Anaesthetic managemet of obesity and airway

Obesity related topic and management

1. Obesity Dr sagar a s Dr Ravi Khadelwal Dr. Shailendra pareek

2. 52 yrs female Weight- 136 kg BMI-52

3. Global Epidemic > 650 million obese adults worldwide. India ranking third. S e c o nd on l y cause t o sm ok i ng as a p r eve n t iv e c ause of death Multisystem disease affecting all organs

4. Classification (WHO)

5. Waist circumference >102 cm male >88 cm women, Or Waist /hip ratio >1 in men, 0.8> women strong predictor of stroke, DM, IHD, death . Independent of total body fat . Waist to height ratio >.55 metabolic syndrome

6. BM I > 40 belo n gs to AS A C l a s s ??

7. Fat distribution

8. Which is Detrimental? Apple/central/android abdominal/visceral Common in men for NIDDM, dyslipidaemia . Si gn i fi cant co r e l a t io n w it h metabolic syndrome C en t r al f a t i s m o r e p r ed i c ti ve • N on s i gn i fi cant co r e l a ti on Pear/gynecoid Excess fat on thigh/buttocks Females with metabolic syndrome

9. Pathophysiology Positive caloric balance stored as fat in adipocytes as TG Adipocytes increased in size.(up to BMI< 40) Absolute increase in total no of fat cells Neurohormonal disturbance leads to inflammation (adipokines and cytokines ) Central adipose tissue is more frequently associated with inflammation

10. Respiratory system Lung compliance may be normal A bd o m i nal f at - c e ph a l a d s h i f t of diaphragm De c r eas ed c he s t wall compliance Res t ri c t iv e l u ng disease Alveolar atlelectasis If FRC<< CC V/Q Mismatch; R-L Shunt, Arterial Hypoxemia, Hypercarbia Decreased FRC Supine ,Trendelenberg, Anaesthesia

11. Obesity and alveolar collapse

12. Inc. Work of Breathing Inc. metabolic rate– inc. Body wt. Inc. O 2 demand Inc. CO 2 production Hypoxia & Hypercarbia TV- may be normal, but reduced in MO ERV, FRC, TLC- dec R V - u n c h a n g ed

13. Airway Fat face and cheeks Large breasts in females Large tongue, Excess palatal and pharyngeal tissue ( MMG- 3,4) Redundant oro-pharyngeal tissue Atlantoaxial joint limitation d/t cervical and thoracic fat pads, and presternal fat deposits Inc neck circumference Short neck

14. O b s t ru c ti v e S l e e p A pn e a A dipo s e d e p o sits in lateral phar y n g eal w al l - mobi l e – protrude into airway Throat muscles become so relaxed and floppy during sleep - cause a narrowing/ complete blockage of the airway. Frequent episodes of apnea or hypopnea during sleep T o t a l ces s ation of air f low for 10 s ec. H ypopnea - 50% reduction in airflow

15. Symptoms Day time sleepiness/fatigue Dry mouth upon awakening Headache in morning Trouble concentrating/forgetfullness Night sweats Sudden awakening with choking sensation

16. Perioperative complications of OSA -MI Arrthymias Hypertension Ischemic stroke Insulin resistance a i rway Hypoxia Upper o b s t r uction Difficult intubation

17. Stop Bang Questionnaire

18. Gold standard to make diagnosis?? Apnea/Hypopnea Index (AHI)- Total number of episodes of apnea and hypopnea per hr of total sleep time. Mild: >5 events/hr Moderate: >15 events/hr Severe : > 30 events/hr Us ually man a ged w it h C P A P a t home

19. Obesity Hypoventilation Syndrome Pickwickian synd. Sleep disordered breathing Obesity (BMI ≥30 kg/m −2 ) Daytime hypercapnia P CO2 ≥45 mmHg during wakefulness 90% OHS- OSA( AHI>5) Hypoxia & hypercapnia Polycythemia– cyanosis Rt. Sided heart failure

20. Cardiovascular system o Inc circulating BV o Inc CO (0.1/min for each kg of excess adipose tissue) o Inc O2 consumption o Atherosclerosis ( coronary ,cerebral vessels) o Hypertension o Prone to arrhythmias (hypoxemia,hypercarbia, MI)

21. Cardiovascular system

22. Gastro Intestinal System Increased abdominal pressure -Hiatal hernias, GERD Larger gastric volume even after NPO Increased risk for aspiration of gastric contents

23. Thromboembolic disease Increased risk of DVT, PE I n c pressure- venous stasis abdominal Immbolisation- venous stasis P o ly c y th e m i a Dec fibrinolysis

24. Endocrine/hepatic NIDDM ( Insulin resistance/ inadequate insulin production ) Hypercholesterolaemia, H y p o t h y r oi d i sm Osteoarthritis Fatty liver/ Inc Hepatic enzymes Gallstones

25. Metabolic Syndrome

26. Drug metabolism D r ug doses of t e n w a r ran t a d just m en t in obese patients. Volume of distribution -determines the loading dose Clearance - determines the maintenance dose .

