Medical Effects: Lung Disorders

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Merc Manual : Symptoms

Last full review/revision November 2006 by James H. Fisher, MD

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Among the most common symptoms of lung disorders are cough, shortness of breath (dyspnea), and wheezing. Less commonly, a blockage in the airways between the mouth and lungs results in a gasping sound when breathing (stridor). Problems in the lungs can also lead to coughing up of blood (hemoptysis), a bluish discoloration of the skin due to a lack of oxygen in the blood (cyanosis), or chest pain. Prolonged lung disease can even produce changes in other parts of the body, including finger clubbing. Some of these symptoms do not always indicate a respiratory problem. Chest pain, for example, may also result from a heart or gastrointestinal disorder, and shortness of breath can be caused by a heart or blood problem.


A cough is a sudden, explosive exhalation of air; the function of a cough is to clear material from the airways.

Coughing, a familiar but complicated reflex, is one way in which the lungs and airways are protected. Along with other mechanisms, coughing helps to protect the lungs from particles that have been inhaled. Coughing sometimes brings up sputum (also called phlegm)—a mixture of mucus, debris, and cells expelled by the lungs.


Coughing occurs when the airways are irritated. Respiratory infections—usually bacterial or viral—irritate the airways and are a common cause of coughing. Allergies can irritate the airways as well. People who smoke often cough. Smoke not only irritates the airways but also damages the cells that line the airways, including the hairlike projections that normally cleanse the airways of debris (cilia). Coughing may also result from postnasal drip, in which nasal secretions drain down the back of the nose into the throat and sometimes into the trachea and other airways, where they produce irritation. Coughing may result from gastroesophageal reflux, in which stomach or esophageal contents flow backward from the esophagus into the trachea and airways, producing irritation. Another cause of cough can be drugs, for example, angiotensin-converting enzyme (ACE) inhibitors (see see High Blood Pressure: Antihypertensive DrugsTables). Narrowing of the airways below the windpipe (bronchoconstriction), foreign bodies, or tumors in the airway can cause cough, wheezing, or both. Bronchoconstriction occurs in asthma, in chronic obstructive pulmonary disease, and heart failure (when fluid accumulates in the lungs).

Coughs vary considerably. A cough may be distressing, especially if coughing episodes are accompanied by chest pain, shortness of breath, blood, or unusually large amounts of or very sticky sputum. However, if coughing increases slowly over decades, as it may in a smoker, the person may hardly be aware of it.


Information about a cough helps a doctor determine its cause. Therefore, a doctor may ask:

  • How long has the cough been present?
  • At what time of day does the cough occur?
  • What factors—such as cold air, body position, talking, eating, or drinking—influence the cough?
  • Is the cough accompanied by chest pain, shortness of breath, hoarseness, dizziness, or wheezing?
  • Does the cough bring up sputum or blood?
  • Are there symptoms of another disorder that could cause a cough (for example, gastroesophageal reflux or postnasal drip)?
  • Could a drug be causing the cough?
  • What color is the sputum?

The appearance of the sputum, especially a change in color or consistency, occasionally helps the doctor identify the cause. A yellowish, greenish, or brownish appearance may indicate a bacterial infection. Clear but very sticky (mucoid) sputum is characteristic of asthma. Occasionally, a doctor may use a microscope to examine a sputum sample. Bacteria and white blood cells are additional indications of infection. The presence of a specific type of white blood cell (eosinophil) suggests asthma. A cough may also produce blood, which commonly suggests bronchitis, but may also suggest more serious disorders. Usually, a chest x-ray or other tests are done when a person develops a cough that is severe or persistent or has no obvious cause.


Because coughing plays an important role in bringing up sputum and clearing the airways, a cough should not be suppressed unless it interferes with sleep. Treating an underlying disorder—such as an infection, fluid in the lungs, or asthma—is more important. For example, antibiotics can be given for an infection, or inhalers can be used for asthma. Depending on the severity of the cough and its cause, a variety of drugs may be used for treatment. When cough results from narrowing of the airways, bronchodilators may provide relief. It is not clear how well other drugs relieve cough.

Antitussive Therapy: Antitussive drugs are given to suppress cough. All opioids are antitussives because they suppress the cough center in the brain. Codeine is the opioid used most often for cough. Codeine may cause nausea, vomiting, and constipation; it may also be addictive. If codeine is taken for a prolonged period, the dose needed to suppress a cough may need to be increased. Opioid cough suppressants can cause drowsiness, particularly when the person also is taking other drugs that reduce concentration (such as alcohol, sedatives, sleep aids, antidepressants, and certain antihistamines). Opioids are not always safe, and doctors usually reserve them for special situations.

