any measure that causes air to flow in and out of a person's lungs when natural breathing is inadequate or ceases, as in respiratory paralysis, drowning, electric shock, choking, gas or smoke inhalation, or poisoning. Respiration can be taken over by an artificial lung (especially in respiratory paralysis), a pulmotor, or any other type of mechanical respirator (see resuscitator ). In emergency situations, however, when no professional help is available, rescuers undertake the mouth-to-mouth or mouth-to-nose method of artificial respiration. First, any foreign material is swept out of the mouth with the hand. The victim is placed on his back, with the head tilted backward and chin pointing upward so that the tongue does not block the throat. The reviver's mouth is then placed tightly over the victim's mouth or nose, with the victim's nostrils or mouth held shut. For a small child or infant, the reviver places his mouth firmly over the mouth and nose. The reviver takes a deep breath and…