Study objective: We sought to assess the effect of nitrates on prehospital mortality among patients with acute pulmonary edema (APE). Methods: The study involved a retrospective evaluation of the records of prehospital outcome in 640 patients with APE rescued by the mobile CCU (MCCU) of Florence, Italy, between January 1980 and December 1991. The MCCU serves an urban environment with a population of 400,000 in a 102-sq km area. In the years 1980 through 1983, patients were treated with oxygen, morphine, furosemide, digoxin, nitrates, aminophylline, or dopamine, according to the attending physician's judgment. From 1984 through 1991, new guidelines for the use of intravenous nitrates, based on differential treatment according to blood pressure, were in use. Results: Overall prehospital mortality rate for APE in all patients was 7.8% (50 of of 640 patients). Mortality after 1984 was significantly lower than before (5.3% versus 13%, P<.01). Nitrates were effective in reducing mortality, even in hypotensive patients. Multivariate analysis showed that outcome was significantly affected by two clinical features (dyspnea and low blood pressure), treatment with nitrates, and calendar period effects (before/after 1984). Conclusion: Our findings suggest that the use of intravenous nitrates improves short-term prognosis in APE. [Bertini G, Giglioi C, Biggeri A, Margheri M, Simonetti I, Sica ML, Russo L, Gensini G: Intravenous nitrates in the prehospital management of acute pulmonary edema. Ann Emerg Med October 1997;30:493-499.]