Philip Drinker invented the iron lung in 1927 and it was first used in the Boston Children's Hospital in 1928. Patients suffering from severe cases of polio who could not breathe independently required iron lungs to survive. The iron lung is designed to assist paralyzed patients with respiration. The iron lung creates an airtight seal around a person's entire body, except for the head. A vacuum causes the pressure inside the chamber to increase or decrease. By decreasing the pressure, air is sucked in to the chamber through the patient's mouth. When the pressure increases, the iron lung forces the patient to exhale.