COPD

Epidemiology

COPD (chronic obstructive pulmonary disease) is one of the leading causes of morbidity and mortality in the world 1. In 2005 there were 65 million people suffering from moderate to severe COPD worldwide, and in 2002 it was the 5th most common cause of mortality. There are around 900,000 diagnosed cases of COPD in the UK, but COPD is often goes undiagnosed resulting in a higher prevalence than is reported. As a result it is estimated that 3 million people suffer from COPD in the UK 12,14,15,16.

Pathophysiology

COPD is a disease of the lungs in which the patient experiences a degree of both emphysema and chronic bronchitis. In emphysema the walls between the alveoli (air sacs) deep in the lungs deteriorate resulting in larger, pathological air spaces called bullae. The lung surface area is reduced and the amount of gaseous exchange decreases; less oxygen moves into the blood causing the patient to become hypoxic and breathless. Chronic bronchitis is an abnormal inflammatory response caused by noxious gases and other airway irritants (especially particles in cigarette smoke) building up in the smaller airways (bronchioles) of the lungs. Large amounts of mucus are produced in an attempt to clear the airways, but eventually this and the inflammation and swelling only increases airway obstruction. COPD is a progressive disease which is essentially irreversible once the patient has symptoms 6,7,8.

Figure 1: a diagram showing the main changes in lung structure in bronchitis and emphysema

Symptoms

COPD has a large impact on quality of life and, over time, causes increased disability. The patient will find simple tasks like walking up the stairs or going to the corner shop difficult as they may rapidly become short of breath. Patients can find this hugely debilitating and feel they are confined at home, especially if they are receiving long-term oxygen therapy 15 hours a day to improve their hypoxia. They may become dependent on others to help with shopping and other daily activities of living.

In addition to this, COPD generates a huge financial burden in healthcare 2,3. With the ever aging population, the number of people suffering from COPD (the prevalence) is presumed to rise 4,5. The main symptoms experienced in COPD are shown in figure 2 9.

Figure 2: the main signs and symptoms of COPD

Causes

COPD is caused primarily by the inhalation of noxious particles and gases which, over a person’s lifetime, will cause inflammation and damage to the epithelium of the airways eventually resulting in permanent damage. One of the most common causes is cigarette and tobacco smoke. Other noxious particulates are from the atmosphere due to burning fuels for cooking or industry. Approximately 80% of COPD patients either currently smoke or have smoked in their lifetime. As COPD is irreversible, the patient will not be able to reverse the damage caused, but they can slow down the progression of the disease by stopping smoking 10,11.

Diagnosis

Although the symptoms described above are classic COPD symptoms, other respiratory conditions such as asthma could present in a similar way. Age is important here, as asthma as more likely to present in a younger person whilst COPD is primarily a disease of the older patient who may have been a smoker for many years. COPD is largely irreversible, so asthma can be ruled out by giving the patient a bronchodilator drug (e.g. salbutamol). If this does not completely reverse airway obstruction, then this suggests that COPD may be the underlying pathology.

The main diagnostic tool used is a spirometer. This machine conducts lung function tests to assess how much air in inhaled and exhaled and measures lung capacity. Other tests that can be carried out include a chest X-ray (CXR), CT (computed tomography) scan of the chest or an ABG (arterial blood gas) test. The CXR and especially the CT will show disease within the lung tissue and can also assess other organs such as the heart or large blood vessels. The ABG is done to assess levels of blood gases, chiefly oxygen and carbon dioxide. In a healthy person with normal lung function, arterial oxygen saturation should be 98-99%. Those with COPD tend to be hypoxic with an oxygen saturation of about 88-95% 13.

Prognosis

This depends on the severity and stage of the disease. Earlier stages have a better prognosis and patients will not have their life expectancy affected greatly. The more severe cases of COPD have a poorer prognosis with reduced life expectancy. Patients who receive lung transplants will have an average life expectancy of five years post-transplant. The mean age of death differs between those with mild and severe COPD. Mild cases have a mean age of death of 78.3 years whereas more severe cases of COPD have a mean age of death of 74.2 years 18.

Treatment

There is currently no cure for COPD. Treatment options aim to relieve symptoms, prevent complications, slow the progression of the disease and improve quality of life for the patient. Initially lifestyle changes are considered; these include smoking cessation and, where possible, avoiding triggers such as dust and toxic gases 17. This can slow the progression of the disease and further treatment can aim to treat and reduce the damage already caused.

One treatment plan available for COPD patients is Pulmonary Rehabilitation which offers a light exercise program to build muscle and improve breathing. A frequent problem with COPD patients is not acquiring adequate nutrition and calories due to the fatigue and dyspnea, so it is important to ensure the patient is supplemented with vitamins and nutrients as well as offering them advice and an eating plan to meet their nutritional requirements 17.

Bronchodilators and steroid medications can also be given to COPD patients. Bronchodilaters are drugs inhaled by the patient from an inhaler. They bind to cells in the trachea and relax the muscle, therefore opening up the airways and reducing obstruction. There are two types of bronchodilators; short and long acting. Short acting bronchodilators work on average for 4-6 hours where as long acting work for around 12 hours. A common type of short acting bronchodilator is salbutamol which can be used whenever the patient feels breathless. This is also the treatment given to those with asthma. Acute symptoms will be treated with the short acting bronchodilators whereas the long acting bronchodilators will treat more severe COPD cases. In most chronic cases of COPD, the patients will be given steroidal inhalers. These also act to reduce inflammation in the airways and allow the airways to open up 17.

