There is more to the removal of furosemide than purely the risks involved in misdagnosing pneumonia.
Patients with acute cardiogenic pulmonary edema (ACPE) have traditionally been treated for having too much fluid - after all, there is fluid in the lungs, so they must have too much fluid everywhere. Hence the use of diuretics in the acute setting. However we know that this is not actually the case. ACPE occurs not because there is too much fluid, but because there is fluid in the wrong place. It is at it's heart a problem with pressure - innappropriate systemic vascular resistance leads to a redistribution in fluid and the subsequent vicious circle of decreased oxygenation, increased sympathetic response aggravating SVR, decreased contractility aggravating back-flow, leading to further decreased oxygenation. Eventually the right heart gets in on the action too, with a RV afterload mismatch caused by hypoxic shunt from increased pulmonary cascular resistance. Bad news.
Most ACPE patients are not in fact fluid overloaded, but euvolemic and in many cases they are actually dry, so diuresis is not going to provide anything beneficial. Whilst some may argue that there is a degree of vasodilation that occurs due to furosemide administration (and this is true) the degree of dilation and the time it takes to happen is extremely variable and not clinically relevant when superior agents such as nitrates are available to achieve the same ends. THere may be some call for furosemide in certain cohorts of patients, such as those with a history of fluid overload, however it should be used with caution if at all.
Now, on top of all of that, there may actually be a place for the use of furosemide in the setting of a patient with pulmonary edema, just not in the acute or pre-hospital setting. It seems that patients who recieve positive pressure ventilation for more than about 24s have a subsequent inappropriate production of anti-diuretic hormone and their fluid balance and CVP and so forht needs to be monitored carefully (which of course will be done in the ICU, not the ambulance)
There are a number of good papers and text books out there that discuss this issue that are not too hard to find if you look for them.
Paramagic