if the heart stop beating and the breath stop after how much time you can tell the person is dead?

Answer 1

The brain can go without circulation of blood and oxygen for about 5 minutes under normal conditions.....
There has been cases IE cold water/conditions where much as 30 minutes has gone by and the dead person was revived and no brain damage was recorded.

Answer 2

Long ago, once heart beat and breathing stops, the person is considered dead.Today that is referred to as "clinical death". Those who are proven to have brain death are considered as "legally dead".

The advent of advances in medicine made the definition of death a bit complex. Different researches had been carried out describing the different length of time of possible revival after "clinical death" according to various factors. The old saying "nobody is dead until they are warm and dead" seem to have some thought. (You may be interested to read the link below.)

Currently, once the heart beat and breathing stops,resuscitation attempt is a must except if it has been determined that the patient is not a candidate for resuscitation.

So in normal situations in a hospital setting (or in a setting with healthcare provider around), the person who stops breathing and heartbeat stops will be given all the resuscitative measures. If there is no any progress after 20 minutes of revival attempt, usual confirmation method done is by checking the eye pupils. Fixed dilated pupils give certainty that a person is dead. Pronouncement of death however can sometimes be delayed as such decision must always be made with absolute certainty.

In any usual situation in a non-hospital setting , after heartbeat and breathing stops without resuscitation, 20-30 minutes would be sufficient time to check on the pupils to tell if the person is dead. Some of the cells will still be alive, so a person can be considered as "totally dead" after 12 hours or so.
http://news.bbc.co.uk/2/hi/health/620609.stm

Answer 3

erm pupil reflex action. shine light into patient's eye. if there is no constriction of the pupil, it means that brain function is lost... so he is dead.

Answer 4

Right away. Just needs confirming.