Even as combat casualties reach a wartime high in Afghanistan, the rate at which the wounded died reached a wartime low. Almost 5,500 American troops were wounded in action in 2010, but fewer than 7.9 percent died, down from 11 percent in 2009, when 2,415 were wounded. Doctors say the improvement is due to simple changes: putting medevac helicopters closer to fighting, encouraging the use of tourniquets, and wearing fire-retardant uniforms and gloves. Where medevac helicopters used to be scarce, now a large fraction of troops reach a hospital within half an hour of being wounded. Another change is that soldiers used to be reluctant to use tourniquets, but now everyone carries one.