Death: Encyclopedia II - Death - When is a person dead?

Death - When is a person dead?

There is an asymmetry between life and death. While cells and organisms may die, they have never been observed to arise from non-living material (spontaneous generation), as found by Louis Pasteur in the late 19th century. In human affairs, we are normally concerned with the life and death of a person, not his or her parts.

Identifying the exact moment of death is important for a number of reasons. It allows for the correct time on death certificates, and helps ensure that a person's legal Will is executed only after he or she is truly deceased. Identifying the moment of death is even more important in cases of transplantation, as organs must be harvested as quickly as possible after the death of the body (not the brain).

Historically, attempts to define the exact moment of death have been problematic. Death was once defined as the cessation of heartbeat (cardiac arrest) and of breathing, but the development of CPR and prompt defibrillation posed a challenge. The previous definition was inadequate. This earlier definition of death is now called "clinical death", and even after it occurs, breathing and heartbeat may be restarted in some cases. Events which were conjoined in the past are now separate, and even without a functioning heart and lungs, a person can be sustained with life-support devices. There are many people who would quickly die if their organ transplants or cardiac pacemakers failed.

Today, where a definition of the moment of death is required, doctors and coroners usually turn to "brain death" or "biological death": people are considered dead when the electrical activity in their brain ceases (cf. persistent vegetative state). It is presumed that a stoppage of electrical activity indicates the end of consciousness. However, suspension of consciousness must be permanent, and not transient, as occurs during sleep, and especially coma. In the case of sleep, EEGs can easily tell the difference.

Brain activity is a necessary condition to legal personhood. "It appears that once brain death has been determined … no criminal or civil liability will result from disconnecting the life-support devices." Dority v. Superior Court of San Bernardino County, 193 Cal.Rptr. 288, 291 (1983)

However, those maintaining that only the neo-cortex of the brain is necessary for consciousness sometimes argue that only electrical activity there should be considered when defining death. Eventually it is likely that the criterion for death will be the permanent and irreversible loss of cognitive function, as evidenced by the death of the cerebral cortex. All hope of recovering human thought and personality is then gone. However, at present, in most places the more conservative definition of death — cessation of electrical activity in the whole brain, as opposed to just in the neo-cortex — has been adopted (for example the Uniform Determination Of Death Act in the United States). In 2005, the case of Terri Schiavo brought the question of brain death and artificial sustainment to the front of American politics. Generally, in such contested cases the cause of death is anoxia. Oxygen deprivation for about seven minutes is sufficient to kill the cerebral cortex.

Even in these cases, the determination of death can be difficult. EEGs can detect spurious electrical impulses when none exists, while there have been cases in which electrical activity in a living brain has been too low for EEGs to detect. Because of this, hospitals often have elaborate protocols for determining death involving EEGs at widely separated intervals.

There are many anecdotal references to people being declared dead by physicians and then coming back to life, sometimes days later in their own coffin, or when embalming procedures are just about to begin. Stories of people actually being buried alive (which must assume no embalming) led one inventor in the early 20th century to design an alarm system, with a bell and a cord that could be pulled from inside the coffin.

Because of the difficulties in determining death, under most emergency protocols, a first responder is not authorized to pronounce a patient dead; some EMT training manuals, for example, specifically state that a person is not to be assumed dead unless there are clear and obvious indications that death has occurred, such as mortal decapitation, rigor mortis (rigidity of the body), livor mortis (blood pooling in the part of the body at lowest elevation), decomposition, or incineration, or other bodily damage clearly inconsistent with life. If there is any possibility of life and in the absence of a do not resuscitate (DNR) order, emergency workers are instructed to begin rescue and not end it until a patient has been brought to a hospital to be examined by a physician. This frequently leads to situation of a patient being pronounced dead on arrival (DOA).

In cases of electrocution, CPR for an hour or longer can allow stunned nerves to recover, allowing an apparently-dead person to survive. People found unconscious under icy water may survive if their faces are kept continuously cold until they arrive at an emergency room. This "diving response", in which metabolic activity and oxygen requirements are minimal, is something we share with cetaceans.

Adapted from the Wikipedia article "When is a person dead?", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki