Obesity-Part 1

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Obesity and related surgery :

Obesity and related surgery Maribeth Massie, CRNA, MS University of New England Master of Science in Nurse Anesthesia

Objectives:

Objectives At the end of this presentation, the participant will be able to: Describe the statistics and possible causes of obesity Understand the pathophysiology of obesity and its associated anesthetic implications Describe the anesthetic management of the obese patient Delineate common surgical procedures that obese patient’s may undergo

Obesity statistics:

Obesity statistics Estimates show ~ 65% of US adults are overweight or obese About one-third of U.S. adults (33.8%) are obese Obesity-related conditions include heart disease, stroke, type 2 diabetes and certain types of cancer, some of the leading causes of death In 2008, medical costs associated with obesity were estimated at $147 billion Medical costs paid by third-party payors for people who are obese were $1,429 higher than those of normal weight By state, obesity prevalence, on the basis of self-report, ranged from 20% in Colorado to 34% in Mississippi in 2011 The South has the highest obesity prevalence (29.4%) followed by the Midwest (28.7%), Northeast (24.9%) and the West (24.1%)

Obesity socioeconomic and ethnicity statistics:

Obesity socioeconomic and ethnicity statistics Non-Hispanic blacks have the highest rates of obesity (44.1%) compared with Mexican Americans (39.3%), all Hispanics (37.9%) and non-Hispanic whites (32.6%) Rate increasing 47% to 73% faster among African-Americans and Hispanics than among the white population Children < 5 years old across all ethnic groups have the highest percentage increases of obesity Among non-Hispanic black and Mexican-American men, those with higher incomes are more likely to be obese than those with low income Higher income women are less likely to be obese than low-income women There is no significant relationship between obesity and education among men Among women, however, there is a trend—those with college degrees are less likely to be obese compared with less educated women Between 1988–1994 and 2007–2008 the prevalence of obesity increased in adults at all income and education levels

Body mass index :

Body mass index BMI= weight (kg) height (m)2 For weight conversion, remember 1 kg = 2.2 lbs For height conversion, remember 1 foot = 12 inches and 1 inch = 2.54 cm (1 cm = .01 meters) Weight (kg) x 10,000 = BMI Height x height (cm) Easy way to do calculation: Weight (lbs)___ x 703 = BMI Height x height (inches) Example: 150 lbs x 703 = 27.4 BMI kg/m2 62 x 62 inches

Body mass index:

Body mass index BMI < 20: low amount of body fat; if an athlete, may be desirable; if not an athlete, weight is too low and could lower immunity BMI 20 – 22: ideal, healthy amount of body fat; associated with lowest incidence of serious illness BMI 22 -24.9: still acceptable range BMI 25 - 29.9 : slightly overweight and at increased risk of illness (up to 20% of predicted weight) BMI > 30: obese and at serious risk for chronic condition (>20% of predicted weight) BMI > 40: morbidly obese (>100# IBW)

Epidemiology of childhood obesity:

Epidemiology of childhood obesity Prevalence of childhood obesity increasing at alarming rate Has doubled in past 2 decades in the United States Children and adolescents at or above 95 th percentile (obesity) for BMI 15.3% of 6 -11-year-olds 15.5% of 12 – 19-year-olds

Ideal body weight:

Ideal body weight Broca’s index: Men: ht in cm – 100= wt kg Women: ht in cm – 105= wt kg Example: male 6’ tall (72 inches) 183 cm-100=83 kg IBW

Maine statistics for obesity:

Maine statistics for obesity Maroon > 29.8% Orange 26.3-29.7% Gold 22-26.2% Pale yellow 0- 21.9% Cumberland County

Childhood to adulthood obesity:

Childhood to adulthood obesity Probability of obesity persisting into adulthood estimated to increase from 20% at 4 years of age to 80% by adolescence Co-morbidities will also start earlier and become more serious in early adulthood

Possible causes of obesity :

Possible causes of obesity Energy intake versus energy expenditure = energy balance Complex interplay among genetic, physiologic, metabolic, social, behavioral, and cultural factors

Genetic, physiologic, and metabolic causes :

Genetic, physiologic, and metabolic causes Recent studies show 25% – 40% of obesity is inherited Family history of obesity Just recently focus has changed from environmental to genetic Twin studies show that being overweight is a 65-75% inherited trait Basal metabolic rate Feeding behavior Alterations in energy expenditure in response to overfeeding Lipoprotein lipase activity Basal rate of lipolysis

Genetic, physiologic, and metabolic causes:

Genetic, physiologic, and metabolic causes Hormones and neurotransmitters that regulate satiety, hunger, lipogenesis, and lipolysis Anterior pituitary hormones Growth hormone: 2011 study at MGH looking at GH effects on visceral fat and CV markers in obese teenage girls Leptin Neuropeptide Y Melanocortin

Phthalates and Bisphenol A:

