Brain death Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab.DCA, Dip. Software statistics- Phd Mahatma Gandhi Medical college and research institute,

Brain death Dr. S. Parthasarathy

MD., DA., DNB, MD (Acu), Dip. Diab.DCA, Dip. Software statistics- Phd

Mahatma Gandhi Medical college and research institute , puducherry , India

History

• In 1902, Cushing first reported cessation of cerebral

circulation when intracranial pressure exceeded

arterial blood pressure in monkeys

• In 1959, Bertrand and colleagues reported the

maintenance of respiration by mechanical means for

3 days after death of a patient with otitis media who

underwent circulatory collapse

History

• first heart implantation by Barnard in 1967• -------------------------------------------------------• Irreversible loss of consciousness

• 1976 • Death is defined as the irreversible loss of the capacity

for consciousness, combined with the irreversible loss of the capacity to breathe.”

Clinical Diagnosis of Brain Death

Diagnostic Criteria for the Clinical Diagnosis of Brain Death

• Prerequisites • absence of clinical brain function when the proximate

cause is known and demonstrably irreversible.   • 1.    Clinical or neuroimaging evidence of an acute

central nervous system catastrophe   • 2.    Exclusion of complicating medical conditions that

may confound clinical assessment (no severe electrolyte, acid-base, or endocrine disturbance)   

• 3.    No drug intoxication or poisoning    • 4.    Core temperature ≥ 32°C (90°F)

Brain death

• The three cardinal findings in brain death are

• coma or unresponsiveness,• absence of brainstem reflexes, • apnea.

Brain is all omnipotent

• Can we test all ??

• Immune . • Endocrine etc

The first one

• Coma or unresponsiveness—no cerebral motor response to pain in all extremities (nail-bed pressure and supraorbital pressure)

• NO • Drug intoxication, severe electrolyte, acid-

base, or endocrine disturbance,

Brain stem reflexes

• Pupils

• 4 – 9 mm • No response to bright light

Ocular movement

1. No oculo cephalic reflex (testing only when no

fracture or instability of the cervical spine is

apparent)

ii. No deviation of eyes to irrigation in each ear with

50 mL of cold water

(allow 1 minute after injection and at least 5 minutes

between testing on each side)

oculocephalic reflex

• reflex eye movement that stabilizes images on

the retina during head movement by

producing an eye movement in the direction

opposite to head movement, thus preserving

the image on the center of the visual field.

COWS • Ice cold or warm water or air is irrigated into

the external auditory canal, usually using a syringe.

• The temperature difference between the body and the

injected water creates a convective current in

the endolymph .

• Hot and cold water produce currents in opposite

directions and therefore a horizontal nystagmus in

opposite directions in patients with an intact brainstem:

Facial response

• I . No corneal reflex to touch with a throat swab

ii. No jaw reflex

• iii. No grimacing to deep pressure on nail bed,

supraorbital ridge, or temporo mandibular joint

Pharyngeal and tracheal reflexes i. No response after stimulation of the

posterior pharynx with tongue blade • ii. No cough response to bronchial

suctioning• Vagus • Failure of the heart rate to increase by more than 5

beats per minute after 1- 2 mg. of atropine intravenously. This indicates absent function of the vagus nerve and nuclei.

Clinical testing Apnea testing

Apnea testing • Prerequisites   

• i.     Core temperature ≥ 36.5°C or 97°F  

•   ii.  Systolic blood pressure ≥ 90 mm Hg   

• iii.  Euvolemia. - +ve fluid balance

• iv.  Normal PaCO2. Option: PaCO2≥ 40 mm Hg   

• v. Normal PaO2. Option: preoxygenation to obtain

arterial PaO2≥ 200 mm Hg

Apnea testing

• Connect a pulse oximeter disconnect ventilator. • Deliver 100% O2, 6 L/min, into the trachea• Observe for respiratory movements • 8 minutes

• Respiratory attempts + means test negative • Motor responses (i.e., the Lazarus sign) may occur

spontaneously during apnea testing- spinal origin

Apnea testing

• Measure arterial PaO2, PCO2, and pH after approximately 8

minutes

• If respiratory movements are absent and arterial PCO2 is ≥

60 mm Hg

• (option: 20 mm Hg increase in PCO2 over a baseline

normal PCO2), the apnea test result is positive (i.e., it

supports the diagnosis of brain death).

