Chronic Bronchitis and Emphysema - Research Paper Example

?Compare and Contrast Chronic Bronchitis and Emphysema Introduction Chronic bronchitis and emphysema are chronic diseases of the lung and are together categorized under chronic pulmonary lung disease. Both the conditions contribute to significant morbidity and mortality. Chronic obstructive pulmonary disease can be defined as "a disease state characterized by the presence of airflow obstruction due to chronic bronchitis or emphysema" (NICE, 2004). According to the National Health Survey, in United States, prevalence of emphysema is 18 per 1000 persons and that for chronic bronchitis is 34 per 1000 persons (Adams, 2008). The exact prevalence of these lung diseases across the globe is not well known. In this article, both the diseases with be discussed by comparing and contrasting with each other. Definitions Chronic bronchitis is defined clinically as a condition in which the patient suffers from expectorant cough for a minimum of 3 months for 2 consecutive years (Celli, 2008). The diagnosis is mainly through clinical presentation. On the other hand, emphysema is defined as a condition in which the patient has permanent and abnormal enlargement of the air spaces distal to the terminal bronchioles and associated with destruction of the walls without any obvious fibrosis (Celli, 2008). Chest radiography and pulmonary function tests are needed to arrive at the diagnosis. Pathophysiology In chronic bronchitis, there is typical inflammation of the bronchi. The endothelium is damaged because of which the mucociliary response is impaired. This leads to improper clearance of bacteria and mucus. Thus, inflammation, along with inadequate clearance of mucus contributes to obstruction in the disease. There is histopathological evidence of goblet cell hyperplasia, mucus plugging, smooth muscle hyperplasia and fibrosis. Alveolar attachments that are supportive are lost, the airways are deformed and the air lumens are narrowed. The capillary pulmonary bed is undamaged. In emphysema, the airspaces distal to the terminal bronchioles are enlarged permanently, because of which alveolar surface area necessary for gas exchange is decreased. Loss of alveolar walls leads to decreased elastic recoil property of the alveoli, causing limitations to airflow. Decrease in the alveolar limiting structure causes narrowing of the airway, causing further limitation of airflow. There are 3 characteristic patterns of morphology in emphysema and they are centriacinar, panacinar and distal acinar. In centriacinar type, destruction is mainly in the central portions of the acini. In panacinar type, entire alveolus is involved. In distal acinar type, only those acini in the distal portion of the airways in involved. (Maclay et al, 2009). Etiology and pathogenesis The most common etiological agent in both chronic bronchitis and emphysema is cigarette smoking. Smoking over a long duration of time triggers the macrophages to release chemotactic factors like elastases which destroy the tissues of the lung. Passive smoking and other environmental factors also can contribute to chronic obstructive pulmonary disease. Airway hyperresponsiveness is a risk factor for chronic bronchitis. Alpha-1 antitrypsin deficiency, a genetic disorder, is an important risk factor for chronic pulmonary obstructive disease, especially emphysema. Intravenous drug abuse is another important risk factor for emphysema. The disease occurs because of the pulmonary vascular damage that occurs due to insoluble fillers present in the drugs. Immunodeficiency syndromes like HIV infection, vasculitis disorders, connective tissue disorders and Salla disease are risk factors for both chronic bronchitis and emphysema (Celli, 2008). Prognosis As far as prognosis is concerned, both the conditions are associated with significant mortality and morbidity. The prognosis is worse in emphysema because of damage to pulmonary vascular bed. Chronic obstructive pulmonary disease is infact, the fourth leading cause of mortality in the United States. Both chronic bronchitis and emphysema cannot be cured. But the symptoms can be controlled and hence regular follow-up and compliance to treatment are very important (NICE, 2004). Clinical presentation Patients with emphysema present during the fifth decade of life with either long standing cough or acute respiratory problem. Cough is worse during morning hours and it is mainly non-productive. Concomitant bronchitis can cause mild sputum expectoration. The most significant symptom is however, breathlessness which occurs late in the course of the disease. Some patients may present with wheezing. Breathlessness can be present in both chronic bronchitis and emphysema, but in later stages. Along with breathlessness, patients can have exercise intolerance and easy fatigability. In patients with antitrypsin deficiency, the clinical presentation occurs earlier. Physical examination in these patients may reveal tachypnea and respiratory distress. Accessory muscle usage and intercostal muscle indrawing may be evident. In advanced disease states, the patients may present with cyanosis, peripheral edema, elevated jugular venous pressure and prolonged forced expiratory time. Auscultation of the chest may reveal wheeze, prolonged expiration, decreased breath sounds and hyper-resonant percussion (NICE, 2004). Management Laboratory evaluation in emphysema varies based on the stage of the disease. Initially, the arterial blood gas analysis may show only mild hypoxemia. This can worsen as the disease progresses and hypercapnia can ensue. Chronic hypoxemia can lead to polycythemia as evident through raised hematocrit values. Chronic respiratory acidosis can occur in long standing severe cases leading to compensatory metabolic alkalosis. Concomitant chronic bronchitis can cause infection and yield positive sputum cultures with pathogens like hemophilus influenza and Streptococcus pneumoniae. Chest radiography in patients with emphysema will reveal hyperinflation and rapid tapering vascular shadows. In those who have developed pulmonary hypertension, the hilar vascular shadows can be prominent associated with right ventricular enlargement and lower retrosternal opacity. Pulmonary function tests in emphysema are mainly done to assess the severity of the disease, disease progression and response to treatment. The total lung capacity is increased. Even the residual capacity and functional residual capacity are increased. The vital capacity is however, decreased. In acute exacerbations, gas exchange and lung mechanics are worsened. 