Phthalates and Bisphenol A Laboratory studies using rats and mice demonstrated that certain chemicals, phthalates and bisphenol A (BPA), found in some plastic toys, and in household and personal care products, can interfere with hormone function (endocrine disruption). BPA has been shown to increase glucose uptake in fat cells of mice, which could be related to the development of insulin resistance

Genetic and endocrine causes:

Genetic and endocrine causes May play a role in dysregulation of energy expenditure versus intake, resulting in weight gain Prader-Willi syndrome Pituitary abnormalities associated with early onset morbid obesity (EMO) Studies show growth hormone may help Bardert-Biedl syndrome Alstrom syndrome Hypothyroidism Cushing’s syndrome Mitochondrial dysfunction 2011 study at MGH to evaluate the effects of intensive exercise on metabolism

Environmental factors:

Environmental factors Home environments with both parents working decreases families eating meals together thus, fostering bad eating habits Families that do not provide adequate cognitive stimulation have more than two-fold risk of developing obesity Breast feeding has been shown to decrease the propensity towards obesity Other dietary factors remain inconclusive Introduction of complementary foods or high protein

Social and behavioral factors:

Social and behavioral factors Lifestyle trends Empty calories at home and at school/work High fructose soft drinks and juices Consumption increased 65% over last decade “Junk” food (sugar and carbohydrate laden snacks); may not contribute as much as previously thought Fast food Accounts for ~30% variance in body weight Larger portions Urbanization of America Reduction on walking and biking to school/work reduced 40% over past 3 decades Reductions in mandatory school physical education classes further lowers physical activity; only 29% of schools have programs presently

Social and behavioral trends:

Social and behavioral trends Sedentary activities Watching television and playing video games has increased over past decade and correlates with rise in obesity According to American Academy of Pediatrics, children who view TV or play video games for more than 4 hours daily have a significantly increased risk of being overweight Studies show urban areas lack a safe outdoor area to play so families stay inside If they do go outside, urban areas wrought with fast food restaurants

Ethnic and cultural factors:

Ethnic and cultural factors Low income families have higher percentage of overweight members Poverty rate among African-Americans and Hispanics ~ 3 times higher than the white population Price of fresh fruits and vegetables has increased 54% but soft drinks and high calorie snacks has decreased 22% in last decade

Anesthesia considerations for the obese surgical patient:

Anesthesia considerations for the obese surgical patient Metabolic disorder that occurs either by over consumption or under utilization of caloric substrate Incidence of DM, HTN, CAD, cancer, cerebrovascular disease, pulmonary compromise and sudden death increases AIRWAY MANAGEMENT, POSITIONING, AND INTRAOPERATIVE MANAGEMENT IS A CHALLENGE WITH THE OBESE PATIENT

Anesthesia considerations of the pathophysiology of obesity:

Anesthesia considerations of the pathophysiology of obesity Cardiovascular Fatty infiltration of heart may interfere with normal conduction, producing dysrhythmias and conduction blockade Cardiac output doubled to compensate for additional blood vessels required to sustain fatty tissue Must increase 2-3 ml/100g tissue/min and each 13.5 kg (29.7 #) of fat gained requires 25 miles of neovascularization to provide blood flow to fatty tissue  co increases 0.1 liter/min/kg of body fat

Cardiovascular considerations:

Cardiovascular considerations Increase in total circulating volume, increased pulmonary blood volume, pulmonary hypertension, and ultimately, right ventricular dysfunction Hypertension incidence is 10 times higher in obese patient, which also leads to left ventricular dysfunction and hypertrophy CHF more common Aortocaval compression may occur

Cardiovascular Implications:

Cardiovascular Implications OICD: obesity induced cardiovascular disease OIH: obesity induced hypertension

Cardiovascular considerations:

Cardiovascular considerations Hyperlipidemia Dyslipidemia (abnormal levels of fat in blood) Vascular disorders Deep vein thrombosis Pulmonary embolism Abnormal arterial function and structure, with an increased intimal-medial thickness Markers for early atherosclerotic changes

Pulmonary considerations:

Pulmonary considerations RESTRICTVE LUNG DISEASE d/t compressive effect of adipose tissue on abdomen, diaphragm and thoracic structures VC, ERV, FRC reduced Chest wall and lung compliance reduced O2 consumption and carbon dioxide production increased (increased work of breathing)  due to increased metabolic demands (adipose tissue metabolically active) Collapse of small airways  V/Q mismatch CO2 retention  Pickwickian syndrome

Pulmonary considerations:

Pulmonary considerations Asthma Higher incidence among overweight individuals Males > Females Studies show they used increased medicine, wheezed more, and made more visits to the ER Decreased exercise tolerance May be genetic link between obesity and asthma B2-adrenergic receptor, tumor necrosis factor a (TNF-a), and insulin growth factor 1 (IGF-1) Leptin and pro-inflammatory role

Pulmonary considerations:

