Extubation Pulmonary Edema: Pathophysiology and Management

Pathophysiology

Post-obstructive pulmonary edema is primarily caused by forceful inspiratory efforts against an obstructed airway, creating negative intrathoracic pressure that increases the hydrostatic pressure gradient across pulmonary capillaries, leading to fluid leakage into the interstitial space 1, 2
Negative intrathoracic pressure is the primary mechanism, generated by forceful inspiratory efforts against an obstructed airway 3
Most commonly caused by laryngospasm (>50% of cases), but can also occur if a patient forcibly bites on a tracheal tube or LMA completely occluding the lumen 4
Occurs in approximately 0.1% of all general anesthetics, with higher prevalence in young muscular adults (male:female ratio 4:1) 5

Negative pleural pressures increase the hydrostatic pressure gradient across pulmonary capillary walls, causing fluid leakage into interstitial spaces 6
Negative intrathoracic pressure increases venous return to the right ventricle, increasing pulmonary capillary blood volume 7
Hypoxia, acidosis, and negative intrathoracic pressure increase pulmonary vascular tone, raising right ventricular afterload 8
Interventricular septum may shift into left ventricular outflow tract, increasing left ventricular diastolic dysfunction and promoting pulmonary edema 9
Catecholamine release, hypoxia, and hypercarbia cause systemic and pulmonary vasoconstriction, further increasing ventricular afterload 10
Increased hydrostatic pressure can disrupt the alveolar capillary membrane (stress failure), increasing permeability 6

Dyspnea, agitation, cough, pink frothy sputum, and decreased oxygen saturation 4
Diffuse bilateral alveolar opacities on chest radiograph 4

Ensure patent airway and administer 100% oxygen 2
PEEP reduces capillary wall pressure gradient and fluid leak into interstitium 3
PEEP also counters alveolar collapse and de-recruitment 3

Use of a bite block during emergence to prevent biting on the endotracheal tube 6
If biting occludes the tracheal tube, deflation of the cuff may allow some inward gas flow and reduce negative intrathoracic pressure 6
Careful extubation technique to minimize risk of laryngospasm 2
Identify patients at higher risk (young muscular adults) 5

With prompt diagnosis and appropriate management, clinical and radiological resolution typically occurs within a few hours 5
Death is rare and usually attributable to hypoxic brain injury at the time of the airway obstruction 5

The American Society of Anesthesiologists recommends relieving any ongoing upper airway obstruction, as this is the precipitating cause in over 50% of cases, with laryngospasm being the most common, by administering propofol or suxamethonium 1 mg/kg IV to achieve cord relaxation and permit ventilation 11
If laryngospasm persists, the American Society of Anesthesiologists suggests administering propofol or suxamethonium 1 mg/kg IV to achieve cord relaxation and permit ventilation 11
In extremis with total airway obstruction, consider surgical airway if pharmacologic measures fail, as recommended by the American Society of Anesthesiologists 11

The American Thoracic Society notes that with prompt diagnosis and management, clinical and radiological resolution typically occurs within a few hours, though delayed presentation up to 2.5 hours after the initial obstruction has been described 11
Obtain chest radiograph showing diffuse bilateral alveolar opacities to confirm diagnosis and exclude aspiration, as recommended by the American College of Radiology 11, 12
Monitor for pink frothy sputum, dyspnea, agitation, cough, and low oxygen saturations as hallmark signs, according to the American Thoracic Society 11, 12

The American Society of Anesthesiologists recognizes that young muscular adults (male:female ratio 4:1) are at highest risk, with an incidence of approximately 0.1% of all general anesthetics 11, 12
The American Society of Anesthesiologists notes that negative pressure pulmonary edema occurs most commonly after head and neck surgery or any procedure with risk of laryngospasm 11

The American Thoracic Society advises not to confuse NPPE with cardiogenic pulmonary edema, though both present with bilateral infiltrates, NPPE occurs in young healthy patients immediately post-obstruction 11
The American College of Chest Physicians suggests not to confuse NPPE with aspiration of gastric contents, as history and timing differ 11, 12