Several non-opioid cough suppressants, such as dextromethorphan. Some Trade Names
and benzonatate Some Trade Names
, are antitussives that also suppress the cough center in the brain. These drugs, and others, are the active ingredients in many over-the-counter and prescription cough medications. They are not addictive and, when used correctly, produce little drowsiness. In certain people, especially those who are coughing up an abundant amount of sputum, frequent use of these cough suppressants is not recommended.

Steam inhalation, for example from a vaporizer, can help stop a cough by reducing irritation in the throat (pharynx) and airways. The moisture from the steam also loosens secretions, making them easier to cough up. A cool-mist humidifier can achieve the same result. Some doctors believe that drinking sufficient water can produce good hydration and is as effective as steam inhalation for loosening secretions.

Expectorants: Some doctors recommend expectorants (sometimes called mucolytics) to help loosen mucus by making bronchial secretions thinner and easier to cough up, although these drugs do not suppress a cough. It is not clear how effective these drugs are. A saturated solution of potassium iodide Some Trade Names
may be prescribed. The most commonly used over-the-counter preparations contain guaifenesin Some Trade Names
or terpin hydrate. A small dose of syrup of ipecac may help in children, especially in those who have croup.

In cystic fibrosis, dornase alfa (inhaled recombinant human deoxyribonuclease I) is used to help thin the pus-filled mucus that results from chronic respiratory infections. Also, inhalation of a saline (salt) solution or use of acetylcysteine Some Trade Names
(for up to a few days) sometimes helps thin excessively thick and troublesome mucous.

Bronchodilators, Corticosteroids, Antihistamines, and Decongestants: Bronchodilators, such as inhaled albuterol Some Trade Names
and similar drugs, and inhaled corticosteroids are effective if a cough occurs as a result of airway narrowing (bronchoconstriction), as happens in asthma and chronic obstructive pulmonary disease. TheophyllineSome Trade Names
, which is taken by mouth, is sometimes helpful. Some people who develop wheezing or prolonged cough after viral respiratory infections appear to benefit from short-term use of bronchodilators.

Antihistamines, which dry the respiratory tract, have little or no value in treating a cough, except when it is caused by an upper airway allergy. With coughs from other causes, such as bronchitis, the drying action of antihistamines can be harmful, thickening respiratory secretions and making them difficult to cough up.

Decongestants such as phenylephrine Some Trade Names
that relieve a stuffy nose are only useful in relieving a cough, that is caused by postnasal drip.


Dyspnea (shortness of breath) is the unpleasant sensation of difficulty in breathing.

An increase in the rate and depth of breathing occurs normally during exercise and at high altitudes, but the increase seldom causes discomfort. Breathing is also increased at rest in people with many illnesses, whether of the lungs or of other parts of the body. For example, people with a fever generally breathe faster.

With dyspnea, faster breathing is accompanied by the sensation of running out of air. The person feels a sensation of not being able to breathe fast enough or deeply enough. Other sensations include an awareness of increased muscular effort to expand the chest when breathing in or to expel air when breathing out, the uncomfortable sensation that inhaling (inspiration) is urgently needed before exhaling (expiration) is completed, and various sensations often described as tightness in the chest.


Lung Disorders: People who have lung disorders often experience dyspnea when they physically exert themselves. During exercise, the body makes more carbon dioxide and uses more oxygen. The respiratory center in the brain accelerates breathing when blood levels of oxygen are low or blood levels of carbon dioxide are high. If the heart or lungs are not functioning properly, even a little exertion can lead to dramatic increases in breathing rates and dyspnea. Dyspnea is so unpleasant that the person avoids exertion. As the lung disorder becomes more severe, dyspnea may even occur at rest.

Dyspnea may result from restrictive or obstructive lung disorders. In restrictive lung disorders (such as idiopathic pulmonary fibrosis), lungs become stiff and require increased effort to expand during inhalation. Severe curvature of the spine (scoliosis) also restricts breathing by reducing the movement of the rib cage. In obstructive disorders (such as chronic obstructive pulmonary disease or asthma), resistance to airflow is increased because the airways are narrowed. Because airways widen on inhalation, air can usually be pulled in. However, because airways narrow on exhalation, air cannot be exhaled from the lungs as fast as normal, and breathing becomes labored.

