SHORTNESS OF BREATH OVERVIEW

Feeling short of breath can be an uncomfortable or frightening experience, especially if it has never happened to you before. It can be caused by problems with the lungs or with the heart, or by a low blood count, but its specific cause can sometimes take a while to pinpoint. Luckily, most causes of shortness of breath can be treated quickly once the cause is identified.

Many cases of shortness of breath are caused by simple, short lived problems, such as respiratory tract infections or allergies. The medical term for shortness of breath is dyspnea.

This article will discuss the main causes of shortness of breath and tests that might be used. More information about shortness of breath is available by subscription. (See "Approach to the patient with dyspnea".)

CAUSES OF SHORTNESS OF BREATH

Acute shortness of breath, which comes on suddenly, over the course of minutes or hours, usually has different causes than chronic shortness of breath, which develops over weeks or months.

Acute shortness of breath — Acute shortness of breath usually happens along with other symptoms. The most common causes of acute shortness of breath include:

• Respiratory tract infections, such as pneumonia. These infections usually cause other symptoms, such as fever, cough, or coughing up sputum or mucus. (See "Patient information: Pneumonia in adults".)
• A severe allergic reaction (anaphylaxis), which usually also causes itching, swelling, a rash, or other symptoms. (See "Patient information: Anaphylaxis symptoms and diagnosis".)
• Asthma, which often causes wheezing. (See "Patient information: Asthma treatment in adolescents and adults" and "Patient information: Asthma treatment in children".)
• A blockage in the respiratory tract, which could happen after accidentally inhaling a foreign object, such as a peanut or partially chewed meat.
• A blood clot or other blockage in an artery in the lungs. (See "Patient information: Pulmonary embolism".)
• A collapsed lung (pneumothorax). (See "Primary spontaneous pneumothorax in adults".)
• Interruptions in blood flow to the heart muscle, which might happen during a heart attack. When this is the cause of shortness of breath, there are often other symptoms, such as pain or pressure in the chest. (See "Patient information: Heart attack".)
• Heart failure, a condition that affects the heart's ability to pump blood throughout the body. (See "Patient information: Heart failure".)
• Pregnancy changes a woman's circulatory and respiratory systems, even before the woman is visibly pregnant. This type of shortness of breath is a normal change that happens during pregnancy. (See "Dyspnea during pregnancy".)

Chronic shortness of breath — Some of the same things that cause acute shortness of breath can also cause chronic shortness of breath. For example, asthma symptoms can come and go over months or years. Heart failure can also continue to cause shortness of breath over months or years.

The most common causes of chronic shortness of breath include:

• Asthma (see "Patient information: Asthma treatment in adolescents and adults" and "Patient information: Asthma treatment in children").
• Chronic obstructive pulmonary disease, a lung condition that often affects current or former smokers. (See "Patient information: Chronic obstructive pulmonary disease (COPD, including emphysema)".)
• Interstitial lung disease, a collection of lung disorders that involve damage or scarring of lung tissue. (See "Approach to the adult with interstitial lung disease: Clinical evaluation".)
• Cardiomyopathy, a heart condition that leads to changes in the heart's shape and size. (See "Patient information: Dilated cardiomyopathy" and "Patient information: Hypertrophic cardiomyopathy".)
• Deconditioning, which is the technical term for being out of shape. For example, if you do not exercise regularly, you may develop shortness of breath when climbing stairs.
• Obesity can cause shortness of breath as extra weight in the chest and abdomen press on the lungs.
• Pulmonary hypertension, which is high blood pressure in the arteries to your lungs. (See "Overview of pulmonary hypertension".)

SHORTNESS OF BREATH SYMPTOMS

People describe shortness of breath in different ways. Some people say they feel "hungry for air," others say they feel as though they "cannot breathe deeply enough."

These descriptions hold important clues about the possible cause of the problem. Here is a questionnaire your healthcare provider may ask you to complete to get a better sense of your symptoms (table 1).

WHEN TO SEEK HELP

Anyone who develops shortness of breath should see a healthcare provider. If you have severe shortness of breath or also have chest pain or nausea, go to the closest emergency room. Shortness of breath is not a symptom to ignore.

SHORTNESS OF BREATH DIAGNOSIS

Your healthcare provider can learn a lot about your condition by listening to your description of the problem, and by asking about any other symptoms you may have. He or she can also learn a lot by listening to your heart and lungs with a stethoscope, and by checking your legs for swelling.

Tests — Your healthcare provider may also order one or more of the following tests to help diagnose the problem:

• A blood test called a hematocrit can check for anemia, a condition that affects the blood's ability to carry oxygen.
• A blood test called a BNP can indicate if you have fluid buildup in your lungs.
• A chest x-ray to look for pneumonia, or lung inflammation or scarring.
• An EKG is a test of your heart muscle that looks for signs of a heart attack.
• Spirometry measures the amount of air your lungs can hold and how effectively your lungs can empty and fill with air. This test can also indicate if you have asthma or emphysema.
• Oximetry measures the amount of oxygen in your blood.

SHORTNESS OF BREATH TREATMENT

The treatment for your shortness of breath will depend a lot on what is causing it. Shortness of breath caused by asthma, for example, will need one type of treatment, whereas shortness of breath caused by heart failure will need quite another.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed every four months on our web site (www.uptodate.com/patients).

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information

Patient information: Pneumonia in adults
Patient information: Anaphylaxis symptoms and diagnosis
Patient information: Asthma treatment in adolescents and adults
Patient information: Asthma treatment in children
Patient information: Pulmonary embolism
Patient information: Heart attack
Patient information: Heart failure
Patient information: Chronic obstructive pulmonary disease (COPD, including emphysema)
Patient information: Dilated cardiomyopathy
Patient information: Hypertrophic cardiomyopathy

Professional level information

Approach to the patient with dyspnea
Dyspnea during pregnancy
Evaluation of the adult with dyspnea in the emergency department
Physiology of dyspnea
Primary spontaneous pneumothorax in adults
Approach to the adult with interstitial lung disease: Clinical evaluation
Overview of pulmonary hypertension

The following organizations also provide reliable health information.

• The National Library of Medicine

     (www.nlm.nih.gov/medlineplus/ency/article/003075.htm)

• American College of Chest Physicians

     (www.chestnet.org/downloads/patients/guides/ShortnessofBreath.pdf)

[1,2]