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- 1. Obesity and Anaesthesia : A review of Management & Recent Advances Dr. P. Enoch Ricky Paul Senior Resident, Department of Anaesthesiology, Alluri Sitarama Raju Academy of Medical Sciences (ASRAMS), Eluru. 1
- 2. Introduction • Why OBESITY? • Very common patients • Global epidemic • India ▫ >23% are obese 5% are morbidly obese 2
- 3. Introduction • Not for just bariatric sx but in general procedures • Keen idea of pathophysiology • Affecting his/her body systems • Accordingly modify anaesthesia plan or approach 3
- 4. Definition • Abnormal high amount of adipose tissue compared with lean muscle mass • More than 25% of body weight in males or more than 30% of body weight in females is attributable to fat • Increased the mortality and morbidity of the patient 4
- 5. Classification • According to Body Mass Index (BMI) kg/m2` • >50 Super Obese • >60 Super Super obese • Morbidly obese - ASA III 5
- 6. Pathophysiology • Weight gain • Calorie intake >> Burned • Till BMI 40 Adipocytes will increase in size • >40 increase in number of adipocytes • Triglyceride storage controlled by Lipoprotein lipase Stored in the form of Triglycerides Adipocytes Adipose tissue 6
- 7. Pathophysiology •Waist Hip Ratio : Independent parameter defining obesity •Males >1 •Females >0.8 •Increased risk of IHD, Stroke, Diabetes mellitus 7
- 9. Pathophysiology State of Chronic Inflammation Adipocytes • Release pro inflammatory cytokines • IL-1 • IL-6 • TNF α • Released by visceral adipose tissues Insulin resistance • Insulin has anti inflammatory properties • Receptors on the tissues are covered by excess adipose tissues • Receptors resistant to insulin Oxidative stress • Metabolic rate is increased • Promotes inflammation 9
- 10. Diseases associated with Obesity Endocrine 1. Metabolic syndrome 2. Type 2 Diabetes Mellitus 10
- 11. Diseases associated with Obesity • Type 2 Diabetes Mellitus • Impaired Glucose tolerance Pro inflammatory cytokines • Worsens glucose tolerance • Decreases secretion of adiponectin • Insulin sensitizer • Sensitizes tissues to insulin Insulin resistance • Insulin has anti inflammatory properties • Receptors on the tissues are covered by excess adipose tissues • Receptors resistant to insulin Infiltration of fat • Infiltration of fat into pancreas • Decreases insulin secretion • May be seen in long standing super obese 11
- 12. Diseases associated with Obesity CARDIO VASCULAR SYSTEM 1. Systemic Hypertension Initial Hyper insulinemia Nor epinephrine release Stimulates adipocytes Stimulates Sympathetic NS Direct Vasopressor action Will release Angiotensinogen Damages and fibrosis of arterial walls Pro inflammatory cytokines Retention of water Hypervolemia Increases renal absorption of Na Stimulates RAAS Arterial wall stiffness 12
- 13. Diseases associated with Obesity 2. Cardiac Output • For 1 kg gain of adipose tissue cardiac output increases by 100ml/min • If a person loose 1kg of adipose tissue ▫ SBP falls by 1mmhg ▫ DBP falls by 2mmhg • Uncontrolled Hypertension ▫ Eccentric LV Hypertrophy ▫ Leads to left Heart Failure ▫ Pulmonary Hypertension 13
- 14. Diseases associated with Obesity • Coronary Artery Disease ▫ Independent risk factor ▫ Glucose intolerance leads to accelerated atherosclerosis ▫ Young and obese more prone for single CAD • Biventricular Failure Hypervolemia + Vascular stiffness HTN Obstructive sleep Apnea Pulmonary HTN Right Heart Failure LVH LV Systolic and Diastolic Dysfunction Left Heart Failure Pulmonary congestion RV Changes 14
- 15. Diseases associated with Obesity • Obesity Cardiomyopathy ▫ Obesity of the heart ▫ Causes conduction defects like SA block, BB block ▫ Adipokines released by adipocytes in the heart may damage myocytes directly ▫ Predominant cause of death in obese 15
- 16. Diseases associated with Obesity RESPIRATORY SYSTEM • LUNG VOLUMES 1. FRC 2. ERV 3. TLC 4. COMPLIANCE V/Q mismatch Rt to Lt Intrapulmonary shunting PaO2 Arterial Hypoxemia 16
- 17. Diseases associated with Obesity • Closing volumes may be more than FRC ▫ May result in early closure of alveoli or closure of alveoli right after normal expiration • Oxygen reserve is less ▫ Early desaturation during apnea High metabolic rate adds another reason • Increased work of breathing ▫ Metabolic demand increased ▫ Leads to increased Oxygen consumption and CO2 production ▫ Tries to increase minute ventilation 17
