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Anaesthesiology
Anesthesia and Obesity
Built from Barash Clinical Anesthesia, 9th Edition
What’s inside
14 sections · 199 slides
Overview
- Scope of this presentation
- Key messages
Definition and Epidemiology
- Definition of obesity
- Prevalence of obesity
- Health consequences of obesity
- Ideal body weight and predicted body weight
- Lean body weight and total body weight
- Body mass index
- Classification of obesity and systemic disease risk by waist circumference
- Reading the obesity classification
- Android and gynecoid fat distribution
- Body circumference indices
Management of Obesity
- Indications for drug treatment of obesity
- Phentermine and phentermine–topiramate
- Lorcaserin, bupropion–naltrexone, and liraglutide
- Orlistat and its perioperative implications
- Over-the-counter and herbal weight-loss products
- Indications for bariatric surgery
- Classification of bariatric procedures
- Laparoscopic approach to bariatric surgery
- Roux-en-Y gastric bypass outcomes
- Gastric banding and less invasive techniques
Respiratory System
- Effect of obesity on chest wall and lung compliance
- Changes in lung volumes
- Effect of obesity, position and anesthesia on lung volumes
- Interpreting the lung volume tracing
- Consequences of a low functional residual capacity
- Effect of anesthesia and supine positioning
- Oxygen consumption and carbon dioxide production
- Arterial oxygenation in obesity
- Obstructive sleep apnea
- Physiologic consequences of obstructive sleep apnea
- Diagnosis and screening for obstructive sleep apnea
- Preoperative management of obstructive sleep apnea
- Preventing pulmonary complications in sleep apnea
- Obesity hypoventilation syndrome
- Ventilatory control in obesity hypoventilation syndrome
- Cardiovascular and pulmonary sequelae of obesity
- Linking the lung and heart consequences
Cardiovascular and Hematologic Systems
- Blood volume and cardiac output in obesity
- Progression to obesity cardiomyopathy
- Silent cardiovascular disease in obesity
- Precipitants of intraoperative ventricular failure
- Causes of cardiac dysrhythmias in obesity
- Electrocardiographic findings in morbid obesity
- Hypertension in obesity
- Sympathetic activity and insulin resistance
- Ventricular remodelling in obesity with hypertension
- Adaptation of the heart to obesity and hypertension
- Reading the cardiac adaptation figure
- Prothrombotic changes in obesity
- Mechanisms of hypercoagulability
Gastrointestinal, Renal and Endocrine Systems
- Gastric volume and acidity in obesity
- Reflux and hiatal hernia in obesity
- Gastric emptying and residual volume
- Hepatic abnormalities in obesity
- Assessing pre-existing liver disease
- Glucose intolerance and diabetes
- Thyroid function in morbid obesity
- Renal changes in obesity
- Metabolic syndrome
- Diagnostic criteria for metabolic syndrome
- Reversing metabolic syndrome
- Implications of the medical consequences of obesity
- Implications of the medical consequences of obesity (continued)
- Implications of the medical consequences of obesity (continued)
- Using the organ system summary
Pharmacology
- Principles of drug dosing in obesity
- Volume of distribution in obesity
- Body composition in extreme obesity compared with reference values
- Reading the body composition figure
- Protein binding and elimination half-life
- Absorption and hepatic metabolism
- Renal clearance of drugs in obesity
- Lipophilicity and volume of distribution
- Practical dose adjustment strategies
- Effect of increased blood volume on plasma concentration
- Intravenous drug dosing in obesity
- Intravenous drug dosing in obesity (continued)
- Intravenous drug dosing in obesity (continued)
- Intravenous drug dosing in obesity (continued)
- Highlights of the intravenous dosing table
- Perioperative medications and antibiotic prophylaxis
- Premedication and aspiration prophylaxis
Preoperative Evaluation
- Aims of the preoperative evaluation
- Anatomic features contributing to a difficult airway
- Obesity as a risk factor for difficult airway management