Heart Failure: The heart pumps blood through the lungs. The heart must function properly for the lungs to function normally. If the heart is pumping inadequately (heart failure), fluid may accumulate in the lungs, a condition called pulmonary edema. This condition causes dyspnea that is often accompanied by a feeling of smothering or heaviness in the chest. The fluid accumulation in the lungs may also lead to airway narrowing and wheezing—a condition called cardiac asthma (see Heart Failure: Symptoms).

Some people with heart failure experience orthopnea, paroxysmal nocturnal dyspnea, or both. Orthopnea is shortness of breath when a person lies down that is relieved by sitting up. Paroxysmal nocturnal dyspnea is a sudden, often terrifying, attack of shortness of breath during sleep. The person awakens gasping and must sit or stand to take a breath. This condition is an extreme form of orthopnea and a sign of severe heart failure (see Heart Failure: Symptoms).

Anemia: Dyspnea can also occur in people who have anemia or blood loss because of a decreased number of red blood cells, which carry oxygen to the tissues. The person breathes rapidly and deeply, in a reflex effort to try to increase the amount of oxygen in the blood.

Other Causes: Someone with severe kidney failure or sudden worsening of diabetes mellitus or someone who has taken certain drugs or poisons feels out of breath and may begin to pant quickly because of an accumulation of a large amount of acids in the blood (a condition called metabolic acidosis). Anemia and heart failure may also contribute to dyspnea in people with kidney failure.

Hyperventilation syndrome causes people to feel that they cannot get enough air, and they breathe heavily and rapidly. This condition is commonly caused by anxiety rather than a physical problem. Many people who experience this syndrome are frightened, may have chest pain, and may believe they are having a heart attack. People may experience a change in consciousness usually described as a feeling that events occurring around them are far away, and they may experience tingling in the hands and feet and around the mouth.

Evaluation and Treatment

Doctors can usually get an idea of what is causing dyspnea from the person's symptoms and the results of a physical examination. A chest x-ray and measurement of levels of oxygen in the blood with arterial blood gas testing or pulse oximetry help determine the cause. The chest x-ray can show evidence of pneumonia and many other lung abnormalities and can often show evidence of heart failure. A low blood oxygen level usually indicates a heart or lung problem. Pulmonary function testing (see Symptoms and Diagnosis of Lung Disorders: Pulmonary Function Testing (PFT)) can measure the degree of restriction or obstruction and the ability of the lungs to transport oxygen from the air to the blood. A lung problem may include both restrictive and obstructive defects as well as abnormal oxygen transport. Other tests may be necessary to diagnose and further evaluate anemia, heart problems, certain specific lung problems, and kidney failure.

Treatment of dyspnea is directed at the cause. People with a low blood oxygen level are given supplemental oxygen using plastic nasal prongs or a plastic mask worn over the face. In severe cases, particularly if a person cannot breathe deeply or rapidly enough, doctors may assist breathing by mechanical ventilation administered through a breathing tube inserted into the trachea or through a tight-fitting face mask.

Chest Pain

Chest pain may be described as sharp (possibly knifelike), dull, burning, or squeezing; it may be located in a specific spot on the chest (such as the chest wall) or may be difficult to locate, often feeling like a deep ache. The pain may be constant or intermittent, lasting seconds, minutes, or longer. It may be worsened by breathing, changes in body position, exertion, eating, or other factors.

Pleuritic pain is a sharp pain that is made worse by deep breathing and coughing. Keeping the chest wall still—for example, by holding the side that hurts and avoiding deep breathing or coughing—can reduce the pain. Usually, the site of the pain can be pinpointed, although it may move over time. Pain may occur in the part of the chest supplied by a nerve between the ribs (intercostal nerve). This pain runs from the spine across the back to the chest in a path roughly parallel to a rib, usually affecting an area no wider than two or three ribs.


Chest pain may arise from structures in the respiratory system, including the pleura (the two-layered membrane covering the lungs). Chest pain can also arise from structures not related to the respiratory system, such as the chest wall, heart, major blood vessels, or esophagus. Some disorders of the heart and major blood vessels are serious; a person may need immediate testing and treatment (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Chest Pain).

Pleuritic pain often results from inflammation of the pleura (pleurisy). There are many causes of pleuritic pain, including viral and bacterial infections, cancer, and inflammation from disorders that can affect many organs, such as rheumatoid arthritis and systemic lupus erythematosus. Blood clots can travel through the bloodstream to the lungs (pulmonary embolism (see Pulmonary Embolism (PE))), lodge in the pulmonary arteries, and cause pleuritic chest pain. Air in the chest cavity (pneumothorax) and inflammation of the membrane surrounding the heart (pericarditis) can also cause chest pain that worsens during deep breathing. Pleural effusion, a fluid buildup in the space between the two layers of pleura (see Pleural Disorders: Pleural Effusion), may produce pleuritic pain at first, but the pain may subside as accumulating fluid separates the two layers.

