr (after test dose); both compounds equally effective

Anemia after bariatric surgery: anemia of chronic inflam-mation  —  presents with abnormally small red blood cells; cyto­kines trigger macrophages to withhold iron and prevent bone marrow from responding to EPO (due to presence of hepci­din); increased levels lead to downregulation of ferroportin (decreases iron absorption and impairs release of iron from iron stores); many patients with inflammation after gastric bypass receive misdiagnosis of iron deficiency; however, chronic inflammation may explain symptoms; other causes of anemia  —  bleeding; decreased gastric acid secretion and exclusion of duodenum may impair iron absorption; reflux; vitamin and mineral deficiencies; patients often ingest less red meat after surgery; blood loss may occur due to marginal ulcers; abnormal menstruation ranked as primary cause of refractory iron deficiency after surgery (many patients require endometrial ablation or hysterectomy); pregnancy may contribute to loss of iron

Increasing Physical Activity in Children and Teens

Sarah E. Barlow, MD, MPH, Associate Professor, Department of Pediatrics, Section of Gastroenterology, Hep­atology, and Nutrition, Baylor College of Medicine, and Director, Obesity Center, Texas Children’s Hospital, Houston, TX

Guidelines for activity level: adults  —  500 to 1000 metabolic equivalents (METs; ie, metabolic rate during activity compared to metabolic rate at rest) per week recommended; equivalent to »150 min of moderate to vigorous phys­ical activity; children  —  60 min/day recommended; increased physical activity found to improve skeletal health, aerobic fitness, muscular strength, and endurance; also found to improve adiposity (in children with obesity) and reduce BP (in children with elevated BP)

Increasing physical activity in children: factors predictive of adequate activity  —  environment with opportunity for activ­ity; social support; influence by active siblings; engagement in community sports; intention to be physically active; sense of competence; male sex; white ethnicity; study of computer programs for self-evaluation of diet and physical activity  —boys given computerized assistance showed slight (but significant) increases in physical activity; office-based counseling  —  studies showed modest effects (at best); future efforts should concentrate on early encouragement of activ­ity; “Exer-gaming”  —  showed trend toward decreased weight in small study; however, no increases in moderate to vigor­ous activity found with accelerometry; free after-school physical fitness and nutrition education in high-risk populations  —study found statistically significant decreases in weight and BMI after 6-wk program

Billing and insurance: physical therapy provided at hospitals or health care centers reimbursed by insurance more often; diagnoses associated with coverage for physical therapy  —  hypertension; diabetes; decreased endurance; general muscle weakness; deconditioning due to cardiac conditions or edema; therapy for obesity or risk factor re­duction not typically covered; recommended forms of physical therapy  —  aerobic conditioning; resistance training; aquatic exercise; endurance training

Suggested Reading

Adams TD et al: Long-term mortality after gastric bypass surgery. N Engl J Med 357:753, 2007; Afolabi BA et al: Cardiovascu­lar complications of obesity surgery in patients with increased preoperative cardiac risk. Surg Obes Relat Dis 5:653, 2009; Daley AJ: Can exergaming contribute to improving physical activity levels and health outcomes in children? Pediatrics 124:764, 2009; Eid GM et al: Effective treatment of polycystic ovarian syndrome with Roux-en-Y gastric bypass. Surg Obes Relat Dis 1:77, 2005; McClung JP, Karl JP: Iron deficiency and obesity: the contribution of inflammation and diminished iron absorption. Nutr Rev 67:100, 2009; Richardson LC et al: Obesity and endometrial cancer: challenges for public health action. Womens Health (Lond Engl) 5:595, 2009; Rochester D et al: Partial recovery of luteal function after bariatric surgery in obese women. Fertil Steril 92:1410, 2009; Scheen AJ et al: Bariatric surgery in patients with type 2 diabetes: benefits, risks, indications and perspec­tives. Diabetes Metab 35:537, 2009; von Drygalski A, Andris DA: Anemia after bariatric surgery: more than just iron deficiency. Nutr Clin Pract 24:217, 2009; Wong WW et al: An innovative summer camp program improves weight and self-esteem in obese children. J Pediatr Gastroenterol Nutr 49:493, 2009; Xanthakos SA: Nutritional deficiencies in obesity and after bariatric sur­gery. Pediatr Clin North Am 56:1005, 2009.