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Understanding the Impact of Obesity on Breathing and Sleep Scot Jones, BA, RRT-ACCS, RCP Is Obesity a Problem? of adults in the United States, or 60 million people, are obese From CDC.gov Is Obesity a Problem? Children worldwide are obese From World Health Organization Is Obesity a Problem? of diabetes of ischemic heart disease certain cancers From World Health Organization Is Obesity a Problem? of United States medical costs may be directly related to obesity From CDC.gov Is Obesity a Problem? Yes. A Few Statements • Poking fun? I think not. • Respect the person, analyze the behavior. • Health professionals should have a (basic) understanding of obesity’s effects on how we deliver care. FACT or FICTION? Obese people tend to be lazier than people who are thinner. FACT AND FICTION! Sedentary lifestyle practices do contribute to obesity, but there are many people who are sedentary, but not obese FACT or FICTION? Obese people eat too much. FACT AND FICTION! Overeating does contribute to obesity, but it is more complicated than just that FACT or FICTION? Obese people are less intelligent FICTION! Obvious? Maybe not socially! FACT or FICTION? Obese people have control over their weight FACT AND FICTION! Weight control is very complex. Calories In Weight Calories Out Where are we heading? • Understanding some terminology • Lung Mechanics • Comorbidities – Obesity Hypoventilation Syndrome • Strategies – Socioeconomic considerations – Critical care considerations • Noninvasive, airway, ventilatory, weaning/extubation How to Define Obesity Methods of Measurement • Body Mass Index (BMI) - calculation • Hydrostatic weight % Body Fat • Body calipers Body Mass Index Body Weight (kg) Height (m2) Flaws •Indirect Measurement •Doesn’t take muscle into account Strengths •Noninvasive •Simple and effective when used in context BMI – NIH/NHLBI Table BMI < 18.5 19-24 25-29 30-34 35-39 40+ Below normal weight Normal weight Overweight Class I Obesity Class II Obesity Class III Obesity National Institutes of Health (NIH), National Heart, Lung, and Blood Institute (NHLBI). The practical guide: identification, evaluation, and treatment of overweight and obesity in adults. Bethesda: National Institutes of Health. 2000, NIH publication 00-4084. Lung Mechanics and Obesity • Diaphragm is pushed upward • Weight on chest wall restricts, and prevents diaphragmatic excursion • Adipose requires blood/oxygen • Increased risk of obstructed upper airway Systemic Proinflammatory State Oversimplified: Proinflammatory molecules lead to a number of metabolic and cardiovascular complications of obesity, which may lead to airway inflammation (think Asthma) Related Diseases and Disorders Obstructive Sleep Apnea From Washington.edu Classifying Severity Apnea Hypopnea Index (AHI) OSA Severity OSA Score 6-20 Mild 1 21-40 Moderate 2 > 41 Severe 3 Adapted from Gross, JB, Bachenber, KL, and Benumof, JL, et al. Practice guidelines for the perioperative management of patients with obstructive sleep apnea. Anesthesiology 2006; 104:1081. Hypertension Traffic/ Workplace Accidents Insulin Resistance OSA Cardiac (HF, Rhythm, MI) Stroke Memory problems Obesity and OSA • 1-SD increase in BMI = 4x increased risk for OSA (Young, et. Al) • BMI > 40 = 40-90% prevalence (Rajala, et. Al) • 10% change in body weight = 30% change in AHI BMI OSA Prevalence Fat Distribution and OSA • Male > Female • Distribution (central pattern around neck/trunk/abdominal) Schwartz, et al. Annals of the ATS, Feb 2008 Obesity Hypoventilation Syndrome Respiratory Load Drive & Strength Mechanisms of Ventilatory Failure •Lung and Chest Wall Elastic Loads •Lung CL •Insp Threshold Respiratory Drive & •Chest Wall Mechanics •Supine Position Load Strength •Resistive Loads •Upper AW Obstruction •Lower AW Obstruction •Other Loads Mechanisms of Ventilatory Failure •Increased CO2 Production •Increased Deadspace •Decreased Drive •Blunted drive in OHS •Resp Depression (Meds) •Sleep Deprivation Respiratory •Hypothyroidism Load •CNS disease Drive & Strength •Decreased Strength •Deconditioning and atrophy from acute illness •Medications •Metabolic Disorders of Ventilatory Failure Mechanisms •Myopathic Effects Apnea/Hypopnea Event ↑ PaCO2 PaCO2/pH return to baseline pH OSA