Electrosurgery Takes High Frequency Strides
Edition: February 2003 - Vol 11 Number 02
In 1926, an electrosurgical generator was first used at Brigham Hospital in Boston to remove a portion of tumor. This cutting edge technology – invented by William T. Bovie, M.D., and his partner, Harvey W. Cushing, M.D. – enabled a surgeon to remove a portion of tumor that couldn’t be taken out using more traditional methods, and with almost no bleeding.
Since then, some vital advances have been made in the technology:
· 1980s. The move from ground reference (a common return point for electric circuits) to isolated units (electrosurgical generator output with no ground reference).
· 1980s. The improvement to discrete output units (only one accessory can be activated at a time).
· 1980s. The improvement in tissue impedance monitoring at the patient plate.
· 1987. Introduction of argon gas enhanced coagulation.
· 1990s. The introduction of tissue response at the active electrode (resistance of the tissue in contact with the electrode is measured, and output is adjusted to achieve a consistent tissue effect).
Uses of Electrosurgery
An electrosurgical unit (ESU) is used for surgical cutting or coagulation at the surgical site. It delivers high-frequency electrical currents and voltages through an active electrode, leading to desiccation, vaporization or a charring of the target tissue.
An ESU can be used to remove warts, spider veins or hair in the doctor’s office, as well as for heart, orthopedic or transplant procedures in the operating room. The cutting or coagulating effects on tissue is achieved using alternating currents at a high frequency.
Monopolar vs. Bipolar
Electrosurgical applications may be monopolar or bipolar. In monopolar electrosurgery, tissue is cut and coagulated by completing an electrical circuit consisting of a high-frequency oscillator, amplifiers, the patient plate, connecting cables and the electrodes. Generally, the electric current runs through the surgical site with an active cable and electrode. The current then disperses through the patient to a return electrode. The energy returns to the generator, completing the circuit.
In bipolar electrosurgery, two electrodes are used – a patient plate isn’t necessary. The electrosurgical current in the patient is restricted to a small area of tissue, allowing the doctor greater control over the area to be coagulated.
Electrosurgery revolves around an extremely concentrated radio frequency current used to induce heat energy. This energy, in turn, can dry out tissue cells (resulting in the coagulation of blood) or vaporize cells (permitting an electrode to physically separate a path through living tissue). In electrosurgery, all of the current is forced to flow through a tiny area where the active electrode makes skin contact.
A generator can deliver its current via discrete or nondiscrete output. Discrete output means that although several active instruments are attached to the ESU, only one accessory can be activated at once. With nondiscrete output, when one accessory is activated, any of the other accessories connected to the unit are also activated. The physician must be careful to isolate all additional accessories from the operation site.
An ESU offers two types of cutting: pure cut and blended cut. Pure cut is intended for dissection – the electrosurgical effect of tissue dehydration and protein denaturation caused by direct contact between the electrosurgical electrode and tissue. Desiccation involves a lower current density and concentration than cutting.
In pure cut, the instrument performs similarly to a stainless steel scalpel, where the surgeon has little control over bleeding. However, it is the current that parts the tissue, not a scalpel. An active electrode encounters little resistance as it passes through tissue, making cutting nearly effortless. Much less pressure must be applied here compared with handling a scalpel, and the surgeon can focus on guiding the instrument.
A blended cut enables the doctor to cut and coagulate simultaneously. While in a pure cut the heat energy is so intense that cells vaporize, in blended cutting cooling periods decelerate the process to a slow dehydration of cellular fluid and protein. This stops the bleeding as the cuts are being made. Various levels of hemostasis can be achieved by adjusting the cutting blend. Typically, an office unit has one or two blend modes, and an operating room unit has between two and four blend modes. Once in a while, a unit offers more blend modes – as does the Aaron 2100 (Aaron Medical), which offers nine modes – but that is unusual.
Equally important to the cutting method is the coagulation process. The two types of coagulation – pinpoint and fulguration (spray) – differ in terms of how they are applied. With pinpoint, the doctor holds the electrode in physical contact with the tissue. When fulgurating, the electrode doesn’t touch the tissue. Instead, the current is delivered via sparks that contact the tissue. Pinpoint coagulation is used to stop local bleeding, while fulguration is useful for sealing off small, hidden bleeders or larger bleeders.
High Frequency Desiccators
Today, surgeons have access to accurate, user-friendly instruments – low-powered electrosurgical devices without cutting power designed for dermatological work. These units are not to be confused with a cautery, which uses heat to perform a task. A high frequency desiccator relies on a specific waveform to desiccate, fulgurate or coagulate. Coagulation may be achieved using either a monopolar hand piece or in bipolar mode. In addition, high frequency desiccators don’t require the physician to use a grounding pad.
Units currently available are the Aaron 800 and 900 models (Aaron Medical) and the Hyfrecator (CONMED Corp., Utica, N.Y.). All three units are used in the same way, although they tout different features. Generally, procedures performed using high frequency desiccators are completed at a power setting under five watts. All three of these units are said to be accurate at low power settings.
· High and low output ports enable switching back and forth between settings, depending on the procedure.
· Remote control hand piece changes power settings.
· Dual microprocessors. One controls the output and functionality of the system, while the other terminates activation if a safety hazard is detected.
· Self-diagnostic testing at start-up.
· Computer memory saves last procedural setting.
· Switches from low to high power via a power control knob rather than separate ports. Power output is adjustable in one step.
· Autoclavable hand piece holds standard 3/32-inch (0.24 centimeters) electrodes.
· Same hand piece is used in footswitch mode.
· Digital error detection.
· Accessories include reusable and disposable electrode grounding options and forceps.
· Rotary control dial permits power setting to be changed in one step.
· Three-button hand piece.
· Same hand piece is used in footswitch mode.
· Digital error detection.
· Package includes disposable electrodes, sharp and blunt dermal tips, power cord, hand piece, wall mount kit and user guide.
High Frequency Plus Cut
Now your customers have one more option to choose from. Aaron Medical has combined features of both a high frequency desiccator and electrosurgical generator in its 950. The result is a high frequency desiccator with cutting power.
The unit is a high frequency desiccator, which can also function as a Bovie Generator with output of 60 watts of cutting power and coagulation capabilities. A three-button pencil allows the user to activate the unit and adjust power output. As a desiccator, the unit offers: fulguration and desiccation – 35 watts; bipolar – 30 watts; and watt increments – 0.1 to 10 watts, adjustable in 0.1-watt increments. As a generator, the unit provides: 60 watts of cut, blend and coagulation; and isolated power. The unit has six preset options for different settings, which can be used in either mode.
Whether your customers’ needs are basic or complicated, electrosurgery is a growing field offering a range of solutions to satisfy even the most finicky physician. For more information on high frequency desiccators, visit www.aaronmedical.com or www.conmed.com.