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What your test results mean to you and your doctor Emily Gilbert, MD Assistant Professor, Dept of Medicine Div of Pulmonary & Critical Care Loyola University Medical Center
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Case 35 year old Caucasian female with eight years of worsening shortness of breath She was diagnosed with asthma but feels no relief from inhalers Further testing is ordered – Chest X-Ray – CT scan of chest – Pulmonary function tests
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Chest X-Ray
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Pneumothorax
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Chest X-Ray Pleural effusion
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Chylous pleural effusion Chlye
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Chest X-Ray
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Chest CT - LAM
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Chest CT - Emphysema
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Why get Pulmonary Function Tests? Obtain baseline of lung function Assess disease progression Assess response to medications Determine prognosis and need for lung transplantation
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“Breathe normally” “Breathe in as deeply as you can” “Breathe out as hard as you can”
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Cleveland Clinic Jnl of Med 2003; 70: 866-881 Volume of air expelled during the entire forced exhalation Volume of air expelled during the first second of the forced exhalation Maximum Inhalation Maximum Exhalation
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Spirometry Measures the exhaled volume and flow of air vs time Tidal Volume: volume of air moved during normal breathing FVC (forced vital capacity): – volume of air expelled during the entire forced exhalation (measured in liters) FEV 1 (forced expiratory volume in 1 second): – volume of air expelled during the first second of the forced exhalation (measured in liters) FEV 1 /FVC: % of air expelled in the first second
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Cleveland Clinic Jnl of Med 2003; 70: 866-881 Volume of air expelled during the entire forced exhalation Volume of air expelled during the first second of the forced exhalation
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FEV 1 /FVC 70-75% of volume expelled during forced expiration should be exhaled during the 1 st second FEV 1 /FVC ratio<70% indicates obstructive lung disease – Asthma – Emphysema – LAM
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Spirometry in LAM Smooth muscle cells proliferate and surround airways Narrowing of airways Air flow decreased Decreased FEV 1
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Normal Spirometry Values Reference value based on: – Age – Height – Ethnicity – Gender Reference value, measured value (L) and % of predicted value are reported % predicted = patient’s value reference value X 100
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Severity Reduced FEV 1 /FVC ratio – FEV 1 /FVC ratio<70% = obstruction FEV1 is decreased due to obstruction of flow Severity of obstruction is based on FEV 1 – FEV 1 80-100% predicted = normal – FEV 1 60-80% predicted = mild obstruction – FEV 1 40-60% predicted = moderate obstruction – FEV 1 <40% predicted = severe obstruction
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<70% = obstruction 50% = Moderate
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Hypothesis for cyst formation
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Bronchodilator Response Bronchodilators (e.g., Albuterol) relax muscles around the airway Spirometry is performed before and after administration of a bronchodilator Positive bronchodilator response: – 200mL increase in FEV 1 and – 12% change
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Average LAM Spirometry Values Average FEV 1 /FVC = 64.5% Average FEV 1 = 70% of predicted – Mild disease Patients with TSC-LAM have more mild disease at the time of presentation Ryu et al. NHLBI LAM registry. AJRCCM 2006; 173:105-111
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Pulmonary Diffusing Capacity Diffusing capacity of the lungs for carbon monoxide (D L CO) Measures the transmission of the CO molecule from alveolar gas to hemoglobin in the pulmonary capillary blood
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Pulmonary Diffusing Capacity 1.Patient exhales completely 2.Breathes in the test gas (10% helium, 0.3% CO + oxygen and nitrogen) to maximum inspiration 3.Breath hold x 10 seconds CO has very high affinity for hemoglobin so crosses membrane and binds quickly to red blood cell 4.Patient exhales quickly and exhaled gas is collected
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D L CO D L CO is adjusted for hemoglobin D L CO 80-100% = normal diffusion capacity D L CO 60-80% = mildly decreased diffusion capacity D L CO 40-60% = moderately decreased diffusion capacity D L CO <40% = severely decreased diffusion capacity Ryu et al. NHLBI LAM registry. AJRCCM 2006; 173:105-111
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Cleveland Clinic Jnl of Med 2003; 70: 866-881 Volume of air left in lungs at end of maximum exhalation Total volume of air in the lungs at maximum inhalation
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Obstruction Air Trapping Increased RV or TLC (>120% predicted) = Air trapping
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Restriction Decreased TLC (<80% predicted) = Restriction Causes of restriction: – Pleural effusion – Pleurodesis for recurrent pneumothorax
