What is Dyspnea on Exertion?
Dyspnea, often known as shortness of breath, is a person’s feeling of having trouble breathing. Each person may experience this differently, and the level of discomfort varies from person to person. This symptom affects a significant number of people. A range of conditions can cause shortness of breath, including heart, lung, nerve, mental health, or overall body illnesses, or a mix of these. There’s also a type called dyspnea on exertion, which makes people feel out of breath when they exercise and feel better once they rest. Any physical activity that requires more oxygen than the body can provide can lead to this feeling of breathlessness. That’s because our bodies rely on oxygen for a key energy process, and when oxygen supply runs low, we feel short of breath.
Here’s a formula for how oxygen gets delivered to the body:
Oxygen Delivery = (Hemoglobin x 1.39 x Oxygen Saturation of Hemoglobin x Heart’s Pumping Power) + (0.003 x Amount of Oxygen in Blood)
Here’s what this equation means:
* Hemoglobin is a protein in our blood that transports oxygen, and its concentration is measured in grams per liter.
* 1.39 refers to the amount of oxygen a gram of hemoglobin can carry.
* Oxygen Saturation of Hemoglobin is the percentage of hemoglobin carrying oxygen. For example, 98% would be 0.98 in this formula.
* Heart’s Pumping Power is the amount of blood the heart pumps every minute, measured in liters.
* 0.003 x Amount of Oxygen in Blood is the volume of oxygen dissolved in the blood, measured in milliliters.
If a person has low levels of hemoglobin, genetic conditions that affect hemoglobin, or certain forms of poisoning that affect hemoglobin, like carbon monoxide poisoning, or if their heart isn’t pumping enough blood, like in cases of heart failure, heart attack, or irregular heart rhythm, they may experience shortness of breath.
What Causes Dyspnea on Exertion?
Feeling short of breath after physical activity can be a symptom of various health problems and not a disease on its own. Two main systems in the body responsible for this symptom are the respiratory system, which involves our lungs and airways, and the cardiac system, which includes our heart. Other general illnesses in the body can also be behind this symptom, sometimes with more than one cause involved.
Respiratory-related reasons can range from conditions such as asthma, a flare-up of chronic obstructive pulmonary disorder (COPD), pneumonia, a blockage in the lung’s blood vessel (pulmonary embolism), lung cancer, collapsed lung (pneumothorax), to inhaling something into the lungs.
Heart-related causes are conditions like congestive heart failure, fluid in the lungs (pulmonary edema) often due to heart problems, acute coronary syndrome – a term for situations where the blood supplied to the heart muscle is suddenly blocked, tamponade – a serious condition where fluid builds up around the heart, a faulty heart valve, high blood pressure in the lungs (pulmonary hypertension), irregular heartbeat, or an abnormal connection between the heart’s chambers.
Other illnesses throughout the body, such as anemia (low red blood cells), acute kidney failure, metabolic acidosis (a condition that occurs when the body produces too much acid or when the kidneys can’t remove enough acid from the body), thyrotoxicosis (high levels of thyroid hormones), liver cirrhosis, severe allergic reaction (anaphylaxis), severe infection (sepsis), angioedema (swelling underneath the skin), and epiglottitis (inflamed windpipe cover) can also cause shortness of breath after exertion.
Risk Factors and Frequency for Dyspnea on Exertion
Dyspnea on exertion is a condition where a person has difficulty breathing during physical activity. The rates of this condition greatly differ based on its cause. The most common reason for this issue is a condition known as congestive heart failure. According to the American Heart Association in 2017, congestive heart failure impacts around 6.5 million Americans over 20 years of age. Another condition related to dyspnea on exertion is known as COPD, which affects approximately 6.3% of the adult population in the United States.
Signs and Symptoms of Dyspnea on Exertion
The history and physical exam aim to discover if the patient has any ongoing heart or lung diseases. Particular points to check in a patient’s history include when their symptoms started, how long they’ve been experiencing them, what makes them worse, and what relieves them. If the patient has a cough, it could point towards conditions like asthma, chronic obstructive pulmonary disease (COPD), or pneumonia. Having a very sore throat could suggest epiglottitis. Chest pain that worsens with deep breaths could mean pericarditis, pulmonary embolism, pneumothorax, or pneumonia. If the patient experiences breathing problems while lying flat, wakes up due to breathlessness at night, or has swelling, we might consider congestive heart failure. If the patient smokes, the chances of having COPD, congestive heart failure, and pulmonary embolism increase. If the patient has heartburn or difficulty swallowing, it could suggest acid reflux or aspiration of gastric secretions into the lungs. A distinctive cough in children could suggest croup. Fever suggests an infection.
