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BARIATRIC ANAESTHESIA

BARIATRIC ANAESTHESIA. (Anesthesia in Obese Patient ). Two Worst enemy of Anesthetist. OBESITY. COPD. Obesity: Definition. A condition in which excess body fat may put a person at health risk. (laymen)

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BARIATRIC ANAESTHESIA

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  1. BARIATRIC ANAESTHESIA (Anesthesia in Obese Patient )

  2. Two Worst enemy of Anesthetist OBESITY COPD

  3. Obesity: Definition • A condition in which excess body fat may put a person at health risk. (laymen) • A chronic metabolic disorder that is primarily induced and sustained by an over consumption or underutilization of caloric substrate (Medical) • The American Heart Association (AHA) defines obesity as body weight 30 percent greater than the ideal body weight (Precise)

  4. Equations • Ideal body weight in Kg (IBW) • (Broca’s Index) • Height in centimeters - 100 for men • Height in centimeters - 105 for women • ----------------------------------------------------- • Body mass index (BMI) • weight in Kg / height (m) 2

  5. Definitions • Obese • 20% > IBW • BMI > 28 – 35 • Morbidly Obese • 2 x IBW • BMI > 35

  6. Obesity Classification Overweight - BMI > 25 kg/m2 Obesity - BMI > 30 kg/m2 Morbid obesity – BMI> 40 kg/m2or 35 with coexisting co morbidities Super obese patient -BMI >50kg/m2

  7. My own BMI • My weight is 80 kg • My height is 5’8” (170 cm or 1.7 meter) • So my BMI 82 / (1.7)2 is 27.68 • So I am Overweight but not obese

  8. Incidence of Obesity in INDIA • 23 % are obese • 5% are morbidly obese • Mortality is 3.9 times that in non-obese

  9. Causes of Obesity • Complex and multifactorial • Genetic predisposition • Socialization • Age • Sex • Race • Economic status • Psychological • Cultural • Emotional • Environmental factors • Cessation of smoking

  10. Diseases Linked to Obesity • Diabetes • Coronary Heart Disease • High Blood Pressure ( Hypertension is about 6 times more frequent in obese subjects than in lean men and women ) • Stroke • Arthritis • Gastroesophageal reflux • Cancer • High cholesterol • Endocrine disease • A 10-kg higher body weight is associated with a 3.0-mm Hg higher systolic and a 2.3-mm Hg higher diastolic blood pressure. These increases translate into an estimated 12% increased risk for CHD and 24% increased risk for stroke

  11. Diseases Linked to Obesity • Hypertrophic Cardiomyopathy • Infertility • Depression • Obstructive sleep apnea • Gallstones • Fatty liver • Stress incontinence • Venous ulcers • end-stage kidney failure • Sudden death

  12. Physical Complications of Obesity • Heart disease • Type II diabetes mellitus • Hypertension • Stroke • Cancer (endometrial, breast, prostrate, colon) • Gallbladder disease • Sleep apnea • Osteoarthritis • Reduced fertility • increased risk of morbidity and mortality as well as reduced life expectancy

  13. Psychological Complicationsof Obesity • Emotional distress • Discrimination • Social stigmatization • anxiety, fear, hostility and insecurity

  14. Diabetes Mellitus Type 2 prevalence is 2.9 times higher in the obese than in non-obese for those 20-75 years of age.Morbidity due to Cardiovascular diseases has been reported to be almost 90 % in those with severe obesity.

  15. Cardiovascular Pathophysiologyin Obesity • Excess body mass •  metabolic demand   CO • For every 13.5 kg of fat gained: • 25 miles of neovascularization occurs • Increased CO of 0.1 L/min for each kg of fat. •  workload • LVH •  pulmonary blood flow and HPV • Pulmonary HTN cor pulmonale  right heart failure

  16. Cardiovascular Pathophysiologyin Obesity • Stroke volume index and stroke work index are the same as non-obese • SV and SW must  • Proportion to body weight •  SV and SW • LVH dilatation

  17. Cardiovascular Pathophysiology •  risk of arrhythmias • Hypertrophy • Hypoxemia • Fatty infiltration of cardiac conduction system •  catecholamines • Sleep apnea • dyslipidemia • glucose intolerance

  18. Cardiac Evaluation: Assess For • Prior MI • HTN • Angina • PVD

  19. ECG Changes That May Occur in Obese Individuals

  20. Cardiac Evaluation: ECG • Determination of • resting rate • Rhythm • Ventricular hypertrophy or strain

  21. Cardiac Evaluation: ECG • Investigate ischemic changes or evidence of coronary artery disease • Low voltage ECG • Excess overlying tissue • Underestimate LVH

  22. Cardiac Evaluation: ECG • Axis deviation and atrial tachyarrhythmias • Sudden cardiac death is more prevalent with • LVH • Ventricular ectopy

  23. Cardiac Evaluation • Indications of LV dysfunction • Limitations in exercise tolerance • History of orthopnea • Paroxysmal nocturnal dyspnea

  24. Vascular Access • Challenging at best • Excessive fat obscures blood vessels • Central line placement • Vessels impeded by distortions of the underlying anatomy by adipose.

