Anesthesia for Bariatric Surgery By Vladimir Melnikov MD

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

Anesthesia for Bariatric Surgery • 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. Current estimates exceed $100 billion The precursors to obesity include 1. Genetic tendency 2. Environmental effect. 3. Education 4. Gender, ethnicity 5. Socioeconomic

Anesthesia for Bariatric Surgery • 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.

Anesthesia for Bariatric Surgery • Bariatrics is the field of medicine that specializes in treating 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. • Over 100, 000 laparoscopic Bariatric procedures were performed in the US in 2004. • Mortality rate for Bariatric surgery is 0. 5% - 1%!

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.

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

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

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

Anesthesia for Bariatric Surgery PREOPERATIVE EVALUATION CV Systems. v v v 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. v v v O 2 consumption & CO 2 production increased WOB increased Chest wall compliance & FRC are low.

Anesthesia for Bariatric Surgery PREOPERATIVE EVALUATION GI System. v v 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.

Anesthesia for Bariatric Surgery ANESTHETIC CONSIDERATIONS PREMEDICATION v v v Avoid heavy sedation. Medication for chronic HTN No diabetic medication on the morning of surgery Antibiotics & heparine prophylaxis H 2 antagonist, metoclopramide? Monitoring v v 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

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

Anesthesia for Bariatric Surgery Induction Agents Larger than usual doses of Propofol or Thiopental are needed due to increased blood volume & CO. Muscle Relaxants Higher doses of succinylcholine 1. 5 mg/kg IW are used. 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. OPIOIDS. There is no evidence that lipophilic opioids last longer in morbidly obese patient.

Anesthesia for Bariatric Surgery TRACHEAL INTUBATION v v v 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. LMA should be available and can serve as abridge until an ETT is placed.

Anesthesia for Bariatric Surgery VENTILATION v v v VT – 10 -12 ML/KG IW Fi. O 2 up to 1. 0 may be needed High Pi. P will be needed PEEP = 5 cm H 2 O N 2 O is avoided Pneumoperitoneum can displace diaphragm causing the ETT to enter bronchus. HEMODNAMIC CHANGES The RTP may cause pooling of blood and hypotention.

Anesthesia for Bariatric Surgery ANESTHETIC TECHNIQUE. • • • OPIOIDS I>V> CONTINUOS INFUSION. CISATRACURIUM I. V. CONTINUOS INFUSION. 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. v v v Nasal or mask O 2. Nasal CPAP Bi. PAP Analgesia: An opioid PCA dosed on the basis of IW NSAIDs