Advancements of Radiofrequency Technology

Radiofrequency

New advancements within radiofrequency technology with regard to laparoscopic surgery is now available for surgeon and gynecologist. Thirty years past radiofrequency (RF) energy has been something a laparoscopic surgeon considered for cutting tissue and coagulating vessels within non-invasive surgery. These days, the medically associated applying this technology tend to be expanding rapidly and can include experimental makes use of like eliminating cancerous tumors while sparing surrounding healthy tissue. Recently the technology even obtained FDA clearance for use in breast biopsies.

The next day, who knows; RF technologies may be a routine a part of an surgeon's armamentarium for use after cesarean delivery or emergency management of the obstetric hemorrhage or breast surgery. However, in this article we will focus on the promise of RF for that gynecologic laparoscopic surgeon, who later on might use this technologies technology to combat bleeding after an ovarian cystectomy or perhaps a uterine myomectomy or hysterectomy.

Radiofrequency energy and other laparoscopic tools

Radiofrequency power (or radiation) is a component from the "electromagnetic spectrum," a term that encompasses all forms of electromagnetic waves which radiate through space in the speed of light-from low-frequency radio waves via higher frequency gamma rays. The particular RF part of the spectrum usually describes frequencies between 3kHz and 300 GHz.

As mentioned, gynecologists initial utilized radiofrequency energy during minimally invasive gynecologic surgery. More than a quarter century ago, we began using monopolar energy to chop and fulgurate tissue and bipolar energy to desiccate tissue and coagulate vessels. However a "new kid on the block" found its way to the first 1970s, whenever gynecologists were brought to the CO2 laser as a laparoscopic tool for cutting and vaporizing tissue while coagulating small vessels for hemostasis. After the CO2 laser became popular, other laparoscopic lasers such as the Nd:YAG laser with a sapphire tip and also the KTP (potassium, titanium, phosphate) laser proved effective for laparoscopic surgery. Today the various tools available to the gynecologic laparoscopic surgeon likewise incorporate ultrasonic energy in the harmonic scalpel and cryoenergy for cutting or destroying tissue, and having hemostasis.

Soon after lasers entered the operating room came standards set through the American Society for Lasers in Medicine and Surgery; then hospitals required training of physicians and personnel to attain "laser certification." As the usefulness of certification courses is debatable (and beyond the scope of this discussion), it's of interest that 50% of laparoscopic surgeons lack any formalized education in electrosurgery and only 20% have experienced One day or even more. 20 % of 400 surveyed surgeons received under One hour of education on electrosurgery (Data on file at Valleylab). The thing is that education is encouraged and often mandated when novel technologies are introduced into the operating room. Electrosurgery technology, however, continues to be "grandfathered" in due to the long good reputation for use. In light of those issues, three new radiofrequency (RF) goods are discussed and their mechanism of action is briefly described.

In the following paragraphs, we'll discuss three new RF products that make use of a common technology of cooling the tissue. Regarding two of the three manufacturers, this is accomplished by activating either monopolar or bipolar energy within the presence of saline; another manufacturer uses pulsed bipolar energy. However we'll briefly review electrosurgical principles to help your reader better understand how and why these products are different from the conventional monopolar and bipolar instruments used today. Basic principles of electrosurgery

An important first principle is the fact that electricity will always seek a ground and can always seek the path of least resistance. The actual flow of electrons in a period of time is called the present and is measured in amperes (I). The pathway taken by the uninterrupted flow of electrons is the circuit. Resistance or impedance may be the obstacle to flow and it is measured in ohms. The voltage (V) may be the power or force pushing the present through the resistance. The strength of electrosurgery is measured in watts (W) and is based on multiplying the volts (V) through the amps (W=V x I).

The effect which electrosurgery has on human tissue results in the heat generated inside the tissue .In a given power setting (watts) with an RF generator, the volts is going to be increased once the setting is set on coagulation but the current intervals are intermittent. The result is really a slower but deeper rise in tissue temperature, collagen melting, and vessel sealing. Alternatively, when the setting is on "cutting," the present is constant, the voltage is reduced, and there is a rapid increase in temperature in superficial tissue that leads to tissue vaporization and cutting

Their education of heat produced is dependent upon the amount of current flowing, the level of resistance to the flow of the current, and the degree that the current is targeted (current density). The more concentrated the power, the higher the thermodynamic effect. Clinically, if a generator is placed in a stable wattage, a little electrode may cause vaporization and cutting, while a larger "ball" electrode may cause coagulation with collagen melting.

