CUSA
®
Clarity Ultrasonic Surgical Aspirator System Operator’s Manual
2-8
Tissue Select Feature
• It draws tissue toward the vibrating tip and creates constant tissue
contact.
• It removes irrigation and fragmentation debris from the surgical site.
• If there is no suction or low suction, tissue contact does not occur,
resulting in minimal tissue fragmentation and increased tissue
temperature.
• Tip acceleration: produces the peak forces and pressures that
fragment tissue.
• Tip cross-sectional area at the tip-tissue contact site
These variables also affect tactile feedback, what the surgeon’s hand
feels when using the handpiece.
Inherent Tissue Selectivity
With all other variables remaining constant, the tip does not fragment all
tissue types equally effectively. Another variable, tissue strength, affects
fragmentation rate.
• “Low strength” soft tissues that are easiest to fragment include the
brain and most organs. Older, partially dried tissues are also easy to
fragment. “High strength” strong tissues that are most difcult to
fragment include vessel structures, tendons, ligaments, healthy skin,
and organ capsules.
• Strength increases and fragmentation rate decreases with tissue
containing greater collagen, elastin, or both (collagen type, quantity,
and organization affect cell structural quality).
Tissue strength also affects tactile feedback. The surgeon can feel a
difference between the tip contacting low strength tissue and the tip
contacting high strength tissue. As the tip works through low strength
tissue, the surgeon feels a smooth, rhythmic sensation from the
handpiece. When the tip contacts high strength tissue, it feels like it is
“bouncing off” the tissue. Also, the smooth, rhythmic sensation becomes
rougher. To avoid fragmenting high strength tissue, the surgeon must
apply less pressure to the tip or move the tip away from the tissue. To
continue fragmenting high strength tissue, the surgeon must manually
apply more pressure.
Continued manual pressure on the footswitch pedals could result in
unintentional damage to critical structures. Using the Tissue Select
feature, the CUSA Clarity system can help the surgeon avoid these
problems when dissecting near critical structures.
Increasing Tissue Selectivity
It is possible to increase the inherent selectivity resulting from variations in
tissue strength while maintaining amplitude, tip acceleration, and suction.
This increase in selectivity results from reducing the adaptive power that
drives the tip. Remember: The ultrasonic generator delivers
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