
17/08/2025
Pulmonary Edema – Causes, Mechanisms, and Prehospital Management
Author: Dimitar Nenchev | Crisis Tech Solutions | Medical Practice | Prehospital Care | Emergency Medicine
🫁 1. Most common causes of pulmonary edema
Pulmonary edema is the accumulation of fluid in the lung tissue and alveoli, impairing gas exchange and leading to acute respiratory failure.
• Cardiogenic causes (most common): acute left ventricular failure, myocardial infarction, hypertensive crisis, valvular disease (mitral/aortic stenosis or insufficiency), arrhythmias.
• Non-cardiogenic causes: ARDS, sepsis, intoxications, aspiration, high-altitude pulmonary edema, severe neurological events.
👉 In practice, cardiogenic pulmonary edema is the leading cause.
🫁 2. Mechanism of fluid movement from interstitium to alveoli
• Under normal conditions, the balance between hydrostatic and oncotic pressures, together with lymphatic drainage, keeps the alveoli dry.
• With elevated hydrostatic pressure or increased capillary permeability → fluid escapes into the interstitium.
• When compensatory mechanisms are exceeded, fluid crosses the alveolar-capillary barrier → fills the alveoli → mixes with surfactant to form frothy secretions → severe hypoxemia.
🫀 3. Left vs right ventricular failure
• Left ventricular failure: causes pulmonary congestion and pulmonary edema (blood backs up into pulmonary veins and capillaries).
• Right ventricular failure: causes systemic venous congestion (peripheral edema, hepatomegaly, ascites), but not pulmonary edema.
👉 Pulmonary edema is typical for left ventricular failure.
💉 4. Medication management in pulmonary edema with left ventricular failure and high blood pressure
• Furosemide: reduces volume and venous return, with additional venodilating effect before diuresis sets in.
• Isoket (nitrates): venodilation → reduced preload; at higher doses also arterial vasodilation → reduced afterload. This improves left ventricular function and decreases pulmonary pressure.
• Safety note: Isoket is suitable only in normotensive or hypertensive patients. Contraindicated in hypotension.
👉 In prehospital care, the combination of Furosemide + Isoket is effective in hypertensive pulmonary edema, as it simultaneously reduces volume, venous return, and afterload.
🔑 Conclusion:
Pulmonary edema is a life-threatening emergency, most often due to left ventricular failure. Understanding the mechanism of fluid shift into the alveoli, differentiating it from right heart failure, and applying the correct medication strategy (furosemide, nitrates) are crucial for successful prehospital treatment and saving the patient’s life.
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