Definition:-
Emphysema is a type of chronic obstructive pulmonary disease (COPD) involving damage to the air sacs (alveoli) in the lungs. As a result, your body does not get the oxygen it needs. Emphysema makes it hard to catch your breath. You may also have a chronic cough and have trouble breathing during exercise.
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The most common cause is cigarette smoking. If you smoke, quitting can help prevent you from getting the disease. If you already have emphysema, not smoking might keep it from getting worse.
It is characterized by an abnormal, permanent enlargement of air spaces distal to the terminal bronchioles. The disease is coupled with the destruction of walls, but without obvious fibrosis. It is often caused by exposure to toxic chemicals, including long-term exposure to tobacco smoke.
As it worsens, emphysema turns the spherical air sacs — clustered like bunches of grapes — into large, irregular pockets with gaping holes in their inner walls. This reduces the number of air sacs and keeps some of the oxygen entering your lungs from reaching your bloodstream. In addition, the elastic fibers that hold open the small airways leading to the air sacs are slowly destroyed, so that they collapse when you breathe out, not letting the air in your lungs escape.
Airway obstruction, another feature of COPD, contributes to emphysema. The combination of emphysema and obstructed airways makes breathing increasingly difficult. Treatment often slows, but doesn’t reverse, the process.
Emphysema is characterized by loss of elasticity (increased pulmonary compliance) of the lung tissue caused by destruction of structures feeding the alveoli, in some cases owing to the action of alpha 1-antitrypsin deficiency.
Classification:-
Emphysema can be classified into primary and secondary. However, it is more commonly classified by location.
Emphysema can be subdivided into panacinary and centroacinary (or panacinar and centriacinar, or centrilobular and panlobular).
Panacinary (or panlobular) emphysema is related to the destruction of alveoli, because of an inflammation or deficiency of alpha 1-antitrypsin. It is found more in young adults who do not have chronic bronchitis.
Centroacinary (or centrilobular) emphysema is due to destruction of terminal bronchioli muchosis, due to chronic bronchitis. This is found mostly in elderly people with a long history of smoking or extreme cases of passive smoking.
Other types include distal acinar and irregular.
A special type is congenital lobar emphysema (CLE).
Congenital lobar emphysema:-
CLE is results in overexpansion of a pulmonary lobe and resultant compression of the remaining lobes of the ipsilateral lung, and possibly also the contralateral lung. There is bronchial narrowing because of weakened or absent bronchial cartilage.
There may be congenital extrinsic compression, commonly by an abnormally large pulmonary artery. This causes malformation of bronchial cartilage, making them soft and collapsible.
CLE is potentially reversible, yet possibly life-threatening, causing respiratory distress in the neonate
Symptoms:
Emphysema symptoms are mild to begin with but steadily get worse as the disease progresses. The main emphysema symptoms are:
*Shortness of breath
*Wheezing
*Chest tightness
*Reduced capacity for physical activity
*Chronic coughing, which could also indicate chronic bronchitis
*Loss of appetite and weight
*Fatigue
When to see a doctor
*You tire quickly, or you can’t easily do the things you used to do
*You can’t breathe well enough to tolerate even moderate exercise
*Your breathing difficulty worsens when you have a cold
*Your lips or fingernails are blue or gray, indicating low oxygen in your blood
*You frequently cough up yellow or greenish sputum
*You note that bending over to tie your shoes makes you short of breath
*You are losing weight.
These signs and symptoms don’t necessarily mean you have emphysema, but they do indicate that your lungs aren’t working properly and should be evaluated by your doctor as soon as possible.
Causes:
The causes of emphysema include:
1.Smoking. Cigarette smoke is by far the most common cause of emphysema. There are more than 4,000 chemicals in tobacco smoke, including secondhand smoke. These chemical irritants slowly destroy the small peripheral airways, the elastic air sacs and their supporting elastic fibers.
2.Protein deficiency. Approximately 1 to 2 percent of people with emphysema have an inherited deficiency of a protein called AAt, which protects the elastic structures in the lungs. Without this protein, enzymes can cause progressive lung damage, eventually resulting in emphysema. If you’re a smoker with a lack of AAt, emphysema can begin in your 30s and 40s. The progression and severity of the disease are greatly accelerated by smoking.
