It “doesn’t look like something you’d want dripping into your veins,” wrote Wil McCarthy in the August 2002 issue of Wired. At the time, he had no way of knowing just how right he was about Hemopure, the artificial blood that seemed so promising. It was universally compatible and had a three-year shelf life (unrefrigerated). But a recent meta-analysis of trials on several substitutes – including Hemopure – contains some gory results. Turns out, the fake bloods scavenge nitric oxide, causing vasoconstriction; patients who get them are 2.7 times more likely to have a heart attack and 30 percent more likely to die. A Journal of the American Medical Association editorial has called for a halt to trials.