Diagnosis

Pulmonary edema

Etiology

Cause [dqo]

1. Cardiogenic Pulmonary Edema: Acute cardiac event -> elevated pulmonary venous pressure -> increased hydrostatic pressure -> transudation of fluid into the pulmonary interstitium/alveoli -> decreased alveolar gas exchange -> respiratory failure

   • Excessive intravascular volume administration

   • Congestive left-sided heart failure

     • Valvular heart disease (mitral stenosis or aortic stenosis)

     • Atrial fibrillation

     • Myocardial infarction

     • Cardiomyopathy

   • Myxoma

   • Hypertensive crisis

   • Pulmonary embolism with associated right heart strain

   • Right to left shunts

2. Non-Cardiogenic Pulmonary Edema: Lung injury -> increased pulmonary capillary permeability

   • Acute respiratory distress syndrome (ARDS)

   • Pneumonia or sepsis/anaphylactic shock

   • Toxin inhalation (smoke, chlorine gas)

   • High-altitude pulmonary edema (HAPE)

   • Neurogenic pulmonary edema (after head trauma or seizures)

   • Drug overdose (opioids, aspirin toxicity)

   • Acute pancreatitis

   • Blood transfusion-related lung injury (TRALI)

   • Pulmonary contusion

   • Radiation

   • Drowning

   • Fat emboli

3. Other:

   • Lymphatic obstruction due to lymphoma, fibrosing lymphangitis or lung transplantation: The lymphatics play an important role in maintaining an adequate fluid balance in the lungs by removing solutes, colloid, and liquid from the interstitial space.

   • Neurogenic pulmonary edema (neurological events associated with elevated intracranial pressure) and high-altitude pulmonary edema.

   • Thyrotoxicosis

   • Myocarditis

   • Myocardial toxins (alcohol, cocaine, chemotherapeutic agents)

Pathophysiology [dqo][rh5]

1. The alveolar gas and capillary blood is separated by the alveolar-capillary membrane (capillary endothelium, interstitial space and alveolar epithelium)

2. Pulmonary edema occurs when there is increased transudation of fluid into the pulmonary interstitium and alveoli -> alveolar flooding -> severe respiratory failure

3. Disruption of the balance of fluid filtration:

   • Increase in intravascular hydrostatic pressure (pulmonary vein pressure)

   • Increase in interstitial hydrostatic pressure

   • Endothelial injury and disruption of epithelial barriers

   • Decrease in oncotic pressure (decreased albumin: hepatic, renal, malnutrition)

   • Lymphatic insufficiency

   • Increased negative interstitial pressure

Complications [dqo]

• Respiratory failure

• ARDS

• Cardiac complications

• Multiorgan failure

Epidemiology

Incidence per 100.000 [rh5][efo]

Approach

• Blood test: Hb, WBC, CRP, electrolytes, brain natriuretic peptide, troponin, albumin

• Blood gas

• Blood culture

• Edema fluid-to-plasma protein ratio [sqy]

• ECG

• Chest x-ray

• Echocardiography

• Lung ultrasound

• CT thorax

• Pulmonary Arterial Catheter

Treatment

1. Initial symptomatic treatment: [dqo]

   • Airways: Suction of mucus

   • Breathing: Oxygen, nasal cannula, face mask, noninvasive/invasive ventilatory support, intubation

   • Circulation: Inotropes if hypotension (Dobutamine, Dopamine, Milrinone)

   • Diuretics: Furosemide 20 to 40 mg IV, bumetanide 1 mg IV

   • Vasodilators for Pre-Load Reduction if systolic blood pressure > 110 mm Hg:

     • IV nitroglycerin lowers preload and pulmonary congestion

     • Sodium nitroprusside

     • Isosorbide dinitrate

     • Nifedipine

     • Nesiritide (with care)

   • Morphine (analgesic/anxiolytic): with care due to respiratory depression

   • Ultrafiltration: Sodium and water removal

   • Monitor: Blood pressure, respiratory rate, pulse, urine output, pedal edema, weight, intake/output

2. Treatment of the underlying condition

Differential diagnoses

Acute liver failure, Acute respiratory distress syndrome, Anaphylaxis, Asthma, COPD, Emphysema, Goodpasture syndrome, Myocardial infarction, Pneumonia, Pneumothorax, Pulmonary embolism, Renal failure, Respiratory failure, Shock, Stroke