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Moderate obstruction + bronchodilator response Mild air trapping Severe defect in gas diffusion
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The diagnosis of LAM is suspected based on Chest CT findings A serum Vascular Endothelial Growth Factor D (VEGF-D) level is drawn
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VEGF-D Serum VEGF-D level of >800pg/mL in female with typical lung cystic changes on CT is specific for S-LAM Higher levels indicate more severe disease Her level returns at 935 pg/mL Based on her CT scan and VEGF-D level, she is given a diagnosis of LAM
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Other testing… MRI brain – To look for evidence of tuberous sclerosis complex (TSC) Abdominal CT scan – To assess for evidence of angiomyolipoma Desaturation screen
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88% oxygen saturation
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Results No evidence of Tuberous Sclerosis on her MRI of the brain No angiomyolipoma on CT of abdomen She desaturates to 84% on room air while ambulating and requires 2L of oxygen to keep saturations >88%
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Next steps She is started on oxygen to keep oxygen saturation >88% while ambulating Given her symptoms and moderate obstruction on spirometry, Rapamycin is started
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Follow-up appointments Rapamycin trough Cholesterol level VEGF-D level CT chest – Every few years – Very slowly progressing disease Pulmonary function tests – Every 6-12 months
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Average lung function decline Nonsmokers without lung disease lose 30ml/year of lung function after age 35
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Lung function decline in LAM PremenopausalPostmenopausal Decline FEV 1, % predicted 2.2% per year0.9% per year Decline FEV 1, mL 90 mL/year55 mL/year Decline D L CO, % predicted 2.8% per year1.9% per year Decline D L CO, mL/mmHg/min 0.78 per year0.58 per year CHEST 2004; 126:1867–1874
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MILES trial N Engl J Med 2011; 364:1595-1606 Rate of change of FEV 1 was primary outcome in the MILES trial Placebo group had an observed FEV 1 decline of 134mL over one year Sirolimus group had improvement in FEV 1 of 19mL over one year
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Value at time of enrollment Value at 12 months Placebo Sirolimus Change from baseline Placebo Sirolimus FEV1 (mL)1367mL (48%) 1272mL1383mL-134mL+19mL FVC (mL)2791mL (79% pred) 2843mL2780mL-129mL+97mL MILES trial N Engl J Med 2011; 364:1595-1606
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Value at time of enrollment Value at 12 months Placebo Rapamycin Change from baseline Placebo Rapamycin FEV1 (mL)1367mL (48%) 1272mL1383mL-134mL+19mL FVC (mL)2791mL (79% pred) 2843mL2780mL-129mL+97mL Serum VEGF-D (pg/mL) 2029pg/mL2444pg/mL862pg/mL-14.8pg/mL-1032pg/mL MILES trial N Engl J Med 2011; 364:1595-1606
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Despite being on Rapamycin, our patient has continued progression of her disease with worsening shortness of breath and increasing oxygen requirements 2010 Value% Predicted FVC3.51105% FEV11.4150% FEV1/FVC40% DLCO7.334
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Despite being on Rapamycin, our patient has continued progression of her disease with worsening shortness of breath and increasing oxygen requirements 20102014 Value% PredictedValue% Predicted FVC3.51105%3.2098% FEV11.4150%0.7925% FEV1/FVC40%25% DLCO7.334%6.930%
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Lung Transplantation Pulmonary function tests help predict when one should be listed for lung transplant Guidelines for lung transplant in LAM: – Severe life-limiting shortness of breath – Uncontrollable, recurrent pneumothorax – Use of oxygen Average lung function of LAM patients at time of transplant: – FEV 1 25% of predicted – D L CO 27% of predicted
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Summary CXR, CT chest can help lead to diagnosis Pulmonary Function tests obtained at baseline and every 6-12 months FEV 1 /FVC ratio <70% indicates obstruction – Severity of obstruction is based on FEV 1 – Rule of 20s to determine severity VEGF-D level can help make diagnosis without biopsy and may decrease with Rapamycin Lung transplant is an option if disease progresses despite therapy
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References Fletcher C. The natural history of chronic airflow obstruction. British Medical Journal 1977;1:1645-1648. Taveira-DaSilva AM et al. Reversible Airflow Obstruction, Proliferation of abnormal smooth muscle cells and impairment of gas exchange as predictors of outcome in LAM. AJRCCM 2001; 164: 1072-1076. Taveira-DaSilva AM et al. Decline in Lung Function in Patients with Lymphangioleiomyomatosis Treated with or without Progesterone. Chest 2004; 126:1867-1874. Orens JB, et al. International Guidelines for the selection of Lung Trasplant Candidates: 2006 update. Jnl of Heart and Lung Transplant 2006; 7: 745-755. McCormack FX. Lymphangioleiomyomatosis: A Clinical Update. Chest 2008; 133:507-516. Taveira-DaSilva AM et al. Reversible Airflow Obstruction in LAM. Chest 2009: 136; 1596-1603. Clements D et al. Lymphangioleiomyomatosis. Eur Respi Mon 2009; 46:176-207. McCormack FX et al. Efficacy and Safety of Sirolimus in Lymphangioleiomyomatosis. N Engl J Med 2011; 364:1595-1606 Henske, EP, McCormack FX. Lymphangioleiomyomatosis – a wolf in sheep’s clothing. JCI 2012;122(11):3807-3816.
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