iron lung (redirected from Negative pressure ventilator)

iron lung, device used to maintain artificial respiration over an extended period of time. Before the successful vaccination program against poliomyelitis, it was used mostly in treatment of that disease. Currently, its main usage is in cases where the respiration control center of the brain has been damaged (e.g. skull fractures, brain tumors and stroke) or where the diaphragm is paralyzed by spinal cord disease or injury. Invented (1928) by Philip Drinker, the iron lung is composed of a cylindrical steel drum, which encloses the entire body with only the head exposed. A rubber diaphragm makes the cylinder airtight without putting undue pressure on the neck. Pumps raise and lower the pressure within the chamber. A number of problems exist with the iron lung machine; food or vomit may be aspirated into the lungs, and serious skin ulcers may develop in a patient who is immobilized for long periods of time.