Biting the laryngeal mask: an unusual cause of negative pressure pulmonaryedema

Purpose: To describe negative pressure pulmonary edema due to biting of the laryngeal mask tube at emergence from general anesthesia. Clinical features: A healthy patient underwent general anesthesia using a l aryngeal mask airway and mechanical ventilation. During recovery, the patie nt strongly bit the laryngeal mask and made very forceful inspiratory effor ts until the mask was removed. Five minutes later the patient developed dys pnea and had an hemoptysis of 50 mi fresh blood. Chest radiograph showed bi lateral alveolar infiltrates. Pharyngo-laryngeal examination was normal. Br onchoscopy revealed no injury but diffuse pink frothy edema fluid. Clinical examination and chest radiograph became normal after 12 hr of nasal oxygen therapy confirming airway obstruction as the most available cause of this pulmonary edema. Conclusion: Airway obstruction due to biting of a laryngeal mask tube may r esult in negative pressure pulmonary edema.