[Asymmetric negative pressure pulmonary edema after acute upper airway obstruction: case report]

Negative pressure pulmonary edema after acute upper airway obstruction is a well-described event, though infrequently diagnosed and reported. This report aimed at presenting a case of upper airway obstruction negative pressure pulmonary edema following acute upper airway obstruction characterized by pulmonary edema asymmetry, being more prominent in the right lung.

A 4-year-old boy, 17 kg, phisical status ASA I submitted to combined tonsillectomy, adenoidectomy and turbinate cauterization under general anesthesia with sevoflurane/nitrous oxide/O2. Surgery duration was 90 minutes without complications. During anesthetic recovery and spontaneously breathing, patient reacted to tracheal tube, which was removed. Following, ventilatory efforts resulted in chest wall retraction without apparent air movement, being impossible to ventilate him with facial mask. Symptoms evolved to severe hypoxemia (50% SpO2) requiring reintubation. At this point, it was observed that the lung was stiffer and there were bilateral rales characterizing pulmonary edema. A chest X-ray showed diffuse bilateral infiltrates, right upper lobe atelectasis and marked pulmonary edema asymmetry (right greater than left). Patient was mechanically ventilated with PEEP for 20 hours when he was extubated. There was a progressive pulmonary edema improvement and patient was discharged 48 hours later.

Negative pressure pulmonary edema (NPPE) is a rare event with high morbidity risk. It is often not diagnosed and requires from the anesthesiologist an updated knowledge and adequate management. It is usually bilateral, rarely unilateral, and exceptionally asymmetric as in this case. Most cases are treated by mechanical ventilation with PEEP or CPAP without any other therapy. The prognosis is favorable, with most cases recovering within the first 24 hours.