Emergency Management of Non-cardiogenic Pulmonary Edema - An Overview

Introduction:

Pulmonary edema is an acute lung disease in which the air-filled sacs in the lungs (alveoli) and the lung spaces get filled with fluid due to various pathological causes. Pulmonary edema often occurs due to life-threatening heart problems such as heart failure (cardiogenic pulmonary edema). However, pulmonary edema can also occur due to various other causes that are not heart-related and are referred to as non-cardiogenic pulmonary edema. For example, certain lung infections, toxins, medications, chest trauma, and exercising at higher elevations can lead to excessive fluid collection in the lung.

When we breathe, we breathe in oxygen-rich air and release carbon dioxide (a waste gas). Lungs filter out the oxygen from the inhaled air and pass it to blood. The blood then supplies oxygen to all the tissues and organs of the body. Rapid respiratory status deterioration (breathing problems) is seen in acute non-cardiogenic pulmonary edema and severely reduces blood oxygen levels (hypoxemia). As the body's vital organs, including the heart and brain, do not get sufficient oxygen, they get damaged, and eventually, organ failure is seen in severe cases. These can be fatal without immediate medical treatment. Emergency management of non-cardiogenic pulmonary edema includes oxygen supplementation, emergency medications, and treating the underlying cause.

What Causes Non-cardiogenic Pulmonary Edema?

The following causes can lead to fluid accumulation in the lungs:

1. Acute Respiratory Distress Syndrome: Severe trauma or injury, sepsis (widespread infection in the body), lung infections such as pneumonia, severe bleeding, and drug overdose can cause the lungs to fill up with fluid rapidly. This emergency condition is known as acute respiratory distress syndrome (ARDS). Liver failure, kidney failure, and rapid fall in blood pressure are the warning signs of this serious disorder requiring prompt emergency care.

2. Drug Overdose: Medications such as Aspirin and other drugs, including illegal drugs such as cocaine and heroin, cause drug reactions leading to pulmonary edema.

3. Pulmonary Embolism (Blood Clots in the Lungs): Blood clots in the lung's blood vessels can lead to fluid accumulation in the lung air sacs. Some underlying chronic diseases can also lead to clots in distant body sites, such as legs, that can dislodge and move to the lungs leading to pulmonary edema.

4. Toxins: Exposure to inhaled or aspirated toxins can lead to pulmonary edema by irritating the lungs and causing fluid buildup.

5. High Altitudes: Mountain climbers, hikers, skiers, and people traveling to higher elevations are more prone to high-altitude pulmonary edema.

6. Near Drowning: Water can enter the airway (passage to the lungs) and the lungs when a person almost drowns, leading to fluid buildup in the lung’s air sacs and spaces.

7. Blocked Upper Airway: When the upper part of the airway (the passage leading to the lungs) gets blocked, it creates a negative pressure in the lungs; if the person tries to breathe through the blockage. This can lead to pulmonary edema.

8. Neurogenic (Related to the Nervous System) Cause: Certain conditions of the nervous system and the brain, such as head injury, seizure, or brain surgery, can lead to pulmonary edema.

9. Inhalation of Smoke: Inhaling smoke and its components (chemicals) in a fire accident damages the lung membranes between the air sacs and the tiny blood vessels in the lungs. As a result, fluid enters the lungs from the blood through the damaged membrane.

10. Blood Transfusion: A blood transfusion can overload the heart’s lower chambers. This leads to excessive fluid accumulation in the lungs and pulmonary edema.

11. Viral Diseases: Viral illnesses like dengue and hantavirus can lead to pulmonary edema.

What Are the Symptoms of Non-cardiogenic Pulmonary Edema?

Non-cardiogenic pulmonary edema can be acute (sudden, rapid) or chronic(long-standing). Rapid weight gain, leg swelling, breathing difficulty or shortness of breath, disrupted sleep due to breathing difficulty, fatigue, and cough are seen in long-standing or chronic non-cardiogenic pulmonary edema. The sudden or acute non-cardiogenic pulmonary edema symptoms are more severe and require emergency care. Call for emergency help or rush to the emergency department in case of the following symptoms:

1. Dyspnea (breathing difficulty) that worsens with activity or rest (lying down).

2. Extreme shortness of breath.

3. Cough with frothy or pink blood-tinged sputum.

4. The heartbeat becomes fast and irregular.

5. Restlessness and anxiety.

6. Skin feels cold and clammy.

7. Wheezing (high-pitched whistling sounds occur while breathing).

8. Gasping for breath.

How Is Non-cardiogenic Pulmonary Edema Diagnosed?

