Definition: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Input: Abstract: Pulmonary edema due to upper airway obstruction can be observed in a variety of clinical situations. The predominant mechanism is increased negative intrathoracic pressure, although hypoxia and cardiac and neurologic factors may contribute. Laryngospasm associated with intubation and general anesthesia is a common cause of pulmonary edema in children. However, only seven cases of pulmonary edema presumably due to laryngospasm have been reported in adolescents and adults. Five of the seven had other risk factors for upper airway obstruction, and in four, the diagnosis of "laryngospasm" could be explained by other factors. Patients with underlying risk factors for upper airway obstruction, such as a forme fruste of sleep apnea or nasopharyngeal abnormalities, appear to be at increased risk for the development of pulmonary edema in the setting of intubation and anesthesia. This form of pulmonary edema usually resolves rapidly without the need for aggressive therapy or invasive monitoring.

Risk.