Determining Brain Death

Permanent, irreversible termination of cerebral and brainstem functions including the ability to regulate respiratory activities. American Academy of Neurology has provided criteria to diagnose brain death but most states and hospitals have their own criteria so make sure to use your local criteria if that is available.

Definition

  • Permanent, irreversible termination of cerebral and brainstem functions including the ability to regulate respiratory activities.

Reason for Diagnosing Brain death

  • Emotional closure for family
  • Organ Donation

Causes

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Causes of Brain Death
Devastating brain injury due to
  • Trauma
  • Subarachnoid hemorrhage
  • Intracerebral hemorrhage
  • Hypoxic-ischemic encephalopathy
  • Ischemic stroke
  • Any condition causing permanent gross brain injury
 

Brain death diagnosis criteria by American Academy of Neurology

Of Note: Most states and hospitals have their own criteria based on the following. Please make sure to use your local criteria if that is available.

Prerequisites

  • Irreversible coma with a known cause
  • Neuroimaging showing coma
  • Evidence (clinical or neuroimaging) of acute central nervous system (CNS) injury
  • Elimination of other potentially confounding medical conditions like severe electrolyte, acid-base, endocrine, or circulatory disturbances e.g, shock)
  • Core temperature >36°C (97°F)
  • Exclusion of possible drug intoxication or poisoning, which includes any sedative drug administered in hospital
  • Systolic blood pressure >100 mmHg
  • No spontaneous respirations

Examination findings

  • Absence of motor response originating from brain which includes response to pain stimulus above neck and other movements arising from brain eg, decerebrate or decorticate posturing, seizures
  • Absence of pupillary light reflex
  • Absence of corneal reflexes: Swing light test shows no response
  • Absence of oculocephalic (doll's eyes) and oculovestibular reflexes (caloric responses)
  • Absence of jaw jerk
  • Absence of gag reflex
  • No facial movement to noxious stimuli at supraorbital nerve, temporomandibular joint
  • Absence of motor response to noxious stimuli in all four limbs (spinally mediated reflexes are permissible)
  • Absence of cough with tracheal suctioning
  • Absence of sucking or rooting reflexes (in neonates)

Apnea test

  • Ventilator adjusted to provide PaCO2 35–45 mm Hg (normocarbia).
  • Patient
    • hemodynamically stable
    • preoxygenated with 100% FiO2 for >10 minutes to PaO2>200 mm Hg
    • well-oxygenated with a positive end-expiratory pressure (PEEP) of 5 cm of water.
  • Provide oxygen via a suction catheter to the level of the carina at 6 L/min or attach T-piece with continuous positive airway pressure (CPAP) at 10 cm H2O.
  • Disconnect ventilator.
  • Spontaneous respirations absent
  • Arterial blood gas drawn at 8–10 minutes, patient reconnected to ventilator.
  • PCO2 ≥60 mm Hg, or 20 mm Hg rise from normal baseline value.
  • Positive apnea test results show no respiratory response to a PaCO2 >60 mmHg or 20 mmHg greater than baseline values and arterial pH of <7.28.

Ancillary/Confirmatory tests

  • Not compulsory but preferred in patients where clinical testing can not be performed reliably or at all.
  • Any of the mentioned tests may produce similar results in patients with severe brain damage but who have not yet fulfilled the clinical criteria of brain death.
  • Tests are listed in order of their sensitivity

Conventional angiography

  • No intracerebral filling at the level of the carotid bifurcation or circle of Willis.

Electroencephalography

  • At least 30 minutes of recording showing no electrical activity
  • Minimal technical criteria for EEG recording in suspected brain death as adopted by the American Electroencephalographic Society.

Transcranial Doppler ultrasonography

  • Initial absence of Doppler signals cannot be interpreted as consistent with brain death as a small percentage of patients may not have temporal insonation windows due to skull thickness.
  • Markedly increased intracranial pressure indicated by small systolic peaks in early systole without diastolic or reverberating flow that indicate notably high vascular resistance

Technetium-99m hexamethylpropyleneamineoxime brain scan

  • “Hollow skull phenomenon” i.e, no uptake of isotope in brain parenchyma.

