What is COPD? What causes Chronic Obstructive Pulmonary Disease?

human-lungs-diagram
 
COPD – short for chronic obstructive pulmonary disease – is a chronic lung condition that is usually associated with tobacco smoking.
 
COPD is a collection of separate lung conditions – usually both chronic bronchitis and emphysema – which cause airflow limitation, i.e. difficulty breathing.1-4
 
Contents of this article:
 
COPD facts, statistics and anatomy
Causes, symptoms and diagnosis of COPD
Treatments for COPD, prevention and management
Fast facts on COPD
Here are some key points about COPD. More detail and supporting information is in the main article.
COPD is a group of diseases that includes chronic bronchitis and emphysema
Most cases of COPD are a result of tobacco smoking
Symptoms of COPD include shortness of breath, coughing and production of sputum
COPD is a progressive and incurable disease, and the third largest cause of death in the US
In 2010, more than 70,000 women died of COPD in the US, compared to more than 64,000 males11
A single symptom of COPD (such as cough, shortness of breath) often arises long before other symptoms.
The lungs of people with COPD suffer structural damage that causes the tiny air sacs to enlarge and become less efficient
Diagnosis is confirmed by a clinical test called spirometry, which measures by how much the breathing is limited
The main way to prevent COPD developing is to avoid smoking
Any patient with COPD can benefit from smoking cessation and there are medical interventions, including drugs, to help with this
COPD cannot be reversed but its symptoms can be eased by drug treatment
Drug treatments are usually inhaled, and most act as bronchodilators through muscle relaxation to ease breathing by opening up the lungs
Other therapy options include pulmonary rehabilitation, oxygen therapy, and surgery
Exacerbations and complications of COPD are an unusual worsening of symptoms and can be life-threatening. Healthcare professionals help patients to prevent complications as far as possible.
What is COPD?[Human lungs diagram]
COPD is irreversible and most often caused by smoking.
COPD stands for chronic obstructive pulmonary disease:
 
Chronic because it is ongoing – it persists lifelong without being fully reversible
Obstructive because normal breathing capacity is restricted
Pulmonary because it pertains to the lungs – it is a respiratory disease.
Chronic bronchitis is continual irritation and inflammation of the lining of the lungs, causing them to thicken and secrete mucus. The diagnosis is made if cough or mucus production persists for long enough.4
 
Emphysema is damage to the structure of the lung in which the walls of the air sacs are destroyed, making the air spaces larger and less efficient.4
 
The airflow limitation in COPD is usually progressive – it gets worse over time – and is associated with an abnormal inflammatory response of the lungs to noxious particles or gases.4 The condition does not change much over the course of several months.3
 
Leading cause of illness and death
The American Lung Association says COPD is the third-leading cause of death in the US, claiming the lives of 134,676 Americans in 2010.11
 
The World Health Organization (WHO) has estimated that prevalence of COPD in the US rose by 41% between 1982 and 1994, with death rates going up by 71% between 1966 and 1985. It also estimates that COPD is responsible for 4.8% of all deaths – or an estimated 2,745,816 deaths in 2002.4
 
In 2011, 12.7 million US adults (aged 18 and over) were estimated to have COPD, but almost 24 million adults in the US have evidence of impaired lung function, suggesting that COPD is underdiagnosed.12,13
 
Increasingly, women are more likely to be affected by COPD, with 2010 the eleventh year in which rates of COPD-related deaths in women have exceeded deaths in men.11 In fact, women are twice as likely as men to be diagnosed with chronic bronchitis, and more women than men are now diagnosed with emphysema (a disease that was historically more prevalent in men).
 
The 2011 statistics for men and women are as follows:13
 
Chronic bronchitis – 3.3 million men/6.8 million women
Emphysema – 2.1 million men/2.6 million women.
Recent development in COPD statistics
COPD cases to rise over next decades
A 2013 report from the European Respiratory Society says the number of people living with COPD will continue to rise.
Anatomy of COPD lung diseaseAlveoli in lungs
The deepest part of the lungs end in tiny air sacs, where gases enter and leave tiny blood vessels. The walls of these sacs are damaged in COPD.
In COPD, the chief site of damage to the anatomy of the lungs occurs in the small airways – the deepest part of the lung tissue which contains no cartilage and where the internal diameter of the tubes is less than two millimetres.6
 
The normal anatomy of the normal lungs is designed to maximise the surface area over which gaseous exchange can occur. This is why the tubes branch off into smaller and smaller diameters, leading to a large number of tiny air sacs.
 
