How the Handpiece Works
Principles of Operation
CUSA EXcel Ultrasonic Surgical Aspirator System Service Manual 6-3
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.
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 (104° F).
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.
To Next Page
Loading...
Need help?
General
