Noncardiac Pulmonary Edema

Definition/Etiology:

Pulmonary edema is non-cardiac if it develops with a normal pulmonary capillary wedge pressure (no fluid overload).

Common causes include:

• Acute respiratory distress syndrome (ARDS)
• Reperfusion after pulmonary embolectomy
• Re-expansion after pneumothorax or pleural effusion
• E-cigarette or vaping associated lung injury (EVALI)

Less common causes:

• Eclampsia
• Transfusion-related acute lung injury (TRALI)
• High altitude pulmonary edema
• Neurogenic pulmonary edema
• Drug toxicity (opiates, aspirin)
• Acute kidney injury

Pathophysiology:

A few examples of causes. Not all of the pathophysiology for the development of non-cardiogenic pulmonary edema is understood at this time:

• Alveolar-capillary membranes can become leaky in Acute Respiratory Distress Syndrome (ARDS) from sepsis and Transfusion-Related Acute Lung Injury (TRALI). This allows protein and fluid to cross over and enter the alveolar space.
• Some people at altitude develop High Altitude Pulmonary Edema (HAPE) due to an abnormal response to hypoxia. This can be fatal and can occur if people ascend too fast. It’s hard to predict who will develop this.
• Neurogenic pulmonary edema develops due to massive catecholamine surgery (fight or flight, epinephrine, norepinephrine) after head injury, intracranial surgery, grand mal seizures, subarachnoid or intracerebral hemorrhage, or electroconvulsive therapy.

Clinical Presentation:

• Acute hypoxemia
• Tachypnea
• Tachycardia
• Diffuse rales/crackles
• Pink frothy sputum
• Hemoptysis

Collaborative Management:

• CXR
• ABGs / BNP
• Respiratory therapy
• Bipap / vent w PEEP / ECMO
• Proning, data unclear

PEEP (positive end expiratory pressure) can help keep alveoli open, but if too high, risks injury.

Evaluation | Patient Monitoring | Education:

• We can’t fix the leaky membrane itself.
• Treat underlying problem (antibiotics).
• Vasopressors for hemodynamic instability.
• Bipap / vent / ECMO until lungs recover.
• Nutrition via nasogastric tube.
• Prognosis is poor with ARDS.

Linchpins: (Key Points)

• Direct or indirect lung injury can cause edema.
• ARDS is the most common cause of non-cardiac pulmonary edema.
• No matter the cause, respiratory failure can occur.
• Many mechanisms can cause leaky membranes.