Obesity-Part 2

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Obesity and Related Surgery Part 2 :

Obesity and Related Surgery Part 2 Maribeth Massie, CRNA, MS University of New England Master of Science in Nurse Anesthesia

Anesthetic management:

Anesthetic management Preoperative Be careful with benzos and opioids  do not want to suppress respirations because of marginal O2 reserves History of OSA, snoring, somnolence, HTN, CHF and CAD EKG: may show increased voltage, atrial /ventricular enlargement and arrhythmias Chest Xray : may show atelectasis , cardiac enlargement, infiltrates, effusions, or pneumothorax CBC: elevations in WBC and Hct may suggest infection and chronic hypoxemia respectively Bicarbonate levels elevated to buffer chronic respiratory acidosis if CO2 retainer


GERD May require pretreatment with H2 antagonist and gastrokinetic agents Ranitidine 150-300 mg administered the night before and then 90-120 minutes before surgery, along with Reglan 10 mg, will increase pH and decrease volume Nonparticulate antacid ( Bicitra ) on arrival to OR

Airway management of obese patient:

Airway management of obese patient Heightened awareness and vigilance Preop planning: thorough airway assessment History of OSA: use of CPAP/ BiPAP May be difficult to ventilate and intubate May have short neck, anterior larynx, large tongue, limited ROM, and small TMD Awake intubation or RSI Consider need for ICU bed postop

Evaluation of Sleep study:

Evaluation of Sleep study Respiratory Distress Index (RDI) Adult values do not correlate to children well Measure the Respiratory disturbance index or apnea/hypopnea index Total number of apneas and hypopneas divided by total sleep time and multiplied by 60 Apnea: cessation of airflow > 10 seconds Hypopnea: “little breath”; defined differently by centers 50% reduction in airflow or respiratory effort; reduction in airflow, effort and decreased oxygen saturation


RDI In children, must pay attention to clinical symptoms and not just numbers Despite kids with low RDI’s, gas exchange has been found to be significantly impaired with frequent desaturations 0-2: no OSA 2-10: mild OSA 10-15: moderate OSA >15: severe OSA


Intubation Assess airway closed; preoxygenate well for 3-5 minutes Keep HOB elevated 30*; can rarely tolerate full supine Place wedge/sheets of shoulders for proper positioning May need awake fiberoptic intubation Even minor respiratory obstruction predisposes patient to development of severe apnea secondary to severely limited O2 reserves


Intubation Usually requires at least 50% O2 Positive pressure ventilation may be necessary b/c spontaneous ventilation may predispose patient to atelectasis and hypoxemia PEEP may be necessary to maintain arterial oxygenation Increase in TV may worsen oxygenation if high PIP impair blood return to chest, decreasing CO and producing V/Q mismatch

Metabolism of anesthetic drugs:

Metabolism of anesthetic drugs Unpredictable in obese patients Increases biotransformation rate of methoxyflurane , enflurane and halothane (? Sevo )  increased fluoride ionsrenal toxicity Forane and Desflurane better choices Volatile anesthetics metabolized more extensively in obese patients

Metabolism of anesthetic drugs:

Metabolism of anesthetic drugs Lipophilic (fat soluble) drugs Opioids, benzos, and barbs  fat stores provide an increased Vd and decreased elimination half-lifelower serum drug concentrations and decreased clearance Fentanyl is lipophilic but has same profile in obese/nonobese Larger loading dose required for same plasma concentration; some base dose on ideal body weight Hydrophilic (water soluble) drugs best to use with obese patients More limited Vd; dose should be based on ideal body weight

Metabolism of anesthetic drugs:

Metabolism of anesthetic drugs Pseudocholinestarase activity increased  larger doses of Sux required (1.5-2.5 mg/kg) NDMR variable

Intraoperative management:

