Dr Gita NathConsultant Anaesthetist

Axon Anaesthesia Associates Hyderabad

Parts of the brain

Cerebral hemispheres: Conscious part of the brainControls thought and memoryFeels sensationsDirects conscious movements

Parts of the brain

ThalamusRelay station for sensory information

to go to the brainHypothalamus Temperature control, controls hormone

systems, food intake, emotions

Parts of the brain

Cerebellum: BalanceCoordination

Parts of the brain

Brain stem: Midbrain + Pons + MedullaAttention, arousal & consciousnessCranial nerve reflexesControl of breathingControl of blood pressure, heart function

Brainstem function is vital for preservation of life!

Coma vs. Brain DeathComaProfound state of unconsciousnessPerson is not rousableFails to respond normally to pain,

light or soundNo voluntary actionsReversible or irreversible –

Depends on cause and severity

Coma vs. Brain DeathCauses of ComaHead injuryBleeding inside the skullHigh pressure inside the skull – tumours,

swellingDrug overdose

AlcoholSedatives, anaesthetic agents

Lack of oxygen – HypoxiaHypothermia - cold

Coma vs. Brain DeathBrain DeathIrreversible cessation of all brain activityBrain is not capable of maintaining life

without advanced life supportBrainstem death is considered equivalent to

brain death, because brainstem is essential to maintain life

Heartbeat may continue!What happens to patients in coma?Some recoverSome enter persistent vegetative stateSome become brain dead

Coma vs. Brain DeathFrog heart experiment:

Heart continues to beat after taking it out of the body

Thus:Brain activity is not necessary for heart beat

Concept of Brain Death1959: Le coma depasse – “A state beyond

coma” Mollaret and Goulon

1968: Ad Hoc Committee of Harvard Medical School defined brain death as ‘irreversible coma’: - totally unresponsive, no cranial reflexes, no respiratory efforts

Growing worldwide acceptance of brain death over next few decades (over 80 countries)

Concept of Brain Death1994: “Transplantation of Human

Organ Act” in IndiaDefined brain deathFormalized brain death certification

PreconditionsPersonnelProtocolTime scale

Brain Death vs Brain Stem DeathUK vs USAUK:1979: Criteria published for diagnosing brain

stem death, this was equated with brain death1995: “Brain stem death” is more correct term

(Working Group of Royal Colleges) but this condition is still equated with death, since there is irreversible loss of capacity for consciousness

USACessation of function of entire brain, including

brain stem required (1981)

Brain Death vs Brain Stem DeathUK vs USAUSA2005 (NY Dept of Health): Diagnosis of brain death

is primarily clinical, consisting of two assessments of brain stem reflexes and one apnea test

When it is not possible to complete the full assessment of brainstem reflexes safely (cervical injuries, hemodynamic instability)

AngiographyEEGNuclear brain scanningSSEPTranscranial Doppler

How do we establish brain death?1. PreconditionsPatient comatose, on ventilatory support.Cause of irreversible structural brain damage known.

How do we establish brain death?1. PreconditionsPatient comatose, on ventilatory support.Cause of irreversible structural brain damage

known.Reversible causes ruled out:

No hypothermia (temperature < 35oC)No metabolic or endocrine disturbancesNo CNS depressant drugs in body – alcohol,

sedativesNo muscle relaxantsNo circulating therapeutic levels of any

drug that could cause coma

How do we establish brain death?2. Cranial nerve reflexesAbsence of pupillary reflex response to

lightAbsence of corneal reflexesAbsence of vestibulo-ocular reflexAbsence of cranial nerve response to painAbsence of gag and cough reflexesAbsence of facial grimacing (cranial

nerve) in response to painful stimulation (anywhere on body)

How do we establish brain death?Pupillary reflex

Shining a bright light causes pupil to constrictPupils are fixed and dilated in brain death.Reflex path – optic nerve and oculomotor nerve

How do we establish brain death?Corneal reflex

Cornea touched with cotton swab rolled into ballNo corneal reflexes in brain death.Reflex path: Trigeminal nerve and facial nerve

How do we establish brain death?Vestibulo-ocular reflex

Doll’s eye movementsHead rotated from side to sideBoth eyes should move in opposite directionAbsence in brain deathReflex path: III, VI and VIII cranial nerves

How do we establish brain death?Vestibulo-ocular reflexCold Caloric test Otoscopy – check

eardrumInject 20 ml ice cold

saline into earNystagmus, fast

component to opposite side (COWS)

Absence in brain death

Reflex path: III, VI and VIII cranial nerves

How do we establish brain death? Gag and Cough reflexes Insertion of suction catheter into oropharynx, for gag reflex

Movement of endotracheal tube, for cough reflex

No reflex response in brain death. Reflex path: Glossopharyngeal and Vagus nerves

How do we establish brain death?Apnoea testingMeasure ABG before starting testOn ventilator, 100% oxygen for 5 minutesDisconnect from ventilatorOxygen insufflation through suction catheter in

endotracheal tubeWatch for any respiratory efforts, monitoring SaO2 and

b.p.After 10 minutes, repeat ABGNo respiratory efforts despite PaCO2 >60 mmHg or

rise >20 mmHg – positive apnoea testStop test if there is hypoxia, hypotension or arrhythmia

How do we establish brain death?Procedure according to Transplantation of Human

Organs ActBrain death certification to be done by a team of 4

doctorsOne of them should be a neurologist or

neurosurgeonOne of them should be on a panel of doctors

approved for brain death testing by the appropriate authority

The other members are the treating physician and member of hospital administration

Certification to be repeated after 6 hours interval

In conclusionBrain death certification is done to avoid

unnecessary prolongation of treatmentSecondly, it is done so that the organs may be

retrieved and used for transplantationIt is crucial that no individual is mistakenly

diagnosed as brain dead prematurely. To this end: Rigorous adherence to protocol with regard to

preconditions and brain stem assessmentTransparencyNo member of the transplant team should be involved

in brain death certification