Pain arising from other lung disorders (such as a lung abscess or tumor) is usually more difficult to describe than pleuritic pain. The pain is often described as a vague, deep-seated ache in the chest. Almost any disorder that damages the lungs or airways can cause such pain.

Pain originating in the chest wall may worsen with deep breathing or coughing and often is confined to one area in the chest wall, which also feels sore when pressed. The most common causes are chest wall injuries, such as broken ribs and torn or injured muscles located between the ribs (intercostal muscles). Even hard coughing can injure these muscles, causing pain for days or weeks. Pain along the area supplied by an intercostal nerve occurs if the nerve is irritated by a tumor or affected by hingles, which is caused by the varicella-zoster virus. In shingles, pain may occur before the tell-tale rash appears.

Evaluation and Treatment

Characteristics of the pain that a person describes provide clues to help doctors determine the cause. A chest x-ray is usually done. It often reveals the cause of chest pain, particularly pain caused by respiratory system problems. If serious disorders of the heart or major blood vessels are suspected, tests that help diagnose them are done, such as an electrocardiogram (ECG) or blood tests. Treatment is directed at the underlying disorder. Until the underlying disorder is controlled, drugs can relieve pain.


Wheezing is a whistling, musical sound during breathing resulting from partially obstructed airways.

Wheezing results from an obstruction somewhere in the airways. It may be caused by widespread narrowing of the airways (as in asthma, chronic obstructive pulmonary disease, and some severe allergic reactions), by a local narrowing (as with a tumor), or by a foreign object lodged in an airway. The most common cause of recurrent wheezing is asthma, although many people who have never had asthma wheeze at some time in their lives. Infections such as pneumonia or bronchitis and, in infants, bronchiolitis can sometimes cause wheezing.

A doctor usually is able to detect wheezing by listening with a stethoscope as the person breathes. Loud wheezing can be heard easily, sometimes even without a stethoscope. To hear mild wheezing, the doctor may need to listen with a stethoscope while the person exhales forcefully. A persistent wheeze that occurs in one location in a smoker may be due to lung cancer. If a person develops wheezing suddenly for the first time, a chest x-ray may help in diagnosis. In people with persistent or repeated episodes of wheezing, pulmonary function testing (see Symptoms and Diagnosis of Lung Disorders: Bronchoscopy) may be needed to help measure the extent of airway narrowing and to assess the benefits of treatment. If doctors suspect a foreign object is lodged in an airway, they can insert a flexible viewing tube (bronchoscope) into the airway to diagnose the problem and remove the object.

Wheezing is relieved with bronchodilators, such as inhaled albuterol Some Trade Names
. Corticosteroids, taken by mouth for a week or two, can often help relieve an acute episode of wheezing if it is due to asthma or chronic obstructive pulmonary disease.


Stridor is a gasping sound during inhalation resulting from a partial blockage of the throat (pharynx), voice box (larynx), or windpipe (trachea).

Stridor is usually loud enough to be heard at some distance. The sound is caused by turbulent airflow through a narrowed upper airway. In children, the cause may be croup, an inhaled foreign object, or, rarely, an infection of the epiglottis (see Bacterial Infections: Epiglottitis). In adults, the cause may be a tumor, an abscess, swelling (edema) in the upper airway, or a malfunction of the vocal cords.

Stridor causing dyspnea when the person is at rest is a medical emergency. In such cases, a tube may be inserted through the person's mouth or nose (tracheal intubation) or by a small surgical incision directly into the trachea (tracheostomy) to allow air to get past the blockage and prevent suffocation. The cause usually becomes clear during tracheal intubation, during which a doctor can see the upper airway directly. If tracheal intubation is not done, the diagnosis is usually determined by inserting a flexible viewing tube through the nose and upper airway (a procedure called nasopharyngeal laryngoscopy).


Hemoptysis is the coughing up of blood from the respiratory system.

Although hemoptysis can often be frightening, most causes turn out not to be serious.


Infection is the most common cause. Sometimes the cause is blood from the nose that has traveled down to the airways and then is coughed up. Unexplained or large amounts of blood in the sputum require evaluation by a doctor.

