Asphyxia. Causes of asphyxia. Symptoms of asphyxia. First aid management for asphyxia. Choking. Risk factors for choking. Signs and symptoms of choking. First aid care for an adult or child who is choking. Back blows and abdominal thrusts. First aid care for a person who is choking in special situations: too large person, pregnant women, person is in a wheelchair, you are alone and choking. First aid care for an infant who is choking: back blows and chest thrusts. First aid care for a person who is choking if the person becomes unresponsive.