Brain Death Flashcards
What is brain death, how does this compare to coma, vegetative state or Locked-in-syndrome?
Brain death is the irreversible loss of all cortical and brainstem function, meaning the complete and permanent cessation of brain function, even though cardiopulmonary function may be maintained through artificial means (e.g., mechanical ventilation). A patient who meets criteria for brain death is legally and medically dead. Brain death is legally equivalent to cardiopulmonary death in the U.S.
What is the first step in evaluating brain death?
Assess the clinical prerequisites:
1. Clinical/brain imaging evidence of devastating known cause, absence of confounding factors (eg, sedatives, metabolic)
2. No evidence of ongoing drug intoxication or poisoning
3. Core temperature >36 C (96.8 F)
4. Systolic BP >100 mm Hg
What must be ruled out before making a brain death diagnosis?
Underlying confounding medical conditions such as drug intoxication, metabolic abnormalities, or hypothermia.
What are the required temperature and blood pressure criteria for a brain death diagnosis?
Temperature must be ≥36°C (96.8 F) and systolic blood pressure must be ≥100 mmHg.
What is required if the clinical prerequisites care not met when diagnosing brain death?
Perform accillilary tests. An example would be a patient who overdosed on fentanyl.
What is the purpose of ancillary testing in brain death?
Ancillary tests such as CTA, MRA, EEG, or cerebral blood flow studies are performed when clinical criteria cannot be fully assessed or if confounding conditions are present.
What would brain death look like in terms of neurologic examination?
- Patients are comatose
- lack of pain response
- lack of primitive reflexes
- lack of response on a caloric test
- No responses from brain stem tests (no pupillary reflex, no corneal reflex, no cough or gag reflex)
What are the absent brainstem reflexes tested in brain death?
- Pupillary light reflex (CN III)
- Corneal reflex (CN V1)
- Oculocephalic (doll’s eyes) reflex (CNs III, IV, VI, and VIII)
- Oculovestibular (cold caloric) reflex (CNs III, IV, VI, and VIII)
- Gag reflex (CNs IX and X)
- Cough reflex (CNs IX and X)
How is the oculovestibular (cold caloric) reflex tested?
Cold water is injected into the external auditory canal; in a normal response, the eyes deviate toward the stimulus and fast nystagmus is contralateral. In brain death, there is no response.
If the neurological assessment is either unable to be performed or the results are not able to be easily inferred due to paralysis or confounding components, what is the best approach?
Ancillary testing with EEG (isoelectric line, absence of somasensory or brainstem-envoked potentials) or Absence of intracranial blood flow (CTA/MRA carotid angiography, TCD, nuclear scan).
What are the three main clinical criteria for brain death?
- Persistent coma caused by a brain injury
- Absent brainstem reflexes
- Lack of spontaneous respirations (positive apnea test).
What is the apnea test in brain death evaluation?
Pre-oxygenate, disconnect ventilator, and observe for respiratory effort. A positive test (confirming brain death) occurs if PaCO2 increases ≥60 mmHg and final pH <7.28 without any respiratory effort.
When is a cerebral blood flow study required for evaluating for brain death?
A cerebral blood flow study is required when there is uncertainty in clinical examination, confounding conditions (e.g., severe metabolic abnormalities), or when other standard tests cannot be completed.
What does a cerebral blood flow study show in brain death?
It shows the absence of intracranial blood flow, confirming brain death.
What is the legal and ethical significance of brain death in the U.S.?
Brain death is legally equivalent to cardiopulmonary death, allowing for organ donation and withdrawal of life support.
What is the role of repeat examinations in brain death diagnosis?
In some cases, a second neurological exam by a different physician is required to confirm the diagnosis, depending on institutional protocols.
What are the mainstays after death has been officially confirmed that are required for organ donation in a patient diagnosed with brain death?
The primary goal of managing a brain-dead organ donor is to maintain:
1. Fluid balance (euvolemia). Volume status is threatened with due to central diabetes insipidus, which can increase urine output to >1000 mL/hr and cause volume depletion.
2. Normal blood pressure (normotensive). Systemic hypotension due to loss of sympathetic tone (and volume depletion) can threaten organs.
3. Normothermic (or mildly hypothermic)
Patients often receive intravenous fluids, desmopressin, and pressor support to prevent the loss of organs. Lastely, mild hypothermia is not threatening, however, hypothermia needs to be avoided.
What is the clinician’s role in the process of organ donation?
Discussions regarding brain death are conducted solely by the physician. Afterward, discussions regarding organ donation are conducted solely by the organ procurement organization. This strategy is known as decoupling and increases the likelihood of organ donation. Patients may continue to receive mechanical ventilation while arrangements with the family are being made. After death, the issue of organ donation becomes relevant. The organ procurement organization (OPO) serves as the intermediary for organ donation. OPOs form a national network, and every hospital is federally mandated to have a relationship with the regional OPO. The OPO is notified about all impending deaths, even if end-of-life goals of care are actively being deliberated or if brain death evaluation is still underway. This early notification protocol is intended to avoid missing potential donors by enabling the OPO to promptly assess the logistical. medical. and legal eligibility of donor candidates. The subsequent roles of the treating physician and OPO are clearly delineated and decoupled as independent processes. The physician guides conversations about brain death with the family and/or surrogates and provides care to the patient until death. The physician defers discussion of organ donation to the OPO. The OPO engages with the patient’s families/surrogates after they have been informed of impending brain death by the physician and have had an opportunity to begin processing the loss of their loved one. It conducts donor discussions, assumes medical care after death, evaluates the suitability of organ donation, and provides counseling and support. Families can understandably find it difficult to detach the physician’s role in healing their loved one from the OPO’s mission to provide a waiting recipient with an opportunity for life. Multiple studies have shown that decoupling physicians’ discussion of brain death from the OPO’s request for organ donation fosters family acceptance of the donation process, promoting higher rates of donation and thereby achieving the best shared outcome to address the present-day continuous shortage of organs.
