fig1 shows an oximeter system 101 for measuring oxygen saturation of tissue , such as a nerve root . the system includes a monitoring console 105 , a nerve root retractor 110 , and a cable 115 connecting the nerve root retractor to the monitoring console . the cable includes optical fiber . the nerve retractor has a handle 113 , a shaft 116 connected at its proximal end 119 to the handle , and a tip 122 connected to a distal end 125 of the shaft . the tip includes a retractor portion or retractor blade 128 and an oximeter sensor 131 . the shaft includes an internal channel or passageway . optical fibers pass from sensor openings on the tip , through the channel , through the handle , and into the cable jacket or cable insulation . see fig9 b , which shows a path of an internal channel ( 930 ) within a retractor . the shaft is made of steel . the system is used by placing the oximeter sensor in contact with the nerve . light is transmitted from the monitoring console , through optical fiber in the cable , out a sensor opening on the tip and into the nerve . the reflected light from the nerve is then received by another sensor opening on the tip , transmitted back to the monitoring console via optical fiber , and then processed . a screen 135 on the console displays the oxygen saturation measurement . fig2 shows a perspective view of a first implementation of a tip 205 . the tip includes a retractor blade and an oximeter sensor 210 attached to a top surface 215 of the tip . the tip attaches to a shaft 220 . the tip also includes a retractor portion 223 . optical fibers are encased in a cable jacket 225 , travel along the shaft , into the oximeter sensor , and are exposed through an opening on a bottom surface 230 of the tip . cable jacket 225 and shaft are wrapped with a tubing 235 . such tubing may be heat - shrink tubing . in a specific implementation of fig2 , the tip of the retractor has a length of about 17 . 5 millimeters , width of about 8 millimeters , and a thickness ( not including the retractor blade ) of about 5 millimeters . fig3 shows a bottom view of the first implementation of a tip 305 . the tip has a retractor blade and slot 310 , within which there are sensor openings . there are four sensor openings for ends of fiber optic cables . the openings 315 a , 315 b , 320 a , and 320 b are for source and detector fibers . fig4 shows a perspective view of a second implementation of a tip 405 with an encasement 410 which contains optical fiber attached to the tip . in a specific implementation of fig3 , the tip of the retractor has a length of about 17 . 5 millimeters , width of about 8 millimeters , and a thickness ( not including the retractor blade ) of about 3 millimeters . fig5 shows a bottom view of the second implementation of a tip 505 . the tip includes a retractor blade and four sensor openings on a bottom surface 510 of the tip . the sensor openings include openings 515 a , 515 b , 515 c , and 515 d . optical fiber is connected to each of the sensor openings . the sensor openings can include sources and detectors . fig6 shows a perspective view of a third implementation of a tip 605 . fig7 shows a bottom view of the third implementation of a tip 705 . the tip includes two sensor openings on a bottom surface 710 of the tip . the two sensor openings include an opening 715 and an opening 720 . the openings include a source and detector . fig8 shows a side view of the third implementation of a tip 805 . a retractor portion or retractor blade 810 is at an angle 815 to a shaft 820 onto which the tip is attached . in an implementation , the angle is about 90 degrees . angle 815 ranges from about 90 degrees to about 179 degrees . in a specific implementation of fig8 , the tip of the retractor has a length of about 5 millimeters , width of about 3 millimeters , and a thickness ( not including the retractor blade ) of about 2 millimeters . fig9 a shows a side view of the third implementation of the tip 805 connected to a nerve retractor 910 . this figure shows the handle of the retractor , having a first end 915 and a second end 920 , as shown . the handle connects to the shaft and the tip via the first end . fig9 b shows a path of an internal channel 930 within a refractor . this description of the invention has been presented for the purposes of illustration and description . it is not intended to be exhaustive or to limit the invention to the precise form described , and many modifications and variations are possible in light of the teaching above . the embodiments were chosen and described in order to best explain the principles of the invention and its practical applications . this description will enable others skilled in the art to best utilize and practice the invention in various embodiments and with various modifications as are suited to a particular use . the scope of the invention is defined by the following claims .
a retractor has an oximeter sensor at its tip , which allows measuring of oxygen saturation of a tissue being retracted by the retractor . the tip includes one or more openings for at least one source and detector . a specific implementation is a spinal nerve root retractor with an oximeter sensor .