Brain Death

Occurs when the intracranial pressure overcomes the ability to supply blood flow to the brain

Defined as the permanent cessation of brain function, characterized by complete absence of any form of consciousness and the absence of brainstem reflexes, including the ability to breathe independently.

Is often accompanied by a period of hyperdynamic circulation as the brain is herniating or "coning" followed by restoration of normal hemodynamics

At times, the extreme release of catecholamines that occurs as a result of the abrupt rise in the intracranial pressures can cause subendocardial ischemia (bona fide scenario where demand outweighs supply) resulting in myocardial suppression and at times, cardiogenic shock

Diabetes Insipidus can also impact the hemodynamics through hypovolemia.

a word on DIABETES INSIPIDUS (DI)

DI is an anticipated complication of Brain Death due to the cut off of the blood supply to the posterior pituitary causing an abrupt fall in antidiuretic hormone levels

DI is never subtle. You do not need to send off a battery of lab investigations in this context to diagnose it

Patients can become hypvolemic and hypernatremic quickly and while we cannot do anything to save the patient who is already brain dead, there is a potential to help others through organ donation.

Preservation of organ perfusion is important. Replace what they've output with 1-2 liters of ringers lactate

Give 5ug of INTRAVENOUS DDAVP

If they are hypotensive, choose vasopressin over norepinephrine as it "kills two birds with one stone" by binding to the V1 Endothelial Receptor and the Aquaporin Receptor in the kidney

Brain Death Examination (declaration)

Prerequisites for assessment of brain death

Clinical or neuroimaging evidence of acute CNS catastrophe compatible with diagnosis of brain death

Exclusion of complicating medical conditions that can confound assessment

pH: 7.35-7.45
PaCO2: 35-45 mmHg
PaO2 > 100 mmHg
Core temp >36.0 degrees Celsius
Na < 150
Phosphate >0.5
SBP >100 mmHg (ok to use vasopressors)

No confounding drug intoxication, sedative, neuromuscular blockers

Absent Brain-Mediated Motor Responses

No response to noxious stimuli above the neck

No response to noxious stimuli to extremities

Absence of posturing

Absent Gag Reflex (CN IX)

Yankaur stimulation to oropharynx

Absent Cough Reflex (CN X)

Endotracheal suctioning

ancillary Testing

Catheter Angiogram Confirmation of Brain Death

Catheter Angiogram Confirmation of Brain Death

Catheter Angiogram Confirmation of Brain Death

A :shows only filling of the external carotid and only filling of the extracranial vertebral and carotid arteries

B: 10 seconds later contrast visible in extracranial ICA and vertebral arteries

C: 15 seconds later: contrast reaches cavernous segments of ICAs with venous outflow in the jugular veins

CTA Confirmation of Brain Death

Catheter Angiogram Confirmation of Brain Death

Catheter Angiogram Confirmation of Brain Death

absence of filling of intracranial vessels

evidence of cut off of flow beyond the extracranial vasculature