Diagnosis and Treatment of Chronic Obstructive Pulmonary Disease


makes smokers and non-smokers more susceptible to a rapidly progressing form of COPD.11


Passive exposure to cigarette smoke


(also known as ‘environmental tobacco’ or ‘secondhand smoke’) can contribute to respiratory symptoms and the development of COPD, as this exposure increases the amount of inhaled particles and toxic tobacco gases in the lungs.12


Moreover, the epidemiologic data indicate


The role of air pollutants in the development of COPD has received increasing attention in recent years, and the World Health Organization estimates that 35% of COPD in low- and medium-income countries is from indoor smoke from solid fuels.14


Toxic injury to the


lung before the patient has reached seven years of age, when the lung finishes developing, might predispose patients to earlier onset of COPD symptoms.15


Clinical Diagnosis


Diagnosis of COPD is based on clinical suspicion in patients presenting with any of the hallmark symptoms (i.e. cough, increased sputum production, and dyspnea), especially in patients with a smoking history.7 The relationship between the degree of airflow obstruction and patient perception of symptoms is variable, as some patients with advanced airflow limitation might be relatively asymptomatic. One survey showed that only 60% of patients with at least moderate COPD complained of symptoms.16,17


that approximately one out of every six patients with COPD has never smoked.13


Table 1: Classification of the Severity of Chronic Obstructive Pulmonary Disease Based on Spirometry Findings


Severity Mild


Moderate GOLD ATS/ERS FEV1 ≥70% BTS


FEV1/FVC <70% FEV1/FVC <70% FEV1/FVC <70% FEV1 ≥80%


FEV1 50–80%


FEV1/FVC <70% FEV1/FVC <70% FEV1/FVC <70% FEV1 50–79%


FEV1 60–69% Moderately severe - Severe Very severe FEV1 30–49%


FEV1/FVC <70% - FEV1 50–59%


FEV1/FVC <70% FEV1/FVC <70% FEV1/FVC <70% FEV1 30–49%


FEV1 35–49% FEV1 <35% FEV1 <30%


FEV1/FVC <70% FEV1/FVC <70% - FEV1 <30%


ATS = American Thoracic Society; BTS = British Thoracic Society; ERS = European Respiratory Society; FVC = forced vital capacity; FEV1 = forced expiratory volume in one second; GOLD = Global initiative for chronic obstructive lung disease.


Figure 1: Posteroanterior and Lateral Chest Films in Chronic Obstructive Pulmonary Disease


Chronic cough and dyspnea remain the two most common symptoms reported by patients with COPD. Recently, an epidemiologic study in The Netherlands reported that cough in smokers was a useful tool for case finding for COPD, in that it was a better predictor of airflow obstruction than was breathlessness or wheezing.18 Chronic cough can be troublesome and may significantly compromise quality of life; it is probably driven by a combination of mucus hypersecretion and airway inflammation.19


By contrast, dyspnea in COPD is characteristically persistent and progressive. In early COPD,


behavior can be modified to limit breathlessness, but when the FEV1 value is <30% predicted, the patient is usually breathless on minimal exertion. Foreshortening of the inspiratory muscles in COPD caused by hyperinflation might substantially reduce their force-generating capacity, leading to mechanical disadvantage of the inspiratory muscles and contributing to the generation of symptoms of dyspnea.20


Spirometry


The American Thoracic Society (ATS) and European Respiratory Society (ERS) standards advocate performing spirometry in all persons with a history of exposure to cigarette smoke and/or environmental pollutants, a family history of COPD, or the presence of a chronic cough, sputum production, or shortness of breath. Additionally, the National Committee for Quality Assurance has recently adopted spirometry as a performance measure for the Health Plan Employer Data and Information Set in patients with a new diagnosis of COPD.21,22


The key


spirometric measurements of COPD are FEV1 and forced vital capacity (FVC). FEV1 is the average volume of air that a patient can expire in one second following a full inspiration. The FVC is the total maximum volume of air that a patient can exhale after a full inspiration. A


post-bronchodilator FEV1/FVC ratio of <0.7 associated with an FEV1 of <80% of the predicted value is diagnostic of airflow limitation and confirms COPD. The disease is now defined as airflow limitation that is ‘partially reversible’.6


US RESPIRATORY DISEASE


A radiograph might be entirely normal in mild disease. However, as chronic obstructive pulmonary disease (COPD) progresses, abnormalities reflect hyperinflation manifesting as a low flattened diaphragm (A) and a vertical narrowed heart shadow (B). The retrosternal airspace is increased on the lateral view (C) and the sternal-diaphragmatic angle exceeds 90° (D).


bronchodilators varies among patients with COPD and can depend, in some instances, on the dose and the type of bronchodilator agent used.


Some patients show increases in both FEV1 and FVC, others show changes in either FEV1 or FVC and a minority show no change in either.23 The ATS, ERS, Global initiative for chronic obstructive lung disease


Disease severity is essential in determining the appropriate therapy for each patient. Spirometry can also be used to track disease progression over time. However, peak expiratory flow rates are not helpful in diagnosing COPD, because they can underestimate the level of airway obstruction.26


Other Diagnostic Tests Imaging


The pattern of spirometric response to


There has been longstanding interest in thoracic imaging and its role in the in vivo characterization of smoking-related lung disease.27 Research in this area has spanned readily available modalities, such as chest X-ray and computed tomography (CT), to more advanced imaging techniques, such as optical coherence tomography (OCT) and magnetic


9


(GOLD), and British Thoracic Society have published guidelines classifying COPD severity based on spirometry findings, as show in Table 1.7,24,25


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