Problem in between ????

• BP < 90 • Desaturation • Arrhythmias

• Reconnect & ABG

• PaCO2 > 60 or increase more than 20 from normal baseline +

• but in between results – indeterminate

After brain death

• Patients become poikilothermic • Hypothermic • No fever • External heat ?? Use • 2 – 24 hours hormones continue to secrete• Immune system • Increased immune mediators, cytokines ?

Organ transplantation success rates

The path

• Brain injury • Progress of ischemia • Sudden hypotension ( vagal ) • Brainstem death • Unopposed sympathetic (storm) • Can damage myocardium

Young RTA patient with brain death

Cerebral Death: Persistent Vegetative State

• Stop of the functions of the cerebral cortices.• Brainstem functions governing the respiratory

centers, autonomic nervous system, endocrine system, and immune system, which are vital for maintaining life, are preserved

• May go for months to years

• That is death ?? Controversial

Brain dead = dead !!

• Central Integrator Theory of the Brain

• In brain death, the body is no more an integrated organism but a mere and rapidly disintegrating collection of organs that have lost forever the capacity of working as a coordinated whole

Infant organs

• Anencephalics

• Organ donors

• Gernamy OKAYs but still concern about • Dead donor rule • Radionucide blood flow and 2 EEG – children

Brain dead mother

• But fetus

• Preserve for weeks • Tocolytics • Ethical , moral and legal issues to be sorted

out

Variability in Policies and Practices for Determining Brain Death

• Law • Guideline • Apnea test • Number of physicians • Observation time • Confirmatory tests • India !!

Confirmatory tests

• Cerebral Angiography• Electroencephalography• Transcranial Doppler Ultrasonography• Cerebral Scintigraphy (99mTc-hexametazime)• Evoked Responses• Positron Emission Tomography

Harvard medical school definition

Brain death • unresponsiveness and lack of receptivity, the

absence of movement and breathing, the absence of brain-stem reflexes, and coma whose cause has been identified.

• Withdraw cardio-respiratory support in accordance with hospital policies, including those for organ donation

Organ donation -- anaesthetic concerns

• Among the brain dead

• 4 % of deaths are fit to donate • Out of which 10 % come to our picture

Donor • A potential donor is any previously healthy

individual who has suffered an irreversible

catastrophic brain injury of known aetiology.

• Exclusion criteria

• old age (greater than 65-70 yr), untreated systemic

sepsis, most extra cranial malignancies, and the

presence of transmissible diseases not amenable to

antibiotic therapy

What organs??

• Donor organs may be divided into • perfusible organs• (kidneys, liver, heart, lung(s), pancreas, and

bowel)• Non perfusable organs and tissues (eyes, skin,

bone, heart valves, and dura).

• Maintain perfusion

Rule of 100

• Systolic blood pressure > 100 mmHg

• Urine output > 100 ml. hr

• PaO2 > 100 mmHg

• Haemoglobin > 100 g.

• Blood sugar around 100 mg%

Anaesthetic problems

Other goals • CVP 6- 10 mmHg • pH – 7.35 to 7.45 • Na – 130 – 140 • K+ -- , calcium, magnesium kept normal • Temperature - > 35.5 – controversial • PaCo2 – normal • Methylprednisolone 15 mg/kg • T3 ( thyroxine)

Anaesthetic concerns

• spinal cords are intact and somatic and visceral reflexes remain,

• Muscle relaxants are necessary to suppress motor activity mediated by spinal reflexes.

• Vasodilators usually are employed to suppress hypertension and tachycardia by noxious stimuli.

• Sedation and analgesia ? !!

Summary

• 1. Establishing the cause of disease • 2. Excluding certain potentially reversible

syndromes that may produce signs similar to brain death

• 3. Demonstrating clinical signs of brain death: coma, brainstem areflexia, and apnea

• Anaesthetic concerns

• Thank you