Chronic obstructive pulmonary disease (COPD) is comprised primarily of three related conditions - chronic bronchitis, chronic asthma, and emphysema. In each condition there is chronic obstruction of the flow of air through the airways and out of the lungs, and the obstruction generally is permanent and may be progressive over time.
While asthma features obstruction to the flow of air out of the lungs, usually, the obstruction is reversible. Between "attacks" of asthma the flow of air through the airways typically is normal. These patients do not have COPD. However, if asthma is left untreated, the chronic inflammation associated with this disease can cause the airway obstruction to become fixed.
That is, between attacks, the asthmatic patient may then have abnormal air flow. This process is referred to as lung remodeling. These asthma patients with a fixed component of airway obstruction are also considered to have COPD.
Often patients with COPD are labeled by the symptoms they are having at the time of an exacerbation of their disease. For instance, if they present with mostly shortness of breath, they may be referred to as emphysema patients.
While if they have mostly cough and mucus production, they are referred to as having chronic bronchitis. In reality, it is better to refer to these patients as having COPD since they can present with a variety of lung symptoms.
There is frequent overlap among COPD patients. Thus, patients with emphysema may have some of the characteristics of chronic bronchitis and chronic asthma and vice a versa.
COPD symptoms from smoking
Typically, after smoking 20 or more cigarettes a day for more than twenty years, patients with COPD develop achronic cough, shortness of breath (dyspnea), and frequent respiratory infections.
Emphysema symptoms of COPD
In patients affected predominantly byemphysema, shortness of breath may be the major symptom. Dyspnea usually is most noticeable during increased physical activity, but as emphysema progresses, dyspnea occurs at rest.
Chronic bronchitis and bronchiectasis symptoms of COPD
In patients with chronic bronchitis as well as bronchiectasis, chronic cough and sputum production are the major symptoms. The sputum is usually clear and thick. Periodic chest infections can cause fever, dyspnea, coughing, production of purulent (cloudy and discolored) sputum and wheezing. (Wheezing is a high pitched noise produced in the lungs during exhalation when mucous, bronchospasm, or loss of lung elasticity obstructs airways.) Infections occur more frequently as bronchitis and bronchiectasis progress.
Advanced COPD symptoms
In advanced COPD, patients may develop cyanosis (bluish discoloration of the lips and nail beds) due to a lack of oxygen in blood.
They also may develop morning headaches due to an inability to remove carbon dioxide from the blood.
Weight loss occurs in some patients, primarily (another possibility is reduced intake of food) because of the additional energy that is required to breathe.
In advanced COPD, small blood vessels in the lungs are destroyed, and this blocks the flow of blood through the lungs. As a result, the heart must pump with increased force and pressure to get blood to flow through the lungs. (The elevated pressure in the blood vessels of the lungs is called pulmonary hypertension.) If the heart cannot manage the additional work, right heart failure also known as Cor pulmonale results and leads to swelling of the feet and ankles.
Patients with COPD may cough up blood (hemoptysis). Usually hemoptysis is due to damage to the inner lining of the airways and the airways' blood vessels; however, occasionally, hemoptysis may signal the development of lung cancer.
Cigarette smoking and second-hand smoke
Smoking is responsible for 90% of COPD in the United States. Although not all cigarette smokers will develop COPD, it is estimated that 15% will. Smokers with COPD have higher death rates than nonsmokers with COPD. They also have more frequent respiratory symptoms (coughing, shortness of breath, etc.) and a more rapid deterioration in lung function than non-smokers. It is important to note that when a COPD patient stops smoking, their decline in lung function slows to the same rate as a nonsmoker. Therefore, it is never "too late" to quit.
Effects of passive smoking or "second-hand smoke" on the lungs are not well-known; however, evidence suggests that respiratory infections, asthma, and symptoms are more common in children who live in households where adults smoke.
Cigarette smoking damages the lungs in many ways. For example, the irritating effect of cigarette smoke attracts cells to the lungs that promote inflammation. Cigarette smoke also stimulates these inflammatory cells to release elastase, an enzyme that breaks down the elastic fibers in lung tissue.
Air pollution can cause problems for persons with lung disease, but it is unclear whether outdoor air pollution contributes to the development of COPD. However, in the non-industrialized world, the most common cause of COPD is indoor air pollution. This is usually due to indoor stoves used for cooking.
Some occupational pollutants such as cadmium and silica do increase the risk of COPD. Persons at risk for this type of occupational pollution include coal miners, construction workers, metal workers, cotton workers, etc. (Most of this risk is associated with cigarette smoking and these occupations, an issue not well controlled for.
These occupations are more often associated with interstitial lung diseases, especially the pneumoconioses) Nevertheless, the adverse effects of smoking cigarettes on lung function are far greater than occupational exposure.
