Based on animal experiments conducted in the sixteenth century by Vesalius, the Royal Humane Society recommended fireside bellows to resuscitate victims of drowning. In the mid-twentieth century, the bellows concept was adapted by Kreiselman and others, though none of these devices gained widespread popularity. However in 1957 the "Ambu Bag" appeared and was an immediate success. The revolutionary design was the creation of Danish anaesthetist Dr Henning Ruben. A similar product was soon developed by Asmund Laerdal of Norway, in collaboration with American anaesthesiologists Drs Elam and Safar. The self-inflating bag is such a simple device, yet it is extremely effective--it has enabled rescuers around the world to support life in virtually any environment, simply by squeezing a bag.