Brain Death Tests

http://www.dundee.ac.uk/forensicmedicine/llb/brstem.htm#Diagnosis

Before the tests are performed the core temperature of the body is taken to ensure that it is above 35°C.

The diagnosis of brain stem death is established by testing the function of the cranial nerves which pass through the brain stem. If there is no response to these tests the brain stem is considered to be irreversibly dead.

The pupils are fixed in diameter and do not respond to changes in the intensity of light.

There is no corneal reflex.

The vestibulo-ocular reflexes are absent, i.e. no eye movement occurs after the installation of cold water into the outer ears.

No motor responses within the cranial nerve distribution can be elicited by painful or other sensory stimuli, i.e. the patient does not grimace in response to a painful stimulus applied to the face or to the limbs.

There is no gag reflex to bronchial stimulation by a suction catheter passed down the trachea.

No respiratory movements occur when the patient is disconnected from the ventilator for long enough to ensure that the carbon dioxide concentration in the blood rises above the threshold for stimulating respiration i.e. after giving the patient 100% oxygen for 5 minutes the ventilator is disconnected for up to 10 minutes. If no spontaneous breathing of any sort occurs within that 10 minutes the brain stem is incapable of reacting to the presence of the carbon dioxide and is thus dead.

Once two doctors have performed these tests twice with negative results the patient is pronounced dead and a death certificate can be issued. It is at this stage that a decision concerning the use of organs for transplantation purposes may be raised and the decision made as to the whether the corpse should be maintained on the ventilator until the organs may be harvested.