Abstract: A device for retrograde hole opening through tissue has a member elongate on an axis with a cross section shaped to insert axially through external tissue. A distal and a proximal end on the member respectively enter the tissue during placement and remain outside the tissue for control. A tip at the distal end has a deployable tissue divider with one or more tissue parting elements and each has a splitter. The tissue parting elements are located within the cross sectional dimensions of the member in a storage position and are movable relative to the tip for placement in an exposed position relative to the tip when shifted from storage so that the splitter thereof splits tissue during retrograde extraction along the axis and contact with tissue. Linkage between the proximal end and the deployable tissue divider retains each of the tissue parting elements with its splitter exposed.

Abstract: The present invention utilizes at least three wavelengths of electromagnetic radiation for determining a blood constituent, such as arterial oxygen saturation, in a patient. The detected radiation scattered by the tissue of the patient is analyzed in a manner that compensates for variations in the detected radiation caused by differences in the scattering of the radiation at different wavelengths. In particular, a result is determined which is equivalent to the sum of a first blood constituent estimate using a first pair of the detected signals, and the difference between the first blood constituent estimate and a second blood constituent estimate, using a different pair of wavelengths, with the difference being multiplied by a multiplicative factor.