The larger the total surface area of the membrane between air sacs and blood vessels, the greater the efficiency of gaseous exchange, whereby oxygen can enter the circulation and carbon dioxide can leave it. The more sacs, the greater the surface area.
 
In COPD, the air sacs become larger and less numerous because of the breakdown of their walls, reducing the overall surface area of the air-blood barrier (or alveolar-capillary barrier – the air sacs are called alveoli and the small blood vessels are called capillaries).
 
 
Doctors are shown summarizing COPD in the short video below from YouTube, produced by the pharmaceutical company Novartis.
 
COPD: Causes, Symptoms and Diagnosis
 
Causes of COPD
The prevalence of COPD among populations in different countries is directly related to levels of tobacco smoking. In some countries, a key contributor to COPD is polluted air caused by indoor burning of wood and other biomass fuels.7
 
While smoking is the most important risk factor, not every case of COPD is caused by it, and not every smoker develops the disease. Estimates show that at around 85-90% of people with COPD have been smokers at some point in their lives.4
 
Man coughing with cigarette in his hand
Almost everyone with COPD has been a smoker at some point.
Genetics also play a part in COPD. A family history of the disease increases the risk that a smoker will also develop the condition – for example, if a sibling has COPD.3,4
 
A small number of cases (about 2-3%) are caused by a genetic condition known as alpha-1 antitrypsin (AAT) deficiency, and the risk of COPD in people with this predisposition is raised further by tobacco smoking. In anyone with AAT deficiency, emphysema is almost inevitable as AAT is a key lung protectant produced by the liver. 3,4
 
Environmental air pollution in western countries (as opposed to the kind of pollution seen indoors in other countries, as discussed above) is also a risk factor, but it is thought to be very small in comparison to tobacco smoke.3
 
Symptoms of COPD
The airflow limitation caused by lung damage in COPD produces characteristic symptoms:1,7
 
Breathlessness, especially after exertion, that is chronic and progressively worsening
Cough
Production of sputum.
Breathlessness, or dyspnea, is a central symptom that is described as an increased effort to breathe, heaviness, ‘air hunger,’ or gasping.7
 
Cough or sputum production sometimes arises years before the difficulty with breathing, sometimes years before. Conversely, the breathing problems can come on alone, unaccompanied by the other symptoms.7
 
Man coughing
Cough is one of the three classic symptoms of COPD but it does not occur in every case.
The symptom of coughing, while being part of COPD, may be dismissed by people who smoke as a direct consequence of smoking rather than an indication of the lung disease.7
 
The production of sputum is an indication of the development of chronic bronchitis, with diagnostic guidelines suggesting that sputum production lasting more than 3 months within 2 consecutive years can indicate COPD. However, there is more variability in the symptoms of COPD than in simple bronchitis.7
 
Finally, wheezing (whistling sound during breathing) and a feeling of chest tightness – also symptoms of asthma – may be experienced by people with COPD.7
 
The American non-profit the COPD Foundation has produced an online tool to help give an indication of whether symptoms indicate a COPD diagnosis.
 
The online screening tool asks five questions about symptoms and risk factors, including shortness of breath, coughing and smoking history.
 
Tests and diagnosis of COPD
Doctors follow internationally established guidelines in the diagnosis of COPD, and they are trained to suspect the condition in any patient, particularly those aged 35 to 40 years or older, and who present with one or more of the following:7,8
 
Difficulty breathing/shortness of breath (dyspnea) that is progressive (worsens with time)
Persistent (chronic) cough, with or without the production of sputum
Persistent production of sputum
History of smoking or of exposure to other risk factors such as smoke from home cooking or heating, or work-related dust or chemicals
Family history of chronic lung disease.
Not all of these factors need to be present at the same time for a diagnosis of COPD to be suspected, and the sputum production, for example, can be intermittent.7,8
 
The diagnosis of COPD is then confirmed by a clinical test of breathing called spirometry. This measures the lung function in terms of the amount of air you can breathe out and the speed of the air flow as you do so.1
 
 
Spirometry lung function tests
To confirm that any lung function impairment is irreversible and so not caused by, for example, asthma, the spirometry test is performed before and after a patient inhales bronchodilator drugs.7-9
 
