To the Editor:—
Kaplan and Barnes (JAMA202:153, 1967) described a case of subcutaneous emphysema and ischemia of the toes caused by accidental injection of helium under the skin. Their patient would have benefited from hyperbaric oxygen. The increased pressure would have compressed subcutaneous gas into less than half it original volume (Boyle's law) and thus would have relieved pressure on soft tissues. Inhalation of oxygen would have reduced blood nitrogen and minimized diffusion of this gas from blood into subcutaneous gas pockets. Compression of subcutaneous gas would have hastened its diffusion into the blood and out of the body, while increased oxygen in the blood would have improved oxygenation of ischemic areas. Rapid diffusion of helium because of its small molecule (Graham's law) would have facilitated escape of this gas. Finally, hyperbaric therapy might have rendered unnecessary any decompressing incisions.