Negative Pressure Pulmonary Edema: A Rare Complication Following Extubation

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We describe a case of Negative PressurePulmonary Edema (NPPE) followed by laryngospasm occurred immediately after extubation. A 24-year-old man underwent a surgical correction of unilateral inguinal hernia by laparoscopy. The tracheal intubation was easy with grade 1 of Cormack-Lehane classification. Anesthesia was maintained with sevoflurane 2, 5%. After fully awake extubation, nearly total upper airway obstruction due to severe laryngospasm was observed by a decrease in oxygen saturation and the presence of large amount frothy pink sputum, suggestive of acute pulmonary edema. A nasal airway was inserted, but face mask ventilation was difficult. Oxygenation of the airway was maintained with support of non invasive ventilation for twenty four hours, with SpO₂ of 92-96 %. 48 hours later, the pulmonary edema disappeared and the patient was discharged without complications.

 Negative pressure pulmonary edema (NPPE) is a non common complication of general anesthesia. The incidence of NPPE is 0.05 to 0.1% in healthy adults who underwent general anesthesia. It is even less common with the use of a laryngeal mask airway. It is usually seen during emergence from anesthesia having a multi factorial pathogenesis. The most common causes of NPPE are upper airway infection, tumor and laryngospasm. In adults about 50% of NPPE occurrences are due to postoperative laryngospasm. The implications of acute NPPE can be severe with mortality as high as 11 to 40%. However, if diagnosed and treated early, these rates decrease. Previous recognition and institution of appropriate Non- Invasive Mechanical Ventilation (NIMV) is important to ensure successful outcomes. We report a case of a previously healthy male who developed NPPE secondary to laryngospasm shortly after extubation following general anesthesia.

He was monitored with electrocardiogram, non-invasive blood pressure, oxygen saturation (SpO₂) and a peripheral vein was catheterized for infusion and drug administration. Anesthesia was induced with intravenously propofol (150mg), fentanyl (250mcg) and atracurium (35mg). The endotracheal intubation using tube 8.0mm was easy with grade 1 of Cormack-Lehane classification. Anesthesia was maintained with sevoflurane (2.0-2.5%). Surgery lasted about one hour and during that time vital signs were normal. Patient recovered from surgery and was extubated successfully.