Alpha-1 antitrypsin deficiency
Another well-established cause of COPD is a deficiency of alpha-1 antitrypsin (AAT). AAT deficiency is a rare genetic (inherited) disorder that accounts for less than 1% of the COPD in the United States.
As discussed previously, normal function of the lung is dependent on elastic fibers surrounding the airways and in the alveolar walls. Elastic fibers are composed of a protein called elastin. An enzyme called elastase that is found even in normal lungs (and is increased in cigarette smokers) can break down the elastin and damage the airways and alveoli.
Another protein called alpha-1 antitrypsin (AAT) (produced by the liver and released into the blood) is present in normal lungs and can block the damaging effects of elastase on elastin.
The manufacture of AAT by the liver is controlled by genes which are contained in DNA-containing chromosomes that are inherited. Each person has two AAT genes, one inherited from each parent. Individuals who inherit two defective AAT genes (one from each parent) have either low amounts of AAT in the blood or AAT that does not function properly.
The reduced action of AAT in these individuals allows the destruction of tissue in the lungs by elastase to continue unopposed. This causes emphysema by age 30 or 40. Cigarette smoking accelerates the destruction and results in an even earlier onset of COPD.
Individuals with one normal and one defective AAT gene have AAT levels that are lower than normal but higher than individuals with two defective genes. These individuals MAY have an increased risk of developing COPD if they do not smoke cigarettes; however, their risk of COPD probably is higher than normal if they smoke.
Though their Alpha-1 antitrypsin blood levels may be in the normal range, the function of this enzyme is impaired relative to normal patient. Some may even develop bronchiectasis instead of emphysema.
The goals of COPD treatment are:
- to prevent further deterioration in lung function;
- to alleviate symptoms;
- to improve performance of daily activities and quality of life.
The treatment strategies include:
- quitting cigarette smoking;
- taking medications to dilate airways (bronchodilators) and decrease airway inflammation;
- vaccination against flu influenza andpneumonia;
- regular oxygen supplementation;
- pulmonary rehabilitation.
Quitting cigarette smoking
The most important treatment for COPD is quitting cigarette smoking. Patients who continue to smoke have a more rapid deterioration in lung function when compared to others who quit. Aging itself can cause a very slow decline in lung function. In susceptible individuals, cigarette smoking can result in a much more dramatic loss of lung function. It is important to note that when one stops smoking the decline in lung function eventually reverts to that of a non-smoker.
Unfortunately, only about one third of the patients can abstain from smoking long-term. Reasons for difficulty in quitting include nicotine addiction, stress in the workplace and at home, depression, peer pressure, and advertising from cigarette companies.
Nicotine in cigarettes is addictive and therefore cessation of smoking can cause symptoms of nicotine withdrawal including anxiety, irritability, anger, depression, fatigue, difficulty concentrating or sleeping, and intense craving for cigarettes.
Patients likely to develop withdrawal symptoms typically smoke more than 20 cigarettes a day, need to smoke shortly after waking up in the morning, and have difficulty refraining from smoking in non-smoking areas. However, some 25% of smokers can stop smoking without developing these symptoms. Even in those smokers who develop symptoms of withdrawal, the symptoms will decrease after several weeks of abstinence.
To help those patients with symptoms of withdrawal during the early weeks of smoking cessation, nicotine chewing gum (Nicorette Gum), nicotine inhalers, and nicotine skin patches (Habitrol, Nicoderm CQ, Nicotrol) are available in the United States. Nicotine replacement therapy can deliver enough nicotine into the blood to reduce but not totally eliminate withdrawal symptoms.
Nicotine replacement methods in conjunction with intense patient education and behavioral modification programs have improved the rates at which individuals quit smoking. Nicotine skin patches are easy to use. They generally are used for four to six weeks, sometimes with a tapering period of several additional weeks. The addiction potential of nicotine skin patches is low.
Sometimes a combination of several nicotine replacement therapies are utilized. It is important to note, that patients that continue to smoke while on replacement therapy are at increased risk for heart complications.
Bupropion (Zyban, Wellbutrin) is an antidepressant that has been found to decrease cravings for cigarettes. It has been shown to be of benefit to patients who want to quit smoking.
Varenicline (Chantix) is a medication is to aid in smoking cessation and has been approved for use in the US. Varenicline works in two ways; by cutting the pleasure of smoking and reducing the withdrawal symptoms that lead smokers to light up again and again. This medicine is taken over a 12 week course and can work in ways that bupropion does not.
