Smaller conducting airways are a major site of obstruction in COPD and studies have shown that in smokers there are structural abnormalities in small airways whether they have COPD or not.
Furthermore, a correlation between severity of COPD and extent of airway occlusion by inflammatory mucus exudates is observed. Inflammation and peribronchial fibrosis contribute to the fixed obstruction of the small airways in COPD, as well as the progression of the inflammation which may result to destructed alveolar attachments on small airways outer walls.
Symptoms & Effects
COPD in general makes it much harder to breathe, symptoms usually do not appear until there is severe lung damage and they usually get worse over time especially if tobacco use or exposure continues. There are many symptoms that may be mild at first, but could progress and become constant making it even more difficult for the patient to breathe and carry out day-to-day activities. For symptoms are mild at first could be easily mistaken for a cold.
Symptoms usually begin with intermittent coughing and shortness of breath. Other early symptoms consist of occasional loss of breath that occurs during or after physical activities. Coughing although mild is still recurrent and the patients feel the need to clear their throat often especially in the morning.
After some time, symptoms can get worse and harder to ignore, as the lungs get more damaged. Latter symptoms include shortness of breath even after mild physical activity such as walking up the stairs. Wheezing is heard, especially during exhalations and the chest tightens. Coughing becomes more common and chronic whether there is mucus or not. Mucus from patient’s lungs needs to be cleared every day and the patient is more susceptible to colds, flu or other respiratory infections. Furthermore, the patients have a lack of energy.
In later stages of COPD symptoms may also consist of fatigue, swelling of feet, ankles or legs and noticeable, unexpected weight loss. The patient may experience wheezing and tightness in the chest or have excess sputum production. Some people with COPD have acute exacerbations, which are flare-ups of severe symptoms.
Very severe symptoms and signs that should be taken care of immediately include lips and fingernails cyanosis as this indicates low blood oxygen levels. Also, if the patient has trouble catching his breath or cannot talk, he feels confused, muddled or faint and he has a high heart rate medical investigation should begin immediately. However, patients may have periods of exacerbation where symptoms suddenly worsen and become more persistent even at earlier stages.
These periods usually last several days or more and can occur around five times per year especially during Winter. As the disease progresses the patient is more susceptible to heart problems, high blood pressure in lung arteries and even lung cancer. Once the diagnosis is made the patient has to make appropriate life changes in order to maintain a good quality of life. Usually early symptoms can be easily managed. As the disease progresses symptoms can be highly limiting and people with severe grade of COPD may not even be able to take care of themselves.
Furthermore, they are at high risk of respiratory infections, heart problems and lung cancer. COPD generally reduces life expectancy, although it varies from patient to patient. People with COPD who do not smoke usually have a modest reduction of life expectancy while former and current smokers have a big reduction. Another factor affecting extend of life expectancy reduction is how well the patient responds to treatment and whether serious complications can be avoided.
Nutritional Abnormalities including caloric intake, BMR, intermediate metabolism and body composition alterations are very common in COPD. About 50% of patients with severe COPD experience unexplained weight loss, while another 10-15% of patients with mild to moderate COPD may also lose weight.
The weight loss is usually skeletal muscle mass and rarely due to fat loss. However, alterations in body composition may also occur even if there is no major weight loss. Very rarely these abnormalities can be due to decreased caloric intake as this does not usually appear to be prominent in COPD patients unless they are going through exacerbation episodes. Furthermore, most COPD patients have an increased BMR which further contributes to weight loss and might be due to increased work of breathing, treatment drugs, systemic inflammation or in extreme cases tissue hypoxia.
Skeletal Muscle Dysfunction is also common, contributing to a large extent to low exercise capacity and reduced life quality. Respiratory muscles on the other hand appear to behave differently, probably due to the different conditions under the two muscle types work in these patients. Skeletal muscles are generally underused while the diaphragm is constantly working against an increased load.
Alterations of nervous system are also observed as the energy metabolism of the brain is altered in these patients and depression is highly prevalent. Autonomic nervous system may also be altered especially in those with low body weight. Dementia may also develop as low oxygen and high carbon dioxide levels can harm the brain. Finally, osteoporosis prevalence is increased in COPD as pro-inflammatory cytokines can significantly alter bone metabolism.
Another common complication is pneumonia which occurs when germs enter the lungs creating an infection. In a patient with an already weakened pulmonary system this could be fatal as it causes further inflammatory damage to the lungs leading to a chain reaction of illnesses that can weaken the lungs even further leading to a rapid deterioration and eventually respiratory failure which is found to be the most common cause of death in COPD patients.
