Starved of oxygen, tissues rapidly die. Oxygen may be prevented from diffusing into the lungs because of chocking, drowning, suffocation, strangulation, paralysis, or injury to the lungs or chest. Lack of oxygen in the air also causes asphyxia.
Symptoms include an increased rate and depth of breathing, noisy breathing, frothing at the mouth, blue lips, unconsciousness, and cessation of breathing.
Remove whatever is causing the asphyxia, or move the casualty into the fresh air. Begin artificial respiration (see Breathing) if necessary, place in the recovery position (see Unconsciousness), and immediately dial 911.