Moreover, tissues that vary in their water and electrolyte content will respond differently to RF energy due to a variance in tissue impedance. Water vapor from tissue vaporization, along with the eschar created from high tissue temperatures, will behave as insulators to RF energy because of their high impedance. (As opposed to conductors-materials by which electrons move freely from one atom to another-insulators are materials which contain fewer moving electrons.) Other variables that impact the tissue effect and the quantity of heat produced include the waveform from the energy produced by the generator, how big the electrode and tissue, time, and the way of manipulating the electrode. In essence tissue that's vaporized or cut, fulgurated (while using noncontact or arcing mode), or desiccated (dried) for coagulation.

The actual monopolar circuit. Finally, the output features from the RF generator are also essential in determining the particular extensiveness of the impact on tissue and the power with which instruments perform. Within the monopolar circuit, there is an active electrode in the surgical site, and a return electrode in a distant site that's generally positioned on the patient's thigh. The current flows through the body between your electrodes. The monopolar RF generator provides three waveform settings: cut, blend, and coagulation.

The bipolar circuit. As opposed to the external nature of the monopolar circuit, within the bipolar system the active and return electrodes can be found within the surgical instrument. The output from the generator is really a continuous sine wave in a low voltage like a monopolar cutting waveform. The ability is usually limited to 70 watts and until recently, has been used exclusively for tissue desiccation and vessel coagulation.

A grasp of the above principles can help the particular gynecologic surgeon understand and evaluate the three new RF technologies from TissueLink Medical (Dover, N.H.), Arthrocare Endo (Sunnyvale, Calif.), and also Gyrus Medical Inc., Maple Grove, Minn.

Debut from the Floating Ball

Although this device has not yet been used in gynecologic surgery, one anticipated future application of the Tissue Link Floating Ball is within achieving hemostasis during a myomectomy. This device is a monopolar RF surface coagulator used chiefly to arrest excessive bleeding in parenchymal organ tissues during open or laparoscopic surgical treatments. As the Floating Ball focuses RF energy near its tip, from which a continuous flow of saline emerges and moistens a stainless-steel spring-loaded ball electrode and also the nearby tissue surface. The flow rate is low and it is supplied by an ordinary gravity drip from an IV bag of normal saline. The main reason the ball is spring-loaded is to provide both a soft tip and also to allow declogging as needed. Since the fine lines indicate, electrically conductive saline from the ball electrode helps in transferring the RF energy from the ball to the tissue, causing the tissue near the tip to rapidly warm up as well as coagulate. Surface tension wicks the saline from the electrode towards the tissue, even if the tip is moving swiftly, enabling the surgeon to color irregular tissue surfaces without any interruption within the delivery of RF energy.

Most of all, the continuous flow of saline also cools the tissue. Since water boils at 100°C, so long as there is a certain minimum flow rate, associated with the RF power setting, the temperature at the surface won't exceed 100°C. Keeping the tissue temperature so cool prevents the development of eschar as well as the accompanying smoke and sticking which are common with conventional electrosurgical devices. Outdoors and laparoscopic products are.

Tissue effect. The main impact on tissue is to shrink Type I collagen inside the walls of blood vessels, bile ducts, and small airways. Shrinkage of up to 50% can occur within 1 second if the tissue temperature exceeds about 75°C. This amount of shrinkage is sufficient to permanently ligate arteries, veins, bile ducts, and airways up to and including diameter of about 2 mm. Since tissue is not carbonized, there isn't any eschar formation and the tissue anatomy remains visible. Tissue coagulated below 100°C and never carbonized also remains soft and blunt dissection is much easier to do than with conventional electrosurgery. In comparison, conventional electrosurgical coagulation often results in only temporary hemostasis through occlusion of a lumen by a fibrin plug or perhaps a superficial scab, both of which are vunerable to fibrinolysis and late rebleeding.

Good reputation for clinical applications. The device can be used with the tip in a stationary position to coagulate one spot at any given time, to paint a line, or to paint a sizable surface, such as painting a line on tissue. In addition, it can be used to prevent active bleeding, or to coagulate tissue before either blunt or sharp dissection.

Various gynecologic applications are on the horizon, but at this time, among the device's most successful clinical applications continues to be for liver resections. By first coagulating the liver along a line of intended resection, the particular dissection through the liver parenchyma can be done with minimal blood loss, often under 100 mL. For many surgeons the Floating Ball has replaced the argon beam coagulator, surface sealants, and topical hemostats to attain hemostasis.

