What Is Pulmonary Oedema?

Overview

Lungs are a pair of sponge-like organs situated in the chest cavity. Each lung is enclosed by a pleura (membrane) and is in contact with the heart and windpipe through pulmonary blood vessels. 

The lungs are part of the respiratory system and help gas exchange. The term gas exchange means the inhalation of oxygen from the environment, which cells need to produce energy, and exhalation of carbon dioxide, the waste byproduct of cells, back to the environment. This mechanism takes place in the alveoli, the tiny air sacs in the lungs. The alveoli are surrounded by pulmonary capillaries, which are small blood vessels. The gases get swapped between the capillaries and alveoli.

Pulmonary oedema is a buildup of fluid in lung tissue and the alveoli. Pulmonary oedema is a life threatening condition, since it impairs gas exchange and the ability of lungs to expand, making it difficult to breathe.¹ 

The fluid buildup in pulmonary oedema can either occur due to heart problems or other existing conditions, such as pneumonia, kidney disease, trauma to the chest wall, medications, toxins, and travelling or exercising at high altitudes. Because of the inability of the lymphatic system to clear the excess fluid, fluid builds up in different parts of the lung, causing a drowning or suffocating sensation.²

Causes of pulmonary oedema

There are two main types of pulmonary oedema, depending on the underlying cause: 

Cardiogenic (heart-related) pulmonary oedema

Cardiogenic pulmonary oedema occurs in patients with known heart disease. The heart and lungs are closely linked through pulmonary circulation, a system of blood vessels that allows blood to receive oxygen from the lungs. 

If the heart stops functioning properly due to a heart attack, congestive heart failure, or other heart problems, it cannot remove oxygenated blood from the pulmonary circulation. In the case of heart failure, this makes the heart pump with higher pressure, forcing blood from vessels to enter the alveoli.³

Pleural effusion is mainly seen in cardiogenic pulmonary oedema. It occurs when build-up fluid inside the lungs escapes to the outer lining of lungs.

Non-cardiogenic pulmonary oedema

Non-cardiogenic pulmonary oedema is usually caused by acute respiratory distress syndrome, a fatal condition with many underlying causes like viral infections and pneumonia.² Neurogenic pulmonary oedema occurs after a brain injury leads to cardiopulmonary dysfunction. 

Non-cardiogenic pulmonary oedema has many other causes, including:³

• Injury to lung tissue
• Sepsis
• Inhaling toxins or smoke
• Pulmonary embolism (blood clot in the lungs)
• Being at high altitudes
• Near drowning
• Drug overdose

Acute pulmonary oedema happens suddenly and is an emergency requiring critical care, or it could result in death.³ 

Risk factors for pulmonary oedema

Some of the risk factors for developing pulmonary oedema include:³

• Heart problems, such asheart valve disease, arrhythmia (irregular heart rhythm), and coronary artery disease
• Hypertension (high blood pressure) 
• Kidney or liver disease
• Alcohol use
• Diabetes

Signs and symptoms of pulmonary edema

The symptoms of cardiogenic pulmonary oedema and non-cardiogenic pulmonary oedema are similar with a few variations:^3,4

• Shortness of breath 
• Coughing up phlegm that may contain blood
• Difficulty breathing
• Wheezing
• Rapid and shallow breathing
• Rapid, irregular heartbeat
• Decreased blood oxygen 
• Feeling of drowning or suffocating
• Pale or bluish skin
• Sweating
• Swollen feet and ankles
• Confusion

Management and treatment for pulmonary oedema

Pulmonary oedema requires immediate medical attention and intensive care. 

First-line treatment is oxygen supplementation to help the patient breathe effectively and raise their blood oxygen levels.³ 

Medications that regulate blood pressure, such as diuretics, furosemide, nitroglycerin, inotropes and ACE inhibitors, are also given, as pulmonary oedema can raise or lower blood pressure.^3,4

Renal replacement therapy (to help filter blood) is used to treat kidney failure that is caused by pulmonary oedema.⁴

Mechanical ventilation and continuous positive airway pressure (CPAP) machines help improve breathing and reduce upper airway obstruction.⁴ 

Diagnosis of pulmonary oedema

A doctor will perform a physical examination and discuss the patient's medical history, including any history of congestive heart failure, heart attack, and other heart problems. Other existing comorbidities are also examined. The doctor will use a stethoscope to listen to the lungs; a crackling sound indicates excess fluid buildup.

Other diagnostic tests include:

• Chest X-ray
• Electrocardiogram to diagnose heart complications
• Lung ultrasound
• Pulse oximetry to measure blood oxygen levels
• Blood tests to check hormone levels
• Pulmonary capillary wedge pressure test - a catheter is inserted into a blood vessel to measure blood pressure in the left chamber of the heart⁴

Prevention of pulmonary oedema

Pulmonary oedema is often a consequence of heart and lung disease. The only way of preventing pulmonary oedema is early diagnosis and management of these conditions.³

Management for heart conditions usually involves controlling blood pressure and cholesterol through lifestyle changes. These can include:³

• Eating fruit, vegetables, and whole grains
• Limiting salt and fat
• Limiting alcohol intake and quitting smoking
• Regular exercise
• Reducing stress

Complications of pulmonary oedema

Amongst those treated for pulmonary oedema, 20% of the patients die due to complications. The lungs could take 6 months or a year of treatment to start functioning normally again in those who survive.⁵ 

Other complications of pulmonary oedema include:³

• High blood pressure in the heart and lungs
• Difficulty breathing
• Pleural effusion
• Swelling in the legs, feet, and abdomen
• Liver congestion and swelling

FAQs

What can I expect if I have pulmonary oedema?

Difficulty breathing, a drowning sensation, wheezing, cough, and shortness of breath. It requires intensive care treatment, including mechanical ventilation and oxygen therapy.  

How common is pulmonary oedema?

Every year, more than 1 million people are admitted to hospital annually because of pulmonary oedema due to underlying heart conditions, while around 190,000 people are diagnosed with an acute lung injury.⁵

When should I see a doctor?

If you experience symptoms such as difficulty breathing, shortness of breath, wheezing, irregular heartbeat, a drop in blood pressure, phlegm with blood, dizziness, and worsening of the condition, immediately consult a doctor.

Summary

Pulmonary oedema is a condition where fluid builds up within the lungs. The fluid accumulation in the alveoli impairs gas exchange, ultimately causing respiratory failure. 

There are two types: cardiogenic and non-cardiogenic pulmonary oedema. Pulmonary oedema is diagnosed through clinical examination and learning the patient’s medical history, particularly a history of heart disease. Diagnostic tests like scans can also be used.

Pulmonary oedema may lead to death without medical intervention because the main symptoms are breathing difficulty and decreased oxygen concentration in the blood. The treatment involves removing the fluid buildup and supplying oxygen.