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Dr.N.Balasubramaniyam Consultant Anaesthetist S.K.S Hospital Salem OBESITY,CHALLENGES IN DAILY LIFE Discussion…. "Overweight" is a sensitive topic. Body mass index (BMI) levels that categorize fatness. BMI can potentially misclassify people as fat ‘Trust your own judgement about your body ! because BMI-based body descriptions can be wrong’. _ by Steven B. HallMD For Adults “Overweight“ BMI of 25 & above “OBESE” BMI of 30 & more - CDC & WHO CHILDREN overweight BMI >85th percentile Obese BMI>95th percentile BMI Classification <25 Normal 25-30 Overweight >30 Obese >35 Morbidly obese >55 Super-morbidly obese Body Weight Calculations Types of Fat distirbution Gynaecoid Typefat distributed in peripheral sites (arms, legs, and buttocks) Android Typecentral fat distribution (intraperitoneal fat) Waist-to-hip ratio >0.8 in women or 1.0 in men is typical of the android distribution Android distribution “Risk of metabolic and cardiovascular complications” - intra abdominal surgery more difficult and is associated with increased fat deposition around the neck and airway Waist or collar circumference More predictive of cardiorespiratory comorbidity than BMI !!! Effects of Fat distribution Comorbidity Hypertension Dyslipidaemia Ischaemic heart disease Diabetes mellitus Osteoarthritis Liver disease Asthma Obstructive sleep apnoea (OSA) Respiratory System OSA Episodes of apnoea or hypopnoea during sleep secondary to pharyngeal collapse Five or more per hour or >30 per night snoring; day-time somnolence, associated with impaired concentration and morning headaches OSA… Pathophysiological changes: Hypoxaemia (leading to secondary polycythaemia) Hypercapnia Systemic vasoconstriction, & Pulmonary vasoconstriction (right ventricular failure) OSA & Airway Adipose tissue in the pharyngeal wall increased pharyngeal wall compliance increased (airway collapse during negative pressure) Airway geometry (Antero-posterior axis is more than lateral) Genioglossus tone increased (less effective in maintaining airway patency) Increased reliance on hypoxic drive -type 2 respiratory failure Obesity Hypoventilation syndrome Relative leptin insensitivity in obesity decreases ventilatory response to Co2 Depressant drugs, including many anaesthetic agents and analgesics, accentuate this Cardiovascular System Blood volume, cardiac output, ventricular workload, oxygen consumption, and CO2 production are all increased Absolute blood volume is increased-45 ml kg-1 'Obesity cardiomyopathy‘ arrhythmias because of: myocardial hypertrophy and hypoxaemia; hypokalaemia from diuretic therapy; coronary artery disease; increased circulating catecholamines; OSA (sinus tachycardia and bradycardia); and fatty infiltration of the conducting and pacing systems. Ischaemic heart disease is more prevalent Pharmacokinetics Calculation of appropriate dosages may be difficult Most of the general anaesthetic drugs are affected by the mass of Adipose tissue Pharmacokinetics of obesity The main factors that affect tissue drug distribution in any patient are plasma protein binding body composition and regional blood flow. Highly fat-soluble drugs - increased volume distribution e.g. benzodiazepines and barbiturates – have prolonged effect Less fat-soluble drugs-No change in volume distribution e.g. neuromuscular blocking agents Exception is succinylcholine & PropofolShould be dosed toTotal body weight Reduce 25% of spinal & epidural dose Preoperative Assessment Many morbidly obese patients have limited mobility and may therefore appear relatively asymptomatic!!! despite having significant cardio-respiratory dysfunction Drug history, Look for Symptoms and signs of cardiac failure OSA Unable to lie flat for Several years So an assessment of the ability to tolerate the supine position may reveal unexpected profound oxygen desaturation, airway obstruction, or respiratory embarrassment IV access by central venous cannulation Ottestad E et al. Anesth Analg 2006;102:1293-1294 ©2006 by Lippincott Williams & Wilkins A chest radiograph obtained after placement of the 20-cm double-lumen subclavian catheter. Ottestad E et al. Anesth Analg 2006;102:1293-1294 ©2006 by Lippincott Williams & Wilkins Preoperative Airway Assesment Predictors of difficult airway BMI Mallampati classification Neck circumference Thyromental distance Obstructive sleep apnoea symptoms Gastro-oesophageal reflux disease Cervical fat pad or hump Positioning Ramped or semi sitting position Head-Elevated Laryngoscopy Position (HELP) Positioning…. Proper head-elevated laryngoscopy position (HELP Positioning….. Intra-Operative Pulmonary atelectasis occurs in 85%- 90% of healthy adults within minutes after the induction of general anesthesia Atelectasis is larger in obese patients or when a high fraction of inspired oxygen (FiO2) is used Degree of head-up tilt may slow the rapid desaturation Awake fibreoptic intubation PEEP short-acting anaesthetic agents Post-Operative Extubated wide-awake in the sitting position CPAP Post-operative ventilation-Awake& Less sedation with PS mode NSAIDs- best omitted Acetaminophen, Patient-controlled opioid analgesia, or regional anaesthesia Early mobilization -reduces postoperative atelectasis & venous thromboembolism Catabolic response to surgery use Insulin to maintain normoglycemia . Keypoints.. Obesity-independent risk factor Plasminogen activator inhibitor-1 Gastric emptying is delayed Rhabdomyolysis Difficulty of laryngoscopy The 400 J of energy on regular defibrillators Take Home… Proper Positioning Early Extubation DVT prophylaxis – during peri operative period Effective postoprative analgesia