Tumors, especially those due to lung cancer, account for up to 20% of cases of hemoptysis. Death of lung tissue (see Pulmonary Embolism (PE)) from blockage of an artery by a blood clot (pulmonary embolism) may also cause hemoptysis.

Other causes include high blood pressure in the pulmonary veins, as may occur in heart failure and mitral valve stenosis. Other lung circulation problems, including arteriovenous malformations or inflammatory conditions of the pulmonary blood vessels, may also cause hemoptysis.


If hemoptysis is severe, persistent, or unexplained, a diagnostic evaluation is necessary. Doctors check for lung cancer in smokers older than 40 (and even in younger smokers if the person started smoking in adolescence) who develop hemoptysis, even if the sputum is only blood streaked. A chest x-ray is usually the first test done. A flexible viewing tube (bronchoscope) may be needed to identify the bleeding site. A scan using a radioactive marker (lung perfusion scan (see Pulmonary Embolism (PE): Diagnosis) or other imaging test may reveal a pulmonary embolism. Despite testing, the cause of hemoptysis is not found in 30 to 40% of cases. When hemoptysis is severe, however, the cause is usually found.


Bleeding may produce clots that block the airways and lead to further breathing problems. Therefore, coughing is important to keep the airways clear and should not be suppressed with antitussive drugs.

Hemoptysis is usually mild and usually stops by itself or when the disorder causing the bleeding (for example, heart failure or infection) is successfully treated.

If a large clot blocks a major airway, doctors may have to remove the clot using bronchoscopy. Rarely, hemoptysis is severe or does not stop by itself. If so, a tube may need to be inserted through the mouth or nose into the windpipe or lower into the airways to help keep the airways open. If the source of bleeding is a major blood vessel, a doctor may try to close off the bleeding vessel using a procedure called bronchial artery embolization. Using x-rays for guidance, the doctor passes a catheter into the vessel and then injects a chemical, fragments of a gelatin sponge, or a wire coil to block the blood vessel and thereby stop the bleeding. Sometimes bronchoscopy or surgery may be needed to stop severe or continuing bleeding, or surgery may be needed to remove a diseased portion of the lung. These high-risk procedures are used only as last resorts. If clotting abnormalities are contributing to the bleeding, a transfusion of plasma, clotting factors, or platelets may be needed.


Cyanosis is a bluish discoloration of the skin resulting from an inadequate amount of oxygen in the blood.

Cyanosis occurs when oxygen-depleted (also called deoxygenated) blood, which is bluish rather than red, circulates through the skin. Cyanosis can be caused by many types of severe lung or heart disease that produce low levels of oxygen in the blood. It can also result from certain blood vessel and heart malformations that allow blood to flow directly to the heart without ever flowing past the air sacs of the lung (alveoli) where oxygen is extracted from the air. This abnormal blood flow is called a shunt. In a shunt, blood from veins in the body, which is oxygen-depleted, may flow directly into blood vessels returning blood from the lungs to the left side of the heart or directly into the left side of the heart itself. The oxygen-depleted blood then is pumped out to the body, to circulate through the skin and other tissues.

The amount of oxygen in the blood can be estimated by pulse oximetry, in which a sensor is attached to a finger or an earlobe, or it can be measured directly by arterial blood gas analysis (see Symptoms and Diagnosis of Lung Disorders: Arterial Blood Gas (ABG) Analysis). Chest x-rays, echocardiography, cardiac catheterization, pulmonary function tests, and sometimes other tests may be needed to determine the cause of decreased oxygen in the blood and the resulting cyanosis.

Oxygen therapy is often the first treatment given, in a similar fashion as for other conditions in which the blood oxygen level is low. Many malformations that cause shunts can be treated with surgery or other procedures.


Clubbing is an enlargement of the tips of the fingers or toes and a change in the angle where the nails emerge.

Clubbing occurs when the amount of soft tissue beneath the nail beds increases. Why this increase occurs is not clear but may relate to the levels of proteins that stimulate blood vessel growth. Clubbing seems to occur with some lung disorders (lung cancer, lung abscess, bronchiectasis), but not with others (pneumonia, asthma, chronic obstructive pulmonary disease). Clubbing also occurs with some congenital heart disorders and liver disorders, or in some cases, it may be inherited and not indicate any disorder. Clubbing itself does not need treatment.

Recognizing Finger Clubbing

Finger clubbing is characterized by enlarged fingertips and a loss of the normal angle at the nail bed.

Last full review/revision November 2006 by James H. Fisher, MD

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