Somatosensory evoked potentials

  • Bilateral absence of N20-P22 response with median nerve stimulation

Movements and clinical observations compatible with brain death diagnosis

  • Occasional manifestations.
  • Should not be misinterpreted as evidence for brainstem function.
  • Movements stemming from spinal cord or peripheral nerves may occur in brain dead patients
  • Triggers can be tactile stimuli or occur spontaneously
  • Examples include:
    • Faint, semi-rhythmic movements of muscles innervated by facial nerve ( due to denervated facial nerve).
    • Flexor movements of fingers.
    • Tonic neck reflexes.
    • Lazarus sign: Neck flexion may be accompanied by complex extremity and truncal movements, mimicking sitting up type movements and neck-abdominal muscle contraction or head turning to one side.
    • Foot stimulation can induce triple flexion response with flexion at the hip, knee, and ankle .
    • Asymmetric opisthotonic posturing of the trunk.
    • Preservation of superficial and deep abdominal reflexes.
    • Positive Babinski sign.
    • Undulating toe sign:
      • Passive displacement of foot causing alternating flexion-extension of toes
    • Upper limb pronation extension reflex.
    • Widespread trunk and extremities fasciculations.
  • Respiratory-like movements without significant tidal volumes
  • Blushing, sweating
  • Tachycardia
  • Normal blood pressure without pharmacologic support or sudden increases in blood pressure
  • No diabetes insipidus

Confounders of brain death diagnosis

  • Conditions that may interfere with clinical diagnosis of brain death.
  • Clinical assessment is not enough in such cases to definitively diagnose brain death. Confirmatory tests are recommended
💡
Box 1: Confounders in Brain Death Diagnosis
  • Severe facial trauma
  • Preexisting pupillary abnormalities
  • Toxic levels of:
    • Sedative drugs
    • Aminoglycosides
    • Tricyclic antidepressants
    • Anticholinergics
    • Antiepileptic drugs
    • Chemotherapeutic agents
    • Neuromuscular blocking agents
  • Chronic CO2 retention due to severe pulmonary disease or sleep apnea

Standard medical record documentation

  • Etiology and irreversibility of condition
  • Absent brainstem reflexes
  • Absent motor response to pain
  • Absent respiration with PCO, 260 mm Hg
  • Confirmatory test justification and result, if used
  • Repeat neurologic examination.

Box 2: Brain Death Determination Note (Example)

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Brain Death Determination Note (*** designated input required)
Patient Identification Information:
Insert NAME, Medical Record number, Age, Date of Birth
Etiology of Coma:
Insert cause of Irreversible Cause
Prerequisite Conditions:
State (***) No below or explain if there are any prerequisite not met or expected
Major Electrolyte Abnormality: ***
Major EndocrineAbnormality: ***
Major Acid Base Abnormality: ***
Toxins or Drugs: ***
Hypothermia (Temp < 36): ***
SBP > 100 mm Hg: ***
Sedative Medications: ***
Other Confounding Variables: ***
NEUROLOGIC EXAMINATION:
Intubated and not sedated; does not follow commands. No vertical gaze or blinking to command. Pupils fixed bilaterally size (INSERT Size). No gaze deviation or dysconjugate gaze. Corneal Reflex; Absent. Facial Grimace, Absent. Gag/Cough: absent
VOR: (Cold Calorics) no response of eye movements
Motor Exam: RUE - No movement to central and peripheral noxious stimulation LUE - No movement to central and peripheral noxious stimulation RLE - No movement to central and peripheral noxious stimulation LLE - No movement to central and peripheral noxious stimulation
Respiratory Drive: NOT overbreathing the ventilator Ventilator: Turned to pressure support without autoflow and elevated flow trigger. No respirations or diaphragmatic movement seen
Apnea Test:
Insert pre and post ABG finding here
No respiratory effort noted during the apnea testing
Confirmatory Test: A confirmatory test is not needed Or a confirmatory test was done and consistent with brain death diagnosis
Autopsy: Discussed with next of kin and family but they declined.
Medical Examiner: Indicate here if a case for medical examiner to review
 
Time of Death 1/1/2024 at 0001. Recorded and Certified. Next of Kin notified
 

Further Reading

  • Young, GB. (2021). Diagnosis of brain death. In Wilterdink, JL, UpToDate. Retrieved September, 06, 2021, from https://www.uptodate.com/contents/diagnosis-of-brain-death
  • Wijdicks EF, Varelas PN, Gronseth GS, Greer DM; American Academy of Neurology. Evidence-based guideline update: determining brain death in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2010 Jun 8;74(23):1911-8. doi: 10.1212/WNL.0b013e3181e242a8. PMID: 20530327.
 

Bibliography

  • Practice parameters for determining brain death in adults (summary statement). The Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 1995 May;45(5):1012-4. doi: 10.1212/wnl.45.5.1012. PMID: 7746374.
  • Goila AK, Pawar M. The diagnosis of brain death. Indian J Crit Care Med. 2009 Jan-Mar;13(1):7-11. doi: 10.4103/0972-5229.53108. PMID: 19881172; PMCID: PMC2772257.