Risk Factors:
Risk factors for emphysema include:
*Smoking. Emphysema is most likely to develop in cigarette smokers, but cigar and pipe smokers also are susceptible, and the risk for all types of smokers increases with the number of years and amount of tobacco smoked.
*Age. Although the lung damage that occurs in emphysema develops gradually, most people with tobacco-related emphysema begin to experience symptoms of the disease between the ages of 40 and 60.
*Exposure to secondhand smoke. Secondhand smoke, also known as passive or environmental tobacco smoke, is smoke that you inadvertently inhale from someone else’s cigarette, pipe or cigar. Being around secondhand smoke increases your risk of emphysema.
*Occupational exposure to fumes or dust. If you breathe fumes from certain chemicals or dust from grain, cotton, wood or mining products, you’re more likely to develop emphysema. This risk is even greater if you smoke.
*Exposure to indoor and outdoor pollution. Breathing indoor pollutants, such as fumes from heating fuel, as well as outdoor pollutants — car exhaust, for instance — increases your risk of emphysema.
*HIV infection. Smokers living with HIV are at greater risk of emphysema than are smokers who don’t have HIV infection.
*Connective tissue disorders. Some conditions that affect connective tissue — the fibers that provide the framework and support for your body — are associated with emphysema. These conditions include cutis laxa, a rare disease that causes premature aging, and Marfan syndrome, a disorder that affects many different organs, especially the heart, eyes, skeleton and lungs.
Complications:-
Emphysema can increase the severity of other chronic conditions, such as diabetes and heart failure. If you have emphysema, air pollution or a respiratory infection can lead to an acute COPD exacerbation, with extreme shortness of breath and dangerously low oxygen levels. You may need admission to an intensive care unit and temporary support from an artificial breathing machine (ventilator) until the infection clears.
Pathophysiology:-
In normal breathing, air is drawn in through the bronchi and into the alveoli, which are tiny sacs surrounded by capillaries. Alveoli absorb oxygen and then transfer it into the blood. When toxicants, such as cigarette smoke, are breathed into the lungs, the harmful particles become trapped in the alveoli, causing a localized inflammatory response. Chemicals released during the inflammatory response (e.g., elastase) can eventually cause the alveolar septum to disintegrate. This condition, known as septal rupture, leads to significant deformation of the lung architecture. These deformations result in a large decrease of alveoli surface area used for gas exchange. This results in a decreased Transfer Factor of the Lung for Carbon Monoxide (TLCO). To accommodate the decreased surface area, thoracic cage expansion (barrel chest) and diaphragm contraction (flattening) take place. Expiration increasingly depends on the thoracic cage and abdominal muscle action, particularly in the end expiratory phase. Due to decreased ventilation, the ability to exude carbon dioxide is significantly impaired. In the more serious cases, oxygen uptake is also impaired.
As the alveoli continue to break down, hyperventilation is unable to compensate for the progressively shrinking surface area, and the body is not able to maintain high enough oxygen levels in the blood. The body’s last resort is vasoconstricting appropriate vessels. This leads to pulmonary hypertension, which places increased strain on the right side of the heart, the side responsible for pumping deoxygenated blood to the lungs. The heart muscle thickens in order to pump more blood. This condition is often accompanied by the appearance of jugular venous distension. Eventually, as the heart continues to fail, it becomes larger and blood backs up in the liver.
Patients with alpha 1-antitrypsin deficiency (A1AD) are more likely to suffer from emphysema. A1AD allows inflammatory enzymes (such as elastase) to destroy the alveolar tissue. Most A1AD patients do not develop clinically significant emphysema, but smoking and severely decreased A1AT levels (10-15%) can cause emphysema at a young age. The type of emphysema caused by A1AD is known as panacinar emphysema (involving the entire acinus) as opposed to centrilobular emphysema, which is caused by smoking. Panacinar emphysema typically affects the lower lungs, while centrilobular emphysema affects the upper lungs. A1AD causes about 2% of all emphysema. Smokers with A1AD are at the greatest risk for emphysema. Mild emphysema can often develop into a severe case over a short period of time (1–2 weeks).
