The use of morphine in acute pulmonary edema: good or bad?

In med schools, we have often been taught that the treatment of acute pulmonary edema is LMNOP where L = Lasix, M = morphine, N = nitrates, O = oxygen, P = position/prop up the patients.

However, many recent studies have shown that the evidence of the use of morphine in acute pulmonary edema is not only weak, but is potentially harmful to the patients.

Here's some notes on the use of morphine