1. Anesthesia for Bariatric Surgery By: Vladimir Melnikov MD UT Dept. of Anesthesiology

2. Anesthesia for Bariatric Surgery Obesity affects millions of persons in the USA and around the world Obesity affects millions of persons in the USA and around the world In 1990 $46 billion - 6.8% of all health care costs- was spent on obesity related problems in the USA. In 1990 $46 billion - 6.8% of all health care costs- was spent on obesity related problems in the USA. Current estimates exceed $100 billion Current estimates exceed $100 billion The precursors to obesity include The precursors to obesity include 1.Genetic tendency 1.Genetic tendency 2.Environmental effect. 2.Environmental effect. 3.Education 3.Education 4.Gender, ethnicity 4.Gender, ethnicity 5.Socioeconomic 5.Socioeconomic

3. Anesthesia for Bariatric Surgery Medical co-morbidities associated with obesity Medical co-morbidities associated with obesity 1.NIDDM 2.HTM 3.CV DISEASES 4.OSA 5.Liver & Gallbladder diseases 6.Arthritis 7.Colon and postmenopausal breast cancer 8.The risk of dying prematurely increases 9.Quality of life issues: depression, social incompetence, etc.

4. Anesthesia for Bariatric Surgery Bariatrics is the field of medicine that specializes in treating obesity. Bariatrics is the field of medicine that specializes in treating obesity. Bariatric surgery is a surgical subspecialty that perform operations to treat morbid obesity. Bariatric surgery is a surgical subspecialty that perform operations to treat morbid obesity. Most of the patho-physiology & medical conditions associated with extreme Obesity are reversible with sustained weight lose following Bariatric surgery. Most of the patho-physiology & medical conditions associated with extreme Obesity are reversible with sustained weight lose following Bariatric surgery. Over 100,000 laparoscopic Bariatric procedures were performed in the US in 2004. Over 100,000 laparoscopic Bariatric procedures were performed in the US in 2004. Mortality rate for Bariatric surgery is 0.5% - 1%! Mortality rate for Bariatric surgery is 0.5% - 1%!

5. Anesthesia for Bariatric Surgery Definitions. A person is considered obese when the amount of body fat increases beyond the point where health deteriorates and life expectancy is shortened. Two general types of obesity 1.Central-andriod Obesity associated with metabolic syndrome 2.Periferal-gynecoid Obesity.

6. Anesthesia for Bariatric Surgery Body Mass Index = weight/height x height BMI = 25 – NORMAL BMI>30 – OBESE BMI>40 OR > with medical co-morbidity – Morbidly obese Ideal Weight = Height - 100 Ideal Weight = Height - 100

7. Anesthesia for Bariatric Surgery PREOPERATIVE EVALUATION 1. CV & RESPIRATORY SYSTEMS 1. CV & RESPIRATORY SYSTEMS a) Tolerance of exercise and ability to lie flat. a) Tolerance of exercise and ability to lie flat. b) Symptoms of sleep apnea should be sought. b) Symptoms of sleep apnea should be sought. 2. Airways. Number of abnormalities may exist 2. Airways. Number of abnormalities may exist a) Limitation of extension and flexion of the C-spine. a) Limitation of extension and flexion of the C-spine. b) Restricted mouth opening from submental fat. b) Restricted mouth opening from submental fat. c) Large tongue. c) Large tongue. d) Redundant intra oral tissue. d) Redundant intra oral tissue. e) Thyromental distance should be assessed. e) Thyromental distance should be assessed. f) Infantile type anterior laryngeal opening. f) Infantile type anterior laryngeal opening. 3. Use of diet tablets (some of them cause valvular regurgitation or 3. Use of diet tablets (some of them cause valvular regurgitation or pulmonary HT). pulmonary HT).

8. Anesthesia for Bariatric Surgery PREOPERATIVE EVALUATION 4. Obesity Hypoventilation Syndrome. Pickwickian syndrome: 4. Obesity Hypoventilation Syndrome. Pickwickian syndrome: Obesity, excessive daytime sleepiness, snoring cor Pulmonale. Obesity, excessive daytime sleepiness, snoring cor Pulmonale. a) Hypercapnia a) Hypercapnia b) Severe hypoxemia b) Severe hypoxemia c) Periodic breathing c) Periodic breathing d) Biventricular enlargement (RT>LT) d) Biventricular enlargement (RT>LT) e) Dependent edema. e) Dependent edema. f) Polycythemia. Pulmonary edema. f) Polycythemia. Pulmonary edema. 5. Metabolic Changes 5. Metabolic Changes Patient scheduled for surgery following previous Bariatric surgery may have chronic metabolic changes. Patient scheduled for surgery following previous Bariatric surgery may have chronic metabolic changes.

