Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ Classification ++Table Graphic Jump LocationTable 14-1 Obesity Categories Based on the Body Mass Index (BMI)View Table||Download (.pdf)Table 14-1 Obesity Categories Based on the Body Mass Index (BMI)BMICategory<18.5Underweight18.5–24.9Normal25–30Overweight>30Obese>40Morbidly obese>55SuperobeseBMI may overestimate the severity of obesity in muscular individuals.Ideal body weight (IBW): many formulas; easiest is to use weight for BMI of 23:IBW (kg) = 23 × [height (m)]2 +++ Physiologic Effects ++Table Graphic Jump LocationTable 14-2 Physiologic Effects of ObesityView Table||Download (.pdf)Table 14-2 Physiologic Effects of ObesityOrgan systemAssociated physiologic effectsRespiratoryRestrictive lung disease (decreased FRC, ERV, TLC)Normal to decreased lung compliance, with significantly decreased chest wall compliance due to adipose tissue depositionIncreased oxygen consumption and minute ventilationIncreased work of breathingOSAObesity hypoventilation syndromeV/Q mismatchCO2 values are either low or normal unless have Pickwickian syndrome (defined as morbid obesity, hypersomnolence, hypoxemia, hypercapnia, pulmonary hypertension, polycythemia)CardiovascularHypertensionIncreased cardiac output secondary to increased ECF and hypervolemiaPulmonary hypertension, RV failureIschemic heart diseaseLVH, heart failureGastrointestinalFatty infiltration of the liverHiatal herniaGERDLarger gastric volumeDecreased gastric emptying (controversial)Increased defluorination of volatile anestheticsCholelithiasisEndocrineDM, dyslipidemiasVascularDVTOtherOsteoarthritisIncreased risk of cancer, especially GI ++ Focused history and physical examination to detect and to assess the severity of any obesity-related comorbidities: Exercise tolerance, CAD, HTN, NIDDM, cardiomyopathyPresence of snoring at night (may suggest undiagnosed hypoventilation syndrome); formal diagnosis of OSA not needed: in doubt, treat as suchAssess for difficult airway and prepare specialized airway equipment as necessary (i.e., awake fiber-optic):Assess for difficult mask ventilation (morbid obesity with redundant tissue, OSA, beard, edentulous)Special focus on:Mallampati classTM distanceNeck range of motionSize of tongueRedundancy of soft tissue in and around airwayNeck circumference at the level of thyroid cartilage >60 cm2Elicit history of past diet medication use (fenfluramine with risk of valve thickening and pulmonary hypertension, amphetamines)Chem 7, CBC (polycythemia), EKG, and CXR (cardiomyopathy); consider TTE (although often poor quality)Ensure medical equipment appropriately sized (e.g., blood pressure cuff)OR table certified for patient’s weight (if needed, use special table, or two tables)Ensure personnel available for positioningConsider aspiration prophylaxisDiscuss increased anesthetic risk with patient +++ Induction ++ Vascular access:Potentially very difficult; consider use of ultrasoundPreoxygenation:Decreased FRC leads to rapid desaturation during even brief periods of apneaMask ventilation:May be difficult/impossibleUse two-person mask, oral airway, head strapUse head of bed elevation, CPAPIntubation:Position in head-elevated laryngoscopy position (HELP) using pillows/towels: align tragus with sternum (Figure 14-1)Large chest may necessitate use of short-handle laryngoscopeAdvanced airway techniques/rescue devices (e.g., video laryngoscopy, LMA) should be ... Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth