Obesity & anaesthesia

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anaesthetic consideration in obese patients

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Obesity & anaesthesia

  1. 1. OBESITY & ANAESTHESIA Co-ordinator – Dr. Chavi Sethi(MD) Speaker – Dr. Uday Pratap Singh
  2. 2. OBESITY LATIN WORD OBESUS, WHICH MEANS FATTENED BY EATING OBESITY: Metabolic disease in which adipose tissue comprises a greater then normal proportion of body tissue and amount of fat tissue is increased beyond a point compatible with physical and mental health and normal life expectancy.
  3. 3. Over wt.: excess of total body wt. including all components(muscle, bone, water and fat) Ideal body wt. ( in Kg): also k/w as Broca,s index Height in cm- 100 for males(105 for females) Relative wt. : Ratio of actual and ideal wt. Body mass index(BMI): also k/w as Quetelet index Body wt.(in Kg)/ Height(met2) Ponderal index Ponderal index = height in cm divided by cube root of body weight in kg Corpulence index: Actual wt/ desire wt. normaly less then 1.2 Harpedence index: normally less then 40 in female and less then 50 in male.
  4. 4. CLASSIFICATION OF OBESITY BMI STATUS < 18.5 underweight 18.5–24.9 normal weight 25.0–29.9 overweight 30.0–34.9 class I obesity(Obese) 35.0–39.9 ≥ 40.0 class II obesity (Morbidly obese) class III obesity(Super morbidly obese)
  5. 5. OBESITY & HEALTH RISKS HEALTH RISKS DEGREE OF OBESITY ABDOMENAL FAT DISTRIBUTION MALE WAIST ≥ 102cm FEMALE WAIST ≥ 88cm
  6. 6. CLINICAL MANIFESTATION 1.Pulmonary 2.C.V.S 3.G.I.T 4.Hepatic 5.Metabolic
  7. 7. PULMONARY MANIFESTATIONS DEC. CHEST WALL COMPLIANCE RESTRICTIVE LUNG DISEASE DEC. FRC ALVEOLAR ATELECTASIS • Lung compliance may normal • Abdominal fat--cephalad shift of diaphragm • Supine & Trendelenburg • anaesthesia • If FRC < CC • V/Q mismatch; R-L shunt; arterial hypoxemia and hypercarbia.
  8. 8. INC. ALVEOLAR VENTILATION • Inc. metabolic rate– inc. Body wt. • Inc. O 2 demand • Inc. CO 2 production HYPOXIA & HYPERCARBIA • Alert to impending complications OBESITY HYPOVENTILATION SYND. • Pickwickian synd. • Hypoxia & hypercapnia • Polycythemia– cyanosis • Rt. Sided heart failure • somnolence
  9. 9. OBSTRSUCTIVE SLEEP APNEA SYNDROME • Frequent episodes of apnea or hypopnea during sleep Total cessation of airflow for = 10 sec. Hypoapnea is 50% reduction in airflow 5 or more episode per hr. or 30 per night are counted as clinically significant • Day time somnolence associated with memory problem , impaired conc. and accident
  10. 10. • Throat muscles become so relaxed and floppy during sleep that they cause a narrowing or complete blockage of the airway
  11. 11. Daytime sleepiness or fatigue Dry mouth or sore throat upon awakening Headaches in the morning Trouble concentrating, forgetfulness, depression, or irritability Night sweats
  12. 12. Restlessness during sleep Sexual dysfunction Snoring Sudden awakenings with a sensation of gasping or choking Difficulty getting up in the mornings
  13. 13. Hypertention Hypoxia Myocardial infarction Arrhythmias Pulmonary edema Stroke Difficult intubation-induction Upper airway obstruction-recovery
  14. 14. GASTROINTESTINAL MANIFESTATIONS HITUS HERNIA GASTROESOPHAGEAL REFLUX POOR GASTRIC EMPTYING HYPERACIDIC GASTRIC FLUID INC. RISK OF GASTRIC CANCER
  15. 15. HEPATOBILIARY MANIFESTATIONS HEPATIC • Fatty infiltration of liver • Abnormal liver function • Volatile anaesthetics defluorinated to greater extent-halothane hepatitis GALL STONES • Abnormal cholesterol metabolism
  16. 16. CARDIOVASCULAR MANIFETATIONS INC. BLOOD VOL • To perfuse Additional body fat INC. STROKE VOL INC. CARDIAC OUT PUT • 0.1 ml / min / kG body fat ARTERIAL HTN INC. CARDIAC WORKLOAD
  17. 17. LT VENTRICULAR HYPERTROPHY PULMONARY HTN & COR PULMONALE • INC. Pulmonary blood flow • Pulmonary vasoconstriction • Persistent hypoxia
  18. 18. Cardiac manifestations of obesity LVH RVH
  19. 19. THROMBO-EMBOLIC DISEASE: • Inc risk of DVT • • • • Inc. intra-abdominal pressure Polycythemia Inc. pressure in deep veins Immobilization-venous stasis
  20. 20. METABOLIC DYSFUNCTIONS TYPE-2 DM • Inc resistance to insulin in periphery HYPERTENTION CORONARY ARTERY DISEASE CHOLILITHIASIS • Abnormal cholesterol metabolism HYPERCHOLESTEROLEMIA HYPERINSULINEMIA • Inc. sympathetic activation
  21. 21. Body Water • Reduction in total body water to 40% of TBW. • Relative dehydration may be present. • Poor tolerance to fluid load.
  22. 22. METABOLIC SYNDROME OBESITY METABOLIC SYND TYPE-2 DM HTN
  23. 23. Clinical Criteria for Diagnosing Metabolic Syndrome * Criteria Defining Value Abdominal obesity Waist circumference >102 cm in men and >88 cm in women Triglycerides ≥150 mg/dL High-density lipoprotein cholesterol <40 mg/dL in men and <50 mg/dL in women Blood pressure ≥130/85 mm Hg ≥110 mg/dL Fasting glucose *Three of five criteria must be met.
  24. 24. OBESITY & DRUGS DOSES LIPID SOLUBLE 1. Inc. vol of distribution 2. Larger loading doses to produce same plasma concentration but maintenance doses less frequent-slow clearance 3. Doses based on actual body wt. WATER SOLUBLE 1. Limited vol of distribution 2. Doses not influenced by fat stores 3. Doses based on ideal body wt. – to avoid overdosing.
  25. 25. • Commonly used anesthetic drugs can be dosed according to total-body weight (TBW) or IBW based on lipid solubility. • Lean body mass is a good weight approximation to use when dosing hydrophilic medications. As expected, the volume of distribution is changed in obese patients with regard to lipophilic drugs. • Three exceptions to this rule are digoxin, procainamide, and remifentanil, highly lipophilic, have no relationship between properties of the drug and their volume of distribution. • Consequently, dosing of commonly used anesthetic drugs such as propofol, vecuronium, rocuronium, and remifentanil is based on IBW. • In contrast, thiopental, midazolam, succinylcholine, atracurium, cisatracurium, fentanyl, and sufentanil should be dosed on the basis of TBW. • maintenance doses of propofol should be based on TBW. Conversely, based on real body weight, smaller amounts of propofol are needed to anesthetize the patient.
  26. 26. Halogenated anaesthetics: • Morbidly obese pt. Metabolize halothane and enflurane more resulting in high serum and urine level or fluoride. • Isoflurane and desflurane are volatile agent of choice bc it produces lower fluoride conc. • Liver and body fat store inhalational anaesthatics long after completion of surgery bt drug conc. In brain and lungs decrease rapidly.