27. Drug Dosing

28. LBW = TBW - mass of fat LBW = IBW + 20 to 40% excess body weight ABW = IBW + 0.4 (TBW kg) IBW (kg) = height (cm) - 100 ( adult males) IBW (kg) = height (cm) -105 ( adult females )

29. Drug dosing according to IBW —-.> UNDERDOSING Drug dosing according to TBW—---> OVERDOSING Drug dosing according to LBM—----> ADEQUATE Increased sensitivity to respiratory depressant effects of BZD and other sedatives Due to comorbidity, functions of organs of elimination can be affected making pharmacokinetics more difficult and complex

30. Inhalational agents Soluble inhalational agents accumulate in adipose tissue and take longer to clear, resulting in more prolonged emergence as compared with less-soluble agents The risk of halothane hepatitis may be higher in obese patients, although overall is still very low. Desflurane (inhalation of choice) display rapid onset and offset.

31. R e g i on a l An e s t h e s i a Technically harder Loss of landmarks Difficult positioning Extensive layers of adipose tissue Need for long needles. Less local anaesthetic is needed for epidurals .  Engorged extradural veins  E xtr a fa t co n stri c tin g th e po t e n t ial space (75-80% of the normal dose)

32. Positioning challenges Ventilatory impairment Compression of ivc/aorta Pressure sores supine Cushioning pads excessive pressure Skin breakdown,tissue necrosis P rone Regular stirrups may not bear weight Nerve injuries/compartement syndrome Lithotomy

33. Perioperative Challenges Difficult mask ventilation and tracheal intubation Rapid desaturation during induction and intubation Difficult surgical access Aspiration of gastric contents Exacerbation of cardiopulmonary comorbidities Altered drug metabolism Risk of DVT

34. Difficult Vascular Access (Vein locator/ultrasound) Difficult transport OT table too small Difficult patient positioning Inapproprite monitoring Difficult RA

35. Anesthetic considerations Preoperative Intraoperative Po s t oper ative

36. Preoperative History Duration of obesity & associated problems Previous operation & anaesthesia, Medication OSA, Use of CPAP Ask Patient can tolerate supine position Assess cardiopulmonary reserve -difficult to assess METS Hx, Physical examination-(BP, Edema) X-Ray chest ECG ABGs ECHO

37. F o c u s e d A i r wa y a s s e s m e n t History of OSA: decrease in oropharyngeal space makes mask ventilation and laryngoscopy difficult. BMI >40 Neck circumference: >40cm is associated with 5% problematic intubation, >60cm is associated with 35% NC/TM ratio: >=5 predicts difficult intubation. Anterior neck soft tissue> 28 mm Limited mandibular protrusion Short neck CPAP>10 ( BMV)

38. Risk for aspiration pneumonia Premedication: Aspiration prophylaxis Avoid sedation & respiratory depressant -Pre-ops hypoxia & hypercapnia • OSA Continue antihypertensive medication LMWH subcutaneous(DVT prophylaxis) IM- Injections …Unreliable

39. Intraoperative Head elevated laryngoscopy position( HELP ): stacked or ramped position so that external auditory canal is in horizontal line with the sternum as well as reverse trendelenburg position

40. HELP

41. Preoxygenation Preoxygenate in 20 degrees head up position (increase FRC, Safe apnea time) Add 10 cm H2O of PEEP/ 5 - 10 cm H2O CPAP Apneic oxygenation - nasal cannula with high flow of O2 at 10 - 15 lit/min after induction

42. Variety of scopes - Long Blade & Short Handle - VL - OPA,NPA - SADs/ FONA Difficult BMV- Awake Intubation-• FOB Rapid sequence intubation Plan for failure

43. Pad pressure points A p ply p n e u m a tic stockings leggings or compression

44. Postoperative challenges  Delayed extubation  Obstruction and /or desaturation after extubation  Need for tracheal reintubation  Exacerbation of cardiopulmonary comorbidities  Inadequate pain mangement  Prolonged hospital stay  Delayed discharge

45. Extubation Strategies The patient should be placed in the ramped or 25° reverse Trendelenburg position for extubation. F u l l y aw ake w it h adequa t e r eve rs al of neu r o m uscu la r blockade. M ay r equ i r e p o ss i b l e r e i n t uba ti on du ri ng e x t uba ti on o f difficult airway cases. Airway exchange catheter-assisted extubation can provide continuous airway access

46. S upp l e m en t a l o x yg e na ti o n i n s e m i r e c u m b e n t position U s e o f C P A P ( r e du c e t h e risk of pulmonary complications, atelectasis) O p i o i d f r e e A n a l ge si a / N S A I D S Ep i d u r a l L A p l u s op i o i d s Pulmonary care( deep breathing/incentive spirometry)

47. Have a good day!!!