Acute pulmonary negative pressure edema (NPPE) also known as post-obstructive pulmonary edema is a life-threatening clinical scenario in which pulmonary edema develops immediately after upper airway obstruction. A review of the literature suggests that in healthy adults undergoing general anesthesia the incidence of NPPE is estimated at 0.05% to 0.1% .4,5. The pathophysiology of post obstructive pulmonary edema is multifactorial, with components of pulmonary edema of negative pressure, hypoxia and hyperadrenergic state. Hypoxia and a hyperadrenergic state are other factors that contribute to the development of EPPN. Hypoxia can increase pulmonary vascular resistance and pulmonary capillary pressure. It can also alter capillary integrity and precipitate a hyperadrenergic state. It is believed that a hyperadrenergic response redistributes blood from the systemic veins to the pulmonary circuit and increases pulmonary vascular resistance. All these events can promote the formation of edema. Finally, hypoxia and acidosis can depress myocardial performance and aggravate pulmonary edema.2In the clinical presentation, initial findings usually include decreased oxygen saturation, with foamy pink foam and abnormalities on the chest x-ray.20 Manifestations of acute airway obstruction include stridor, supraslary and supraclavicular retractions, urgent use of accessory muscles of inspiration and panic in facial expression. As NPPE develops, auscultation usually reveals crackles and occasional wheezing. Pulmonary edema causes both impaired oxygen diffusion and lack of ventilation / perfusion matching, leading to sudden and possibly severe hypoxemia. The typical chest radiograph will show diffuse interstitial and alveolar infiltrates. Treatment strategies vary according to the severity of the symptoms of POPE but are similar for type I treatment and type II. Support measures include the maintenance of a patent. Airway and ensuring adequate oxygenation through supplements. Oxygen with the addition of positive end expiratory pressure (PEEP) or continuous positive airway pressure guided by physical examination, pulse oximetry and arterial blood gases determinations.