Renal Compensation ↑ HCO3 Depression of Ventilation Apnea/Hypopnea Event ↑ PaCO2 PaCO2/pH fails to return pH OHS Strategic Considerations Meta-Analysis • LOS / BMI are directly related statistically • > BMI may have a “protective effect” • > LOS may be due to > difficulty in dx and tx, not mobilizing pt as often • > LOS = > Mortality (long-term) BMI and Disease Risk Sociocultural Question #1 As a Health Professional, is it your responsibility to be concerned with a patient’s weight? Sociocultural Question #2 As a Health Professional, is it your responsibility to counsel patients on their weight status (overweight or underweight) “Sir, You’re Fat.” A Few Cautions • Most people are already aware that they are obese • Many people are sensitive about their weight • Most people will not (can not?) make major, sweeping changes • Consider your own motives and attitudes about people who are obese Dilemmas in Diagnostics • Diagnostics become increasingly difficult – everything: – The X-Ray – CT Scanning – Ultrasound – Access for blood-related lab tests – Clinical confusion of multiple comorbidities + The Airway Bergler, et al., 1997 The Airway The Ideal Airway Airway Strategies • Assess the physiology • Proactive use of “difficult airway equipment” • Consider back-up plan – what will you do if you cannot intubate? • Consider NOT using paralytics or heavy sedation if possible • Consider trial of noninvasive ventilation Nutrition • Actual Body Weight may overestimate (HarrisBenedict Equation) • Consider Indirect Calorimetry • Consider in context of failure-to-wean The Nutrition Balance • Caloric Restrictions – Catabolic-induced muscle loss impairs wound healing – Weakens diaphragmatic muscles – delays ventilator weaning – Moderate restriction may be okay • Excessive Calories – Increases production of CO2 which will increase minute ventilation (tachypnea) -> failed SBT -> potential delays in weaning Noninvasive vs. Invasive • Treat OSA and OHS • Pre-intubation – PaO2 higher with NPPV preparation. Futier, et. Al, Anesthesiology, Vol 114(6), 1354-1363 • Post-extubation – Support earlier extubation attempts by extubating directly to NPPV To Trach or Not to Trach • Unable to Wean, repeated intubations, longterm needs • CPAP failure with OSA • BiPAP failure with OHS (opportunity for ventilatory support at night) To Trach or Not to Trach • Controlled environment (OR) • Trach changes may be a challenge • Specialized trachs • Early Tracheostomy Positioning • Consider Reverse Trendelenberg (sitting upward while lying down) Early Mobility • Laying in a hospital bed quickly results in muscle wasting, and it is much more difficult to get it back once it is gone • Early mobilization is a key (yes, even if the patient is in the ICU, and on a vent, and on high FIO2, and on high PEEP) • Use of adapted mobility equipment Ventilation Strategies • What we know: – High pressures hurt the lungs – Large volumes hurt the lungs – There is a greater incidence of later-onset ARDS in patients who are obese than there are in leaner patients (Gong, et al.; Thorax. 2010;65(1):44-50) Ventilation Strategies The Big Question: Appropriate VT should be set by: a.) b.) c.) d.) Height Weight Waist circumference Whatever feels right How do we offset, then, the weight on the chest? Ventilation Strategies Answer: Using Applied (or therapeutic) PEEP Consider starting point of . . . +8 to +10 cmH2O +15? +20? Ventilator Pressures Lung Protective Strategy: Maintain Pplat < 30 cmH2O Obese Patients: There can be a battle between maintaining safe pressures and maintaining adequate ventilation. Consideration: Watch pressures carefully: Consider measuring transpulmonary pressures and maintaining < 35 cmH2O Weaning Considerations • • • • Adequate Support Provide adequate hemodynamic support Consider tracheostomy with subsequent wean Consider specialized unit and systemized approach • Future direction of weaning Medication Considerations • Pain/Sedation + adipose storage = prolonged period of recovery • Significant concern of ventilatory depression with adequate pain management (loss of airway!) • Medication administration by IBW, TBW, or DW? Obesity is not just a comorbidity. It is a disease. Clinical Diagnosis is Complicated So is recovery. When the body is BIG The lungs are not