More testing to do but an elegant step by University of British Columbia towards addressing life-threatening intraoperative or traumatic internal bleeding (also see http://tinyurl.com/qdmrjp5). Micro-particles of calcium carbonate mixed with solid acid generate carbon dioxide gas through contact with blood. The gas propels the particles in the bloodstream to the bleed site. With the particles porous, a cargo of clotting agent in the pores goes directly to the site and into the vasculature.