Defining death take 2

As a physician, one of the actions we have to take is to pronounce someone's death. Now this is not as straight-forward as it seems to be. You could maybe attempt to check the patient's vital signs mainly respiratory movements, pulse. But when these stop, as in a respiratory arrest or cardiac arrest, not only this doesn't mean death in most cases, but on the contrary it means that emergency measures may be indicated to revert the condition and trying to keep the person alive, and with a quality of life. So what I'm saying is that at the moment of the arrest his neurons, myocites are still alive and have potential to stay alive.
These emergency measures are an attempt to get new oxygen into your blood and to get your blood flowing in your body taking that oxygen to your organs.
So that doesn't count as death. Patients can also be kept alive through mechanical ventilation, through drugs that keep their blood pressure at a minimum to oxygenate their organs, in hopes that the condition that led them to need these measures will be reversible and the patient will be able to maintain his blood pressure without drugs and be able to breath well without help from a respirator.
Sometimes this condition is not reversible, such as a damage so severe to the brain that there is no hope. In this kind of patient, for example young people who suffer from car accidents, their hearts have no disease and could be kept alive indefinitely with mechanical aid. But sometimes, this patient may brain dead. So maybe this is the best definition of death. How to define this is not easy as well. Because of organ donation, rigid protocols have been estabilished. They usually involve the observation of the absence of primitive reflexes and more elaborate exams such as an electroencephalogram or as my previous post a functional MRI attested by more than one physician.