Pulmonary considerations Obstructive sleep apnea (OSA) has been identified in infants as young as 6 months old 59% of obese individuals with a positive history have OSA Snoring Daytime somnolence (not seen as often in children) Nighttime awakening Orthopnea Difficulty awakening in morning Mouth breathing Enuresis Causes include greater fat mass, increased muscle relaxation, and enlarged tonsils and adenoids

Obesity syndromes:

Obesity syndromes Obstructive sleep apnea syndrome (OSAS): 30 apneic periods of > 20 seconds over 7 hours Obesity hypoventilation syndrome (OHS): decreased ventilatory response to CO2 and O2, resulting in sleep apnea, hypoventilation, hypercapnea, pulmonary hypertension, and hypersomnolence Pickwickian syndrome: OHS PLUS hypoxemia, polycythemia, biventricular failure

Pickwickian syndrome:

Pickwickian syndrome Also called obesity-hypoventilation syndrome by some but not completely accurate definition Occurs in 5% of morbidly obese patients Historical origin: from Charles Dickens’ The Pickwick Papers Describes a morbidly obese boy who is known to fall asleep at odd times

Pickwickian syndrome:

Pickwickian syndrome Characterized by hypercapnea 2* to alveolar hypoventilation Hypercapnea in obese patients is suggestive of intrinsic disease of the respiratory center of the ventilatory system An inadequate ventilatory response combined with worsening hypoxia, leads to pulmonary hypertension and transudation of fluid in lungs

Pickwickian syndrome:

Pickwickian syndrome Clinical characteristics Somnolence Hypercapnea Alveolar hypoventilation Hypoxemia Pulmonary hypertension Right sided heart failure Secondary polycythemia (cyanosis-induced)

Gastrointestinal/hepatic considerations:

Gastrointestinal/hepatic considerations High risk for GERD  gastric acid aspiration Increased intra-abdominal pressure and decreased lower esophageal sphincter tone Poor gastric emptying Hyperacidic gastric fluid Increased incidence of hiatal hernia Cholelithiasis Stones form when bile is saturated with cholesterol and crystallize Associated with ingestion of simple sugars and saturated fat

Hepatic considerations:

Hepatic considerations Nonalcoholic steatohepatitis (fatty liver) disease Most common form of liver disease in children Fatty infiltration of the hepatocytes Hepatocyte rupture results in increased levels of lactic dehydrogenase and aspartate aminotransferase, triglycerides, and cholesterol If not treated, fibrosis occurs leading to c irrhosis Cirrhosis occurs 1.5-2.5 times more frequently Detected on ultrasound and diagnosed on biopsy

Endocrine/metabolic considerations:

Endocrine/metabolic considerations Type 2 diabetes May be discovered on routine urinalysis Often presents typically as polyuria, polydipsia, or ketoacidosis Much higher risk of diabetes associated complications, especially kidney failure by middle age and death from a CV event, compared to adult onset diabetes

Obesity and DM:

Obesity and DM AODM occurs 7 X more frequently in obese patients Insulin resistance promininent feature of both obesity and NIDDM Insulin action impaired by decreasing insulin suppression of hepatic glucose production and decreasing glucose utilization at muscle At increased risk for hyperglycemia and hyperinsulinemia

Endocrine/metabolic considerations:

Endocrine/metabolic considerations Metabolic syndrome ( central adiposity) Recognized as major risk for cardiovascular disease in adults Signs and symptoms Obesity Insulin resistance Hypertension Other metabolic derangements Present in nearly 50% of obese individuals and worsens with increasing BMI Abnormal glucose tolerance tests, high triglycerides, and low HDL

Body Fat Distribution:

Body Fat Distribution Central android or abdominal visceral obesity (apple shaped)  malignant form of fat distribution Peripheral gynecoid or gluteal femoral obesity (pear shaped) medical risks less with this fat distribution

Endocrine/metabolic considerations:

Endocrine/metabolic considerations Polycystic ovary syndrome (PCOS) Polycystic ovaries Hyperandrogenism Irregular menses Hirsutism Acne

Renal effects:

Renal effects Proteinuria occurs in 40% of obese patients GFR is increased 40% 2* development of focal segmental glomerular sclerosis and decreased renal function

Musculoskeletal considerations:

Musculoskeletal considerations Slipped capital femoral epiphysis (SCFE) Limp Limitation of motion of hip Hip and/or knee pain Blount disease Tibia vara Knee pain Predisposed to fractures due to greater bone density Osteoarthritis

Neurological/psychological considerations:

Neurological/psychological considerations Individuals with OSA can have neurocognitive effects Reduction in attention, motor efficiency, graphomotor ability Pseudotumor cerebri Idiopathic intracranial hypertension Presents with visual loss and papilledema Depression Depressed affect, poor school/work performance, suicidal ideation Anxiety Excessive worry, emotional eating pattern Poor self-esteem Decreased participation in social/school/work activities

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