Ischemia Sensing Organ Retractor

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Ischemia Sensing Organ Retractor

• THE PROBLEM
• Excessive retraction forces and time can result
  in ischemic tissue damage due to cut-off oxygen
  supply.
• Need a way of interactively measuring tissue
  oxygenation levels intra-operatively.

Babcock retractor and close-up of sensors

• THE SOLUTION
• We developed a smart retractor system that
  allows for monitoring of tissue oxygen
  saturation.
• The device currently uses optical technology
  similar to pulse oximetry.
• Red and IR LEDs directed into the tissue are
  sequentially pulsed
• The response of the two wavelengths is measured
  with photodiodes
• The relative saturation of Red and IR light
  varies with oxygen saturation of hemoglobin in
  blood.

Retractor setup with Deaver retractor Sensing
capabilities for oxygenation and retraction forces

• THE IMPACT
• This device allows for real-time acquisition of
  the tissue of interests oxygen saturation level.
• Will be able to prevent tissue damage due to lack
  of oxygen supply while being retracted.

Attenuation of light as a function oxygen
saturation and wavelength Figure courtesy of
Nellcor
Preliminary results of photodiode response for
Red and IR light on finger

• THE FUTURE
• Will allow for arrays of sensors to give oxygen
  saturation distribution of tissue.
• Determine correlation between force and time of
  retraction with tissue oxygenation levels
• Allows for a safe method for robotic organ
  retraction. Can use to close the high level
  control loop of robotic retractor based on
  tissue oxygenation.
• In-Vivo studies in progress.

Preliminary results from retraction of porcine
liver tissue

• PEOPLE INVOLVED
• Graduate Student Greg Fischer
• Undergrad Students Hana Chang
• Takintope Akinbiyi
• Clinicians Dr. Jason Zand
• Dr. Mark Talamini

• PUBLICATIONS
• MICCAI 2003 A Modular 2-DOF Force-Sensing
  Instrument For Laparoscopic Surgery
• Provisional patent for sensing surgical retractor
  submitted January 2004

Porcine trials with the system in MISTIC lab

• SUPPORTED BY
• Core NSF CISST/ERC

Engineering Research Center for Computer
Integrated Surgical Systems and Technology