Until you do a CAT scan.

NYT: Autopsies of War Dead Reveal Ways to Save Others

Col. Howard T. Harcke, a 71-year-old Marine Corps radiologist who delayed retirement to read CT scans at Dover, noticed something peculiar in late 2005. The emergency treatment for a collapsed lung involves inserting a needle and tube into the chest cavity to relieve pressure and allow the lung to reinflate. But in one case, Colonel Harcke could see from a scan that the tube was too short to reach the chest cavity. Then he saw another case, and another, and half a dozen more.

In an interview, Colonel Harcke said it was impossible to tell whether anyone had died because the tubes were too short; all had other severe injuries. But a collapsed lung can be life-threatening, so proper treatment is essential.

Colonel Harcke pulled 100 scans from the archives and used them to calculate the average thickness of the chest wall in American troops; he found that the standard tubing, five centimeters long, was too short for 50 percent of the troops. If the tubing was lengthened to eight centimeters, it would be long enough for 99 percent.

“Soldiers are bigger and stronger now,” Colonel Harcke said.

The findings were presented to the Army Surgeon General, who in August 2006 ordered that the kits given to combat medics be changed to include only the longer tubing.

This reminds me of a story, possibly apocryphal, of a study done in WWII. The army wanted more armor on bombers to protect them, but needed to be selective about where it was placed, lest the speed and/or range suffer too much. And they didn’t really want to take planes in production to test them, since they were all needed in battle. So some people analyzed the damage pattern of planes that returned from missions. They assumed that anti-aircraft bursts were basically random, so the pattern of damage from returning aircraft indicated non-critical harm, and were areas that didn’t need reinforcing — it was the gaps in the pattern which indicated the fatal hits. and that was where additional armor would do the most good.