Chronic Lung Disease

After formation, plaques are detectable as vessel narrowing as indicated with angiography. This and related techniques only detect severe disease. However, the rupture of the plaque and arterial occlusion from thrombosis can occur within seconds or minutes with less than severe cases of atherosclerosis. Ruptured plaques are known as complicated plaques because the extracellular matrix that separates the lesion from the lining of the arterial wall is disrupted and blood flow is impaired by debris or by thrombus formation. The obstructed artery is what causes the symptoms of heart attack or stroke.

Serious disease is not indicated by a certain degree of stenosis but by having an unstable or vulnerable plaque with any degree of stenosis but is vulnerable to occlusion. Things like carotid intimal media thickness measurement (by ultrasound), calcium scoring of the coronary arteries by CT scanning, and lab tests, such as a homocysteine level, hs-CRP level, lipid levels, and Hgb A1c levels will detect disease before angiography can show a significant lesion. Certain imaging that are not commonly used (such as the PET scan and the SPECT scan) can detect the severity of plaque formation.

The main preventative measures in ASCVD is the avoidance of modifiable risk factors (such as smoking, obesity, and poor dietary habits). Exercise improves circulation and will decrease the patient’s chances of obesity. Statins will lower cholesterol levels and antihypertensives will decrease blood pressure. Aspirin taken daily will prevent blood clots that lead to arterial occlusion. Surgical or interventional strategies are used as prevention of complications when drugs and lifestyle modifications do not control the atherosclerosis.

Treatments of ASCVD are not as effective as preventative measures. Combined approaches are more effective than singular treatments. Treatments include anticoagulation measures, anti-diabetic drugs, statin drugs, and antihypertensive drugs. Behavioral methods include increasing fruits and vegetables in the diet. Dairy product reduction has no effect. Serious cases require bypass or cardiovascular intervention procedures.

Chronic lung diseases are primarily secondary to smoking, although there are other causes of these diseases. The most common classification of chronic lung disease is COPD or chronic obstructive pulmonary disease, of which there are two types: chronic bronchitis and emphysema. These are terms used for different manifestations of this disease state and have slightly different symptoms. In chronic bronchitis, a productive cough must be present for two years and for at least three months each year.

Tobacco smoke combined with things like air pollutions, occupational exposures, and genetics to create the disease state. Poor ventilation and cooking fires contribute to COPD in the developing part of the world. While lung testing (spirometry) is the gold standard for testing for COPD, it can mimic asthma but doesn’t improve when beta-agonists are given.

About 2.4 percent of people throughout the world have COPD, primarily in patients who are older than 40 years and who smoke. More than 90 percent of deaths come from people in developing countries, where there is limited access to treatment. The incidence is increasing in developing countries because of higher smoking rates and increased longevity.

There are several characteristic symptoms associated with COPD including dyspnea, productive cough, and sputum production. They are present for a long period of time and have exacerbations. The cough is the first symptom to develop. There is usually sputum production but it can be dry. The patient also has an increase in respiratory infections. Dyspnea starts with exertion and progresses to dyspnea at rest, often with pursed lips breathing. There is prolonged outflow breathing and chest tightness, which is less common. Barrel-chestedness and clubbing can be signs of the disease, but these are less common. Cor pulmonale is the end stage of the disease. This involves hypertension of the arteries of the lungs, associated with leg edema, ascites, and distention of neck veins.

Figure 1 shows hyperinflation of the lungs consistent with COPD:

Figure 1

Because of shared risk factors, there can be other diseases linked to COPD, including type 2 diabetes, hypertension, coronary artery disease, lung cancer, anxiety disorder, depression, osteoporosis, and sexual disorders. Severely affected patients will have fingernail clubbing and chronic disease. Exacerbations are common and involve increased sputum (that becomes yellow or green), increased cough, and increased dyspnea. The patient may have cyanosis, tachypnea, diaphoresis, and tachycardia.

The major risk factor for COPD is tobacco smoke. About 20 percent of smokers will develop COPD with half of lifelong smokers at risk for the disease. About 80-95 percent of patients with COPD have been or

are already smokers. The longer one smokes, the greater is their chances of COPD. Women have a more severe reaction to cigarette smoke and have an increase in secondhand smoke as a cause of the disease. Besides cigarettes, other smoking can cause COPD, including pipes, cigars, and marijuana. Women who smoke in pregnancy can confer a risk of COPD to the child.

Air pollution causing COPD is usually indoor pollution, such as cooking fires indoors (which is the case 80 percent of the time in places like sub-Saharan Africa, China, and India). Urban air pollution plays a much smaller role in the disease process. Certain occupational exposures will lead to COPD, including cotton textile industrial exposure, gold mining, and coal mining, as well as agricultural exposure and exposure to welding. Exposure to silica and fiberglass dust can cause COPD.

Genetics play a small role in COPD. People born with alpha-1-antitrypsin disease or AAT (an autosomal recessive disease) have an increased risk of emphysema. This disease accounts for 1-5 percent of cases of COPD and occurs in about 0.4 percent of people. Other genetic factors are likely present but have not yet been identified. Poverty increases the risk of COPD and having other diseases, like HIV/AIDS and tuberculosis, will increase the risk.

Exacerbations are caused by infections, lack of medications, or exposure to pollutants. Infections are the primary cause of COPD exacerbations (causing 50-75 percent of cases). Environmental pollutants, smoking, and secondhand smoke are less likely to cause exacerbation. Cold outdoor temperatures account of a small percentage of exacerbations. Severely affected patients will have up to 4 exacerbations per year, mostly in the winter months. A pulmonary embolism can also cause an exacerbation.

COPD should be considered in anyone of middle age or older who has the symptoms of the disease. Several tests can be done that include spirometry (the gold standard of testing), chest x-ray, and CT of the chest. Spirometry involves forcefully blowing into a tube, obtaining the FEV1 (forced expiratory volume in 1 second) as well as the forced vital capacity (FVC) and FEV (force expiratory volume). Patients with COPD will have a prolonged FEV1. A bronchodilator should be used to look for reversibility. The patient with COPD will have an FEV1/FVC ratio that is less than 70 percent. The FEV1 will be less than 80 percent of predicted. Peak flow measurements do not diagnose the patient with COPD.

GOLD grading of COPD includes mild disease (GOLD 1), with an FEV1/FVC of less than 80 percent and leads to GOLD 4 (very severe disease), with an FEV1/FVC of less than 30 percent. There is a British questionnaire for COPD, called the COPD assessment test (CAT), that can determine disease severity. Things like muscle weakness and weight loss will also determine the severity of the disease. ABGs can also determine disease severity.

The differential diagnosis of COPD includes things like a pneumothorax, asthma, pneumonia, pulmonary artery disease, and heart failure. The main difference between COPD and asthma is that beta-agonists improve spirometry readings with asthma, which is not the case for COPD. Chronic bronchitis without spirometry changes is not suggestive of COPD.

When treating COPD, the patient should have a pneumococcal vaccination and an annual influenza vaccination. Smoking cessation is the most important treatment for COPD. It is the only known way of decreasing disease progression. There are many ways to stop smoking, including nicotine replacement methods, varenicline (Chantix), or bupropion. Decreasing exposure to occupational dusts or fumes will