Acute, cardiogenic pulmonary edema, causes, symptoms and therapies

By Cristiano Antonino On Apr 10, 2023

Pulmonary edema is a condition characterized by an increase in fluid in the extravascular space (interstitium and alveoli) at the level of the lung parenchyma

Acute pulmonary edema can be secondary to an increase in hydrostatic pressure in the pulmonary capillaries (acute heart failure or AHF), mitral stenosis or to an alteration of the alveolar capillary membranes (inhalation of irritating substances, infectious processes).

By accumulating inside the alveoli, the structures in which oxygen exchanges between the air and the blood take place, the fluids cause respiratory problems.

The risks of pulmonary edema

The accumulation of fluid in the lungs that causes pulmonary edema requires immediate intervention to avoid serious complications.

If left untreated, it can in fact lead to an increase in pressure in the pulmonary artery and, in some cases, to suffering of the right ventricle of the heart.

The increased pressure affects the right atrium and, consequently, different parts of the body, leading to swelling in the abdomen and legs, accumulation of fluid around the lungs, and congestion and swelling of the liver.

What are the causes of pulmonary edema?

In most cases, pulmonary edema is caused by heart problems, such as coronary heart disease, cardiomyopathy, heart valve problems, and high blood pressure.

However, fluids can also accumulate due to lung infections, kidney disease, inhalation of chemical fumes, drugs, a narrow escape from drowning and acute respiratory distress syndrome.

The exact causes of high altitude pulmonary edema – a form that typically affects above 2,400 meters of altitude or those who practice sports at altitude without first acclimatising – are not known, but it appears to be a problem associated with pressure increase caused by the constriction of the pulmonary capillaries.

Starling’s force imbalance pulmonary edema

Pulmonary edema may be the result of an imbalance in the Starling forces that hold plasma fluids within the capillary bed or an alteration of the alveolar-capillary membranes:

Increased pulmonary capillary pressure (heart failure, mitral stenosis, overflow edema);
Decreased plasma oncotic pressure (hyponchia);
Decreased pulmonary interstitial pressure (rapid expansion of collapsed lung due to pneumothorax);
Excessive decrease in intrapleural pressure (increase in end-expiratory volume in asthma).

Acute pulmonary edema from heart failure

Acute cardiogenic pulmonary edema (secondary to severe heart failure e.g. from myocardial infarction or severe bradyarrhythmia) is due to ventricular pump dysfunction resulting from acute or chronic lesions of cardiac structures.

The pump deficit results in an insufficient accumulation of liquids upstream of the ventricle, with an increase in hydrostatic pressure in the venous districts that drain the tissues; in this case, the increase in venous outflow pressure has repercussions on the level of the pulmonary capillaries: here, the increase in vascular pressure leads to an extravasation of liquids at the level of the pulmonary interstitium. This situation is called “interstitial oedema”.

At this point, a further increase in capillary pressure can lead to the rupture of the occluding junctions of the pulmonary alveoli with flooding of the same.

This situation is called “alveolar edema”.

What are the symptoms of pulmonary edema?

Sudden pulmonary edema is manifested by very shortness of breath and breathing difficulties that are worse on lying down, a feeling of choking, crackling or wheezing, anxiety and worry, excessive sweating, coughing (sometimes bloody), pale skin, palpitations and, in some cases, chest pain.

Chronic pulmonary edema is characterized by shortness of breath and difficulty breathing while exercising, wheezing, night-time awakenings due to shortness of breath, loss of appetite, swollen legs and ankles, tiredness and, in case of heart failure, rapid weight gain.

The symptoms of high altitude edema are headache, insomnia, fluid retention, cough and shortness of breath.

How to prevent pulmonary edema?

Pulmonary edema is often not preventable, but a lifestyle aimed at the prevention of cardiovascular disease also helps reduce the likelihood.

For this reason it is important to keep stress, blood pressure and cholesterol levels under control, practice regular physical activity, maintain a healthy weight, follow a diet rich in fresh fruit, vegetables and low-fat dairy products, limit consumption of salt and alcohol and not smoking.