Pathogenesis
Severe emphysemaWhile A1AD provides some insight into the pathogenesis of the disease, hereditary A1AT deficiency only accounts for a small proportion of the disease. Studies for the better part of the past century have focused mainly upon the putative role of leukocyte elastase (also neutrophil elastase), a serine protease found in neutrophils, as a primary contributor to the connective tissue damage seen in the disease. This hypothesis, a result of the observation that neutrophil elastase is the primary substrate for A1AT, and A1AT is the primary inhibitor of neutrophil elastase, together have been known as the “protease-antiprotease” theory, implicating neutrophils as an important mediator of the disease. However, more recent studies have brought into light the possibility that one of the many other numerous proteases, especially matrix metalloproteases might be equally or more relevant than neutrophil elastase in the development of non-hereditary emphysema.
The better part of the past few decades of research into the pathogenesis of emphysema involved animal experiments where various proteases were instilled into the trachea of various species of animals. These animals developed connective tissue damage, which was taken as support for the protease-antiprotease theory. However, just because these substances can destroy connective tissue in the lung, as anyone would be able to predict, doesn’t establish causality. More recent experiments have focused on more technologically advanced approaches, such as ones involving genetic manipulation. One particular development with respect to our understanding of the disease involves the production of protease “knock-out” animals, which are genetically deficient in one or more proteases, and the assessment of whether they would be less susceptible to the development of the disease. Often individuals who are unfortunate enough to contract this disease have a very short life expectancy, often 0–3 years at most.
Prognosis and treatment
Emphysema is an irreversible degenerative condition. The most important measure to slow its progression is for the patient to stop smoking and avoid all exposure to cigarette smoke and lung irritants. Pulmonary rehabilitation can be very helpful to optimize the patient’s quality of life and teach the patient how to actively manage his or her care. Patients with emphysema and chronic bronchitis can do more for themselves than patients with any other disabling disease.
Emphysema is also treated by supporting the breathing with anticholinergics, bronchodilators, steroid medication (inhaled or oral), and supplemental oxygen as required. Treating the patient’s other conditions including gastric reflux and allergies may improve lung function. Supplemental oxygen used as prescribed (usually more than 20 hours per day) is the only non-surgical treatment which has been shown to prolong life in emphysema patients. There are lightweight portable oxygen systems which allow patients increased mobility. Patients can fly, cruise, and work while using supplemental oxygen. Other medications are being researched, and herbal organic remedies are being offered by companies.
Lung volume reduction surgery (LVRS) can improve the quality of life for certain carefully selected patients. It can be done by different methods, some of which are minimally invasive. In July 2006 a new treatment, placing tiny valves in passages leading to diseased lung areas, was announced to have good results, but 7% of patients suffered partial lung collapse. The only known “cure” for emphysema is lung transplant, but few patients are strong enough physically to survive the surgery. The combination of a patient’s age, oxygen deprivation and the side-effects of the medications used to treat emphysema cause damage to the kidneys, heart and other organs. Transplants also require the patient to take an anti-rejection drug regimen which suppresses the immune system, and so can lead to microbial infection of the patient. Patients who think they may have contracted the disease are recommended to seek medical attention as soon as possible.
A study published by the European Respiratory Journal suggests that tretinoin (an anti-acne drug commercially available as Retin-A) derived from vitamin A can reverse the effects of emphysema in mice by returning elasticity (and regenerating lung tissue through gene mediation) to the alveoli.
While vitamin A consumption is not known to be an effective treatment or prevention for the disease, this research could in the future lead to a cure. A follow-up study done in 2006 found inconclusive results (“no definitive clinical benefits”) using Vitamin A (retinoic acid) in treatment of emphysema in humans and stated that further research is needed to reach conclusions on this treatment…..click & see
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Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
Resources:
http://en.wikipedia.org/wiki/Emphysema
http://www.mayoclinic.com/health/emphysema/DS00296