Intraoperative management Technical considerations Transfer to OR table  2 tables may need to be pushed together to accommodate weight; specialty tables are available in excess of 350# Positioning may be difficult  increased risk of nerve injury; carefully place padding to prevent peripheral neuropathy and watch brachial plexus; use sleds to protect tucked arms and to prevent patient from falling off table

Intraoperative management:

Intraoperative management Technical considerations Limited range of motion  have reduced range of motion; frequent palpation of pulses, generous padding, correct alignment, and repeated inspection help to reduce neuropathy Difficult venous access  excess adipose tissue makes vascular access difficult; central line or venous cutdown may be required Inaccurate blood pressure readings  blood pressure will be artificially elevated if cuff too small for arm; cuff must encircle 75% of upper arm circumference; may require arterial line

Intraoperative considerations:

Intraoperative considerations Reverse trendelenberg 16-18 G PIV x 2 NS/LR @ 8-12 ml/kg/hr Slightly greater than with normal weight patient to reduce postop renal failure Fluid warmer May require arterial line due to inaccurate noninvasive BP readings +/- CVP Gastric tube


Emergence Obese patient should be alert, awake, and able to sustain head lift > 5 seconds Reverse all NDMR RR < 30 bpm PaO2 > 80 mmHg and PaCO2 < 45-50 mmHg if no preop values available NIF > -25-30 cmH2O VC 10-15 ml/kg TV > 5 ml/kg IBW


Postoperative At increased risk for hypoxemia 4-7 days postop Supplemental O2 necessary with patient in sitting position (even before extubated) Aggressive pulmonary care May require ICU for monitoring DVT: encourage early ambulation if able; if not, Low molecular weight heparin and SCD’s PCA/opioids to decrease postop splinting and hypoventilation Epidural opioids facilitate earlier ambulation and decrease pulmonary complications

Treatment of obesity:

Treatment of obesity Multimodal approach Dietary interventions Exercise Behavior modifications Drug therapy Surgery

Drug therapy:

Drug therapy Noradrenergic sympathomimetic agents: Stimulate the release of norepinephrine or inhibit its reuptake into nerve terminals Biggest side effect is hypertension Goal is to affect satiation (level of fullness) and satiety (level of hunger after eating) Meridia ( sibutramine hydrochloride): No longer approved in most countries due to cardiovascular stability  uncontrolled hypertension Adipex ( phentermine ) and Tenuate ( diethylpropion ): approved for short term use (<12 weeks) Schedule IV drugs so potential for abuse Ephedra and Ma Huang: removed from US market but still can be found on black market Works by increasing thermogenesis and reducing food intake

Drug therapy:

Drug therapy Gastrointestinal lipase inhibitors Blocks absorption of dietary fat Xenical ( orlistat ) Only drug available for long term use for obesity Alters fat digestion by inhibiting pancreatic lipases Biggest side effect is GI symptoms Rare reports of severe liver and kidney injury have been reported

Drug therapy:

Drug therapy Other medications that may be used in combination with the prior drugs: Antidepressants Antiepileptics Diabetes drugs Hormones

Obesity-related Surgical procedures:

Obesity-related Surgical procedures Metabolic: Cholelithiasis Cholecystectomy , appendectomy Thromboembolism Peripheral vascular disease Urolithiasis Mechanical: Osteoarthritis Varicose veins Esophagitis Hiatal hernia Abdominal wall hernia, inguinal wall hernia

Obesity-related Surgical procedures:

Obesity-related Surgical procedures Neoplastic : Cancer Endometrial, breast, prostate, colorectal, renal Fibroadenoma of the breast Gynecologic: Uterine fibroma Ovarian cysts Cesarean section Stress urinary incontinence

Common surgical procedures associated with obesity:

Common surgical procedures associated with obesity Tonsillectomy and Adenoidectomy Adenotonsillar hypertrophy is most effective treatment for OSA OSA may persist May be from increased visceral fat having an effect on decreasing airway tone  airway collapse May be from increased fat in the neck decreases caliber of airway Hold off on opioids until extubated