Spirometry involves taking in a deep breath before blowing out into a tube as hard as possible. The machine the tube is connected to takes two measurements of lung capacity:7,9
 
Forced expiratory volume in one second (FEV1) – the amount of air that is blown out in one second
Forced vital capacity (FVC) – the total amount of air that can be exhaled when blowing out hard.
The two readings are used to derive a ratio from the FEV1 reading divided by the FVC. If this ratio is 0.7 or under, COPD is confirmed.7,8
 
Sometimes the ratio is expressed as a percentage, so the diagnosis is made when the value is 70% or less.2
 
If the ratio is above 0.7, but risk factors remain, such as smoking history and breathing problems, this result will not rule out COPD, which may still be considered a risk.8
 
Pulmonologists, respiratory physicians, who manage COPD also consider ‘predicted’ values of lung function, comparing the spirometry test results for FEV1 with normal values that would be expected according to age, height and sex. Normal lungs generally can empty more than 80% of their volume in six seconds or less.3
 
The clinical results given are then worked out as a percentage of the predicted normal values. This percentage is used to indicate the severity of COPD, as follows. In any patient with COPD already confirmed by an FEV1/FVC reading of 0.7:3,7,8
 
Mild (stage 1) COPD is an FEV1 of 80% or more of predicted value
Moderate (stage 2) – FEV1 of 50-79% predicted
Severe (stage 3) – FEV1 of 30-49% predicted
Very severe (stage 4) – FEV1 of less than 30% predicted.
Recent developments in COPD diagnosis
Doctors are missing chances to diagnose COPD
A 2014 study in The Lancet Respiratory Medicine suggests many patients could benefit from an earlier diagnosis of COPD if earlier signs of lung disease presented to doctors are tested by spirometry. The authors call for patients as well as doctors to take lung symptoms more seriously.
 
New blood marker may detect COPD earlier
Research in April 2012 suggested a protein biomarker could be used to detect COPD before it is picked up by lung function tests, although no blood test has yet been developed for clinical use.
Research to find smokers’ individual risk of COPD
The National Institutes of Health has backed research to find biomarkers of individual risk for COPD, with a grant worth $6.5 million in 2012.
 
COPD: Treatment and Prevention
 
reatment and prevention of COPD
COPD is an incurable and progressive lung disease, but there are management options that may:1,7,8
 
Ease symptoms
Reduce the rate of decline in lung function
Increase ability to undertake physical activities
Prevent complications.
 
Smoking cessation[Man crushing cigarettes]
Quitting smoking normally slows the progression of the disease.
Every patient with COPD who is addicted to nicotine should be offered help to quit smoking since smoking increases the rate of lung function decline. Quitting smoking can help improve symptoms and slow down disease progression.8
 
For patients who are motivated to stop smoking, supportive medical interventions are available, including:8
 
Individual and group counseling
Nicotine replacement therapy available over the counter, such as nicotine patches
Drugs available on prescription, such as bupropion (Zyban).
Since most cases of COPD are caused by exposure to tobacco smoke, cessation is also a preventive step.
 
 
Drug treatment
The role of pharmacological treatment in COPD is to:8
 
Reduce or eliminate symptoms
Increase ability to do physical activities
Reduce and prevent complications/exacerbations
Improve overall health status and quality of life.
Drug treatments do not, however, change the natural course of the disease. They do not cure COPD or reverse damaged lung function – the underlying decline in lung function will continue at the same rate.8
 
The drug doses are usually delivered directly to the lungs via inhaler devices – metered-dose inhalers (MDIs) or dry-powder inhalers (DPIs).8
 
The following drugs are prescribed for COPD:1,7,10
 
Bronchodilators (which relax the muscles to open the airways and make breathing easier)
Beta-agonists (which also act on muscles to open up the airways and ease breathing; there are short- and long-acting versions)
Anticholinergic drugs (also have a bronchodilator action)
Methylxanthines (also have a bronchodilator action)
Glucocorticoids (steroids that reduce inflammation).
Some inhalers deliver a combination of bronchodilators and glucocorticoids, recommended for more severe COPD.
 
More detailed information about each of these groups of drug treatment for COPD is available from the American Thoracic Society.10
 
Pulmonary rehabilitation
Pulmonary rehabilitation is a program organised by a multidisciplinary group of healthcare professionals that helps with daily activities and may include an exercise program, disease management training, and nutritional and psychological counseling.1,8
 
The rehabilitation program is individually designed to preserve social independence while living with COPD.
 
