Bringing the Hospital to the Field: New Tech Improving Combat Care.

• Author: Halpern, Guye
• Position: INDUSTRY PERSPECTIVE

* The United States has achieved impressively high survival rates for wounded soldiers, with approximately 92 percent of those injured in Iraq and Afghanistan surviving. This is reported to he the highest percentage in the history of warfare, despite the rising severity of battle injuries from increasingly lethal weapons. For context, about 75 percent of soldiers injured in Vietnam made it back alive.

While this figure is impressive, and military medical personnel should be proud, it is only a part of the larger picture. Take, for example, the story about Abraham Wald and the missing bullet holes.

Wald, born in 1902 in what was then the Austro-Hungarian Empire, was a natural mathematician from a young age and became a member of the Statistical Research Group during World War II.

During the war, the Allied powers realized they were losing many aircraft and wanted to understand how to better arm them to increase their survivability. But this posed a problem, as arming planes increased their weight, and heavier aircraft are less maneuverable and use more fuel. The Statistical Research Group was tasked with finding the optimal amount of armor for a plane so that it was both protected and efficient.

The military brought forward data it thought would be useful: when American aircraft came back from engagements over Europe, they were covered in bullet holes. But the damage wasn't uniformly distributed across the platforms. There were more bullet holes in the fuselage, not so many in the engines.

The officers saw an opportunity for efficiency--you can get the same protection with less armor if you concentrate the armor on the places with the greatest need, where the planes are getting hit the most. But exactly how much more armor belonged on those parts of the aircraft? That was the answer they came to Wald for. But this was not the answer they got. The armor, Wald said, does not go where the bullet holes are; it goes where the bullet holes are not--namely on the engines.

Wald's insight was simply to ask: where are the missing holes that would have been all over the engine casing if the damage had been spread uniformly across the plane? Wald posited that the missing bullet holes were on the missing aircraft. The reason planes were coming back with fewer hits to the engine was not because they weren't being hit there, but because planes that got hit in their engine weren't coming back. Whereas the large number of aircraft returning to base with a...