The MERCK Manual of Medical Information-Second Home Edition
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 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. 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).
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?
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.
Dyspnea (shortness of breath) is the unpleasant sensation of difficulty in breathing.
> Lung Disorders
> Heart Failure
> Other Causes
> Hyperventilation syndrome
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(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.
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.
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.
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
Stridor is a gasping sound during inhalation resulting from a partial blockage of the throat (pharynx), voice box (larynx), or windpipe (trachea).
Hemoptysis is the coughing up of blood from the respiratory system.
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.
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.
Cyanosis is a bluish discoloration of the skin resulting from an inadequate amount of oxygen in the blood.
Clubbing is an enlargement of the tips of the fingers or toes and a change in the angle where the nails emerge.