  25. Volume Replacement • Adult total body water percentage is 60% to 65%. • Severely obese total body water is 40%. • Estimated blood volume in obese patient is 45 to 55 mL/kg actual body weight • 70 mL/kg for the non-obese

  26. Volume Replacement • Avoid rapid rehydration • Lessen cardiopulmonary compromise. • Administer Hetastarch at recommended volumes per kilogram of IBW • 20 mL/kg • Albumin 5% and 25% used as indicated • Support circulatory volume and oncotic pressure. • Replace blood loss with crystalloid • 3:1 ratio

  27. Respiratory Pathophysiology • There is a clear association between dyspnea and obesity. Obesity increases the work of breathing because of the reductions in both chest wall compliance and respiratory muscle strength • Excess metabolically active adipose +  workload on supportive respiratory muscle •  CO2 production • Hypercarbia •  O2 consumption • Hypoxia

  28. Respiratory Pathophysiology • Restrictive lung disease • Decreased chest wall compliance • Diaphragm forced cephalad • Decreased lung volumes • Accentuated by supine and Trendelenberg positions • FRC may fall below closing capacity • Alveolar collapse • Ventilation / perfusion mismatch

  29. Changes in Pulmonary Volumes and Function Tests • Tidal volume • Normal or decreased • Inspiratory reserve volume • Decreased • Expiratory reserve volume • Greatly decreased

  30. Changes in Pulmonary Volumes and Function Tests • FRC • Greatly decreased • Direct inverse relationship between BMI and FRC • FEV1 • Normal or slightly decreased

  31. Respiratory Pathophysiology • Relatively hypoxemic • Occasionally hypercapnic • Obesity-hypoventilation (Pickwickian syndrome) • Obesity usually extreme • Hypercapnia • Cyanotic / hypoxemia • Polycythemia • Pulmonary HTN • Biventricular failure • Somnolence • Obstructive sleep apnea syndrome(OSAS)

  32. OSAS • Definition • 10 seconds or more of total cessation of airflow despite respiratory efforts • Clinically relevant • 5 episodes per hour • 30 episodes per night

  33. OSAS • Snoring • Dry mouth and short arousal during sleep • Partners report apnea pauses during sleep

  34. OSAS • More vulnerable to airway obstruction • Opioids • Sedatives • More vulnerable in supine or Trendelenberg position

  35. OSAS and Difficult Intubation • 15% of obese patients are a difficult intubation • Short thick neck • Obesity and short thick neck • Related to OSAS and to each other • Fat in lateral pharyngeal walls are difficult to exam awake

  36. Detecting OSAS • Nocturnal polysomnography

  37. GI Pathophysiology •  incidence • Gastroesophageal reflux • Hiatal hernia •  abdominal pressure • Severe risk of aspiration

  38. GI Pathophysiology • After 8 hour fast • 85 – 90% of morbidly obese patients have • Gastric volumes > 25 ml • Gastric pH < 2.5

  39. Anesthetic Considerations: Preoperative •  risk for aspiration pneumonitis if reflux history • Consider H2 antagonist ( pre, intra and post ) • Metoclopramide, Ranitidine or Ondansetron • Sleep apnea, asthma, smoking • Avoid unnecessary respiratory depressants • BHT (breath holding time) • Assess for • Cardiopulmonary reserve • ECG & X-ray Chest, if necessary echocardiography • LFT & RFT • ABG • PFT’s

  40. Obesity: Anesthetic Issues • Airway • proper positioning can be difficult • may need extra support under back • POSITION, POSITION, POSITION

  41. Anesthetic Considerations: Preoperative • BP with appropriate size cuff • Plan / examine for venous / arterial access • Possible regional anesthesia

  42. Mallampati Classification Class I = visualization of the soft palate, fauces, uvula, anterior and posterior pillars.Class II = visualization of the soft palate, fauces and uvula.Class III = visualization of the soft palate and the base of the uvula.Class IV = soft palate is not visible at all.

  43. Anesthetic Considerations: Preoperative • If HTN – good control • Atherosclerosis then ECG &/or Stress Echo • Previous anesthesia exposure and any problem to ask

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