Pulmonary edema: what it is, symptoms, causes and possible treatments

Pulmonary edemas are disorders caused by excess fluid within the lungs .

This fluid collects in the tiny air sacs in our lungs, called alveoli. When filled with liquid, oxygen cannot pass into the blood normally and breathing is also difficult. Sudden onset of pulmonary edema requires immediate medical attention.

In this article we will talk about pulmonary edema, its causes, symptoms and some of the treatments used to remedy this disease.

Causes of pulmonary edema

There are several reasons why fluid can accumulate in the lung, causing edema . The main cause is heart problems, but there are other types of pulmonary edema in which the circulatory system is not directly to blame. In general, we can separate edema into cardiogenic and non-cardiogenic , depending on whether the cause is heart dysfunction or not.

Below we list and explain the main causes of pulmonary edema.

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1. Cardiogenic edema

Cardiac reasons for pulmonary edema are due to interactions between the pulmonary circulatory system and the heart. Normally the cause of this type of edema is a malfunction of the left ventricle of the heart .

When the left ventricle fails to expel blood correctly, there is an increase in the internal pressure of the pulmonary veins and capillaries. This increased pressure causes the blood vessels to release fluid, which will collect inside the alveoli .

The origins of these cardiac dysfunctions are varied. In some cases it is caused by the accumulation of lipid plaques in the coronary arteries, in others the heart muscle or the mitral or aortic valves fail directly. A failure in the mitral valve can cause blood to return to the lung very quickly, causing edema of great severity and rapid onset.

Chronic hypertension and kidney circulatory problems, although they are not effects directly related to cardiac activity, are problems of the circulatory system that can cause pulmonary edema.

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2. Non-cardiogenic edema

Non-cardiogenic explanations for pulmonary edema are much less frequent, but they do exist. These edematous factors have very varied origins . We would also find circulatory causes, such as alveolar capillaries with a higher than normal permeability that leave fluid inside the alveoli, but there are also non-circulatory causes.

Acute respiratory distress syndrome, caused by chest trauma, systemic infections (sepsis processes), pneumonia or heavy bleeding, can cause pulmonary edema through this syndrome, where the accumulation of fluid in the alveoli is accompanied by immune cells that They increase the inflammatory response, worsening the situation.

Pulmonary edema can also be caused by disorders of the nervous system , which would be called a neurogenic pulmonary edema. This type of pulmonary edema is usually preceded by head injuries or seizures, in addition to being able to occur after brain surgeries.

Other causes of edema are exposure to drugs such as cocaine, heroin or even aspirin (which has a small risk of causing edema), some types of viral infections such as dengue, aspiration of vomit, pulmonary embolism or blockage of the upper respiratory tract, among others.

3. High altitude edema

We separate the appearance of pulmonary edema due to altitude in its own category, although it would really fall within non-cardiogenic edema . This type of pulmonary edema occurs when we suddenly find ourselves in an environment with an altitude above 2,400 meters above sea level.

If we travel to places of high elevation and do not go through the acclimatization process (which usually lasts a few days to a week), participate in physical activity or increase our altitude more than 360m per day (for example, on a climbing expedition) we puts you at risk for high-altitude pulmonary edema.

The mechanism of this type of edema is not yet resolved, but evidence indicates that it would be related to the constriction of the pulmonary capillaries.

Symptoms

Regardless of its origin, pulmonary edemas usually have very similar symptoms .

We can differentiate them according to whether they are acute edema (sudden onset and more severe symptoms) or chronic edema, which lasts over time and presents symptoms that are very similar to acute edema, although they are milder. Chronic edema can also worsen suddenly, depending on its origin .

The symptoms of acute pulmonary edema are basically:

• Shortness of breath that worsens with exercise or lying down
• Choking sensation that worsens when lying down
• Labored breathing, sometimes accompanied by noises
• Cold skin
• Anxiety
• Cough, which may produce frothy sputum accompanied by blood
• bluish lips
• Rapid and irregular heartbeat.

While the symptoms of chronic edema are:

• Shortness of breath after physical activity
• Breathing difficulty linked to exercise and/or lying down
• rapid weight gain
• Swelling in feet and legs
• Fatigue
• Sleep interrupted by cough or shortness of breath, which improves when sitting down.

The symptoms of high altitude pulmonary edema are similar to those of acute edema , but they have particularities that can help us detect it quickly. Acting quickly against pulmonary edema improves the prognosis of the disease. These symptoms are:

• Respiratory difficulty linked to exercise, which evolves into respiratory difficulty also at rest
• Cough
• Fever
• Fatigue
• Difficulty walking while climbing elevation, which also evolves to affect us on the flat.
• palpitations
• chest discomfort
• Headache, which is usually the first symptom

If we do not treat pulmonary edema in time, it can easily get complicated . This can cause problems in other parts of the body besides the lungs, such as the liver. In the liver, as a result of increased blood pressure, we can suffer congestion and inflammation that can cause serious damage to this organ.

Treatment and prevention

The most effective prevention of pulmonary edema in general is to maintain good cardiovascular health . This means maintaining a balanced diet, not abusing salt, not smoking, maintaining a healthy weight, exercising regularly and avoiding stress whenever possible.

If we are at risk of suffering from pulmonary edema, it is important that we control that our blood pressure remains at normal levels (pulmonary edema can form when blood pressure exceeds 25mmHg, much higher than 15mmHg under normal conditions). It is also vitally important to keep track of our blood cholesterol levels.

Those people who are at risk of high altitude pulmonary edema should overcome the acclimatization period before engaging in intense physical activity. Some climbers skip this step with medication such as sildenafil (viagra), which appears to lower the risk of developing pulmonary edema.

The treatment of pulmonary edema will depend on its origin. As a general rule, in all cases it is treated with supplemental oxygen , in addition to appropriate medication to treat the root of the problem.

Bibliographic references

• Purvey, M., & Allen, G. (2017). Managing acute pulmonary edema. Australian prescriber, 40(2), 59–63. doi:10.18773/austprescr.2017.012.
• Paralikar SJ (2012). High altitude pulmonary edema-clinical features, pathophysiology, prevention and treatment. Indian journal of occupational and environmental medicine, 16(2), 59–62. doi:10.4103/0019-5278.107066.
• Jensen JD, Vincent AL. High Altitude Pulmonary Edema (HAPE) [Updated 2018 Dec 24]. Treasure Island (FL): StatPearls Publishing; Retrieved from: https://www.ncbi.nlm.nih.gov/books/NBK430819/ on 07/11/2019.