Smita De (BioRobotics Lab)
Department of Bioengineering (Doctoral
Student)
"Measurement of Tissue Damage
Due to Mechanical Stresses During MIS"
ABSTRACT
While there are many benefits to minimally invasive surgery, force feedback,
or touch sensation, is lacking in the currently available MIS tools, including
surgical robots. This creates the potential for excessive force application
during surgery that can result in clinically relevant consequences.
The goal of this work was to develop a methodology with which to identify
stress magnitudes and durations that can be safely applied with a grasper
to different tissues, helping to improve MIS device design and increase patient
safety. Using the porcine model, stresses typically applied in MIS
were applied to liver, ureter, and small bowel using a motorized endoscopic
grasper. Acute indicators of tissue damage including cellular death,
activation of the coagulation cascade, and infiltration of inflammatory cells
were measured using histological and image analysis techniques. Finite
element analysis provided estimations of the stress distributions between
the grasper jaws, allowing for more accurate correlations of damage to stress.
ANOVA and post-hoc analyses were used to detect stress magnitudes and durations
that caused significantly increased tissue damage. Preliminary data
show a graded non-linear response between applied stress magnitude and apoptosis
in liver and small bowel as well as granulocyte infiltration in small bowel.
These results suggest that this methodology is appropriately sensitive for
the ultimate goal of identifying damage ‘thresholds’ and stress dose response
curves for multiple organs during grasping.