- 18. Diseases associated with Obesity • Airway resistance is increased • Mainly obesity follows restrictive pattern • But obstructive pattern is also seen as narrowing of airway due to fatty tissues around • Reduced FEV1 In normal patients FRC decreases by 20% in GA In Obese patientes FRC may decrease upto 50% in GA 18
- 19. Diseases associated with Obesity Obstructive Sleep Apnea (OSA) • Episodic complete cessation of breathing for more than 10 seconds occurring >5 times per hour of sleep accompanied with desaturation by 4% Obstructive Sleep Hypopnea (OSH) • Episodic partial reduction of airflow by 50% for >10seconds occurring >15 times per hour of sleep with desaturation by 4% 19
- 20. Diseases associated with Obesity • Diagnosis by Polysomnography • Result by AHI (Apnea Hypopnea Index) ▫ Total (Apnea + Hypopnea) Episodes ▫ Total Sleep Time • Grading ▫ Mild 5-15/hr ▫ Moderate 15-30/hr ▫ Severe >30/hr 20
- 21. Diseases associated with Obesity Treatment : Mild – weight loss, sleep on side etc Mod and Severe – Use CPAP and BiPAP Undergo Surgery of uvuloplasty pharyngoplasty • Pre op optimization if AHI >5/hr, CPAP or BiPAP for 2 to 12 weeks T.Oneill, J Allan/Current Anaesthesia & Critical care 21 (2010) 16-23. 21
- 23. 23
- 24. 24 Guidelines according to SOBA UK management of obese patients for surgery
- 25. Diseases associated with Obesity PICKWICKIAN SYNDROME • Obesity Hypoventilation Syndrome • Patient will be hypercapnic at rest as well as awake • Resting hypercapnia PaCO2 >45mmHg 25 Morbid Obesity Hypersomnolence Plethora Edema
- 26. Diseases associated with Obesity GI system • Non Alcoholic fatty liver • Cholelithiasis • GERD, etc Immune system • Pro inflammatory cytokines increased • Impairs neutrophil function • More prone to infections 26
- 27. Diseases associated with Obesity Musculo Skeletal • Joint Pains • Arthritis • Fragile bones CNS • Depression, low mood • Neuropathies • Migraine, etc 27
- 28. Diseases associated with Obesity Thrombo embolism • Polycythemia ▫ Makes blood more thick and prone for thrombus formation • Fibrinogen results in Fibrin lysis • Intra abdominal Pressure leads to venous stasis • Immobilization of the patients 28
- 29. Pre operative Evaluation Goals 29 Timely identification of comorbidities Optimizing medical therapies Risk stratification Appropriate selection/ technique Optimizing outcome
- 30. Pre operative Evaluation 30 •Coexisting Comorbidities •OSA and OHS •Airway •Consent and Councelling •Plan of Anaesthesia •Logistic Issues
- 31. Pre operative Evaluation • Detailed History ▫ Chest pain ▫ Breathlesness ▫ Fatigue ▫ Syncope ▫ h/o OSA ▫ h/o HTN and Medication ▫ Right Heart Failure ▫ Left Heart Failure 31 Distended JVP Hepatomegaly Spleenomegaly Acites Pedal edema Cough Crepetations Wheeze Orthopnea PND
- 32. Pre operative Evaluation • Clinical examination may not be reliable • Cardiac function difficulty to assess due to limitation in mobility • METS not relaible • Trans Esophageal Dobutamine Stress Echo test – Ideal • If patient can exercise, CPET useful tool • Ability to tolerate supine position 32
- 33. Pre operative Evaluation Respiratory and Airway • OSA • Facial fat • Short neck • Neck circumference • Large tongue • Restricted mouth opening • If patient is on any CPAP or BiPAP, ask the patient to bring to hospital 33
- 34. Pre operative Evaluation 5 D Anticipation • Difficult Mask ventilation • Difficult Laryngoscopy and intubation • Difficult SGAD • Difficult FONA • Difficult Extubation 34
- 35. Pre operative Evaluation • GERD symptoms • Acid reflex • Heart burn • Patient on any PPI ▫ if not, to be started • Delayed Gastric emptying ▫ 12 hour NBM • LFT and Lipid profile to be done as fatty infiltration is seen 35
- 36. Pre operative Evaluation • Posted for bariatric surgery • Higher risk for thrombo embolism 36 Patient related Age >55 years BMI >55 kg/m2 h/o VTE h/o Venous disease OSA Pulmonary Hypertension Surgery Related Open > laparoscopic Surgery time> 3 hrs Anastamotic leak RYGB > Sleeve > Lap banding Revision > Primary Bariatric surgery in head up position
- 39. Pre-habilitation • Nutritional support • Exercise and diet control (Liver Shrinking Diet) • Deep Breathing exercise & Pre Op CPAP therapy • Cessation of alcohol and smoking • Optimization of all co-morbidities • Counseling of patient and family with information and educating them • Fasting guidelines : encourage clear fluids 3hrs prior to surgery 39
