Respiratory Complications of Obesity Diana Wilson, M.D. ACP Educational Session September 16, 2017 1
Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory, BRFSS, 2011 Prevalence estimates reflect BRFSS methodological changes started in 2011. These estimates should not be compared to prevalence estimates before 2011. *Sample size <50 or the relative standard error (dividing the standard error by the prevalence) 30%.
Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory, BRFSS, 2012 Prevalence estimates reflect BRFSS methodological changes started in 2011. These estimates should not be compared to prevalence estimates before 2011. *Sample size <50 or the relative standard error (dividing the standard error by the prevalence) 30%.
Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory, BRFSS, 2013 Prevalence estimates reflect BRFSS methodological changes started in 2011. These estimates should not be compared to prevalence estimates before 2011. *Sample size <50 or the relative standard error (dividing the standard error by the prevalence) 30%.
Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory, BRFSS, 2014 Prevalence estimates reflect BRFSS methodological changes started in 2011. These estimates should not be compared to prevalence estimates before 2011. *Sample size <50 or the relative standard error (dividing the standard error by the prevalence) 30%.
Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory, BRFSS, 2015 Prevalence estimates reflect BRFSS methodological changes started in 2011. These estimates should not be compared to prevalence estimates before 2011. *Sample size <50 or the relative standard error (dividing the standard error by the prevalence) 30%.
Prevalence of Self-Reported Obesity Among U.S. Adults by State and Territory, BRFSS, 2016 Prevalence estimates reflect BRFSS methodological changes started in 2011. These estimates should not be compared to prevalence estimates before 2011. *Sample size <50 or the relative standard error (dividing the standard error by the prevalence) 30%.
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Outline Impact of obesity on respiratory mechanics Impact of obesity on lung volumes/spirometry Impact of obesity on gas exchange Obesity hypoventilation syndrome: What we know, we don t know Perioperative considerations in the obese patient 9
OBESITY RELATED CHANGES IN PULMONARY PHYSIOLOGY Increased work of breathing Increased airway resistance Tendency to breathe at low lung volumes which increases airway resistance Reduced respiratory system compliance Restrictive effects of mass loading on chest wall Increased pleural pressures Low end expiratory volumes Expiratory flow limitation Gas trapping due to early airway closure Intrinsic PEEP VQ mismatching J Thorac Dis 2015;7(5):943-952 10
Pulmonary Mechanics in the Obese Patient Reduced respiratory system compliance as much as 66% Reduced compliance of the chest wall Reduced distensibility of extrapulmonary structures Reduced compliance of the lung Increased pulmonary blood volume, increased closure of dependent airways Influenced by BMI Influenced by body fat distribution Influenced by body position Clin Chest Med. 2009 September ; 30(3): 11
Combined lung chest wall compliance Lung compliance Chest wall compliance Anesthesia & Analgesia. 87(3):654-660, 1998. 12
Lung volumes a review 13
Jones Chest 2006 14
Jones Chest 2006 15
O Donnell, Pulmonary Medicine 2012 16
O Donnell, Pulmonary Medicine 2012 17
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Sin, Arch Intern Med. 2002;162(13): 19
If Not Obstruction, What Drives Dyspnea? 20
Dyspnea Not Driven By Deconditioning Babb, et al.am J Respir Crit Care Med Vol 178. 2008 21
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Oxygen Cost of Breathing Not Deconditioning Babb, et al.am J Respir Crit Care Med Vol 178. 2008 23
Oxygen Cost of Breathing Before and after Weight Loss Int J Obes. 2016; 40(6) 24
Sood,Clin Chest Med. 2010 25
Obesity And Gas Exchange No reduction in DLCO (increased) Most studies show normal or mild reduction in PaO2 Most studies demonstrate normal or mildly increased CO2 levels Studies vary by Inclusion criteria (BMI, etc.) Awake or anesthetized Waist hip ratio Body position Primarily driven by VQ mismatch 27
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Anesthetized A-a O2 PCO2 Anesthesia & Analgesia. 87(3):654-660, September 1998. 29
CHEST 2007 131, 362-367DOI: (10.1378/chest.06-1513) Figure 1
CHEST 2007 131, 362-367DOI: (10.1378/chest.06-1513) Figure 2
CHEST 2007 131, 362-367DOI: (10.1378/chest.06-1513) Figure 3
VQ Mismatch Lung bases relatively overperfused and underventilated Closure small airways in dependent lung zones Correlates to reduction in ERV Exacerbated by recumbency 33
Figure 1 CHEST 2015; 147 ( 4 ): 1127-1134 CHEST 2015; 147 ( 4 ): 1127-1134
OHS- Definition BMI greater than 30 Hypercapnia while awake (PaCO2) 45 mm Hg Other causes of hypercapnia excluded The presence of sleep disordered breathing 35
Piper, AJRCCM, vol 183, 2011 36
Why some and not others? Greater central fat distribution which may magnify all of the above Is there yet to be identified myopathic process? Is respiratory muscle performance affected by acidosis/hypoxemia? Does hypoxemia interfere with the synthesis of neurotransmitters involved in central respiratory control? Is it driven by the severity of sleep-disordered breathing, severity of oxygen desaturation/co2 retention during sleep, duration of events? Is leptin involved? Growth hormone? Inflammation? Bicarb- chicken or egg? 37
Pip Piper, AJRCCM, vol 183, 2011 38
Respir Care 2015;60(5):666 672 39
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Leptin Protein produced by adipocytes Acts on hypothalamic receptors to inhibit eating Knock out mice develop OHS characteristics Decreased HCVR Increased PCO2 Decreased resp compliance Decreased lung volumes Impaired resp muscle function Leptin replacement reverses the above Piper, AJRCCM, vol 183, 2011 41
Thank you Light-colored bars indicate simple obesity; dark gray bars indicate obesity-associated hypoventilation. Nowbar. Am J Med. 2004;116:1 7. 42
Nowbar. Am J Med. 2004;116:1 7. 43
Respir Care 2015;60(5):666 672 44
Nowbar. Am J Med. 2004;116:1 7. 45
PULMONARY CONSIDERATIONS FOR THE OBESE PATIENT UNDERGOING SURGERY Supine positioning mechanically disadvantageous due to: Increased diaphragmatic impedance Lower lung volumes Increased upper airway collapse Impaired capacity to tolerate apneic episodes with early and more dramatic oxygen desaturation Increased incidence of OSA J Thorac Dis 2015;7(5):943-952
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Chung F et al Anesthesiology 2008 48
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Pre-Operative CPAP/NIPPV Ventilation strategy Positioning Anesthesia selection-regional Minimize opiates Postop location J Thorac Dis 2015;7(5):943-952 50
Intra op PAP Recruitment maneuvers Positioning 51
Post op CPAP/NIPPV Monitoring SPO2/CO2 PT Positioning Mobilzation Fluid Management 52
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Tjeertes et al. BMC Anesthesiology (2015) 15:112 54
Tjeertes et al. BMC Anesthesiology (2015) 15:112 55
Kaw, et al. Br J Anaesth 2012;109:897-906. 56
Kaw, et al. Br J Anaesth 2012;109:897-906. 57
Kaw, et al. Br J Anaesth 2012;109:897-906. 58
Kaw, et al. Br J Anaesth 2012;109:897-906. 59
Kaw, et al. Br J Anaesth 2012;109:897-906. 60
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