For patients in low-perfusion states such as severe shock, septicemia, hypovolemia, vasoconstriction and peripheral vascular disease, it is beneficial to measure oxygenation at a central site, such as the earlobe. The earlobe is easily accessible, features small vasculature, and provides a quick response rate. The M1194A is also well-suited for surgical patients, because the finger is often inaccessible during surgery.