- 40. Pre operative Evaluation Investigations • Complete blood picture • Electrolytes • FBS • RFT • LFT • Thyroid functions • HbA1C • ECG • Chest X ray 40 •Echo DSE •ABG •PFT •Polysomnography •Airway Imaging •POCUS in obese To look at gastric antrum to predict the severity of GERD and assess the risk of aspiration
- 41. Intra operative • Appropriate sized equipments are to be kept ready • Trolleys • Self arrival and self positioning (BEST) • Hovermatt Transfer matress • OT Table (Hercules 450kg – 500kg) • Strapping patient to OT bed • Staff ▫ Strong and trained people ▫ Pre op Team breifing • Pressure point padding • Do not give any pre medication (sedatives) in the pre-op room 41
- 42. Intra operative • Venous access might be difficult • USG guided central venous catheter • Severe Pulm HTN or RVF for long duration ▫ Consider PA catheter or TEE • If patients has high risk of DVT/PE especially posted for Bariatric Surgery ▫ Consider prophylactic placement of IVC filter • Maintain normothermia ▫ Use forced air warmers 42
- 43. Anaesthesia Technique • Regional anaesthesia > General anaesthesia • Intra op analgesia • Post operative analgesia • Opioid need is less • No/ Less airway involvement 43 •But techincally very difficult •Difficulty in assessing the land marks •Expertise and availability ofUltrasound •Extra long Needles
- 44. Anaesthesia Technique • Regional anaesthesia > General anaesthesia Spinal and Epidural ▫ 20-30 % of less drug is needed ▫ Epidural fat collection ▫ Engorged epidural veins ▫ Increased abdominal pressure 44
- 45. General Anaesthesia • Use of BZD’s controversial – Not to use • Emergency airway cart to be kept ready • ENT surgeon stand by • Pre Oxygenation much needed 45 SGAD Video Laryngoscope FOB Oral and Nasal Aiways Stylet&Bougie Emergency Drugs 100 % FiO2 for atleast 3 min CPAP with 1o cm H2O for 5 min DURING INDUCTION CPAP with PEEP of 10 cm H2O prolongs apnea time by 50% HFNC THRIVE
- 46. Positioning Optimal Position Ramped Position or HELP(Head elevated laryngoscopic position) Reverse trendelenberg position Align external auditory meatus to sternal notch 46
- 47. Dosing Scalars • Total Body weight • Ideal body weight ▫ Height in cms – 100 (Males) ▫ Height in cms – 110 (Females) • Lean Body weight ▫ 1.3 x IBW • Hepatic drug clearance usually unaffected • If heart failure or decreased hepatic blood flow, drug clearance slows down • Increased renal blood flow and GFR ▫ So Renal Drug clearance increased 47
- 48. Dosing Scalars • Highly Lipophilic drugs – Increased VD • Initial loading dose acc to TBW • Maintenance dose according to IBW/LBW if clearance is normal • If clearance is higher, maintenance dose will also be on TBW 48 Propofol Benzodiazapines Barbiturates Atra/Cisatracurium Fentanyl Sufentanyl
- 49. Dosing Scalars • For Hydrophilic drugs • Like muscle relaxants, Dose acc to IBW/LBW • For scoline ▫ Dose acc to TBW upto 140kg ▫ >140 kg max dose is 120 – 140mg • Neostigmine – TBW • Avoid N2O ? Pulmonary Hypertension • Inhalational agents ▫ Desflurane > Sevoflurane > Isoflurane • If in doubt always titer and monitor the drug effects 49
- 51. Fluid management • Goal Directed • Crystalloids can be liberally used guided by stroke volume variation • Minimize ▫ Hypotension due to PEEP ▫ PONV ▫ Rhabdomyolysis – imp complication occurs in dehydrated patients and prolonged sx • Optimize ▫ Reduced renal perfusion due to abdomen compartmment syndrome 51 Creatine kinase levels should be checked Fluid resustiation Diuresis Alkanization of urine
- 52. Ventilation strategy • Avoid Volutrauma • VT acc to IBW • PEEP upto 10 cm of H2O • Recruitment manuevre (Sigh/Valsalva/High VT for 7-8 sec) ▫ BMI >40 use PaW 55 cm H2O ▫ BMI <40 use PaW 40 cm H2O ▫ Opens collapsed alveoli • If we keep PEEP more than 20 cm H2O ▫ May start affecting cardiac output and hemodynamics 52
- 53. Extubation strategy • More prone for apnea after extubation • Fully awake • Shift to PSV + PEEP • Recruitment maneuver to be done prior to extubation • Head lift >5 seconds • Obey verbal commands • Complete reversal TOF >0.9 • RAMP/HELP position • Emergency airway cart to be available 53
- 54. Extubation strategy • Extubate over Airway exchange catheter • Use of nasopharyngeal airway • Head up position >30o • O2 supplementation with continuous saturation monitoring 54
- 55. Post operative management • Poistion • Oxygenation • Analgesia ▫ Opioid sparing • DVT prophylaxis • Continuous pulse-oximetry • Encourage early ambulation • Incentive spirometry 55
- 56. Multi Modal Analgesia for Obese 56
- 57. Summary 57
- 58. 58
Editor's Notes
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