COPD patients are also often given oxygen therapy to counteract their hypoxia and improve oxygen delivery to their organs. The oxygen is given via a mask and enables the patient to breathe better as well as protecting their organs from ischemia 17.

Surgery for COPD patients is only considered when the treatments above are not able to reduce symptoms and the patient’s condition is worsening. There are three main surgical options for COPD patients: a bullectomy, lung volume reduction and lung transplant. In emphysema the walls between the alveoli deteriorate and cause the formation of bullae, which increase breathlessness in the patient. Therefore one option is to remove these bullae in a bullectomy so that breathing can resume more efficiently with the remaining healthy lung tissue. Lung volume reduction is a form of surgery which removes any damaged lung tissue, not just bullae, to help the patient breathe better. Lung transplants are considered when the entire lung is damaged and the patient is not responding to any other treatments. The healthy lungs are usually from a deceased donor and can greatly improve quality of life for the patient. The problem with any transplant is that the patient will be on anti-rejection medications for life which will suppress their immune system making them more prone to infections. Surgery and anaesthesia also have their own risks and the patient may struggle to recover after surgery or may not even survive 17.

References

1. Calverley PM, Walker P. (2003). Chronic Obstructive Pulmonary Disease. Lancet. 362 (9389): 1053-1061.
2. Sullivan SD, Ramsey SD, Lee TA. (2000). The economic burden of COPD. Chest. 117(Supplement 2): 5S–9S.
3. Ferrer M, Alonso J, Morera J, Marrades RM, Khalaf A, Aguar MC, Plaza V, Prieto L, Antó JM. (1997). Chronic obstructive pulmonary disease stage and health-related quality of life. The Quality of Life of Chronic Obstructive Pulmonary Disease Study Group. Annals of Internal Medicine. 1027(12): 1072-1079.
4. Murray CJ, Lopez AD. (1997). Alternative projections of mortality and disability by cause 1990-2020: Global Burden Study of Disease. Lancet. 349(9064): 1498-1504.
5. Feenstra TL, van Genugten ML, Hoogenveen RT, Wouters EF, Rutten-van Mölken MP. (2001). The impact of aging and smoking on the future burden of chronic obstructive pulmonary disease: a model analysis in the Netherlands. American Journal of Respiratory and Critical Care Medicine. 164(4): 590-596.
6. Pierson DJ. (2006). Clinical practice guidelines for chronic obstructive pulmonary disease: a review and comparison of current resources. Respiratory Care. 51(3): 277-288.
7. Kumar P, Clarke M. (2012). Clinical Medicine . 8th Edition. Spain: Elsevier. Pages 812-819.
8. National Heart Lung & Blood Institute. (2008). What is COPD?. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/copd/ (Last accessed: 31 January 2012).
9. Rycroft CE, Heyes A, Lanza L, Becker K. (2012). Epidemiology of chronic obstructive pulmonary disease; a literature review. International Journal of Chronic Obstructive Pulmonary Disease. 7: 457-494.
10. Global Initiative for Chronic Obstructive Lung Disease (GOLD). (2011). Global Strategy for the Diagnosis, Management and Prevention of Chronic Obstructive Pulmonary Disease (Revised 2011). Available at: http://www.goldcopd.org/uploads/users/files/GOLD_Report_2013_Feb20.pdf (Last accessed: 13 March 2013)
11. Fletcher C, Peto R. (1977). The natural history of chronic airflow obstruction. British Medical Journal. 1: 1645-1648.
12. Halbert RJ, Natoli JL, Gano A, Badamgarav E, Buist AS, Mannino DM. (2006). Global Burden of COPD: a systematic review and meta-analysis. European Respiratory Journal. 28(3): 523-532.
13. Pauwels RA, Buist AS, Calverley PM, Jenkins CR, Hurd SS, GOLD Scientific Committee. (2001). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Global Initiative for Chronic Obstructive Lung Disease (GOLD) Workshop summary. American Journal of Respiratory and Critical Care Medicine. 163(5): 1256-76.
14. Antó JM, Vermeire P, Vestbo J, Sunyer J. (2001). Epidemiology of chronic obstructive pulmonary disease. European Respiratory Journal. 17(5): 982-994.
15. Raherison C, Girodet PO. (2009). Epidemiology of COPD. European Respiratory Review. 18(114): 213-221.
16. World Health Organisation. (2013). Burden of COPD. Available at: http://www.who.int/respiratory/copd/burden/en/index.html (Last accessed: 17 February 2013).
17. National heart, lung and blood institute. (2015). Explore COPD. Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/copd/treatment (last accessed: 19 August 2015)
18. Medicinenet. (2015). What is the prognosis and life expectancy for a person with COPD? Available at: http://www.medicinenet.com/copd_chronic_obstructive_pulmonary_disease/page6.htm (last accessed: 24/08/2015)

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