Positive pressure ventilation: The provision of air under pressure by a mechanical respirator, a machine designed to improve the exchange of air between the lungs and the atmosphere. The device is basically designed for administering artificial respiration, especially for a prolonged period, in the event of inadequate spontaneous ventilation or respiratory paralysis.
The mechanical ventilator was invented in 1927 by Philip Drinker and Louis Agassiz Shaw. It consisted of an iron box (and so was called an iron lung) plus a bed and two vacuum cleaners. The next model was made by Warren Collins and was inaugurated on October 12, 1928 at the Children's Hospital in Boston to help a girl with polio breath.