Grand larceny at the cellular level.

Our awareness of vascular thievery dates back to 1961 when Reivich et al 1 described the "subclavian steal." In this syndrome blood is siphoned from the opposite vertebral-basilar system to a vertebral artery deprived of its blood supply by a proximal subclavian artery obstruction. The ensuing reversal of blood flow causes symptoms of cerebral ischemia in the areas supplied by the unobstructed vessel. Similar hemodynamic mischief has since been recognized in other situations wherein blood is shunted either by siphoning or by other mechanisms responsible for circulatory redistribution. 2 Theft of blood is theft of oxygen. The latter, however, may occur without the former. Fox and his associates 1 describe a syndrome of oxygen theft by the large numbers of immature leukocytes in leukemic patients. Having observed a degree of arterial hypoxemia disproportionate to the lung involvement in several such patients, these investigators studied arterial Po 2 in multiple blood specimens