Orthopedic procedures:

Orthopedic procedures Slipped capital femoral epiphysis (SCFE) Occurs when proximal femoral epiphysis separates from the femoral neck through growth plate Considered orthopedic emergency (urgency)  risk of avascular necrosis of femoral head Seen in up to 30% of obese children High incidence of premature degenerative joint disease General +/- regional anesthesia: Femoral sciatic block or epidural



Orthopedic procedures:

Orthopedic procedures Blount’s disease (tibia vara) Caused by excessive weight on growth plate Knee pain Characterized by bowing of knees medially Tibial osteotomy and lengthening General +/- regional anesthesia Femoral block or epidural

Bariatric surgery :

Bariatric surgery Goal is to reduce morbidity and mortality and improve metabolic and organ function Meta-analyses show that: Evidence supporting a benefit of bariatric surgery was strongest in patients with a BMI of >40, while the benefits in those with BMI of 35 to 39 were less clear Diabetes completely resolved in 77 percent and resolved or improved in 86 percent Hyperlipidemia improved in 70 percent or more of patients Hypertension resolved in 62 percent and resolved or improved in 79 percent Obstructive sleep apnea resolved in 86 percent and resolved or improved in 84 percent GERD improved in most patients Urinary stress incontinence decreased by 47%

Bariatric surgery:

Bariatric surgery Indications: Be well-informed and motivated Have a BMI >40 Have acceptable risk for surgery Have failed previous nonsurgical weight loss Adults with BMI > 35 kg/m2 who have serious comorbidities such as diabetes, OSA, OICD, or severe joint disease Contraindications Untreated major depression or psychosis Binge eating disorders Current drug and alcohol abuse Severe cardiac disease Severe coagulopathy Inability to comply with nutritional requirements Controversial: Age > 65 or < 18; may be considered

Bariatric surgery:

Bariatric surgery Malabsorptive : rarely performed at this time Jejunoileal bypass Biliopancreatic bypass Biliopancreatic diversion with duodenal switch Restrictive Vertical banded gastroplasty (VBG) Laparascopic adjustable gastric banding (LAGB) Second most commonly performed bariatric procedure in US but is becoming more popular due to simplicity in technique, adjustability, reversibility, and relatively low perioperative mortality; less weight loss compared to LRYGB Sleeve gastrectomy Malabsorptive and restrictive Laparascopic Roux-en-Y gastric bypass (LRYGB) Combines gastric restriction with minimal degree of malabsorption Most commonly performed bariatric procedure in US Can have significant metabolic complications

Gastric banding:

Gastric banding Restrictive procedure Compartmentalizes the upper stomach by placing a tight, adjustable prosthetic band around the entrance to the stomach The gastric band consists of a soft, locking silicone ring connected to an infusion port placed in the subcutaneous tissue Injection of saline into the port leads to reduction in the band diameter, resulting in an increased degree of restriction

Roux-en-y gastric bypass:

Roux-en-y gastric bypass Anastomosis of proximal gastric pouch to a segment of proximal jejunum Bypasses most of stomach and entire duodenum Roux limb (or alimentary limb) is anastomosed to the new gastric pouch and functions to drain consumed food

Future areas of investigation:

Future areas of investigation Infectobesity Refers to obesity of infectious origin and the emerging field of medical research that studies the relationship between pathogens (disease-causing organisms, such as viruses and bacteria) and weight gain Term was coined in 2001

Future areas of investigation:

Future areas of investigation Capascin (University of Toronto) Injected in diabetic mice and killed vascularization; Studies shown to prevent fat cells, or adipocytes, from growing into mature cells ?“antiobesity” properties; ?anticancer properties Sertraline-1 Role in anti-aging and DM with metformin

“Master Switch” gene for obesity:

