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The blood bag (1950)

In the early history of medicine, various medical practitioners have tried to mix or transfuse the blood of different individuals or animals, with varying degrees of success. But it wasn’t until 1901 that blood transfusions were set on a firm scientific footing, with the discovery of the three human blood groups by a Viennese doctor called Karl Landsteiner.

About 25 years earlier, other doctors had noted that when blood from animals is transfused into humans these foreign red blood cells become clumped together and break apart, releasing their cargo of oxygen-carrying haemoglobin, the pigment that makes blood red. Landsteiner observed a similar phenomenon when the blood of one person was transfused into the bloodstream of a second person. He proposed that this reaction was the cause of the shock, jaundice, and haemoglobinuria – excretion of haemoglobin in the urine – seen in earlier, often fatal, attempts at transfusing blood.

His suggestions received little attention, however, until 1909 when he classified the blood of humans into the now well-established groups of A, B, AB and O. He showed that transfusions between individuals within the same blood group do not result in destruction of new blood cells. This only occurred when a person was transfused with the blood of a person belonging to a different blood group.

Landsteiner won the 1930 Nobel Prize in Physiology or Medicine for his efforts, and by the mid-20th Century blood transfusions were becoming a routine part of medicine, based on the knowledge of the blood groups that each of us inherit from our parents.

However, it was William Murphy, an American doctor and inventor, working with colleague Carl Walter, who gave medicine the simplest of transfusion tools in the shape of the blood bag. In 1950, this simple, plastic bag replaced the breakable glass bottles that were used until that point. The idea came out of Murphy’s work on dialysis machines, with support from the US Army because of concerns about exposure of military personnel to radiation from the US atomic weapons tests. The sterile plastic bag offered many advantages over the glass bottle, most obviously in it being unbreakable, easy to fill without exposing the contents to air and convenient to carry around.

We now know that the basis of human blood groupings is down to the different genes for red blood cell antigens we all inherit. Landsteiner demonstrated the existence of the human blood groups experimentally, and Murphy and Walter invented the device – the now ubiquitous plastic blood bag – that enabled transfusions to become simple, effective and routine.