- Cardiopulmonary evaluation
- Recognising pulmonary hypertension
- Preoperative assessment for sleep apnea
- Criteria for outpatient surgery in sleep apnea
- Metabolic and nutritional assessment
- Acute postgastric reduction surgery neuropathy
- Thromboprophylaxis in the obese surgical patient
- Risk factors for postoperative deep venous thrombosis
- Inferior vena cava filters and heparin decisions
Intraoperative Considerations
- Operating room equipment for the obese patient
- Effects of supine positioning
- Positive end-expiratory pressure versus head-up position
- Prone and lateral decubitus positioning
- Positioning-related injuries
- Blood pressure measurement in obesity
- Invasive monitoring in the obese patient
- Preoxygenation in the obese patient
- Adjuncts to delay peri-induction hypoxemia
- Mask ventilation technique in obesity
- Planning for anticipated difficult intubation
- Awake intubation in the obese patient
- Ramped position for laryngoscopy
- The ramped position and stacking
- Intubating equipment and attempt limits
- Rapid sequence induction in obesity
- Dosing of induction agents and succinylcholine
- Choice of neuromuscular blocking agent for intubation
- Maintenance of anesthesia
- Opioids and adjuncts during maintenance
- Muscle relaxation for laparoscopic bariatric surgery
- Pneumoperitoneum pressure limits
- Intragastric devices and leak testing
- Fluid management goals
- Acute tubular necrosis after bariatric surgery
Mechanical Ventilation and Emergence
- Challenges of ventilating the obese patient
- Tidal volume selection
- Positive end-expiratory pressure
- Recruitment maneuvers
- Benefits and limits of recruitment and PEEP
- Inspired oxygen fraction during anesthesia
- Extubation of the morbidly obese patient
- Walter Henderson maneuver for patient transfer
- Transfer devices for the obese patient
- Monitored anesthesia care and sedation
- Capnography during sedation
Regional Anesthesia and Analgesia
- Advantages of regional techniques in obesity
- Limitations of regional techniques in obesity
- Respiratory effects of neuraxial anesthesia
- Circulatory effects of neuraxial anesthesia
- Regional techniques and opioid sparing
- Positioning for neuraxial block placement
- Landmark and needle problems in neuraxial placement
- Ultrasound for neuraxial placement
- Neuraxial needle length
- Spinal anesthesia in the obese patient
- Cerebrospinal fluid volume and local anesthetic dose
- The buttock Trendelenburg effect
- Epidural anesthesia in the obese patient
- Preventing epidural catheter dislodgement
- Management after inadvertent dural puncture
- Combined spinal–epidural technique
- Peripheral nerve blocks in obesity
- Technical difficulty of peripheral blocks
- Ultrasound guidance for peripheral nerve blocks
Postoperative Considerations
- Postoperative ventilatory management
- Adjuncts to prevent postoperative hypoventilation
- Components of the postoperative pain plan
- Opioids and postoperative respiratory risk
- Practice guidelines for perioperative management of patients with obstructive sleep apnea
- Postoperative monitoring after neuraxial or parenteral opioids
- Selecting obese patients for ambulatory surgery
- Factors to consider when scheduling obese patients for ambulatory surgery
- Risk factors after ambulatory surgery
- Does BMI alone exclude ambulatory surgery
- Undiagnosed sleep apnea in ambulatory practice
- Value of a preoperative sleep apnea diagnosis
Critical Care, Morbidity and Mortality
- Critical care of the obese patient
- Obesity, acute lung injury and ventilation research
- Cardiopulmonary resuscitation in morbid obesity
- Emergency invasive airway access in obesity
- Perioperative risk with increasing body mass index
- Common postoperative adverse events
- Reducing thromboembolic and infective complications
- Metabolic syndrome and mortality in extreme obesity
Summary
- Summary: pathophysiology
- Summary: pharmacology and airway
- Summary: intraoperative and postoperative care
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Edition