During the physical exam, doctors first check the patient’s airway, breathing, and circulation (the ABCs). When these are stable, a complete physical exam can be done. To understand how severe the patient’s breathlessness is, doctors observe their effort of breathing, usage of extra muscles for breathing, mental state, and ability to speak. Swelling of the neck veins might suggest severe COPD, congestive heart failure, or excessive pressure in the heart due to fluid buildup. An unusually large thyroid may suggest hyperthyroidism or hypothyroidism. By tapping on the chest, doctors can identify areas of lung consolidation and fluid accumulation. Unusual hollow sounds when tapping on the chest might indicate pneumothorax or severe emphysema. No breath sounds might suggest a tumor, pleural effusion, or lung cancer. Wheezing is common in asthma and COPD but could also suggest pulmonary edema or pulmonary embolism. Problems like pulmonary edema and pneumonia could cause crackling sounds in the lungs. By listening to the heart, doctors can identify abnormal heart rhythms, murmurs, or additional heart sounds. Murmurs might suggest problems with the heart valves, and very faint heart sounds might suggest a buildup of fluid around the heart. Inflammation of the heart membrane might cause a specific sound that doctors can hear. Furthermore, signs like an enlarged liver, fluid retention in the abdomen, and a positive blood reflux test in the liver might suggest congestive heart failure. Swelling in the legs could be due to congestive heart failure or deep vein thrombosis, which could potentially cause a pulmonary embolism. Finally, unusual curving of the fingertips and nails suggests lung cancer or chronic low oxygen levels, and bluish discoloration of the skin suggests low oxygen levels.
Testing for Dyspnea on Exertion
When a patient is undergoing an evaluation, the first step should be to quickly check the patient’s basic health measures, which are usually shortened to ABC (Airways, Breathing, Circulation). Once the doctor determines that the patient isn’t in immediate danger, they can start a detailed history and physical exam. Doctors will then check things like heart rate, respiratory rate, body temperature, body mass index (BMI), and oxygen saturation. It’s also important to see how the oxygen level changes when the patient exerts themselves, as it might be normal when they’re at rest.
A fever might mean that the patient is dealing with an infection. The first test doctors usually perform when a patient is experiencing shortness of breath is a chest x-ray. If this test shows something abnormal, it’s likely the cause is a heart problem or an issue in the lungs. Doctors may use an echocardiogram to examine heart function and check for damage or abnormalities in the heart’s tissues and valves.
They might also order an electrocardiogram to look for signs of a heart attack or a strain pattern in the right side of the heart. If the doctors suspect congestive heart disease, they might look for elevated levels of a hormone called pro-brain natriuretic peptide(BNP). Exercise stress testing can also help monitor cardiac function and the body’s oxygen levels during physical activity.
If the chest x-ray doesn’t show anything unusual, then a spirometry test can be performed to measure how well the lungs function. If the spirometry test comes back abnormal, it might suggest diseases such as asthma, COPD, interstitial fibrosis, physical airway obstruction or weaknesses in the respiratory muscles. If this test is normal, then the doctors would need to look at whether low oxygen levels might be causing the patient’s shortness of breath.
Additional tests can separate obstructive and restrictive lung diseases. In obstructive diseases, total lung capacity is increased, while in restrictive diseases, it’s reduced. Illnesses that affect the lung’s air sacs or make them thicker, like emphysema, pulmonary embolism, CHF, and obesity, can cause a decrease in the lung’s ability to facilitate the transfer of oxygen and carbon dioxide.
Doctors might also use a test called an arterial blood gas test, which can help detect low oxygen levels and check for an acidotic state. This test can also be used to calculate the A-a gradient.If the oxygen levels in the blood is low with a normal chest x-ray result, then the patient might have a pulmonary embolism. This condition usually causes the blood’s pH to increase somewhat as the body tries to compensate by getting rid of carbon dioxide to relatively increase the pressure of oxygen.
In a pregnant woman, the doctors would first order a d-dimer test (which checks for blood clots), a leg ultrasound and a lung scan. If the lung scan shows areas of low blood flow, then a diagnosis of pulmonary embolism might be considered. Alternatively, a Spiral CT scan of the chest can also be used, especially in acute settings where it is considered the gold standard.
For cases of chronic shortness of breath on exertion, a lung scan can help diagnose chronic thromboembolic pulmonary hypertension (CTEPH), which is considered the gold standard. If the scan result is normal, a cardiac catheterization test is needed to check for potential conditions like pulmonary hypertension, intracardiac shunting, or coronary artery disease.
