Apnea or apnoea refers to the suspension of breathing. If someone is in apnea, his inhalation muscles have no movement, and the volume of his lungs initially remains unchanged. According to how blocked his airway is, there may or may not exist a flow of gas between his lungs and the outside. However, the gas exchanges between his lungs and cellular respiration works well.
Besides, asphyxiant and apnea have very close meaning, but asphyxiant can also refer to a substance that can cause unconsciousness or even death by asphyxiation.
Keywords: apnea; apneas; apnoea; asphyx; asphyx+; asphyxiant; asphyxiant+; asphyxiated; asphyxiated__; asphyxiated+; asphyxiating; asphyxiating+; define apnea