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Obstructive lung disease
Classification and external resources
MeSH D008173

Obstructive lung disease is a category of respiratory disease characterized by airway obstruction.

MeSH includes the following in this category:[1]

Cystic fibrosis is sometimes also included in this category.[2]

FEV1/FVC ratio is usually decreased.

Contents

Overview table

Following is an overview of the main obstructive lung diseases. Chronic obstructive pulmonary disease is mainly a combination of chronic bronchitis and emphysema, but may be more or less overlapping with all conditions.[3]

Condition Main site Major changes Causes Symptoms
Chronic bronchitis Bronchus Hyperplasia and hypersecretion of mucus glands Tobacco smoking and air pollutants Productive cough
Bronchiectasis Bronchus Dilation and scarring of airways Persistent severe infections Cough, purulent sputum and fever
Asthma Bronchus
  • Smooth muscle hyperplasia
  • Excessive mucus
  • Inflammation
Immunologic or idiopathic Episodic wheezing, cough and dyspnea
Emphysema Acinus Airspace enlargement and wall destruction Tobacco smoking Dyspnea
Bronchiolitis
(subgroup of chronic bronchitis)
Bronchiole Inflammatory scarring and bronchiole obliteration Tobacco smoking and air pollutants Cough, dyspnea
Unless else specified in boxes then reference is [3]

Scope

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), also known as chronic obstructive airways disease (COAD) or chronic airflow limitation (CAL), is a group of illnesses characterised by airflow limitation that is not fully reversible. The flow of air into and out of the lungs is impaired.[4] This can be measured with breathing devices such as a peak flow meter or by spirometry. The term COPD includes the conditions emphysema and chronic bronchitis although most patients with COPD have characteristics of both conditions to varying degrees. Asthma being a reversible obstruction of airways is often considered separately, but many COPD patients also have some degree of reversibility in their airways.

In COPD, there is an increase in airway resistance, shown by a decrease in the forced expiratory volume in 1 second (FEV1) measured by spirometry. COPD is defined as a forced expiratory volume in 1 second to forced vital capacity ratio (FEV1/FVC) that is less than 0.7[5]. The residual volume, the volume of air left in the lungs following full expiration, is often increased in COPD, as is the total lung capacity, while the vital capacity remains relatively normal. The increased total lung capacity (hyperinflation) can result in the clinical feature of a "barrel chest" - a chest with a large front-to-back diameter that occurs in some individuals with COPD. Hyperinflation can also be seen on a chest x-ray as a flattening of the diaphragm.

The most common cause of COPD is cigarette smoking. COPD is a gradually progressive condition and usually only develops after about 20 pack-years of smoking. COPD may also be caused by breathing in other particles and gases.

The diagnosis of COPD is established through spirometry although other pulmonary function tests can be helpful. A chest x-ray is often ordered to look for hyperinflation and rule out other lung conditions but the lung damage of COPD is not always visible on a chest x-ray. Emphysema, for example can only be seen on CT scan.

The main form of long term management involves the use of inhaled bronchodilators (specifically beta agonists and anticholinergics) and inhaled corticosteroids. Many patients eventually require oxygen supplementation at home. In severe cases that are difficult to control, chronic treatment with oral corticosteroids may be necessary, although this is fraught with significant side-effects.

COPD is generally irreversible although lung function can partially recover if the patient stops smoking. Smoking cessation is an essential aspect of treatment[6]. Pulmonary rehabilitation programmes involve intensive exercise training combined with education and are effective in improving shortness of breath. Severe emphysema has been treated with lung volume reduction surgery, with some success in carefully chosen cases. Lung transplantation is also performed for severe COPD in carefully chosen cases.

Alpha 1-antitrypsin deficiency is a fairly rare genetic condition that results in COPD (particularly emphysema) due to a lack of the antitrypsin protein which protects the fragile alveolar walls from protease enzymes released by inflammatory processes.

Asthma

Asthma is an obstructive lung disease where the bronchial tubes (airways) are extra sensitive (hyperresponsive). The airways become inflamed and produce excess mucus and the muscles around the airways tighten making the airways narrower. Asthma is usually triggered by breathing in things in the air such as dust or pollen that produce an allergic reaction. It may be triggered by other things such as an upper respiratory tract infection, cold air, exercise or smoke. Asthma is a common condition and affects over 300 million people around the world[7]. Asthma causes recurring episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning.

Asthma is diagnosed by the characteristic pattern of symptoms.


A peak flow meter can record variations in the severity of asthma over time. Spirometry, a measurement of lung function, can provide an assessment of the severity, reversibility, and variability of airflow limitation, and help confirm the diagnosis of asthma[7].

Asthma is treated by identifying and removing the triggers that set it off, if possible. The main form of long term management involves the use of inhaled corticosteroids. Inhaled bronchodilators, particularly beta agonists are used to relieve and control symptoms by reducing muscle spasm around the airways. An alternative way to control mild asthma is with a leukotriene antagonist tablet.

Other obstructive lung diseases

In many parts of the world, the most common cause of obstructive lung disease is lung scarring after tuberculosis infection.

References

  1. ^ MeSH Obstructive+lung+disease
  2. ^ Restrepo RD (September 2007). "Inhaled adrenergics and anticholinergics in obstructive lung disease: do they enhance mucociliary clearance?". Respir Care 52 (9): 1159–73; discussion 1173–5. PMID 17716384. http://www.rcjournal.com/contents/09.07/09.07.1159.pdf. 
  3. ^ a b Table 13-2 in: Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson (2007). Robbins Basic Pathology: With STUDENT CONSULT Online Access. Philadelphia: Saunders. ISBN 1-4160-2973-7.  8th edition.
  4. ^ Kleinschmidt, Paul. "Chronic Obstructive Pulmonary Disease and Emphysema". http://www.emedicine.com/emerg/topic99.htm. Retrieved 2008-04-19. 
  5. ^ "GOLD – the Global initiative for chronic Obstructive Lung Disease disease". http://www.goldcopd.com/. Retrieved 2008-05-06. 
  6. ^ "What is chronic obstructive pulmonary disease (COPD)?". http://besttreatments.bmj.com/btuk/conditions/14422.html. Retrieved 2008-04-19. 
  7. ^ a b "GINA – the Global INitiative for Asthma". http://www.ginasthma.com. Retrieved 2008-05-06. 







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