A normal oxygen saturation level points to the possibility of carbon monoxide poisoning, methemoglobinemia, or an abnormality in the hemoglobin molecule. Still, if this level is normal and the patient’s blood oxygen level is above 70 mm Hg, a complete blood count test might be warranted. This test checks the hemoglobin content and the percentage of red blood cells in the total blood volume.
If the cause of shortness of breath is still uncertain, a cardiopulmonary exercise test may be conducted. If the test does not show any cardiac or pulmonary issues, then the probable cause of dyspnea upon exertion may be physical deconditioning.
All these tests are focused on diagnosing the problem based on the doctor’s suspicion and the patient’s symptoms, medical history and physical exam, with the goal of avoiding unnecessary tests and reducing patient costs.
Treatment Options for Dyspnea on Exertion
Treatment for shortness of breath when exercising depends on the root cause. Initially, doctors will rule out any immediate life-threatening causes by checking the patient’s airway, breathing, and circulation (ABCs). Once the patient is stable and doesn’t need immediate medical intervention, they can then determine the next steps of treatment.
For patients who smoke, quitting smoking is crucial. Different types of inhalers can be used for lung diseases, including ones that have an immediate or longer-lasting effect, ones that block certain nerve impulses, and inhaled steroids. Continuous supplemental oxygen therapy, which provides extra oxygen, can help ease discomfort if the oxygen levels in the blood drop during exercise.
If a heart problem has been identified, it needs to be treated promptly to optimize the heart’s function. If a heart attack is suspected based on an electrocardiogram reading or other test results, quick medical intervention should be performed by a heart specialist. Common treatments include aspirin, cholesterol medication, ACE inhibitors, blood pressure medication, blood thinners, and nitrate medication, as long as there are no contraindications.
Sometimes, medications like beta-blockers and calcium-channel blockers can cause shortness of breath during exercise by decreasing heart function. This can be detected with a Cardiopulmonary Exercise Test (CPET). If this is the case, these medications should be reduced or stopped if possible. If congestive heart failure is causing the shortness of breath, diuretics can be used to help reduce fluid overload.
If a person is overweight or out of shape, they should start physical therapy or an exercise plan. If the shortness of breath during exercise is due to psychological issues, a type of antidepressant along with counseling might be helpful. Weight loss, particularly in women who are obese, can also improve symptoms.
What else can Dyspnea on Exertion be?
If you’re finding it hard to breathe after strenuous activity, it could be due to a number of things like:
- Heart diseases like a blockage in blood flow to the heart (acute myocardial ischemia) or heart failure
- A serious condition where fluid builds up around the heart (cardiac tamponade)
- Blood clot in your lungs (pulmonary embolism)
- Collapse of part or all of a lung (pneumothorax)
- Lung infections including bronchitis or pneumonia
- A blockage in your upper airway because of choking or an allergic reaction (anaphylaxis)
On the other hand, if you’ve been having difficulty breathing over a long period of time, it might be due to conditions such as:
- Asthma or chronic obstructive pulmonary disease (COPD)
- Long term heart failure (congestive heart failure)
- Diseases affecting your lung tissue (interstitial lung disease)
- Conditions that affect how your heart works (myocardial dysfunction)
- Being overweight (obesity)
- Physical deconditioning
The most common reason for feeling breathless after doing some physical activity is congestive heart failure.
What to expect with Dyspnea on Exertion
Experiencing shortness of breath during physical activity is usually harmless and a normal part of the body’s response. However, because it’s a symptom and not a disease in its own right, it could be a sign of an underlying condition. The outcome greatly varies and relies on the root cause and any other existing health issues.
Possible Complications When Diagnosed with Dyspnea on Exertion
If dyspnea, or shortness of breath, is not treated promptly, it can escalate into acute respiratory failure. This could lead to an over or under-oxygenation of the blood, potentially resulting in life-threatening respiratory or cardiac arrest, or both.
Preventing Dyspnea on Exertion
Patients must understand how serious the condition of experiencing shortness of breath during physical exertion can be. It’s crucial that they seek immediate medical help if their symptoms return, as this can be potentially dangerous. It’s also important for patients with congestive heart failure (CHF) to learn about ways to manage their condition. This includes limiting fluid intake, modifying their diet, tracking their weight daily, and taking prescribed medications, including water pills, as directed by their doctor.
Managing CHF can be stressful and could potentially lead to emotional ups and downs, and even depression. Therefore, patients should be checked for mental health conditions regularly and should consult a mental health specialist, if necessary.
