Negative pressure pulmonary edema
- Also known as post-obstructive pulmonary edema
- Forced inspiration against obstructed airway causes large negative intrathoracic pressure, leading to pulmonary edema
- 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. 
- Patients have an airway obstructive process either from an allergy, laryngospasm, trauma, and commonly in the case of hangings.
- Hypoxemia (may be sudden and large - beware "fake" or "not real" SpO2), stridor, retractions, accessory muscle use, crackles/wheezes
- Respiratory distress
- Increased jugular venous distension
- Signs of poor organ perfusion
Pulmonary Edema Types
Pulmonary capillary wedge pressure <18 mmHg differentiates noncardiogenic from cardiogenic pulmonary edema
- Cardiogenic pulmonary edema
- Noncardiogenic pulmonary edema
- Negative pressure pulmonary edema
- Neurogenic causes
- Iatrogenic fluid overload
- CXR shows diffuse interstitial and alveolar infiltrates
- CT shows preferential central/nondependent distribution of edema (as opposed to other forms of pulmonary edema)
- 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
- Admit, often ICU
- Bhaskar B, Fraser JF. Negative pressure pulmonary edema revisited: Pathophysiology and review of management. Saudi J Anaesth. 2011 Jul-Sep; 5(3): 308–313.
- Bhattacharya M, Kallet RJ, Ware LB, Matthay MA. Negative-pressure pulmonary edema. Chest. 2016;150(4):927-33.
- 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.
- Clark SB, Soos MP. Noncardiogenic Pulmonary Edema. In: StatPearls. Treasure Island (FL): StatPearls Publishing; October 1, 2020.