Clinical applications in general surgery have included liver transplants, laparoscopic cholecystectomies for acute cholecystitis, laparoscopic partial splenectomies, and partial nephrectomies. In thoracic surgery, these devices has been used to perform nodulectomies, to stop air leaks at staple lines, and to stop chest wall bleeding in difficult lung transplants. Though the device has yet to be utilized in gynecologic surgery, likely applications include achieving hemostasis during a uterine myomectomy or after cesarean delivery, as well as use with an ovarian bed following an ovarian cystectomy.

Pros and cons. Pros and cons of this technology are listed. A big plus, of course, is that it quickly stops bleeding and reduces blood loss (just like another two products we're going to discuss). But one should stay away from the present electrode tip like a blunt dissector, because it may become clogged with tissue.

Benefits and drawbacks from the Floating Ball

Advantages

Achieves rapid hemostasis on soft tissue, minimizing the chance that laparoscopic procedures will have to be converted due to uncontrolled bleeding

Reduces blood loss and also minimizes or even eliminates the requirement for transfusion or cell salvage

Works together with general purpose RF generators and a standard IV set connected to a bag of normal saline

Disadvantages

Excessive saline pooling near the tip can disperse the RF energy and slow the tissue effect Sometimes requires suction to removeWorks poorly when the electrode suggestion is immersed in saline, as a result of too widely dispersed RF field

Do not use the present electrode tip like a blunt dissector (that it was not designed), as it might become clogged with tissue

Future of the technology. I've described the technology as it pertains to a monopolar surface coagulator to coagulate vessels under 2 mm in the surface of parenchymal organs like the liver, lung, and spleen. But a bipolar coaptive device is due to launch this season, and other products are also under development for other applications generally surgery. The Floating Ball devices currently available on the market are being evaluated clinically for gynecological use, and new applications they are under consideration. White papers on clinical experiences and preclinical studies can be found about the manufacturer's Site at //www.tissuelink.com .

Coblation way of laparoscopic surgery

ArthroCare Endo has recently launched its system for RF ablation in general, gynecologic, and laparoscopic procedures. The corporation defines its patented coblation technology like a process that uses bipolar RF technology to get rid of tissue with "minimal thermal harm to collateral tissue." These devices is used in other surgical specialties, including arthroscopic, spinal, ENT, neurologic, and plastic surgery.

ArthroCare Endo has also developed disposable wands to be used using its system. Included in this are a number of hooks and blades for cutting and volumetrically removing tissue. Bipolar forceps (that have been to be released in March 2002) can coagulate larger vessels as well as rapidly cut tissue.

The actual bipolar RF coblation technique eliminates the thermally damaging vaporization and pyrolysis inherent in standard RF systems with molecular disintegration via a "cool" ablative process. This is done by employing an electrically conductive fluid (isotonic saline) within the physical gap between your electrode and the tissue. Upon applying a sufficiently high voltage difference between these structures, the saline is converted into an ionized vapor layer, or plasma field. Due to the voltage gradient across the plasma layer, charged particles are accelerated for the tissue. At sufficiently high voltage gradients, these particles achieve enough energy to break down the molecular bonds inside the tissue. This molecular dissociation achieves the goal of volumetrically getting rid of tissue. Because of the short range of the accelerated particles inside the plasma, however, this dissociative procedure is limited to the top layer from the target tissue. In this manner, coblation removes precise tissue only, while producing minimal necrosis of collateral tissue.

At the same time the coblation technique is eliminating tissue, it's able to coagulate smaller vessels which are adjacent to the zone of ablation. The residual current flow within the tissue, which stretches beyond the plasma/tissue boundary, permits it to do so. Another coagulation function of the bipolar product is for coagulating larger arteries. The operator activates this option by lowering the applied voltage impact on an amount below the threshold for plasma formation and molecular dissociation.

Coblation is "cool or controlled ablation"

  • Bipolar energy in saline = Plasma field
  • Ionized particles break down organic molecular bonds inside tissue
  • Result: Tissue removing and also hemostasis with decreased heat penetration

Of special interest to the gynecologist are two 5-mm instruments: A grasper (the plasma forceps) that can be used for tissue desiccation and cutting and a bipolar hook (the Plasma Dissector 90) which is used primarily for cutting while sealing small capillary vessels.

