Determination of Death by Neurologic Criteria

Establish Permanence and Exclude Confounders

Brain death/death by neurologic criteria (BD/DNC) is a distinct determination of death, not a prediction of poor functional recovery. Follow applicable law, institutional policy, examiner qualifications, and the 2023 AAN/AAP/CNS/SCCM consensus guideline. Identify a catastrophic permanent brain injury with a known mechanism capable of causing loss of all brain function and compatible neuroimaging. If the injury is primarily infratentorial, confirm that it has also produced catastrophic supratentorial injury before initiating evaluation.

Allow enough observation to establish permanence. The guideline includes age- and injury-specific minimums: in children younger than 24 months, wait at least 48 hours after acute brain injury; in patients aged at least 24 months with hypoxic-ischemic injury, wait at least 24 hours. Other circumstances may require longer observation, including time after interventions intended to reduce ICP. Meeting a minimum interval does not establish permanence by itself.

Core temperature must be at least 36 °C. If it was 35.5 °C or lower, wait at least 24 hours after rewarming to at least 36 °C. This observation period is separate from drug elimination. Sedatives can persist longer with hypothermia, obesity, or renal or hepatic dysfunction. Use appropriate drug levels when available or allow at least five half-lives, extended for those factors and the actual exposure. If pentobarbital was given, the level must be below 5 micrograms/mL or below the laboratory detection limit. A short-lived response to an antagonist does not establish durable absence of drug confounding.

Exclude pharmacologic paralysis with an appropriate peripheral nerve response or preserved deep tendon reflexes under the guideline. Correct severe metabolic, acid–base, and endocrine disturbances. Some uncorrectable metabolic confounders require ancillary testing after the remainder of the examination is performed as fully as possible; high sedative concentrations and hypothermia cannot be bypassed in this way.

Blood Pressure and Clinical Examination

In adults, maintain both SBP at least 100 mm Hg and MAP at least 75 mm Hg, using fluids and vasoactive support if necessary. In children, maintain SBP and MAP at or above the fifth percentile for age. Consider known chronic baseline pressure when applying the guideline. Hypotension can suppress function and invalidate assessment.

Demonstrate coma without brain-mediated response to visual, auditory, tactile, and noxious stimulation. Test pupillary, corneal, oculocephalic when safe, oculovestibular, gag, and cough responses according to the complete protocol. Do not move an unstable cervical spine to test oculocephalic responses. Facial trauma or anatomic limitations may prevent valid assessment and require an ancillary pathway.

Spinal reflexes can persist after BD/DNC and do not themselves exclude it. If a movement cannot confidently be classified as spinal rather than brain-mediated, obtain appropriate expert assessment and ancillary testing as indicated. Any observed brain-mediated activity precludes the determination; a perfusion study cannot override it. Pupils need not have one fixed size, but light responses must be absent bilaterally.

Apnea Testing

Assess the risk of hypoxemia and circulatory instability before testing. Preoxygenate with 100% oxygen for at least ten minutes to achieve PaO2 above 200 mm Hg, establish appropriate baseline PaCO2 and pH, and obtain a baseline gas. Use an accepted oxygenation method that prevents ventilation while maintaining oxygen delivery; CPAP methods can preserve recruitment. Adult catheter insufflation, when used, follows diameter, flow, and position precautions. Pediatric methods differ.

Observe continuously for respiratory effort and obtain gases according to the protocol. The endpoint in a patient without chronic CO2 retention requires all of the following:

• No spontaneous respirations.
• Arterial pH below 7.30.
• PaCO2 at least 60 mm Hg and at least 20 mm Hg above the pretest baseline.

For known chronic hypercarbia, use the known elevated premorbid baseline for the required rise. If chronic retention is suspected but the premorbid baseline is unknown, the guideline requires ancillary testing in addition to an otherwise qualifying apnea assessment. Do not automatically normalize a chronic retainer's baseline and ignore this distinction.

Abort for spontaneous respirations, adult SBP below 100 or MAP below 75 despite support, pediatric pressure below the age-specific threshold despite support, progressive saturation below 85%, or an arrhythmia with hemodynamic instability. Do not wait an invented additional 30 seconds after a dangerous threshold. When instability threatens, obtain an ABG before reconnecting if feasible and safe; subsequent interpretation or repeat testing depends on whether valid endpoints were reached. Stabilize the patient and choose a supported repeat or ancillary strategy rather than persisting through unsafe physiology.

Examinations and Ancillary Tests

Adults require at least one complete examination and one apnea test; policy or law may require more. Children require two independent examinations by two qualified clinicians, at least 12 hours apart, and two apnea tests, one after each examination, when safely possible. This 12-hour inter-examination minimum applies across the pediatric ages covered by the guideline, not the older age-dependent 24/12-hour scheme. Testing does not apply below 37 weeks corrected gestational age.

EEG, evoked potentials, CTA, and MRI/MRA are not accepted ancillary tests under this guideline. Perform the clinical examination and apnea testing to the fullest safe extent before ancillary testing. These tests are not standalone alternatives to establishing prerequisites and do not permit declaration when brain-mediated activity is present. Document the examination, testing limitations, results, and determination under the relevant policy.

Source checked October 17, 2026: 2023 consensus guideline and published clarification.