TABLE 1.

Glossary of terms

Term	Definition19,32,46
Permanent cessation	Ceases in perpetuity because it will not resume on its own and will not be resumed through medical intervention, based on a legally and ethically valid decision
Irreversible cessation	Ceases in perpetuity and cannot be resumed with available technology
Brain function	The brain’s vital functions include consciousness and behavior, coordination and control of movement, and the ability to breathe.
Brainstem function	Refers to brainstem reflexes including the capacity to breathe without mechanical support and the generation of consciousness arising from the reticular activating system
Brain activity	Physiologic or electrophysiologic properties of cells and groups of cells that can be measured by laboratory means. Not necessarily indicative of function
Brain blood flow	Steady movement of blood through the intracranial and/or brainstem vessels
Brain/brainstem perfusion	Capillary-level flow in target tissue
Consciousness	Awareness, including capacity for sensory perception or coordinated responsiveness to the external environment, and wakefulness