Brain death

1. 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

2. History • In 1902, Cushingfirst reported cessation of cerebral circulation when intracranial pressure exceeded arterial blood pressure in monkeys • In 1959, Bertrand and colleaguesreported the maintenance of respiration by mechanical means for 3 days after death of a patient with otitis media who underwent circulatory collapse

3. 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.”

4. Clinical Diagnosis of Brain Death

5. 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)

6. Brain death • The three cardinal findings in brain death are • coma or unresponsiveness, • absence of brainstem reflexes, • apnea.

7. Brain is all omnipotent • Can we test all ?? • Immune . • Endocrine etc

8. 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,

9. Brain stem reflexes • Pupils • 4 – 9 mm • No response to bright light

10. 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)

11. 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.

12. 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:

13. 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 temporomandibular joint

14. 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.

15. Clinical testing Apnea testing

16. 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

17. 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

18. 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).

19. Problem in between ???? • BP < 90 • Desaturation • Arrhythmias • Reconnect & ABG • PaCO2 > 60 or increase more than 20 from normal baseline + • but in between results – indeterminate

20. 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

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

22. Young RTA patient with brain death

23. 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

24. 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

25. Infant organs • Anencephalics • Organ donors • Gernamy OKAYs but still concern about • Dead donor rule • Radionucide blood flow and 2 EEG – children

26. Brain dead mother • But fetus • Preserve for weeks • Tocolytics • Ethical , moral and legal issues to be sorted out

27. Variability in Policies and Practices for Determining Brain Death • Law • Guideline • Apnea test • Number of physicians • Observation time • Confirmatory tests • India !!

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

29. 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

30. Organ donation -- anaesthetic concerns • Among the brain dead • 4 % of deaths are fit to donate • Out of which 10 % come to our picture

31. 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

32. 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

33. Rule of 100 • Systolic blood pressure > 100 mmHg • Urine output > 100 ml. hr • PaO2 > 100 mmHg • Haemoglobin > 100 g. • Blood sugar around 100 mg%

34. Anaesthetic problems

35. 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)

36. 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 ? !!

37. 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

38. Thank you