In addition to nicotine withdrawal symptoms, quitting cigarette smoking also may lead to weight gain of about 8-10 pounds on average though more in some patients. Quitting smoking also can lead to depression and worsening of symptoms of chronic ulcerative colitis. Therefore quitting smoking should be undertaken with a doctor's supervision. Nevertheless, the benefits of quitting smoking (decreasing the rate of lung deterioration, decreasing risks of heart attack, lung cancer and other cancers, decreasing the chance of developing stomach ulcers, etc.) far outweigh these potential negative effects.
Treating airway obstruction in COPD with bronchodilators is similar but not identical to treating bronchospasm in asthma. Bronchodilators are medications that relax the muscles surrounding the small airways thereby opening the airways. Bronchodilators can be inhaled, taken orally or administered intravenously. Inhaled bronchodilators are popular because they go directly to the airways where they work. As compared with bronchodilators given orally, less medication reaches the rest of the body, and, therefore, there are fewer side effects.
Metered dose inhalers (MDIs) are used to deliver bronchodilators. An MDI is a pressurized canister containing a medication that is released when the canister is compressed. A standard amount of medication is released with each compression of the MDI. To maximize the delivery of the medications to the airways, the patient has to learn to coordinate inhalation with each compression. Incorrect use of the MDI can lead to deposition of much of the medication on the tongue and the back of the throat instead of on the airways.
Chlorofluorocarbons (CFCs) have been removed from all MDI inhalers because of the environmental effects on the ozone layer. These have been replaced by a new propellant, hydrofluoroalkane (HFA). Patients may notice that the jet they feel in the back of their throat is less intense when compared with the CFC inhaler. They should be instructed that they are still receiving the same amount of medication though it may feel different than their older inhaler.
Another very important point that patients must be aware of is that "floating" these new inhalers does not help in determining the amount of medication left in the MDI. In the past, the CFC devices could be floated in a bowl of water. With more medicine in the inhaler, the canister would sink and gradually float as it emptied. This is not the case with the HFA inhalers.
The number of inhalations must be counted to determine if medication is still left in the inhaler. Shaking the inhaler is not an effective method of determining how much medication is left. Often propellant (HFA) will continue to come out of the inhaler even after the medication is used up. At the present only one albuterol inhaler comes with a counter device and this is Ventolin-HFA.
Historically, one of the first medications used for asthma was adrenaline (epinephrine). Adrenaline has a rapid onset of action in opening the airways. It is still used in certain emergency situations for attacks of asthma. Unfortunately, adrenaline has many side effects including rapid heart rate,headache, nausea, vomiting, restlessness, and a sense of panic. Therefore, it is not used in the treatment of COPD.
Beta-2 agonists have the bronchodilating effects of adrenaline without many of its unwanted side effects. Beta-2 agonists can be administered by MDI inhalers or orally. They are called "agonists" because they activate the beta-2 receptor on the muscles surrounding the airways. Activation of beta-2 receptors relaxes the muscles surrounding the airways and opens the airways.
Dilating airways helps to relieve the symptoms of dyspnea (shortness of breath). Beta-2 agonists have been shown to relieve dyspnea in many COPD patients, even among those without demonstrable reversibility in airway obstruction. The action of beta-2 agonists starts within minutes after inhalation and lasts for about 4 hours. Because of their quick onset of action, beta-2 agonists are especially helpful for patients who are acutely short of breath.
Because of their short duration of action, these medications should be used for symptoms as they develop rather than as maintenance. Evidence suggests that when these drugs are used routinely, their effectiveness is diminished. These are referred to as rescue inhalers.
Examples of beta-2 agonists include albuterol (Ventolin HFA, Proventil HFA, Proair), metaproterenol (Alupent), pirbuterol (Maxair), terbutaline(Brethaire), isoetharine (Bronkosol), and levalbuterol (Xopenex). Albuterol is a chemical that comes mixed in two forms, mirror images of itself, a left and right hand. Levalbuterol is a purer form of albuterol, the left hand component. There are some theoretical advantages to this form including possibly reduced side effects.
Side effects of beta-2 agonists include anxiety, tremor, palpitations or fast heart rate, and low blood potassium (hypokalemia).
Acetylcholine is a chemical released by nerves that attaches to receptors on the muscles surrounding the airway causing the muscles to contract and the airways to narrow. Anti-cholinergic drugs such as ipratropium bromide(Atrovent) dilate airways by blocking the receptors for acetylcholine on the muscles of the airways and preventing them from narrowing.
Ipratropium bromide (Atrovent) usually is administered via a MDI. In patients with COPD, ipratropium has been shown to alleviate dyspnea, improve exercise tolerance and improve FEV1. Ipratropium has a slower onset of action but longer duration of action than the shorter-acting beta-2 agonists. Ipratropium usually is well tolerated with minimal side effects even when used in higher doses. Tiotropium (Spiriva) is a long-acting and more powerful version of Ipratropium and has been shown to be more effective.
