Publications of the Week, October 26

2020-10-26

Minimum criteria for the clinical diagnosis of brain death. An attempt at consensus. Part 1 

Greer DM, Shemie SD, Lewis A, et al. Determination of Brain Death/Death by Neurologic Criteria: The World Brain Death Project. JAMA. 2020 Aug 3. doi: 10.1001/jama.2020.11586. Epub ahead of print. PMID: 32761206.

The concepts of brain death or death by neurologic criteria (BD/DNC) were first proposed about 50 years ago. As the existing diagnostic criteria for BD/DNC differ across geographic areas, a consensus statement was developed by a multidisciplinary group of critical care, neurologic, and neurosurgical clinicians to harmonize the definition of BD/DNC.

While acknowledging lack of high-quality evidence, this document follows the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology concepts and provides a distinction between strong recommendations , which according to the authors should be followed unless there is a compelling reason not to, and weak suggestions , where alternative courses of action may easily differ depending on patients, societal values, and available resources.

This is Part 1 of the recommendations. For Part 2, click here.

Selected clinical prerequisites, recommendations, and suggestions

1. It is recommended that the BD/DNC be defined as the complete and permanent loss of brain function defined by an unresponsive coma with loss of capacity for consciousness, brainstem reflexes, and the ability to breathe independently.

2. It is recommended that the patient have an established neurologic diagnosis, the nature and severity of which is capable of resulting in the irreversible loss of the capacity for consciousness, irreversible loss of all brainstem reflexes, and irreversible loss of ability to breathe spontaneously in the face of a respiratory acidosis (hypoventilation) challenge.

Note: It is suggested that prior to making a determination of BD/DNC there be neuroimaging evidence of intracranial hypertension (severe cerebral edema and herniation) or intracranial pressure measurements that equal or exceed the mean arterial pressure. It is also suggested that in the absence of herniation on neuroimaging, caution be taken when considering an evaluation for BD/DNC and that the assessment of BD/DNC be performed by 2 examiners (except the apnea test).

3. It is recommended that an adequate observation period take place prior to clinical testing for BD/DNC (a minimum of 24 hours for anoxic brain injury after resuscitated cardiac arrest; the minimum observation time in other situations is unclear).

4. It is recommended that confounding factors be eliminated before considering a diagnosis of BD/DNC, that is:

  • Pharmacologic paralysis be excluded by a train-of-four stimulator (stimulation of peripheral nerves by electrical impulses, normally leading to muscular contraction; the response to nerve stimulation is abolished by pharmacologic neuromuscular blockade) or, if not available, through the presence of deep tendon reflexes.
  • A toxicology screen be performed if there is any concern about the presence of toxic or sedating substances.
  • The influence of central nervous system toxins be excluded, taking into account ≥5 elimination half-lives and the potential prolongation of such time, especially in the presence of liver or renal dysfunction.
  • Ancillary tests be performed if the above is not possible (see Part 2, published November 9).

5. Clinical tests universally include the (lack of) pupillary, corneal, oculocephalic, and oculovestibular reflexes; motor response of limbs and face; and gag and cough reflexes.

6. It is recommended that the confirmation of the inability to breathe independently (apnea test) be conducted under specific circumstances and conditions (see Table 1).

Table 1. Apnea testing
Recommendation: Perform apnea testing after the rest of the clinical evaluation is completed and found to be consistent with BD/DNC.
Recommendation: Perform apnea testing if there is no spontaneous respiration in a normocarbic state.
Recommendation: Perform apnea testing if there is no high cervical spinal cord injury.
Suggestion: That the starting point for apnea testing be SBP ≥100 mm Hg or MAP ≥60 mm Hg; temperature ≥36 degrees Celsius; preoxygenation with 100% O2 for ≥10 minutes; and normocarbia (PaCO2 35-45 mm Hg).
Suggestion: Application of CPAP/PEEP is allowed (but not required).
Suggestion: Oxygen may be delivered by a tracheal cannula if a ventilator is not used.
Suggestion: That target values of the tests include a rise in PaCO2 to ≥60 mm Hg (or an elevation ≥20 mm Hg if there is preexisting hypercapnia) and a drop of pH to <7.30.
Recommendation: Interrupt the test if it is not possible to maintain oxygenation (ie, there is sustained oxygen desaturation <85%) or blood pressure or if an unstable arrhythmia occurs.
Recommendation: That the tests last 10 minutes, unless point-of-care testing is available and dictates the test duration, in which case the measurements are to be performed every 2 to 3 minutes past the 10-minute time point.
Suggestion: That apnea testing be guided by arterial PaCO2 rather than by noninvasive capnography.
BD/DNC, brain death/death by neurologic criteria; CPAP, continuous positive airway pressure; MAP, mean arterial pressure; PaCO2, partial pressure of carbon dioxide in arterial blood; PEEP, positive end-expiratory pressure; SBP, systolic blood pressure.
See also
  • Publications of the Week, November 9 A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: criteria for the clinical diagnosis of brain death (part 2).
  • Publications of the Week, September 14 A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: corticosteroid therapy for hospitalized critically ill patients with COVID-19 who required respiratory support.
  • Publications of the Week, August 24 A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: data on the association of estrogen plus progestin or estrogen alone with breast cancer incidence and mortality.
  • Publications of the Week, August 10 A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: different types of P2Y12 inhibitors in acute coronary syndrome.
  • Publications of the Week, July 13 A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: triple vs dual therapy with or without glucocorticoids in moderate to very severe COPD.
  • Publications of the Week, June 2
    First review of all available evidence
    A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: the first review of all available evidence looking at how physical distancing, facemasks, and eye protection affect the spread of COVID-19, SARS, and MERS.
  • Publications of the Week, May 27
    Reports on remdesivir
    A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: first RCT data on remdesivir use in COVID-19.
  • Publications of the Week, May 11 A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: surgery versus conservative care for persistent sciatica.
  • Publications of the Week, February 17 A digest of noteworthy publications curated by editors from McMaster University. This week’s focus: To transfuse or not to transfuse? Here are the answers (part 1).

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