  27. 27. Pharmakinetics • Alternation in drug binding, distribution, and elimination of many anesthetic drugs. • Dose calculation based on IBW rather than TBW. • IBW calculated as : Men = 49.9 Kg + 0.89 kg/cm above 152.4 cm WoMen = 45.4 Kg + 0.89 kg/cm above 152.4 cm
  28. 28. ANAESTHETIC CONSIDERATIONS PREOPERATIVE INTRAOPERATIVE POSTOPERATIVE
  29. 29. PREOPERATIVE HISTORY • Duration of obesity & associated problems • Previous operation & anaesthesia • Medication
  30. 30. INVESTIGATIONS • Blood • Urine • LFTs • RFTs • ECG • X-Ray chest • Echocardiography • ABGs
  31. 31. RISK FOR ASPIRATION PNEUMONIA • Premedication: • Anticholinergic agent • H2-antagonist • Metoclopramide • Sodium citrate(oral antacid 30 ml of 0.3M) • LMWH subcutaneous(DVT prophylaxis) AVOID RESPIRATORY DEPRESSANT • Pre-ops hypoxia & hypercapnia • OSA IM- Injections…Unreliable
  32. 32. ASSESS CARDIOPULMONARY RESERVE • • • • • History Physical examination-(BP,Edema) X-Ray chest ECG ABGs IV & IA ACCESS • Technical difficulties
  33. 33. REGIONAL ANAESTHESIA-DIFFICULTIES • Obscured landmarks • Difficult positioning • Extensive layers of adipose tissue AIRWAY ASSESSMENT IN OBESE • • • • • • • • • Difficulty in mask ventilation Difficult intubation--Consider FOB Temporomandibular joint-limited mobility Atlanto-ooccipital—limited mobility Narrow upper airway Distance b/w mandible & sternal fat pads-limited Large breasts Excessive palatal & Pharyngeal soft tissue. Short and thick neck(if circumference >14cm then difficult intubation)
  34. 34. INTRAOPERATIVE GA • PRE-OXYGENATION • POSITIONING • INDUCTION & INTUBATION • MAINTAINACE REGIONAL ANAESTHESIA • Technical difficulties • Doses of LA • Complications • Advantages
  35. 35. PREOXYGENATION SLIGHTLY HEAD UP POSITION NECESSARY BECAUSE • Dec FRC • FRC Dec more on lying • Supine • After induction • Obese rapidly desaturate • Intubation may be difficult
  36. 36. OBESITY & V/Q MISMATCH • Chest obesity • Inc intraabdominal pressure DEC. FRC ATELACTASIS FRC < CC • Supine position • Induction • Muscle relaxation • Rt to Lt shunt • Rapid hypoxia V/Q MISMATCH
  37. 37. POSITION IN INDUCTION & INTUBATION PRE-OXYGENAT & INTUBATE IN SLIGHTLY HEAD UP POSITION FOLDED BLANKETS PLACED UNDER UPPER BODY,NECK & HEAD • Sternal notch & external auditory meatus are in line
  38. 38. INDUCTION & INTUBATION DIFFICULT TO VENTILATE WITH MASK RAPID SEQUENCE INTUBATION • Risk for aspiration VAREITY OF SCOPES • Long blade & short handle AWAKE INTUBATION-IF DIFFICULT • FOB
  39. 39. PEEP DURING INDUCTION Application of positive endexpiratory pressure during the induction of general anesthesia: • prevents atelectasis formation. • improves oxygenation and probably increases the margin of safety before intubation.
  40. 40. CONFIRMATION OF INTUBATION DIFFICULT TO CONFIRM BY AUSCULTATIONCLINICALLY CONFIRMED BY END TIDAL CO2
  41. 41. MAINTAINACE OF ANAESTHESIA HIGH INSPIRED O2 CONCENTRATION • LITHOTOMY,TRENDELENBURG & PRONE CONTROLLED VENTILATION – HIGH TIDAL VOLUMES PEEP-WORSEN PULMONARY HTN IN EXTREME OBESE
  42. 42. POSTOPERATIVE COSIDERATIONS EXTUBATION • Delayed until effects of NMBAs completely reversed • Fully awake • Adequate airway maintenance • Adequate tidal volume • Supplemental oxygenation • Modified sitting position
  43. 43. POSTOPERATIVE COMPLICATIONS RESPIRATORY FAILURE • Major complication • Inc risk• Pre-ops hypoxia • Thoracic & upper abdominal Surgery DEEP VENOUS THOROMBOSIS PULMONARY EMBOLISM WOUND INFECTION
  44. 44. THANK YOU
  45. 45. CPAP CIRCUIT
  46. 46. APPLICATION OF CPAP
  47. 47. DIFFICULT INTUBATION IN OBESE
  48. 48. ATELACTASIS IN OBESE
  49. 49. MONITORING INVASSIVE MONITORING— HAEMODYNAMIC INSTABILITY • CVP • INTRA-ARTERIL LINE • PULMONARY ARTERY CATHETER

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