The therapeutic basis of electrosurgery is the production of heat at the cellular level. High frequency (RF or Radio Frequency) alternating current is generated by an electrosurgery generator unit (ESU) and flows to tissue via an assortment of suitable accessories. Water within cells heated very quickly vaporizes and causes the cell membranes to burst. These vaporized cells separate tissue along a cleavage plane directed by the accessory. We say the separated tissue has been electrosurgically "cut." Cells that are heated more slowly desiccate or coagulate without vaporizing. The proportions of how many cells coagulate and how many vaporize, as well as how much tissue is involved, is referred to as the "tissue effect."
Current density is the arbiter of the final tissue effect. It is a measure of current concentration or intensity. Many variables contribute to the ultimate current density. Some of these contributors are independent of the ESU as they are patient, tissue and/or technique dependent.
Non-ESU variables can play a definitive role in the final outcome. The time that current is delivered to a target site (how long the foot pedal is depressed) is a strongly influential variable over which the physician has total control. Time multiplied by watts equal total joules of heat delivered. (Energy in Joules=Power in watts X Time in seconds) A very rapid closing of a snare or a slow controlled close is an example of how time can influence the amount of energy that flows through any one area. In argon coagulation applications time can be a greater determiner of tissue injury depth than the power setting.
Other variables include the amount of target tissue, such as a large polyp versus a small one. Resection attempts of very large amounts of tissue decrease the current density and slow the cutting initiation. A technique of tightly strangling a large amount of tissue may exacerbate this effect as the snare wire is totally embedded and surrounded by large amounts of low impedance tissue. More coagulation will be produced until tissue temperatures rise to the point of rapid cell vaporization and cutting. A snug and smooth resection technique may help initiate the cutting action more effectively and safely. The thickness of cutting wires and the composition of different tissues are also factors. Bleeding risk is greatly influenced by patient factors such as anticoagulant use.
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Important variables that change the tissue effect are selections the user makes on the ESU. One of these is the type of current waveform, often called "cut" or "coag" or "blend." These names are not standardized but can be compared by using quantitative measures. This information is contained in the user manual making it possible to determine which output name most closely resembles another.
Myth: It is NOT true that if a waveform is named “Coag” it will not have any cutting effect, or if named “Pure Cut” it has no coag effect. The only coagulation waveforms that cannot cut (a truly "pure" coag) are those with Vp less than 200. Even ‘"Pure Cut" waveforms leave some margin of coagulation. The only PURE cut is a cold cut!
The selection name on the ESU interface is the means by which users can choose different waveform outputs. Current waveforms that deliver energy constantly at high enough voltages create a lot of cell vaporization or cutting. Interrupting the waveform (modulating the current) heats cells more slowly thus reducing the cutting and increasing the amount of coagulation. How high the voltage spikes within the waveform helps determine how deeply coagulation penetrates. Higher voltages are more powerful in driving a deeper and wider thermal effect.
Waveforms held below 200Vp (volt peak) can never heat living tissue fast enough to produce any cutting. These very low voltage continuous waveforms produce soft coagulation outputs which are ideal for contact coagulation with either monopolar or bipolar accessories. These continuous very low voltage outputs are usually named SoftCoag®
[a registered trademark of Erbe Electromedizen, Tubingen, Germany] or TouchSoft®
[a registered trademark of Genii, Inc., St Paul, MN]. Similar bipolar outputs are often named "Ideal GI Bipolar," Bipolar or Soft Bipolar.
Changing waveforms change the balance of cut and coagulation:
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Microprocessor Control and Power Curves
Since the 1980s, ESUs have been produced with microprocessor technology. This continually advancing technology has made possible dispersive (grounding pad) sensing and other safety alarms as well as computerized feedback monitoring of tissue impedance (resistance) and the microprocessor control of output power as tissue impedance changes when it is electrosurgically cut and coagulated.
Myth: It is NOT true that only one brand of electrosurgical generator has microprocessor control. All modern generators use these ubiquitous electronic components and most have feedback tissue sensing and impedance monitoring.
Ohm’s Law is the primary physical and mathematical law that governs electrosurgical technology. The most useful observation of this law for the clinician is Ohm’s proof that as tissue becomes coagulated it becomes more resistant to current flow. With microprocessor monitoring, an ESU can track an impedance baseline and subsequent changes in the impedance during the electrosurgical activation. For example, the Genii gi4000
takes an impedance measure every 250 micro seconds. Using these millions of data points, every generator’s software programming (algorithm) tells the generator how to regulate the current and/or voltage (which together equal the power) being delivered during the activation. A graphic representation of how a particular output is designed to react to changes in impedance is called a "Power to Impedance Curve" or "Power Curve." Some people use marketing terms such as “power dosing” as a less correct technical term to describe this action but the terms are synonymous.