In comparing ipratropium with beta-2 agonists in the treatment of patients with COPD, studies suggest that ipratropium may be more effective in dilating airways and improving symptoms with fewer side effects. Ipratropium is especially suitable for use by elderly patients who may have difficulty with fast heart rate and tremor from the beta-2 agonists. In patients who respond poorly to either beta-2 agonists or ipratropium alone, a combination of the two drugs sometimes results in a better response than to either drug alone without additional side effects.
Theophylline (Theo-Dur, Theolair, Slo-Bid, Uniphyl, Theo-24) and aminophylline are examples of methylxanthines. Methylxanthines are administered orally or intravenously. Long acting theophylline preparations can be given orally once or twice a day. Theophylline, like a beta agonist, relaxes the muscles surrounding the airways but also prevents mast cells around the airways from releasing bronchoconstricting chemicals such as histamine.
Theophylline also can act as a mild diuretic and increase urination. Theophylline also may increase the force of contraction of the heart and lower pressure in the pulmonary arteries. Thus, theophylline can help patients with COPD who have heart failure and pulmonary hypertension. Patients who have difficulty using inhaled bronchodilators but no difficulty taking oral medications find theophylline particularly useful.
The disadvantage of methylxanthines is their side effects. Dosage and blood levels of theophylline or aminophylline have to be closely monitored. Excessively high levels in the blood can lead to nausea, vomiting, heart rhythm problems, and even seizures. In patients with heart failure orcirrhosis, dosages of methylxanthines are lowered to avoid high blood levels. Interactions with other medications, such as cimetidine (Tagamet), calcium channel blockers (Procardia), quinolones (for example, ciprofloxacin (Cipro, Cipro XR, Proquin XR), and allopurinol (Zyloprim) also can alter blood levels of methylxanthines.
When airway inflammation (which causes swelling) contributes to airflow obstruction, antiinflammatory medications (more specifically, corticosteroids) may be beneficial. Examples of corticosteroids include prednisone andprednisolone (Pediapred Oral Liquid, Medrol). Twenty to thirty percent of patients with COPD show improvement in lung function when given corticosteroids by mouth.
Unfortunately, high doses of oral corticosteroids over prolonged periods can have serious side effects including:
- bone fractures,
- diabetes mellitus,
- high blood pressure,
- thinning of the skin and easy bruising,
- emotional changes,
- weight gain.
Therefore, many doctors use oral corticosteroids as the treatment of last resort. When oral corticosteroids are used, they are prescribed at the lowest possible doses for the shortest period of time to minimize side effects. When it is necessary to use long term oral steroids, medications are often prescribed to help reduce the development of the above side effects.
Corticosteroids also can be inhaled. Inhaled corticosteroids have many fewer side effects than long term oral corticosteroids.
Examples of inhaled corticosteroids include:
- beclomethasone dipropionate (Beclovent, Qvar, and Vanceril),
- triamcinolone acetonide (Azmacort),
- fluticasone (Flovent),
- budesonide (Pulmicort),
- mometasone furoate (Asmanex),
- flunisolide (Aerobid).
Inhaled corticosteroids have been useful in treating patients with asthma, but in patients with COPD, it is not clear whether inhaled corticosteroids have the same benefit as oral corticosteroids. Nevertheless, doctors are less concerned about using inhaled corticosteroids because of their safety. The side effects of inhaled corticosteroids include hoarseness, loss of voice, and oral yeast infections.
To decrease the deposition of medications on the throat and increase the amount reaching the airways, spacers can be helpful. Spacers are tube-like chambers attached to the outlet of the MDI canister. Spacer devices can hold the released medications long enough for patients to inhale them slowly and deeply into the lungs.
A spacing device placed between the mouth and the MDI can improve medication delivery and reduce the side effects on the mouth and throat.Rinsing out the mouth after use of a steroid inhaler also can decrease these side effects. It is less clear whether spacing devices help with deposition or side effects of other inhaled medications.
Advair, a powered inhaler device, contains both salmeterol (a long acting beta-agonist) and fluticasone (an inhaled steroid). This medication has shown to be effective in COPD patients with chronic bronchitis. Its major side effects include the possible development of thrush (oral candidiasis) and hoarseness. Another combination medication available in an MID device is budesonide and formoterol (Symbicort).
Treatment of Alpha-1 antitrypsin deficiency
Emphysema can develop at a very young age in some patients with severe alpha-1 antitrypsin deficiency (AAT). Replacement of the missing or inactive AAT by injection can help prevent progression of the associated emphysema. This therapy is of no benefit in other types of COPD.