Time to loss of brain function and activity during circulatory arrest.
Brain function during the dying process and around the time of cardiac arrest is poorly understood. To better inform the clinical physiology of the dying process and organ donation practices, we performed a scoping review of the literature to assess time to loss of brain function and activity after circulatory arrest.



Medline and Embase databases were searched from inception to June 2014 for articles reporting the time interval to loss of brain function or activity after loss of systemic circulation.



Thirty-nine studies met selection criteria. Seven human studies and 10 animal studies reported that electroencephalography (EEG) activity is lost less than 30seconds after abrupt circulatory arrest. In the setting of existing brain injury, with progressive loss of oxygenated circulation, loss of EEG may occur before circulatory arrest. Cortical evoked potentials may persist for several minutes after loss of circulation.



The time required to lose brain function varied according to clinical context and method by which this function is measured. Most studies show that clinical loss of consciousness and loss of EEG activity occur within 30seconds after abrupt circulatory arrest and may occur before circulatory arrest after progressive hypoxia-ischemia. Prospective clinical studies are required to confirm these observations.
Division of Neurology, McGill University Health Center, Montreal, QC, Canada. Electronic address: raluca.pana@mail.mcgill.ca.
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R
Pana
Division of Pediatric Critical Care, Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada; Deceased Donation, Canadian Blood Services, Ottawa, ON, Canada.
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L
Hornby
Deceased Donation, Canadian Blood Services, Ottawa, ON, Canada; Division of Critical Care, Montreal Children's Hospital, McGill University Health Centre, McGill University, Montreal, QC, Canada.
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SD
Shemie
Children's Hospital of Eastern Ontario, Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada.
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S
Dhanani
Division of Neurology and Neurosurgery, McGill University Health Center, Montreal Neurological Institute, Montreal, QC, Canada.
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J
Teitelbaum
D000818:Animals; D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D006323:Heart Arrest / Q000503:physiopathology*; D006801:Humans; D013997:Time Factors; D009927:Tissue and Organ Procurement; D014474:Unconsciousness / Q000503:physiopathology
Brain activity; Brain function; Cardiac arrest; Death; Donation after circulatory death; Organ donation