Negative pressure pulmonary edema

Background

  • Also known as post-obstructive pulmonary edema
  • Forced inspiration against obstructed airway causes large negative intrathoracic pressure, leading to pulmonary edema[1]
  • Mostly due to postoperative laryngospasm, sudden drops in PEEP (high PEEP to manual BVM), trauma such as hanging, strangulation, foreign bodies, etc.
  • The negative pressure causes hydrostatic edema that can be life-threatening if not but minimized if treated early, usually resolves after 24-48 hours. [2]
  • Patients have an airway obstructive process either from an allergy, laryngospasm, trauma, and commonly in the case of hangings.[3]

Clinical Features

  • Hypoxemia (may be sudden and large - beware "fake" or "not real" SpO2), stridor, retractions, accessory muscle use, crackles/wheezes
  • Crackles
  • Respiratory distress
  • Increased jugular venous distension
  • Signs of poor organ perfusion

Differential Diagnosis

Pulmonary Edema Types

Cardiogenic pulmonary edema

Noncardiogenic pulmonary edema

Evaluation

  • CXR shows diffuse interstitial and alveolar infiltrates
  • CT shows preferential central/nondependent distribution of edema (as opposed to other forms of pulmonary edema)

Management

  • Relieve airway obstruction/obstructive processes
  • Vent with generous PEEP and diuretics
  • Intubation is often required
  • Patients with severe pulmonary edema that do not respond to standard ventilator strategies may require proning or even ECMO

Disposition

  • Admit, often ICU

See Also

External Links

References

  1. Bhaskar B, Fraser JF. Negative pressure pulmonary edema revisited: Pathophysiology and review of management. Saudi J Anaesth. 2011 Jul-Sep; 5(3): 308–313.
  2. Bhattacharya M, Kallet RJ, Ware LB, Matthay MA. Negative-pressure pulmonary edema. Chest. 2016;150(4):927-33.
  3. Contou D, Voiriot G, Djibre et al. Clinical features of patients with diffuse alveolar hemorrhage due to negative-pressure pulmonary edema. Lung. 2017;195(4):477-487.