Brain death is the irreversible loss of all brain function (both the cerebral hemispheres and the brainstem) while cardio-circulatory function is maintained. Brain death concerns patients generally hospitalized in intensive care units and placed under artificial respiration.

“Brain death or encephalic death is defined by the irreversible destruction of the encephalon (brain) with loss of all activity of the cortex and the brainstem following the complete cessation of cerebral circulation,” explains Professor Schwebel. “Brain death legally defines the death of a patient even though cardiac activity persists” indicates Professor Carole Schwebel, head of the Intensive Medicine – Resuscitation department at CHU Grenoble Alpes

A specific legislative framework governs diagnosis and treatment with a view to organ donation.

The patient presents a deep coma reactive to the various stimuli. “He is without any spontaneous respiratory activity and this apart from any sedation (anesthesia) and curarization, apart from a context of intoxication or low body temperature, in the absence of explanatory biological abnormality (absence of heart disease). liver, hypoglycemia, sodium disorder…) and with preserved blood pressure ”, continues the Professor.

These clinical situations – poisoning, biological abnormalities, temperature (<35 ° C) or arterial pressure (<65 mm Hg mean pressure) - can indeed be responsible for these same symptoms without cerebral destruction and especially reversible with restitution ad integrum.

The main cause of brain death is ischemic or hemorrhagic stroke (stroke).

Other causes of brain death are head trauma and anoxia (lack of oxygen).

The diagnosis of brain death is attested by several criteria:

The total absence of consciousness and voluntary motor activity

The total absence of consciousness, voluntary motor activity or in response to stimuli and respiratory activity.

The disappearance of all brainstem reflexes

This disappearance concerns the following reflexes: 

• Photomotor reflex: no pupillary contraction in the light;

Brain death and organ donation

“Contrary to the observation of banal death, a specific legislative framework governs the diagnosis of brain death in the perspective of organ, tissue or cell donation”, specifies the specialist.

Namely the obligation:

• From an observation by 2 doctors of the abolition of all brainstem reflexes apart from all confusing situations (Cf. above)

• the observation of 2 flat electroencephalograms (EEG) carried out 4 hours apart;

The diagnosis of brain death is the clinical situation that can lead to the donation of organs, tissues or cells for therapeutic purposes for transplant (s).

“It is in this perspective that relatives are approached and consulted by a transplant team, that the national register of refusals is questioned to know the position of the – of the – patient during his lifetime”, continues Professor Schwebel. . “If there is no obstacle to donation, a report is signed by 2 independent doctors who attest to the diagnosis (see above). The different functions of the organs are evaluated and specific intensive care is initiated as part of a parallel administrative procedure ”.

If there is no transplant plan, the doctor is authorized to suspend the ventilator which keeps the patient artificially alive. The date of death is that of the finding of brain death and not that of the cardiac arrest.