Liu R, Wang J, Zhao G, Su Z. Negative pressure pulmonary edema after general anesthesia: A case report and literature review. Medicine (Baltimore). 2019 Apr;98(17): e15389. doi: 10.1097/MD.0000000000015389.
It is widely accepted that the central mechanism of postoperative NPPE is related to rapid negative intrapleural pressure increasing due to forceful inspiration against the obstruction, which can be up to 10 times or more that of normal breathing.  A typical event leading to acute airway obstruction associated with postoperative NPPE is laryngospasm. Other procedure that increases the risk of NPPE includes oropharyngeal, head, and neck surgery. Five [8–12] of the reported 29 cases involved upper respiratory tract surgery, and 10 [1,3,6,7,13–18] of the cases involved head and neck surgery, which may be related to tissue swelling and the sensitive dilator muscle of the upper airway in head and neck surgeries.