Emphysema

Emphysema

Emphysema is a chronic or long term lung disease. This disease is typically called hyperinflation.

What happens in emphysema?

Just like a balloon the lungs are over-inflated so that they lose their elasticity and elastic recoil. There are balloon like bullae or blisters in the lung tissues.

 Because carbon dioxide is trapped in the bullae, the body is deprived of fresh air flowing into the lungs. The lungs begin by compensating by taking deeper breaths.

This further expands the lung tissues and makes it lose its elasticity. With loss of elasticity more carbon dioxide accumulates in the lungs leaving less space for fresh air and this leads to shortness of breath.

With time the muscles and ribs begin to expand to contain the expanded lungs. The diaphragm that lies beneath the lungs and is normally dome shaped also flattens and lose their functional capacity.

Causes of emphysema

One of the most important causes of emphysema is cigarette smoking. Other causes include air pollution, work hazards, and lung infections.

Cigarette smoke changes the structure and function of the lungs by causing irritation and inflammation of the narrow airways. This leads release of enzymes in the lungs that destroy lung tissues and an increased size in the air sacs eventually leading to emphysema.

The destroyed lung tissues form bullae (holes) and lose elasticity - a typical finding in emphysema.

Alpha-1 antitrypsin deficiency is a rare genetic condition where there are decreased levels of the protective protein, alpha-1 antitrypsin. Alpha-1 antitrypsin protects the lungs from the destructive effects of enzymes. Patients who lack this enzyme thus have lungs that are damaged by enzymes called elastases at an early age.

Diagnosis and treatment of emphysema

Emphysema is typically characterized by shortness of breath and wheezing. It is now considered to be a part of chronic obstructive lung disease. The destruction of lung tissue seen with emphysema leads to a reduction in the functional capacity of the lungs.

Early diagnosis and management can help prevent gross damage to the lungs. Several breathing tests as well as imaging studies like X rays are used in diagnosing emphysema.

Medical treatment for emphysema includes:-

  • Bronchodilators – these are drugs that open up the narrowed airways to allow for more oxygen intake into the lungs. There are several types of bronchodilators. Beta 2 agonists include Salbutamol, Salmeterol etc. Antimuscarinic agents that are one of the important agents used include Ipratropium and Tiotropium. Theophyliline is another group of bronchodilators that is administered orally as pills rather than by inhalation as with other bronchodilators.
  • Steroids – These may be given by inhalation, pills (during flare ups) and even by injection during severe cases. They reduce inflammation within the lungs.
  • Antibiotics are recommended on in case of lung infections during flare ups.
  • Oxygen therapy.

Surgery

Lung transplantation and lung volume reduction surgery are surgical options that are available. These should be used only when the use of all medical treatments as well as pulmonary rehabilitation have been tried and symptoms continue to persist.

Emphysema Pathology and Function

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease. It is typically characterized by cough, breathlessness and production of mucus. Emphysema and bronchitis (chronic) may both lead to COPD. In both conditions there is severe lack of oxygen in the air sacs of the lungs.

Pathology

There is gross destruction of the air sacs or the alveoli in emphysema. There is persistent over-inflation that leads to damage to the elasticity of the lungs.

The lungs are like a balloon. In emphysema the lungs are over-inflated so that they lose their elasticity and elastic recoil. There are balloon-like bullae or blisters in the lung tissues. Because carbon dioxide is trapped in the bullae, the body is deprived of fresh air flowing into the lungs.

The lungs begin to cope with this lack of fresh air by taking deeper breaths. This further expands the lung tissues and makes it lose its elasticity. With loss of elasticity more carbon dioxide accumulates in the lungs leaving less space for fresh air and this leads to shortness of breath.

With time the muscles and ribs begin to expand to contain the expanded lungs. The diaphragm that lies beneath the lungs and is normally dome shaped also flattens and lose their functional capacity.

Causes of emphysema and its relation with pathology

One of the most important causes of emphysema is cigarette smoking. Other causes include air pollutants, inhalation of chemicals, fumes, dust etc.

Cigarette smoke changes the structure and function of the lungs by causing irritation and inflammation of the narrow airways. This leads release of enzymes in the lungs that destroy lung tissues and an increased size in the air sacs eventually leading to emphysema. The destroyed lung tissues form bullae (holes) and lose elasticity.

