**8. Perioperative negative pressure pulmonary edema versus pulmonary aspiration**

Negative Pressure Pulmonary Edema (NPPE) also known as Post-Obstructive Pulmonary Edema (POPE), is a form of non-cardiogenic pulmonary edema that can occur perioperatively due to laryngospasm during anesthesia or following extubation in adults. NPPE is a potentially life-threatening complication following general anesthesia and is manifested by upper airway obstruction, followed by strong inspiratory effort (negative pressure). This occurs in 0.05–0.1% of cases as a life-threatening complication of general anesthesia with tracheal intubation [60]. NPPE was first hypothesized in 1927 by Morre and was described later by Oswalt in 1977. It is essential to notice the potential causes, make differential diagnosis and determine the effective treatment. NPPE usually presents with respiratory distress, hypoxia, cyanosis, frothy pink sputum, and hemoptysis. It is important to distinguish negative pressure pulmonary edema from pulmonary aspiration at the end of general anesthesia, however the diagnosis requires a strong suspicion as the presentation mimics aspiration pneumonia. In general, NPPE often demonstrates marked bilateral perihilar alveolar infiltrates on chest X-ray. Treatment modality includes supportive care such as careful post-op monitoring, reliving airway obstruction, oxygen supplementation, Bilevel Positive Airway Pressure (BIPAP) and assisted ventilation [61, 62].
