CUSA- Cavitational Ultrasonic Surgical Aspiration
- Anbu Arasan
- Aug 2, 2020
- 4 min read
The Cavitron Ultrasonic Surgical Aspirator(CUSA) is a special tool for precise removal of tissues resulting in improved sensitivity, decreased bleeding with shorter operating time. It is widely used in multiple surgical subspecialties, including Neurosurgery, Liver Surgery, Gastrointestinal, Hepatobiliary Surgery, Gynecology, and Urology.
CUSA is using low-frequency ultrasound energy to dissect or fragment tissues with low fiber content. It is basically an ultrasound probe (acoustic vibrator) combined with an aspirator device.
CUSA is an Ultrasonic Surgical Aspirator, where Fragmentation, Suction, and Irrigation occur simultaneously, allowing the surgeon to remove tissue with accurate control.
The system includes the following components:
Console: The Console Body houses Electronics, Pumps, Mechanical parts, and Control Panel (which allows users to control the functions of the system).
Handpiece: It is a handheld surgical device with a tip that is applied to patient tissue.
Accessories: manifold tubing, tips, tip torquing bases, torque wrenches, sterilizer cases, and contamination guard.
Gall Bladder Cancer Surgery Using CUSA
You can also combine the CUSA System with electrosurgery using the optional CUSA Electrosurgical Module (CEMâ„¢). The Average cost of CUSA medical devices is currently $1,208 in Rs 75L(INR).
It performs three functions:
Fragmentation
Irrigation
Aspiration (Suction)
Fragmentation/Cavitation
It is an Electromechanical Operation, the console provides alternating current at 23 or 36 thousand cycles per second (kHz) to the handpiece (the frequency depends on the type of handpiece connected to the console).
Inside the handpiece, current passes through a coil, which induces a magnetic field. The magnetic field excites a transducer made of nickel alloy laminations, resulting in an oscillating motion in the transducer laminated structure (transducer vibrates at 23 or 36 kHz along its long axis).
The vibrations are transmitted through a metal connecting body to an attached surgical tip. The frequency of vibration at the tip is 23 or 36 kHz, but the amplitude of motion varies inversely (lower is the frequency, greater will be the amplitude; similarly higher is the frequency, lesser is the amplitude).
Amplitude also varies with the transducer, connecting body and tip configuration. The handpiece angle reduces tip amplitude. When the vibrating tip contacts tissue, it breaks cells apart and fragments them.
Tissue Fragmentation is based on Tissue Strength. Tissues with weak intracellular bonds like a tumor, Organ, Fat are easy to fragment. Tissues with strong intracellular bonds like Nerves, Tendons, Vessel Walls, and Ducts contain less fluid more collagen and elastin are more resistant to fragmentation.
Cooling
The high-frequency vibration generates heat; to reduce the heat, the system includes a closed, recirculating cooling water system. This system pumps water from a cooling water reservoir, through a tube in the handpiece cable, and a return tube to the cooling water reservoir. The cooling water flows at 35 to 50 ml/min, as it passes through the handpiece, the water removes heat using distilled water.
Irrigation
Sterile irrigation fluid flows from an IV set (bottle or bag) to a variable speed peristaltic pump. The pump pushes the fluid through the manifold irrigation tubing to a flue, a sleeve surrounding the vibrating tip. As the irrigation fluid passes through the flue, it cools the tip. When the fluid reaches the distal end of the tip, as much as 99% of it passes through two pre-aspiration holes in the tip, eliminating fluid pooling in the sterile field and continue clearing the suction system.
Aspiration (Suction)
The suction, which produces an air stream moving towards the vacuum pump, pulls irrigation fluid, fragmented tissue, and other materials like Debris, Blood through the distal end of the surgical tip. From the tip, the aspirated materials pass through the manifold suction tubing into the suction canister.
Handpieces
A Handpiece and CUSA console form an ultrasonic surgical aspirator system. This system has three functions: Fragmentation, Irrigation, and Aspiration (Suction). All three functions can occur at the same time.
The CUSA System includes three handpiece configurations:
36 kHz, straight (smaller handpiece, black body, blue connector)
23 kHz, straight (gray body, green connector)
23 kHz, angled (gray body, green connector).
A variety of Handpieces with Disposal Tips are available. Tips vary in the inside diameter, length, and shape (straight or curved).
Working Principle:
In the handpiece, current passes through a coil and induces a magnetic field. The magnetic field excites a transducer of a nickel alloy which expands and contracts to produce an oscillating motion in a longitudinal axis with a frequency of 23 or 26khz.
The piezoelectric crystals with the alloy help the handle tip to oscillate. Ultrasound mechanical vibrations are magnified over the length of the handpiece. The amount of oscillation varies, with low frequency there is greater amplitude with high frequency there is lower amplitude.
The oscillating tip brought into contact with tissue causes fragmentation of the tissue by producing ultrasound cavitation at the cell level with low pressure outside the cell leading to cellular disruption.
The high-frequency vibration produces heat, which reduces heat via closed recirculating cooling of the probe’s tip. This system maintains the temperature of the tip at approximately 40°C.
The other function is to carry away the tissue fragmented debris. It is done by the Vacuum pump/suction connected to the cavitational ultrasound surgical aspirator using the tube for irrigation using saline or distilled water and debris is carried away with fluids and collected in the sample container.
Advantages
1. No Bleeding
2. A rapid removal of tumor- Less Operating Time.
3. Controlled removal of Tumors Safe
4. Better Visibility for the removal of firm Tumors an obscure location.
5. Minimal manipulation of structures surrounding the tumor.
Disadvantages
1. Apparatus assembling is difficult to understand for nursing staff.
2. Some studies show the risk of nerve injuries in relation to intensity and duration of probe application.
Note : This Article is intended to develop Basic Knowledge on Medical Equipments.
Do not try to operate Equipments without Practical Training.