Determining Brain Death

Authors:

Anber Mahboob MBBS,

Harshadayani Jagadish Kumar MBBS,

Junaid Kalia MD

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

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

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)

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.