30 percent of the patients with emphysema can have increased forced expiratory volume (GOLD, 2008). In patients with chronic bronchitis, during acute exacerbations, sputum may need to be sent for culture. Chest radiography may show signs of consolidation in case of infection. Spirometry does not have much role in the diagnosis and management of chronic bronchitis (GOLD, 2008). Before initiation of treatment in patients with chronic obstructive pulmonary disease, it is very important to ascertain the severity of the disease. Important aspects to measure the severity of the disease are frequency of exacerbations, degree of airflow obstruction and prognostic factors like forced expiratory volume, degree of breathlessness, body mass index and exercise capacity. The goals of treatment in both chronic bronchitis and emphysema are relief of symptoms, prevention of progression of the disease, improvement in exercise tolerance, improvement in quality of life, prevention and management of acute exacerbation, and reduction in mortality and morbidity. The single most effective treatment strategy in patients with chronic obstructive pulmonary disease is cessation of smoking. For this, patient education is very important. Support programs are important to help patients quit smoking. Cessation of smoking not only decreases symptoms and exacerbations, it also prevents progression of the disease. Pharmacological interventions are necessary to treat symptoms like oral and nebulized bronchodilators and antibiotics for infection during acute exacerbations. Some patients may even need cough suppressants. Certain have been approved for cessation of smoking like varenicline. Chewing gum with nicotine and nicotine patches are also available to cause cessation of smoking in those who are not able to control the urge to smoke and in those who have withdrawal symptoms. In both chronic bronchitis and emphysema, the backbone of pharmacological treatment is bronchodilator therapy. Short acting bronchodilators include beta-2 agonists and anticholinergic agents. Long acting bronchodilators include long acting beta-2 agonists, long acting muscarinic agents and oral phosphodiesterase inhibitors (NICE, 2004). Anti-inflammatory therapy is essential in patients with chronic bronchitis to suppress chronic airway inflammation and inhaled and oral corticosteroids are effective in this regard. Patients with chronic bronchitis may have thick mucus secretions which can cause airway plugging. Mucolytic agents in those patients help reduction of the viscosity of sputum and thereby decrease chest discomfort and cough. However, they may not improve lung function or breathlessness. In patients with alpha-antitrypsin deficiency, anti-trypsin levels can be increased by administering inhaled or intravenous antitrypsin or by augmenting the production of this protein by liver by certain drugs like tamoxifen. In those with hypoxemia, inhaled oxygen may be useful but this must be administered carefully to avoid the deleterious side effects of oxygen therapy. Vaccination against pneumococcal infections and influenza is mandatory in both the conditions (GOLD, 2008). In many patients, a combination of physical therapy and pharmacotherapy is used for adequate management. Pulmonary rehabilitation programme is useful in those with breathlessness. The programme encompasses education about the disease and cessation of smoking, nutritional intervention, behavioral therapy and psychological support. The programme is intended to improve exercise intolerance, decrease breathlessness, improve quality of life, prevent complications, decrease exacerbations and improve coping skills and autonomy. Physical therapy involves aerobic and anaerobic exercises, body positioning for increased oxygenation, breathing exercises and chest clearance methods to decrease infections (NICE, 2004). Conclusion Chronic bronchitis and emphysema fall under the category of chronic obstructive pulmonary disease. They contribute to significant morbidity and mortality. Smoking is a common risk factor in both the conditions. While productive cough is the main presenting symptom in chronic bronchitis, breathlessness is the main feature in emphysema. The pathophysiology is in the bronchi in chronic bronchitis with intact pulmonary bed. In emphysema, the pathology is in the alveolar sacs and damage to pulmonary bed exists. Goals of treatment are similar and treatment is individualized. References Adams, P.F., Barnes, P.M., Vickerie, J.L. (2008). Summary health statistics for the U.S. population: National Health Interview Survey, 2007. Vital Health Stat, 10, 1-104. Celli, B.R. (2008). Update on the management of COPD. Chest, 133(6), 1451-62. Global Initiative for Chronic Obstructive Lung Disease (GOLD) (2008). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. National Guideline Clearinghouse. Retrieved on 6th of December, 2012 from http://emedicine.medscape.com/article/807927-overview. Maclay, J.D., Rabinovich, R.A., MacNee, W. (2008). Update in chronic obstructive pulmonary disease. Am J Respir Crit Care Med., 179(7), 533-41. NICE Guidelines. (2004). Chronic Obstructive Pulmonary Disease. Retrieved on 6th of December, 2012 from http://www.nice.org.uk/nicemedia/pdf/CG012_niceguideline.pdf Read More