We can trace electrosurgery as we know it today to the work of William T. Bovie, PhD, a physicist who pioneered research in high-frequency electrical power. In 1924, fellow Harvard academic Harvey W. Cushing, MD, a neurosurgeon and professor of surgery, saw Dr. Bovie's device in action: "I happened to see Dr. Bovie's electrified loop being used for the purpose of bloodlessly scooping out bits of malignant tissue for examination," he wrote. "I realize that here was a new tool which might possibly be utilized." The Liebel-Flarsheim Company in 1927 manufactured the first commercially produced electrosurgical unit of a Bovie design.

The evolution that has occurred since then has made the current-generation units safer and has minimized the risk of tissue damage, but manufacturers continue to develop and refine ESU technologies. Here's what to consider when purchasing an ESU. We've also compiled thumbnail sketches of the newest features electrosurgery generators have to offer.

General-use ESUs
General-use electrosurgical units are used across specialties in the outpatient spectrum - GYN, urology, general surgery and dermatology rely especially heavily on this equipment. It's pretty much standard nowadays that these units have both monopolar modes and bipolar modes in one box. Monopolar mode cutting power ranges from 100 watts to 400 watts; bipolar power ranges from 40 watts to 80 watts. Beyond these basics, there is a wide range of price points among general-use ESUs based on several variables. Here are some considerations to keep in mind when purchasing an ESU.

• Power and waveforms. While high-end and low-end ESUs deliver the same shock value at the end of the pen, how that power is controlled and how consistent and repeatable the results are is where the price differential happens. Simple units have analog (dial) controls for power settings and fixed output waveforms. More expensive units are digitally controlled, have selectable waveforms, pre-programmed settings for different specialties, and provide visual or audible feedback to the surgeon on bipolar power output.
• Features. Surgeons favor user-intuitive, digital machines they can operate using one-finger hand switch or a foot switch because they let docs switch modes quickly and easily. Surgeons also might like ESUs that come with many standard presets that let them choose the setting based on the procedure and reduce the need to change between settings. Safety features that are nice to have include automatic electrode output and contact monitoring, audible and visual signals, and built-in smoke evacuators.
• Cost of disposables. The ESU is tied to a steady - and expensive - stream of disposable electrode pads, cords, cut-cautery pens, and single-use bipolar and tissue-ablation instruments. Many ESU manufacturers offer various programs that roll the capital expense of the ESU into the cost of their brand of disposable supplies. Participating in such a program might get you a new ESU without any out-of-pocket expense, but the manufacturer will bind you to using that company's supplies for set periods of time and cost.

Not that this is always a bad thing - manufacturers offer these programs in response to facility demands. Just be sure to do your financial homework before signing a long-term agreement. Buying the ESU apart from any supply agreement might offer your facility the best opportunity to negotiate pricing on both the capital equipment and the supplies while maintaining flexibility to change supply vendors.

Specialty ESUs
You might want to consider buying a specialty ESU for certain applications, such as urology and other so-called under water procedures. Take a look at your caseload to determine whether a single ESU will fulfill all of your surgeons' requirements or if supplemental, specialty-specific ESUs are also indicated.

It all comes down to selectable waveforms - the currents, in electrical terms, are shaped differently, and that differentiates cutting and coagulating characteristics. For example, a machine with a higher frequency might have a unique waveform that is more delicate in its operations, and therefore suitable to dermatological or plastic/cosmetic procedures.

Another example are the machines that employ argon gas to achieve coagulation. This happens when an electrically neutral jet of plasma energy is applied to tissue. They might be better suited to more bloody cases, as they are said to work well on large blood vessels.

But many of the new digitally controlled, general purpose ESUs have the ability to emulate the power and waveforms of such specialty units. In situ - in the lab - you can see a lot of differences between the waveforms; but in vivo - in practice - a lot of surgeons cannot tell the difference. Go with what they're comfortable using and paying for, and you'll likely get the results you want.