One of the most critical complications in COPD is heart failure as it is the second most common COPD- related cause of death. People suffering from COPD have lower oxygen levels in their bloodstream and lung function which is closely related to heart function. According to American Thoracic Society the above symptoms can lead to severe pulmonary hypertension causing right-sided heart failure in 5-10% of people with advanced COPD. Furthermore, many of the symptoms of heart failure are similar or even the same to those of COPD making it difficult for the patient to recognise that they actually suffer from heart issues.
One of the most severe problems that are thought to be related to COPD is lung cancer and is also found to be the third most common cause of death in COPD patients. Both diseases have common risk factors with number one risk factor being smoking. Also both diseases are thought to be associated with some genetic predisposition.
In 2009 it was estimated that between 40-70% of people with lung cancer also had COPD and this same study concluded that COPD is a major risk factor for lung cancer. Another study carried out in 2015 suggests that COPD and lung cancer may actually be different aspects of the same disease and that COPD is a driving factor leading to lung cancer. Furthermore, there have been many cases where patients did not know they had COPD until they were diagnosed with lung cancer. However, being a COPD patient does not mean that lung cancer will develop, although it does mean there is higher risk.
COPD is the third leading cause of death in the US as doctors usually are not able to give exact prognosis after a patient is diagnosed with COPD. However, all of the above complications can be prevented with close monitoring and management of symptoms in order to slow COPD progression.
Diagnosis, Stages & Prognosis
There is no single test for COPD therefore in order to diagnose a patient with Chronic Obstructive Pulmonary Disease clinical history must be taken, carry out a physical examination and then proceed to further diagnostic testing to confirm whether the patient suffers from COPD as suspected and exclude any differential diagnosis.
Common differential diagnosis includes asthma, congestive heart failure, bronchiectasis, bronchiolitis obliterans, cystic fibrosis and tuberculosis. The main tool for diagnosis of COPD is the spirometer. Spirometry test is a simple, non-invasive and easy test that measures how well the patient’s lungs work. Furthermore, spirometry is recommended prophylactically to current or former smokers or people who have been exposed to harmful lung irritants for a long period or have alpha-1 Antitrypsin deficiency as COPD is not usually detected until in the moderate stage.
Also, it can be used to check how the disease progresses and monitor how well treatment works. During spirometry the patient has to blow all the air out of his lungs into a mouthpiece and the spirometer will calculate the amount of air blown out the first second, represented as FEV1 and the air blown out in 6 seconds or more represented as FVC. People with COPD usually have an FEV1/FVC ration less than 70% with FEV1 percentage indicating the severity of the obstruction.
Beyond spirometry complete pulmonary function testing that include lung volume, diffusing capacity and pulse oximetry measurement, may be used to distinguish COPD from asthma. Other methods of diagnosing COPD include chest X-ray which can show emphysema and also rule out other lung problems or heart failure.
A CT scan can also help detect emphysema and determine whether the patient would benefit from a surgery. Another very important test is arterial blood gases analysis which measures how well lungs transfer oxygen to blood and remove carbon dioxide and is recommended to rule out severe hypoxemia or hypercapnia in patients with more severe COPD. A blood test is also recommended to rule out any other conditions that have similar symptoms to COPD and also check whether alpha-1 antitrypsin deficiency is present, this is usually done for people who develop COPD symptoms at a younger age, before 45.
Spirometry is not only used for diagnosis but also for grading COPD. GOLD and NICE classifications are used for determining severity in order to help form a prognosis and make the best treatment plan for each patient. GOLD classification is based on FEV1 results (severity increases as FEV1 decreases), the patient’s individual symptoms and the history of acute exacerbations. GOLD classification consists of four grades from mild to very severe.
In all four stages the FEV1/FVC ratio is expected to be less than 70%. In mild stage FEV1 appears to be at least 80% of predicted value and the patient may have some symptoms. In moderate stage FEV1 is between 50% and 80% of predicted value and the patient may have chronic symptoms.
In severe stage FEV1 is expected to be between 30% and 50% of predicted value and the patient may present with chronic symptoms. In very severe stage FEV1 is less than 30% of predicted value, except in some cases where it is found to be less than 50% but very severe chronic symptoms are observed in both cases. Although these stages are very useful for prognosis and treatment they cannot determine how long the patient is expected to live or to what extend the symptoms will affect the quality of life.
Prognosis is affected by many factors. Some people may live for months while others could live for years. However, life expectancy depends on patient’s age at the time of diagnosis and other health issues the patient may have, while lifestyle plays a major role. People with moderate to severe COPD usually have a lower life expectancy despite their age.