resuscitator (rĭsŭsˈĭtāˌtər) [key], device used to revive a person whose normal breathing has been disrupted. Several types are in wide use. The automatic tank resuscitator consists of a face mask that fits tightly over the nose and mouth and is connected by a tube to one or more tanks of gas. Pressurized oxygen enters the mask through the action of automatic valves. A second tank may contain carbon dioxide, small amounts of which are mixed with oxygen, serving to activate the respiratory center in the brain. In a similar device, the manual tank resuscitator, the oxygen flow is regulated by the operator. The self-inflating, bag-mask resuscitator consists of an airtight mask that fits over the nose and mouth, a self-inflating bag, and often an oxygen tube connector. When the bag is squeezed, air or oxygen enters the patient's lungs. The bag inflates automatically when released. Air from the lungs leaves the mask by an escape valve without returning to the bag.