The healthcare professional promptly examines the patient and performs several diagnostic tests to assess the lungs and identify the cause of the pulmonary edema. These include:

1. Chest X-ray.

2. Lung ultrasound.

3. Chest computerized tomography.

4. Pulse oximetry (to check blood oxygen levels).

5. Blood Tests:

   1. Arterial blood gas to assess the oxygen and carbon dioxide levels in the blood.

   2. B-type natriuretic peptide test to assess the presence of heart-related causes.

   3. Other blood tests include complete blood count and kidney, thyroid, and liver function tests.

6. Tests to Check the Heart:

   1. Electrocardiogram (to check heart’s electrical activity).

   2. Echocardiogram (to check the heart structure, valves, and muscles).

   3. Cardiac catheterization (to check for blocks in the heart and its blood vessels).

How Is Non-cardiogenic Pulmonary Edema Managed in the Emergency Department?

Management depends upon the patient's presentation, signs, and symptoms and is tailored from patient to patient. The goal of the treatment is to ensure adequate oxygenation and provide supportive care till the lungs recover. The initial general management of cardiogenic pulmonary edema by the emergency team as the patient arrives includes the following:

• The airway (passage to the lungs) is assessed immediately upon first contact with the patient. The airway is made clear to ensure sufficient oxygen-rich air reaches the lungs.

• The breathing is assessed (including the breathing pattern and oxygen saturation).

• The circulation and vital signs (blood pressure, heart rate) are assessed. The heart function is checked and promptly managed to ensure sufficient blood flow and oxygen supply to all body parts and organs. Cardiopulmonary resuscitation is initiated if required.

• Proper patient positioning to assist in breathing.

• Oxygen supplementation is the first line of treatment for non-cardiogenic pulmonary edema. Depending on the patient's condition, there are various ways to provide oxygen to the body. These include:

  • Bag-Mask Ventilation - Oxygen is pumped through a bag attached to the mask.

  • Noninvasive Positive Pressure Ventilation (NPPV) - Using tubes or masks, mild air is blown into the airway to keep it open.

  • Ventilator - A machine that helps to support breathing and provides oxygen to the lungs.

  • Tracheostomy - Oxygen is supplied through a hole (surgically made) in the windpipe.

  • Extracorporeal Membrane Oxygenation (ECMO): Artificial lungs can be used for several days to weeks until the lung recovers.

• Tubes are inserted into the airway to help to breathe and clear the excessive fluids.

• Access into veins (intravenous access) is obtained to give medications if needed.

• The patient’s urine output is monitored.

After the initial emergency care and resuscitation of the patient’s airway, breathing, and circulation, specific treatment is initiated depending on the cause. Emergency management focuses on supporting the lungs till they recover and managing the underlying cause. Then, surgical treatments and other invasive interventions are initiated depending on the reason for fluid accumulation in the lungs. In addition, the following medications are administered after assessing the cause and severity of the pulmonary edema:

1. Diuretics: Diuretic medications that help the body get rid of excess fluid (salt and water), such as Furosemide, are administered to reduce the pressure in the lungs and heart.

2. Drugs to Manage Blood Pressure: Blood pressure medications are administered to manage the blood pressure variations (low or high, depending on the cause) seen in pulmonary edema. In addition, medications such as Nitroglycerin and Nitroprusside are given to lower the pressure in the heart whenever required.

3. Morphine: Drugs such as Morphine are administered (used with extreme care) to relieve anxiety and breathing difficulty.

4. Other Medications: Intravenous Inotropes are given to ensure heart function if heart failure is seen.

Conclusion:

Noncardiogenic pulmonary edema is a severe lung disease in which the air-filled sacs in the lungs (alveoli) and the lung spaces are filled with fluid due to various pathological causes (unrelated to the heart). Fluid in the lungs leads to lower oxygen levels in the blood, which can be fatal without immediate medical treatment. Emergency management of non-cardiogenic pulmonary edema includes oxygen supplementation, emergency medications, supporting the lungs till it recovers, and treating the underlying cause.