“Master Switch” gene for obesity Recent study published in journal Nature Genetics (May 2011) Since fat plays important role in metabolic disease, regulating gene could be target for drugs Found a link between KLF14 gene, which is linked to Type 2 DM and cholesterol, and other genes found in fat tissue Seems to act as master switch in controlling processes that connect changes in SQ fat to disturbances in muscle and liver that contribute to other metabolic conditions Nature Genetics Volume: 43, Pages: 561–564 Year published: (2011)

Ethical Issues in the OR:

Ethical Issues in the OR Does obesity qualify as child abuse? http://www.latimes.com/health/la-he-childhood-obesity-custody-20110829,0,3696579.story http://jama.ama-assn.org/content/306/2/206.short How young is too young to perform bariatric surgery? http://onlinelibrary.wiley.com/doi/10.1111/j.1758-8111.2010.00003.x/full http://journals.lww.com/jpgn/pages/articleviewer.aspx?year=2004&issue=07000&article=00002&type=fulltext Are anesthesia providers cognizant of the increased risk with the obese pediatric patient? http://journals.lww.com/anesthesiology/pages/articleviewer.aspx?year=2008&issue=03000&article=00009&type=fulltext http://bja.oxfordjournals.org/content/106/3/359.full

References :

References American Academy of Pediatrics. Prevention of Pediatric Overweight and Obesity. Pediatrics 2003; 112 (2): 424 – 430. Anderson PM, Butcher KF. Childhood Obesity: Trends and Potential Causes. The Future of Children 2006; 16 (1): 19 – 45. Caprio S. Treating Childhood Obesity and Associated Medical Conditions 2006; 16 (1): 209 – 227. CDC, BMI – Body Mass Index for children and teens. Available at www.cdc.gov/nccdphp/dnpa/bmi/childrens . Accessed September 5, 2011. CDC, Childhood Overweight and Obesity. Available at www.cdc.gov/obesity/childhood/ . Accessed September 7, 2011. CDC, Healthy Youth. Available at www.cdc.gov/healthyyouth/obesity/facts.htm. Accessed September 7, 2011. Choudhary AK, Donnelly LF, Racadio JM, Strife JL. Diseases Associated with Childhood Obesity. American Journal of Roentgenology 2007; 118 : 1118 – 1130.


References Daniels SR. The Consequences of Childhood Overweight and Obesity. The Future of Children 2006; 16 (1): 47 – 67. Matricardi PM, Gruber C, Wahn U, Lau S. The asthma-obesity link in childhood: open questions, complex evidence, a few answers only. Clinical and Experimental Allergy 2007; 37 (4): 476 - 484 Miller JL, Goldstone AP, Couch JA, Shuster J, He G, Driscoll DJ, Liu Y, Schmalfuss IM. Pituitary abnormalities in Prader-Willi syndrome and early onset morbid obesity. American Journal of Medical Genetics Part A 2007 Mullen, M. (2009). The obesity-ethnicity link. The Ohio State University Alumni Magazine, p.30 National Institutes of Health (2009). Retrieved October 13, 2010, from http://obesityresearch.nih.gov/About/about.htm Noller DT, Paulk DP. Childhood obesity: Curbing an American epidemic. Journal of the American Academy of Physician Assistants 2005


References Sakurai K, M Kawazuma , T Adachi, T Harigaya , Y Saito, N Hashimoto, and C Mori. 2004. Bisphenol A affects glucose transport in mouse 3T3-F442A adipocytes. Brit. J. Pharm. 141:209-214 Setzer N, Saade E. Childhood obesity and anesthetic morbidity. Pediatric Anesthesia 2007; 17 (4): 321 – 327 McAuliffe, M.S., Gambrell , P.G., & Edge, M.J. Obesity and Anesthesia Practice. In: Nagelhout JJ, Plaus , KL, eds. Nurse Anesthesia , 4 th edition. St. Louis: Elsevier Saunders; 2010: 1024 – 1044.

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