Pulmonary Edema

How pulmonary edema develops

Fluid moves between lung blood vessels and the surrounding tissue depending on pressure and on how leaky the vessel walls are. Lymph vessels normally drain any excess. Pulmonary edema develops when fluid leaks out faster than it can be removed.

Cardiogenic pulmonary edema

When the left ventricle cannot pump effectively, or a valve blocks or leaks, blood backs up into the left atrium and the pulmonary veins. Rising pressure in the lung capillaries pushes fluid into the lungs. Causes include:

• heart failure of any cause, the most common
• heart attack damaging the heart muscle
• valve disease: aortic stenosis, mitral valve disease, or sudden valve rupture
• fast or irregular rhythms such as atrial fibrillation
• a sudden surge in blood pressure (hypertensive emergency)
• fluid overload in someone with a weak heart, from excess salt, IV fluids or stopping diuretics

Flash pulmonary edema is a sudden, severe episode, often triggered by very high blood pressure, ischemia or narrowing of the kidney arteries.

Non-cardiogenic pulmonary edema

Here the heart is working normally, but the lung blood vessel walls become leaky or pressure changes in other ways:

• Acute respiratory distress syndrome (ARDS) from sepsis, pneumonia, major trauma, pancreatitis or aspiration
• High-altitude pulmonary edema (HAPE), usually above 2,500 m (8,200 ft), from uneven constriction of lung vessels. See altitude sickness
• Kidney failure causing fluid overload
• Neurogenic pulmonary edema after a seizure, head injury or brain hemorrhage
• Transfusion-related lung injury and transfusion-associated fluid overload
• Toxins: smoke, chlorine and other gases, aspirin overdose, opioid overdose, some chemotherapy
• Re-expansion edema after draining a large pleural effusion or collapsed lung
• Immersion pulmonary edema in swimmers and divers
• Negative-pressure pulmonary edema after breathing hard against a blocked upper airway

Symptoms

• breathlessness, initially with effort then at rest
• breathlessness lying flat and waking up gasping
• cough, wheeze, and frothy white or pink sputum
• rapid breathing, rapid heartbeat, sweating and anxiety
• leg swelling and weight gain in heart failure
• low oxygen, with blue lips in severe cases

For recognizing early warning signs at home, see fluid in the lungs.

Diagnosis

• Examination: crackles at the lung bases, raised neck veins, leg swelling, heart murmurs.
• Pulse oximetry and blood gases: measure oxygen and carbon dioxide.
• Chest X-ray: shows hazy lungs, a "bat-wing" pattern, enlarged heart and effusions.
• Lung ultrasound: shows "B-lines," a quick bedside sign of fluid.
• BNP or NT-proBNP: high levels support a heart cause. Normal levels make heart failure unlikely.
• ECG and troponin: look for a heart attack or rhythm problem.
• Echocardiogram: measures heart pumping function and valves.
• Kidney function and blood counts.

Treatment

Emergency treatment

• Sit upright and give oxygen to keep levels safe.
• Noninvasive ventilation (CPAP or BiPAP) through a tight mask pushes fluid back and reduces the work of breathing. Severe cases need a breathing tube and ventilator.
• Diuretics such as furosemide given through a vein to remove excess fluid through the kidneys.
• Nitrates (nitroglycerin) to widen blood vessels and lower pressure in the lungs, if blood pressure allows.
• Treating the trigger: emergency angioplasty for a heart attack, rhythm control, blood pressure lowering, valve surgery.
• Medicines to support the heart if blood pressure is low (cardiogenic shock).
• Dialysis for fluid overload in kidney failure.

Non-cardiogenic edema

Treatment focuses on the cause and lung support. ARDS is managed in intensive care with protective ventilation. HAPE is treated by descent, oxygen and, in some cases, nifedipine.

Long-term management

For heart failure, long-term medicines reduce hospital admissions and improve survival: these include ACE inhibitors, ARBs or sacubitril-valsartan, beta-blockers, mineralocorticoid antagonists and SGLT2 inhibitors, along with diuretics to control fluid.

Complications

• respiratory failure needing ventilation
• cardiogenic shock and multi-organ failure
• pleural effusions
• congestion of the liver and gut, with poor appetite
• right-sided heart failure over time

Outlook

The outlook depends on the cause. Episodes from a reversible trigger, such as a rhythm problem or missed medicines, usually respond within hours. Acute pulmonary edema in heart failure signals advanced disease and is associated with a significant risk of readmission, so close follow-up and optimized treatment matter.

Prevention

• Take heart failure medicines as prescribed and attend follow-up.
• Limit salt and follow fluid advice.
• Weigh daily and report sudden gains.
• Control blood pressure and diabetes.
• At altitude, ascend slowly (no more than about 500 m or 1,600 ft of sleeping altitude per day above 3,000 m).

Frequently asked questions

What is the main cause of pulmonary edema?

The most common cause is heart failure, where the left side of the heart cannot pump effectively and pressure backs up into the lungs. Heart attacks, valve disease, irregular rhythms, kidney failure, ARDS and high altitude are other causes.

What is the difference between cardiogenic and non-cardiogenic pulmonary edema?

Cardiogenic edema is caused by raised pressure from a failing heart or valve. Non-cardiogenic edema happens when lung blood vessels become leaky or pressure changes for other reasons, as in sepsis, pneumonia, high altitude or toxic inhalation, with a normal heart.

How is pulmonary edema treated in hospital?

Treatment includes sitting upright, oxygen, a breathing mask that applies pressure (CPAP), intravenous diuretics to remove fluid, nitrates to lower blood pressure in the lungs, and treatment of the cause, such as a heart attack or rhythm problem.

Can you recover from pulmonary edema?

Yes, many people recover fully from an episode, especially when the trigger is treatable. The long-term outlook depends on the underlying condition. In heart failure, ongoing medicines, salt restriction and daily weights reduce the chance of it happening again.