Alpha-1 antitrypsin deficiency is a rare genetic condition where there are decreased levels of the protective protein, alpha-1 antitrypsin. Alpha-1 antitrypsin protects the lungs from the destructive effects of enzymes. Patients who lack this enzyme thus have lungs that are damaged by enzymes called elastases at an early age.

Apart from chronic inflammation caused by irritation there is also a theory of increased oxidative stress that can contribute to increased destruction and/or impaired lung maintenance and repair in emphysema.

The major consequence of the oxidative stress is thought to be the activation of the transcription factor nuclear factor-kB. This in turn activates proinflammatory cytokine transcription that causes destruction of the lungs. Cigarette smoking also inhibits histone deacetylase. This also promotes the release of proinflammatory cytokines.

A theory goes that there is an imbalance between proteases (protein break down enzymes) and antiproteases in emphysema. A delicate balance between protease and antiprotease activity is required for proper lung maintenance. When this balance changes there is increased destruction and inappropriate repair of lungs leading to emphysema.

Emphysema Pathogenesis

While 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. Perhaps the most interesting 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.

Sourced and Abstracted from information found at Wikipedia (Creative Commons Attribution-ShareAlike License), CDC, NIH.

Emphysema Treatment

Emphysema is one of the common lung diseases that form part of the chronic obstructive pulmonary disease (COPD). The management of this condition includes lifestyle changes, exercises, pulmonary rehabilitation as well as pharmacotherapy and surgery.

Cessation of smoking

Smoking (as well as passive exposure to cigarette smoke) remains one of the best known and most closely associated causes of emphysema. The first step to treating emphysema is to quit smoking.

Nicotine replacement therapy and other smoking cessation aids and medications may be used to stop smoking.

Studies like the Lung Health Study have shown that stopping smoking at any time even after diagnosis of emphysema may help reduce the risk of progression of lung damage.

Lifestyle changes

Healthy lifestyle habits include a healthy balanced diet as well as regular physical exercise. Patients are encouraged to avoid dust, air pollutants, exposure to second hand smoke etc.

Regular immunizations

Some regular immunizations are necessary for emphysema patients. These include immunization against influenza with annual influenza vaccination and immunizations against pneumococcal infections at least once and repeated in 5-10 years. This is particularly important for people over the age of 50.

Pulmonary rehabilitation program

A pulmonary rehabilitation program may be suggested in patients living in areas where community respiratory services are available.

Oxygen therapy is administered to maintain the normal blood levels of oxygen. The goal of oxygen therapy is to maintain PaO2 ≥ 60 mmHg or SpO2 ≥ 90% at rest. Oxygen therapy may be a useful addition to pulmonary rehabilitation

Medication in management of emphysema

The management of emphysema is similar to management of COPD. The main treatment is with the use of bronchodilators. These help in opening up of the narrowed airways and thus provide relief from breathlessness by increasing fresh air flow into the lungs.

  • Bronchodilators – these may be a short-acting inhaled beta2 agonist like Salbutamol or antimuscarinic inhaled agent like ipratropium. In mild cases they are to be used as needed. Ipratropium is the first step in therapy. For moderate to severe cases regular use of ipratropium or a long-acting antimuscarinic agent tiotropium or long-acting beta2 agonist (LABA) like Salmeterol, Formoterol etc. are advised. Concurrent use of tiotropium and ipratropium is not recommended.
  • Mucolytic medicine is given as tablets or syrup and makes sputum thinner and runnier, making it easier to cough up.
  • Corticosteroids – these reduce the inflammation within the lungs. For patients with moderate to severe COPD with a history of exacerbations that occur more than one per year on average, for two consecutive years, inhaled corticosteroids (e.g. budesonide, fluticasone etc.) may be advised. These can be used regularly in combination with tiotropium and LABA therapy to reduce exacerbations. For flare ups and exacerbations, oral or injectable steroids may be used
  • Theophylline is another group of bronchodilator that is taken as pills. These are advised in patients with persistent symptoms despite optimal inhaled therapy.
  • Antibiotics – these are prescribed for the lung infections that are common in patients with emphysema. The common microbes that affect these patients include H. influenzae, S. pneumonia, C. pneumoniae, and M. pneumoniae. These agents are effectively treated with macrolides, fluoroquinolones, second generation cephalosporins, cotrimoxazole, or doxycycline for five to seven days.