Brain death

Question 1

Define brain death

Answer 1

neurologically determined death is the irreversible loss of the capacity for consciousness combined with the irreversible loss of all brainstem functions, including the capacity to breathe

Question 2

What is the minimum criteria for NDD

Answer 2

Established etiology capable of causing neurological death
deep coma
absent brain stem reflexes, including gag, cough, and bilateral absence of motor responses (sans spinal), corneal responses, pupillary responses, vestibuloocular responses
absent respiratory effort based on apnea test
absent confounding factors

Question 3

List some confounding factors for the diagnosis of NDD?

Answer 3

Unresuscitated shock
hypothermia (>34 degrees)
severe metabolic disorder causing reversible coma (glucose, electrolytes, liver, kidneys
peripheral muscle or nerve dysfunction
clinically significant drug intoxication (alcohol, barbiturates, sedatives)

Question 4

What are the thresholds for completion of apnea test?

Answer 4

PaCO2 >60, and >20 rise above baseline
pH <7.28
must continuously observe patient for respiratory effort

Question 5

When are ancillary tests performed? give an example

Answer 5

only when it is impossible to complete the minimum clinical criteria
Demonstration of global absence of intracranial blood flow

Question 6

What physiologic changes occur with NDD?

Answer 6

Central diabetes insipidus
vasodilation
apnea
hypothermia
hypothyroidism
hypoadrenalism

Question 7

What differentiates NDD from permanent vegetative state?

Answer 7

Spontaneous breathing in PVS
maintenance of cardiovascular stability in PVS
sleep/wake cycles in PVS
duration of condition:
 PVS: months to years
NDD: hours