Thunberg's Barospirator, a Fully Encasing Predecessor of the Iron Lung.

Used as a ventilator for assisting victims of polio, the barospirator was described by Swedish physician-scientist Torsten Thunberg in 1924. An immediate predecessor of the iron lung of Philip Drinker, the barospirator fully encased the entire body. Cyclic air-pressure changes within the chamber achieved ventilation during equilibrations of intrapulmonary and ambient pressures. Pulmonary medicine innovator Alvan Leroy Barach used a modified barospirator for lung rest as a treatment of tuberculosis in the 1940s. Adverse effects included damage to patients' tympanic membranes. Despite its limited clinical success, the barospirator was successfully used by one of Drinker's competitors, John H. Emerson, to invalidate Drinker's US patent filings.