The new plasma forceps is a disposable common surgery device based on coblation technology that received FDA 510(k) clearance last fall. Later on, it's likely to be used in laparoscopically assisted vaginal hysterectomies. This product was created to contend with ultrasonic and bipolar cutting forceps and it is being promoted as an instrument that may do the job of several, permitting the surgeon to visit past grasping to complete blunt dissection, cut via vessels and tissue, in addition to coagulate vessels.

PlasmaKinetics

The word PlasmaKinetics (PK) was made by Gyrus Medical to describe formation of vapor pockets within tissue using bipolar energy. Their PlasmaKinetic (PK) Tissue Management System, which is based on bipolar technology, includes a proprietary PlasmaKinetic generator and particular instruments, designed as a system. The PK system uses high-powered pulsed energy and can supply across medical specialties. It offers vapor pulse coagulation, vessel ligation, in addition to minimal thermal spread and adherence to tissue.

Additionally, the system has several user-friendly features to simplify its operation by physicians, nurses, and other operating room personnel. Instrument identification feature. The generator identifies the instrument that's plugged into it and automatically sets the parameter. Impedance monitor. The generator visually and audibly indicates alterations in tissue impedance so the clinician can be confident how the tissue is fully desiccated. Instrument shorting indicator. When the jaws of the PlasmaKinetic instrument touch each other, as with any instrument of this type, the system won't provide deliverable energy. Should such shorting occur, a visual and audible tone (distinct in the impedance monitor) will alert the clinician to slightly move the jaws apart to restore energy delivery. Mechanism of action and benefits

In the Vapor Pulse Coagulation mode (VPC), the generator delivers high levels of pulsed energy to the tissue. This pulsed energy uniquely coagulates the tissue by creating vapor pockets inside the tissue, resulting in controlled and repeatable outcomes. The consistency of coagulation is greater while using the pulsed energy of the PlasmaKinetic System in comparison with the continuous energy delivered by conventional bipolar generators. The use of pulsed energy reduces thermal margins and virtually eliminates sticking because it curtails time it really takes to deliver energy. Each one of the PK instruments runs on the customized output load curve that tailors the pulse rate to improve performance.

Advantages include a narrower thermal margin, much less sticking, and improved large vessel sealing. Much less thermal margin. Due to energy efficiency, much less energy is needed to achieve coagulation. Much less sticking. Also due to energy efficiency, tissue is not over desiccated to achieve coagulation. Much better large vessel sealing. For the similar reason, tissue is much more uniformly and completely coagulated.

PlasmaKinetics permits the surgeon to do something quickly when bloody fields are present, improves coagulation inside the tissue, reduces or eliminates sticking and low thermal margin, and may seal large vessels. The product may be used for any wide variety of procedures within gynecology.

In addition to the generator, the system's instruments include: Cutting forceps with 5-mm or 10-mm shaft diameters in a number of lengths-for laparoscopic and open procedures, dissecting forceps, scissors, macro and micro jaw forceps, MOLly bipolar forceps employed for tubal sterilization, needle electrodes, and hooks.

All individual instruments in the system have the features I've discussed for that system as a whole. In addition, the instruments perform multiple functions to reduce the amount of instrument exchanges required and thereby reduce procedure times and charges.

Although there is little experience using these new technologies in gynecologic surgery, the three technologies have unique features for specific applications. The TissueLink floating ball is fantastic for sealing surface vessels with minimal tissue penetration. Potential applications include the closing of peritoneal surface area vessels on the pelvic sidewall. In addition, it may be helpful for the treatment of benign ovarian cysts and vessel sealing during laparoscopic myomectomies. The particular Arthrocare coblation technology has applications in adhesiolysis and tissue resection, for example in endometriosis treatment. The Gyrus PlasmaKinetic system can be effective in sealing large vessels when performing laparoscopic hysterectomies and also oophorectomies.

Conclusions

A surgeon or gynecologist is no stranger to traditional radiofrequency energy, as we've become comfortable using it to cut and coagulate tissue. That familiarity, combined with fact that RF technology provides consistently been less expensive compared to laser beam and ultrasound technology, leaves little doubt that you will see many more new RF technologies in our armamentarium. The three described here use a common technology of cooling the tissue to produce higher power density in the presence of saline (TissueLink­ monopolar and Arthrocare­bipolar) or pulsed energy (Gyrus). What's obvious is that the technology is creative and simple. This should go a long way in gaining physician acceptance and maintaining down the cost of new technology.