(D) FEV1/FVC<0.7 and FEV1<30% predicted [?]Hallmark of COPD is airflow obstruction.oPulmonary function test shows airflow obstruction with a reduction in FEV1 and FEV/FVC.oWith worsening disease severity, lung volumes may increase, resulting in an increase in total lung capacity, functional residual capacity, and residual volume.oIn patients with emphysema, the diffusing capacity may be reduced, reflecting the lung parenchymal destruction characteristic of the disease.oDegree of airflow obstruction is an important prognostic factor in COPDoIt is the basis for the Global Initiative for Lung Disease (GOLD) severity classificationGOLD CRITERIA FOR COPD SEVERITYGold StageSeveritySymptomsSpirometry0At riskChronic cough, sputum, productionNormalIMildWith or without chronic cough or sputum productionFEV1 /FVC<0.7 & FEV1 >80% predictedIIAModerateWith or without chronic cough or sputum productionFEV1 /FVC<0.7 & >=50%FEV1 but <80% predictedIIISevereWith or without chronic cough or sputum productionFEV1 /FVC<0.7SFEV1 >=30% but <50% predictedIVVery SevereWith or without chronic cough or sputum productionFEV1 /FVC<0.7 & FEV1 <30% predicted or FEV1 <50% predicted with respiratory failure or signs of right heart failure[?]Stage IV: Very Severe COPD:oSevere airflow limitation (FEV1/FVC<70%;FEV1<.30% predicted) or FEV1<50% predicted plus chronic respiratory failure.-Quality of life is appreciably impaired.-Exacerbations may be life-threatening.oAvoid risk factorsoOffer influenza vaccinationoAdd short-acting bronchodilators as neededoAdd rehabilitationoAdd inhaled glucocorticoids if repeated exacerbationsoAdd long-term oxygen if chronic respiratory failureoConsider surgical treatments-Arterial blood gases & Oximetry may demonstrate resting or exertional hypoxemia.-Radiographic studies may assist in the classification of the type of COPD.-CT scan is the current definitive test for establishing the presence or absence of emphysema in living subjects.-Recent guidelines have suggested testing for a, AT deficiency in all subjects with COPD or asthma with chronic airflow obstruction.-Only three interventions-smoking cessation, oxygen therapy in chronically hypoxemic patients & lung volume reduction surgery in selected patients with emphysema have been demonstrated to i influence the natural history of patients with COPD.