9. Anesthesia for Bariatric Surgery PREOPERATIVE EVALUATION CV Systems. CV Systems.  The degree of cardiac abnormality is correlated with the degree of obesity.  LV dysfunction is often present in young asymptomatic patient  HTN  Increased Pre-load & After-load  Increased PAP (dyspnea, fatigue, syncope). Pulmonary System.  O2 consumption & CO2 production increased  WOB increased  Chest wall compliance & FRC are low.

10. Anesthesia for Bariatric Surgery PREOPERATIVE EVALUATION GI System. GI System.  No difference in gastric volume or PH between lean and obese surgical patient.  NIDDM and Gastroparesis.  Fatty Liver w or w/o liver dysfunction is common.  Gall bladder disease is also common.

11. Anesthesia for Bariatric Surgery ANESTHETIC CONSIDERATIONS PREMEDICATION PREMEDICATION  Avoid heavy sedation.  Medication for chronic HTN  No diabetic medication on the morning of surgery  Antibiotics & heparine prophylaxis  H 2 antagonist, metoclopramide? Monitoring Monitoring  NIBP can be obtained from the wrist or ankle.  A-line highly recommended.  CVP or PA lines?  Nerve stimulator: needle electrodes are recommended (surface electrode

12. Anesthesia for Bariatric Surgery Pharmacological Considerations 1. Drugs are often administered on the basis of dose per unit body weight. 2. This assumes that clearances and distribution volumes are proportional to weight. 3. The assumptions 1&2 are not valid for obese patients.

13. Anesthesia for Bariatric Surgery Induction Agents Larger than usual doses of Propofol or Thiopental are needed due to increased blood volume & CO. Larger than usual doses of Propofol or Thiopental are needed due to increased blood volume & CO. Muscle Relaxants Muscle Relaxants Higher doses of succinylcholine 1.5mg/kg IW are used. Higher doses of succinylcholine 1.5mg/kg IW are used. Neuromuscular recovery time is similar in obese & non-obese patient with CIS-ATRACURIUM (NIMBEX) Neuromuscular recovery time is similar in obese & non-obese patient with CIS-ATRACURIUM (NIMBEX) Complete paralysis is especially important during laparoscopy. Neuromuscular blockade must be completely reversed before extubation. Neuromuscular blockade must be completely reversed before extubation.OPIOIDS. There is no evidence that lipophilic opioids last longer in morbidly obese patient. There is no evidence that lipophilic opioids last longer in morbidly obese patient.

14. Anesthesia for Bariatric Surgery TRACHEAL INTUBATION  Increasing weight or BMI is not a risk factor for difficult laryngoscopy.  FOB intubation is rarely necessary.  Rapid induction with Propofol &Succinylcholine is the best for establishing an airway. Since mask ventilation can be difficult a second person experienced with airway management should be present to assist. Since mask ventilation can be difficult a second person experienced with airway management should be present to assist. LMA should be available and can serve as abridge until an ETT is placed. LMA should be available and can serve as abridge until an ETT is placed.

15. Anesthesia for Bariatric Surgery VENTILATION  VT – 10-12ML/KG IW  FiO 2 up to 1.0 may be needed  High PiP will be needed  PEEP = 5cm H2O  N2O is avoided  Pneumoperitoneum can displace diaphragm causing the ETT to enter bronchus. HEMODNAMIC CHANGES The RTP may cause pooling of blood and hypotention.

16. Anesthesia for Bariatric Surgery ANESTHETIC TECHNIQUE. OPIOIDS I>V> CONTINUOS INFUSION. OPIOIDS I>V> CONTINUOS INFUSION. CISATRACURIUM I.V. CONTINUOS INFUSION. CISATRACURIUM I.V. CONTINUOS INFUSION. INHALATION ANESTHETIC DEFLURANE. INHALATION ANESTHETIC DEFLURANE. POSTOPERATIVE CONSIDERATIONS. Position: Upper body elevated 30-45 degree. Oxygenation: Restoration of normal pulmonary function after abdominal surgery may take several days.  Nasal or mask O2.  Nasal CPAP  BiPAP Analgesia: An opioid PCA dosed on the basis of IW NSAIDs