Oxygen therapy
If lung capacity is so reduced that it results in low blood oxygen levels, hypoxemia, long-term oxygen therapy may be needed to improve survival, exercise, sleep and mental ability.1,8
 
The oxygen is given via a mask or nasal prongs and the equipment can be used at home. It may be used at certain times of the day or continuously.1
 
Surgery
Surgical procedures are considered a last resort in the treatment of COPD and include the option of a lung transplant, a bullectomy and lung volume reduction surgery. A bullectomy is an operation to remove large air sacs that restrict breathing, while lung volume reduction surgery involves the removal of damaged lung tissue.8
 
Like any surgery, lung operations in COPD patients can lead to fatal and non-fatal complications, including infection and scarring, and can also increase symptoms.
 
Recent developments in COPD treatment
COPD drug Tudorza Pressair wins FDA approval
The FDA announced in July 2012 its approval for the sale of a new drug for the treatment of COPD, aclidinium bromide inhalation powder (Tudorza Pressair), for the long-term maintenance treatment of bronchospasm (airways constriction).
New inhaler drug approved by FDA for chronic COPD
The FDA announced in May 2013 its approval for the sale of a new drug for the treatment of COPD, fluticasone furoate and vilanterol inhalation powder (Breo Ellipta).
Managing the complications of COPD[lungs diagram turquoise]
A lung infection can cause COPD symptoms to worsen quickly.
Symptoms of COPD usually worsen slowly over time, but sometimes they can get worse suddenly, such as when the patient contracts a lung infection, including flu.1 Flu vaccination is recommended for all patients with COPD.
 
Exacerbations of COPD range from level one exacerbations treated at home, to those needing hospitalization, and to cases of respiratory failure. Exacerbations can lead to death.8
 
Exacerbations are defined as a decline in the patient’s baseline breathlessness, cough, and/or sputum that needs a change in treatment. The decline is beyond the typical day-to-day variability in symptoms that the patient experiences.8
 
One of the aims of pulmonary rehabilitation is to assist the individual COPD patient in the prevention of exacerbations and complications.
 
The 6-minute walking distance (6MWD) test is used to assess the impact of COPD on physical activity, with recent research finding that this test is predictive of survival rate in patients.14 In this study, 237 patients with severe COPD who were referred for pulmonary rehabilitation were assessed using the 6MWD and categorized into one of three groups: at least 250 m, 150 m to 249 m, 149 m or less.
 
After three years, 58% of the patients were still alive, with the following mean survival times for those in each of the above groups:14
 
At least 250 m – 42.2 months (3-year survival – 81%)
150-249 m – 37 months (3-year survival – 66%)
149 m or less – 27.8 months (3-year survival – 34%).
Following pulmonary rehabilitation, the average change in 6MWd was 62 m, with 72% of patients having an improvement of at least 30 m. The patients in the 149 m or less group who did not achieve the minimal improvement distance of 30 m had a much lower survival rate, as did those who were older, male and with a shorter initial 6MWD.14
 
Study links a healthy diet to lower risk of COPD
 
Smoking is the primary cause of chronic obstructive pulmonary disease in the US, accounting for 80-90% of all cases. For the remaining 10-20%, it is believed exposure to air pollution, secondhand smoke and genetic factors are involved. But in a new study published in The BMJ, researchers suggest an unhealthy diet could be a contributing factor.
man-crushing-cigarettes
Smoking and lung disease found to have genetic links
Chronic obstructive pulmonary disease is a global public health concern, and the third leading cause of death worldwide. New research published in The Lancet Respiratory Medicine suggests that genetic factors, as well as smoking, may trigger lung disease.
Another recent study found that combining resistance and endurance training has more significant benefits for people with COPD compared to resistance training alone.15 This study looked at 36 patients with moderate to severe COPD who underwent combined training, resistance training or no intervention for 12 weeks.
 
Those in the combined training group had a 19% improvement in muscle power, a 13% improvement in maximal exercise capacity, and reductions in heart rate and blood lactate (a measure of muscle fatigue) at a submaximal workload, in addition to the improvements in the 6MWD test and quality of life measurements seen in those just engaging in once-weekly resistance training.

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