COPD vs Emphysema
Emphysema is a part of Chronic Obstructive Pulmonary Disease (COPD). There can be emphysema without COPD but not the other way around. This article will talk about these diseases in detail, highlighting their clinical features, symptoms, causes, investigation and diagnosis, prognosis, and also the course of treatment/management they require.
Chronic Obstructive Pulmonary Disease (COPD)
Chronic obstructive pulmonary disease (COPD) consists of two closely related clinical entities; chronic bronchitis (long-standing inflammation of large airways characterized by cough and sputum most days of 3 months of two successive years) and emphysema (loss of elastic recoil of lung and, histologically, enlargement of airway smaller than terminal bronchioles and destruction of walls of alveoli). Patients may have either asthma or COPD but not both. (Read more: Difference Between COPD and Asthma). If the patient is above 35 years of age, has a history of smoking, long standing production of sputum, cough, shortness of breath without clear variations throughout the day, COPD is likely. NICE (National Institute for Healthcare Excellence) recommends the name COPD.
Smoking is the main risk factor for COPD. The tendency to develop COPD rises with the number of cigarettes smoked and all lifelong smokers get COPD. Individuals who work in gold mines, coal mines, textile plants, may also get COPD due to the chemicals and dust exposure that cause an elevated state of reactivity in airways. Similar to cigarette smoke these molecules increase airways secretions and cause constriction of airways. There is familial trend of heightened risk of COPD too. Some schools hypothesize that COPD has an autoimmune component, as well. They theorize that the reason for COPD getting worse even after cessation of smoking is due to continued inflammation because of breakdown in self-tolerance.
Shortness of breath, increased effort required to inhale and exhale, use of accessory muscle of respiration, enlarged barrel shaped chest, exhalation through pursed lips, prolonged exhalation, cough, and sputum production are common clinical features of COPD. Pink puffers and blue bloaters are names coined to identify two ends of a spectrum of COPD patients. Pink puffers have good ventilation of alveoli, near normal oxygen pressures and low/normal carbon dioxide pressures in blood. They are not cyanosed (bluish discoloration of lips). Blue bloaters have poor ventilation of alveoli and low oxygen pressures in blood. They may develop heart failure as a result of COPD (heart failure will cause body swelling).
COPD is a lung disease, but it doesn’t affect only the lungs. It can get aggravated due to cold weather, smoking, infections and allergic reactions. This is known as an acute exacerbation. Enlargement of small airways can progress to a stage where small enclosed collections of air (bullae) form. These bullae may rupture, and air enters the space between the lung and the chest wall (pneumothorax). Smoking causes lung cancer. Therefore, COPD and lung cancer can co-exist. Due to long standing low levels of oxygen in blood, bone marrow forms more hemoglobin (oxygen transporter in the blood) to ensure normal levels of oxygen get to peripheral tissues. This is known as polycythemia. In severe polycythemia, blood may need to be extracted to reduce shortness of breath. Because of long standing injury to the lung tissue, blood pressure in the lung vessels (elevated pulmonary pressures) rises. This causes a strain on the right ventricle and atrium of the heart. In severe cases, right heart failure can occur (cor pulmonale).
There is no cure for COPD although it is manageable. Acute exacerbations are treated at emergency units with bronchodilators, steroids and antibiotics. Drugs that dilate airways (inhalable) are the mainstay of treatment. Salbutamol, terbutalin, salmetrol, ipratropium are some of the common drugs used. Steroids reduce the reaction of airways to inhaled harmful agents such as cigarette smoke. This reduces the airways secretions. Beclomethasone and hydrocortisone are two common steroids used. Oxygen is given with care in COPD. Due to the long standing low oxygen levels on the blood the chemical sensors in the brain drives the respiration continually because it senses a low level. When high flow oxygen is given via a mask, the blood oxygen levels rise, and the signal telling the brain to continue breathing will stop suddenly causing a respiratory arrest. Therefore, oxygen saturation is maintained in low 90s.
Emphysema is loss of elastic recoil of lung and, histologically, an enlargement of airway smaller than terminal bronchioles and destruction of walls of alveoli. Smoking, inhalation of toxic fumes and certain inherited disorders like connective tissue disorders reduce the elastic recoil of lungs.
What is the difference between Emphysema and COPD?
Emphysema is just the loss of elastic recoil of lungs while COPD is loss of recoil coupled with airway inflammation.
Also read the Difference Between Chronic Bronchitis and Emphysema