Valleylab CUSA EXcel-8 - Cooling; Fragmentation

How the Handpiece Works
The transducer transmits vibrations through a metal connecting body to
an attached surgical tip. The frequency of vibration remains the same at
the tip (23 or 35.75 kHz), but the amount of motion (amplitude) at the tip
varies: Lower frequency, greater amplitude; higher frequency, smaller
amplitude.
Amplitude also varies with the transducer /connecting body /tip
configuration: Handpiece angle reduces tip amplitude.
A small feedback coil in the handpiece generates a signal (voltage) that is
proportional to the amount of motion in the transducer. The console uses
the feedback signal to adjust the power sent to the handpiece. For
example, if the transducer motion decreases due to resistance from tissue,
the feedback signal decreases. As the feedback signal decreases, the
console increases power to the handpiece to return transducer motion to
normal value.
Fragmentation
Fragmentation occurs when the vibrating tip interacts with tissue. As the
tip begins to move toward tissue, it accelerates, impacts the tissue, then
penetrates the tissue. The acceleration, impact, and penetration produce a
combination of direct mechanical forces and hydrodynamic pressures that
burst cells.
4021940
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Cooling
The high frequency vibration generates heat. To reduce the heat, the
CUSA EXcel system includes a closed, recirculating cooling water system.
This system pulls water from a cooling water reservoir, through a tube in
the handpiece cable, through the handpiece, and through a return tube in
the handpiece cable to the cooling water reservoir. Cooling water flows at
35 to 50 cc/min.
As it passes through the handpiece, the water removes heat.Normal
handpiece temperature, in sustained heavy use, remains at about 40° C.
Use distilled water for the cooling water system because it does not
contain natural minerals, chemical additives, or organic materials that are
present in tap water. Any of these impurities in tap water can cause
problems within the cooling water system.
CUSA
EXcel-8
System
Service
Manual
6-3