Why pulmonary edema is a problem


Pulmonary edema is a serious condition that occurs when excess fluid begins to fill the air sacs in the lungs ( alveoli ). When the alveoli are filled with fluid, they cannot add enough oxygen to the blood or remove carbon dioxide. Therefore, pulmonary edema causes significant breathing difficulties and can often become a life-threatening problem .


Why is pulmonary edema a problem?

The real work of the lungs takes place in the alveoli. In alveolar air sacs, the fresh air we breathe enters the immediate vicinity of the capillaries, through which blood with a low oxygen content is drawn from the tissues of the body. (This oxygen-poor blood is simply pumped from the right side of the heart to the lungs through the pulmonary artery . )

Through the thin walls of the alveoli, there is a critical gas exchange between the air in the alveolar sac and the "residual" blood in the capillaries. Oxygen from the alveoli is absorbed by the capillary blood and carbon dioxide from the blood diffuses into the alveoli. The blood, now rich in oxygen again, is transported to the left side of the heart, which pumps it into the tissues. The "used" alveolar air is exhaled into the atmosphere when we breathe.

Life itself depends on the efficient exchange of gases in the alveoli.

With pulmonary edema, some of the alveolar sacs fill with fluid. Critical gas exchange between inhaled air and capillary blood can no longer take place in fluid-filled alveoli. If enough of the alveoli are affected, severe symptoms occur. And if the pulmonary edema is enlarged, death can occur.


Pulmonary edema can occur acutely, in which case it usually causes severe shortness of breath (shortness of breath), as well as coughing (often producing pink, frothy phlegm) and wheezing. Sudden pulmonary edema can also be accompanied by intense anxiety and palpitations . … Sudden pulmonary edema is often called "sudden pulmonary edema" and most often indicates a sudden worsening of an underlying heart problem. For example, acute coronary syndrome can cause sudden pulmonary edema, as can acute stress cardiomyopathy.

Acute pulmonary edema is always a medical emergency and can be fatal.

Chronic pulmonary edema, which is often seen in heart failure , tends to cause symptoms that get worse and worse over time as more or less alveoli are affected. Common symptoms are dyspnea on exertion, orthopnea (difficulty breathing while lying down), paroxysmal nocturnal shortness of breath (waking up at night with severe shortness of breath), fatigue, swelling of the legs (edema), and weight gain (due to fluid build-up). until).

Causes of pulmonary edema.

Doctors usually divide pulmonary edema into one of two types: pulmonary edema and extracardiac pulmonary edema.

Pulmonary cardiac edema

Heart disease is the most common cause of pulmonary edema. Pulmonary cardiac edema occurs when an underlying heart problem causes increased pressure on the left side of the heart. This high pressure is transmitted back through the pulmonary veins to the alveolar capillaries. Due to the increased pressure in the pulmonary capillaries, fluid leaks from the capillaries into the alveolar air space and pulmonary edema occurs.

Almost any heart disease can eventually lead to increased left-sided heart pressure and, as a result, pulmonary edema. The most common types of heart disease that cause pulmonary edema are:

In chronic cardiac pulmonary edema, increased pressure in the capillaries can eventually cause changes in the pulmonary arteries. As a result, high pressure can occur in the pulmonary artery, a condition called pulmonary hypertension . If the right side of the heart has to pump blood against the increased pressure in the pulmonary artery, eventually right-sided heart failure can develop.

Extracardiac pulmonary edema

In some conditions, the alveoli can fill with fluid for reasons other than high heart pressure. This can happen when the capillaries in the lungs become damaged and, as a result, "leak" and allow fluid to enter the alveoli.

The most common cause of this non-cardiac pulmonary edema is acute respiratory distress syndrome (ARDS) , which is caused by diffuse inflammation in the lungs . Inflammation damages the alveolar walls and promotes fluid accumulation. ARDS is commonly seen in critically ill patients and can be caused by infection, shock, trauma, and a variety of other conditions.

In addition to ARDS, extracardiac pulmonary edema can also be caused by:

  • Pulmonary embolism
  • Altitude sickness
  • Drugs (especially heroin and cocaine)
  • Viral infections
  • Toxins (such as inhalation of chlorine or ammonia)
  • Neurological problems (such as brain injury or subarachnoid hemorrhage )
  • Smoke inhalation
  • Almost drowned


Prompt diagnosis of pulmonary edema is essential and it is especially important to correctly diagnose the underlying cause.

Diagnosis of pulmonary edema is usually made relatively quickly by physical examination, blood oxygen measurement, and chest x-ray.

Once pulmonary edema has been detected, immediate steps must be taken to determine the underlying cause. A medical history is very important in these efforts, especially if there is a history of heart disease (or an increased risk of cardiovascular disease), drug use, exposure to toxins or infections, or risk factors for pulmonary embolism.

An EKG and echocardiogram are often very helpful in identifying an underlying heart condition. If heart disease is suspected that cannot be demonstrated by noninvasive testing, cardiac catheterization may be required. If a non-cardiac cause is suspected, other tests may be required.

Extracardiac pulmonary edema is diagnosed when there is pulmonary edema in the absence of increased pressure on the left side of the heart.

Treatment of pulmonary edema

The immediate goal of pulmonary edema treatment is to reduce fluid build-up in the lungs and restore blood oxygen levels to normal. Oxygen therapy is almost always done right away. In the presence of signs of heart failure, diuretics are also urgently prescribed. Medications that dilate blood vessels, such as nitrates , are often used to reduce pressure on the heart.

If blood oxygen levels remain critically low despite these measures, mechanical ventilation may be required. Mechanical ventilation can be used to increase pressure in the alveoli and return some of the accumulated fluid to the capillaries.

However, definitive treatment for pulmonary edema, be it a heart condition or a non-cardiac cause, requires identifying and treating the underlying medical problem.

Get the word of drug information

Pulmonary edema is a serious condition caused by excess fluid in the alveoli of the lungs. It is most commonly associated with heart disease, but it can also be caused by a number of non-cardiac medical problems. It is treated by quickly addressing the underlying cause with diuretics and sometimes mechanical ventilation.

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