Determination of Brain Death Donn Dexter, MD, FAAN Douglas T. Miller Symposium April 29, 2011

Disclosures Full time physician at Luther-Midelfort Mayo Heath System, Eau Claire, Wisconsin. No financial relationships or interests that pertain to organ donation.

Outline What is Brain Death? How Do You Declare Brain Death? Clinical Evaluation Neurologic Evaluation Apnea Test Ancillary Tests Conclusion

Determination of Brain Death Uniform Determination of Death Act (UDDA). An individual who has sustained either: 1) irreversible cessation of circulatory and respiratory function or 2) irreversible cessation of all function of the entire brain, including brain stem, is dead. A determination of death must be made with acceptable medical standards.

Determination of Brain Death The American Academy of Neurology (AAN) delineated the medical standards for brain death in 1995. This practice parameter was reviewed in 2010 (Neurology 74, June 8, 2010).

Determination of Brain Death Question for the 2010 AAN review: Are there patients who fulfill the criteria of brain death who recover brain function? In adults, the recovery of brain function has not been reported after clinical declaration of brain death using the 1995 AAN brain death criteria.

Determination of Brain Death Determination of Brain Death – 4 Steps 1) Establish irreversible and proximate cause of coma. 2) Achieve normal core temperature. 3) Achieve normal systolic blood pressure. 4) Perform neurologic examination.

The Clinical Evaluation Establish Irreversible and Proximate Cause of Coma Usually obvious. Exclude drugs (including alcohol above legal limit). No recent or persistent neuromuscular blocking agents (train of 4 twitches to nerve stimulation). No severe electrolyte, acid-base, or endocrine disturbance (ABGs, lytes, chem panel).

The Clinical Evaluation (cont.) Achieve Normal Core Temperature Core body temperature > 36 degrees C. Important for apnea test. Warming blanket and warmed IV fluids may be required.

The Clinical Evaluation (cont.) Achieve Normal Systolic Blood Pressure Neurologic examination usually reliable with systolic BP > 100 mmHg. UW-OPO requires systolic BP > 100 mmHg. May require vasopressors to maintain adequate BP (dopamine and neosynephrine often preferred).

The Clinical Evaluation (cont.) Perform Neurologic Examination One examination is sufficient. Examiner should be intimately familiar with brain death criteria. Most commonly a critical care specialist, neurologist, or neurosurgeon. Varies by state. Outside WI check with state statute.

The Neurologic Examination Coma No evidence of responsiveness. No eye opening to noxious stimuli. No motor response to noxious stimuli other than spinally mediated reflexes (may require expertise to distinguish).

The Neurologic Examination (cont.) Absence of Brainstem Reflexes No pupillary response to bright light (typically fixed @ 4-9 mm). Absent corneal reflex. Absent facial muscle movement to noxious stimulus. Absent pharyngeal and tracheal reflexes (gag and deep suction).

The Neurologic Examination (cont.) Absent Brainstem Reflexes (cont.) Absent eye movements to oculocephalic testing (doll’s eyes test); integrity of cervical spine must be certain. Oculovestibular testing (cold water calorics) – Head of bed 30 degrees, 50 mL ice water irrigation of each patent ear canal with 5 minutes observation and 5 minutes between tests.

The Apnea Test Preconditions Normothermia. Systolic BP > 100 mm Hg. Euvolemia (positive fluid balance). Eucapnia (PaCO2 35-45 mmHg). No evidence for CO2 retention (COPD, severe obesity, severe OSA).

The Apnea Test (cont.) Preoxygenate for 10 minutes to PaO2 >200 mm Hg. Reduce ventilation frequency to 10 bpm and PEEP to 5 cm H2O. If pulse oximetry remains > 95%, check baseline ABG. Disconnect ventilator and preserve oxygenation with 100% O2 @ 6-10 lpm via catheter through the ET at level of carina.

The Apnea Test (cont.) Watch closely for respiratory movements (abdominal or chest excursions). If no respiratory efforts, draw ABGs at 3-5 minutes and again at 7-10 minutes. If arterial PaCO2 is 60 mm Hg or greater or if >20 mmHg over baseline, the test is positive. If inconclusive, may extend to 10-15 minutes if clinically stable.

The Apnea Test (cont.) Abort Apnea Test for: Spontaneous respiratory effort. Significant cardiac ectopy. Pulse oximetry <90%. Systolic blood pressure < 90 mmHg.

Ancillary Testing EEG, TCD, CTA, MRI/MRA, cerebral angiography, and nuclear scans have all been used to confirm brain death. Used when standard testing impossible or inconclusive (i.e. aborted apnea test). EEG, cerebral angiography, and nuclear scan preferred.

Documentation Follow checklist closely! Time of death is the time PaCO2 reached target. If apnea test aborted, the time of death is the time ancillary test is interpreted.

Conclusion Have a clear and available protocol for the determination of brain death at your institution (UW-OPO has a good one). Review it regularly; test it formally. Follow it closely.