artificial respiration, 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 blows into the victim's mouth, nose, or both. If there is no exchange of air, the reviver checks the position of the head. If there is still no exchange, the victim should be turned on his side and rapped between the shoulder blades to dislodge any foreign matter that may be blocking the air passages. A child can be held by the ankles and rapped between the shoulder blades. The reviver stops blowing when the chest expands, turns his head away, and listens for exhalation. If the victim is an adult, blowing should be vigorous, at the rate of about 12 breaths per minute. A child's breaths should be shallower, about 20 per minute, and an infant's breaths should come in short puffs. When victims vomit, they must be turned on their side and the airway cleaned before continuing artificial respiration. If the victim has had the larynx removed, the above method is used, but the reviver must breathe into the stoma (surgical opening made in front of neck for breathing). Breathing into the subject should be continued until natural breathing resumes or until professional help arrives. Since the heart often stops beating when breathing is interrupted, cardiopulmonary resuscitation (CPR) is typically administered simultaneously. This entails compressing the chest above the heart at 60 or more thrusts per minute, with two breaths being administered after every 15 chest thrusts. See first aid.