Brain death Flashcards
What is death?
Irreversible biological event characterized by the permanent cessation of critical function of an organism as a whole
T/F: Tissues can survive in isolation after the system has died
True, but the survival of these tissues requires removal from the organ system as a whole whose integrative function has been lost
Are coma and brain death the same thing?
No
Why is brain death considered death?
Brain is central to integrated functioning of the body
Describe coma
Coma is a lack of responsiveness
Unarousable unresponsiveness
Brainstem reflexes may still work
Patient may retain a drive to breath
When does anoxic brain injury occur?
Cardiac arrest
Massive stroke
Carbon dioxide intoxication
Drug overdose
Head trauma
Is anoxic brain injury considered brain death?
No
What can cause a persistent vegetative state?
Severe anoxic brain injury
Is a persistent vegetative state considered brain death?
No
Describe how a patient in a persistent vegetative state presents
No evidence of awareness of self or environment and inabilty to interact with others
No evidence of sustained, reproducible, purposeful or voluntary behavioral responses to visual, auditory tactile or noxious stimuli
No evidence of language comprehension or expression
Intermittent wakefulness manifested by the presence of sleep wake cycles
What can a persistent vegetative state represent?
Represents a transition
Between coma and recovery
Between coma and death
Describe a minimally conscious state
Intermittent limited interactions with environment
Is a minimally conscious state brain death?
No
What behaviors might a patient in a minimally conscious state exhibit?
Visual tracking
Following simple commands
Signalling yes or no
Verbalizing intelligently
Behaving purposefully in restricted circumstances
Retain sleep wake cycles
What limitations does a patient with locked in syndrome have?
Cannot move muscle in limbs trunk or face
What can cause locked in syndrome?
Follows focal injury to the base of pons while preserving consciousness
What can a patient with locked in syndrome do?
Can voluntarily blink and move eyes vertically
What are the prerequisites required to diagnose brain death
Clinical or neuroimaging evidence of an acute central nervous system catastrophe
Exclusion of complicating medical conditions that may confound clinical assessments
No drug intoxication or poisoning including medically administered sedatives
Core temp > 36 celsius
Systolic BP > 100 mmHg even if vasopressors are required
What complicating medical conditions that may interfere with diagnosing brain death?
Disturbances of electrolytes, acid-base, endocrine or circulation (shock)
What will the pupils look like in a patient who is brain dead?
Pupils are mid position and do not respond
3.5-4 mm
What is considered a normal pupillary response?
Dilate in low light
Contract in bright light
What is a normal corneal reflex?
Move eye away from stimulus
Describe the corneal reflexes of a patient with brain death
Absent
What do normal oculocephalic reflexes look like?
Look towards the ear being filled with water
What reflexes are absent in brain dead individuals?
Jaw jerk
Gag reflex
Cough with tracheal suction
Sucking or rooting (neonates)
Describe the oculocephalic reflexes of a brain death patient
Resemble doll eyes
What is considered an abnormal oculovestibular reflex?
No reaction to cold water placed in ear with syringe
What movements in a brain dead patient do not count towards discounting brain death?
Movements originating from the spinal cords or peripheral nerves
What physiologic conditions must be present to perform an apnea test?
Core temp > 97
Systolic blood pressure > 100 mmHg
Eucapnia on mechanical ventilation
Absence of hypoxia
Euvolemia
What can movements originating from the spinal cords or peripheral nerves look like?
Subtle motions
Sitting up
Head turning to one side
How should the vent be set to prepare to for the apnea test?
Vent frequency should produce eucapnia
PEEP should be reduced to 5
What is indicated if the patient demonstrates effort?
The patient is not brain dead
How should the patient be prepared for the apnea test?
Preoxiginate for 10 minutes
Reach a maximum of 200 mmHg PaO2
PaCO2 exceeds 40 mmhg
When SpO2 is > 95% obtain an ABG
How is the apnea test performed?
Disconnect patient from ventilator
Place smooth bore oxygen tubing down ETT and run 10 Lpm oxygen
Observe 8-10 minutes
Return patient to ventilator
What happens if no patient effort is recorded during apnea test?
ABG is drawn
What must levels PaCO2 reach in order to confirm brain death?
Must be greater than 60 mmHg or 20 mmHg above baseline
Demonstrates that brain is not reacting to increased CO2 levels in blood and not triggering breaths
What conditions would prompt you to stop the apnea test?
Systolic blood pressure falls below 90 mmHg
SaO2 < 85% for > 30 seconds
If cardiac arrhythmias occur
If a patient cannot undergo the apnea test, what other tests are viable?
Cerebral angiograph
Electrecephalography
What does a cerebral angiograph analyze?
The movement, or lack thereof, of blood through the brain
What does electroecephalography analyze for?
Electrical activity of the brain
What is electroencephalography used for?
Seizure detection
Detect sleep stages