The power curves associated with each output selection are so important to understanding the operation of any generator that in the USA, FDA requires that these graphs be included in every generator’s user manual. International standards also require them. Clinicians would be well served to read and understand this section of the user manual before putting a new generator into service.
Most GI physicians are familiar with this automatic control in bipolar methods. A "narrow" curve is the most commonly suggested for use with GI bipolar endostasis accessories, such as the Boston Scientific GoldProbe™ or the Genii biSmart™ probe
. When coupled with a very low voltage, continuous wave form, this power curve is often referred to as the "GI Ideal Bipolar Output" or the "Tucker Ideal Bipolar Output."
This narrow curve depicts the generator "ramping up" toward the selected power setting very quickly at the start of the application. It is clinically important to deliver power quickly into the low impedance, bleeding tissue. Once the tissue is adequately coagulated (usually at about 600 to 1000 Ohms of resistance) the starting power has automatically dropped off to only a few watts. (Ohm’s math: Current= Voltage/Resistance and Power= Voltage X Current. Therefore with Voltage capped at a low 200Vp, power drops quickly as resistance rises). This narrow curve gives the output its characteristic self-limiting nature. Coupled with bipolar hemostasis probes, this method is a well-studied, first line therapy for large upper GI bleeds and other indications for bleeding control.
A common bipolar starting power setting is 15-20 watts on many ESUs. Even though the user does not see the display on the generator change during the activation, the actual power being delivered is not the full 15 or 20 watts over the entire time. These bipolar narrow curves with low voltage outputs are found on currently marketed Boston Scientific EndoStat™ generators; Conmed/KLS Martin Beamer®
Mate and BiCap®
III units; Erbe ICC™200, VIO®
300D and VIO®
200S; and the Genii gi4000
. There may be others.
Low voltage narrow power curves are also excellent choices for monopolar contact coagulation methods. (Recall that monopolar circuits require the use of a dispersive (grounding) pad to return the energy to the ESU to complete the circuit.) When used with a monopolar circuit these outputs are named “Soft Coag®
” or “TouchSoft®
”. These are excellent outputs to pair with the Olympus Coagrasper™ or the Genii TouchSoft Coagulator®
. At least one study has described successful use of a snare tip with a soft coagulation output for touch ups during the resection of large colonic lesions. While the end tissue result from this monopolar contact coagulation method is very similar to the result from using bipolar endostasis probes with a low voltage narrow power curve, the suggesting starting powers are higher for the monopolar method due to the greater impedance in the longer circuit. Manufacturer’s suggested starting powers for this method tend to be about 40 to 60 watts.
The narrow power curves just described would NOT be effective for snare polypectomy or sphincterotomy. The low voltages don’t produce any cut and the power drop during the resection would lead to stalling or snare entrapment. For these indications, higher voltage outputs which have at least some cutting ability are matched with “broad” power curves. In these broad curves, as resistance rises during the resection, the ESU keeps the voltage and current being delivered to a tightly controlled range around a selected setting. Some have likened this feature to ‘cruise control’. Broad curves are a bit like an automobile cruise control which automatically adjusts fuel (current and voltage which together equal power) to keep the car going at a smooth speed either up or down hill.
Broad power curves paired with waveforms using a variety of output types are ideal for many clinical applications. Often paired with cut, blend, and coag type waveforms and snares, sphinctertomes or needle knives, they are widely used for polypectomy, endoscopic mucosal resection (EMR), sphincterotomy (especially when the energy delivery is ‘pulsed’ or fractionated as in EndoCut®
[a registered trademark of Erbe Electromedizen, Tubingen, Germany] or other equivalent Pulse Cut modes), endoscopic submucosal dissection (ESD) and other applications.
It is incorrect or a Myth to describe an entire generator as falling into EITHER a "voltage controlled" OR a "constant" or broad power output type. These terms refer to each of the many individual output selections on each generator. Output choices of both are found in most modern generators. All modern generators use microprocessors to adjust power by adjusting both voltage and current to achieve the power curve dictated by the algorithm design.
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Monopolar accessories complete the electrical circuit with the aid of a return "dispersive" or "grounding" pad. A monopolar accessory is unidirectional: all of the energy flows away from the accessory (such as a snare) and takes a current path of least resistance to a remote "dispersive electrode" or grounding pad. When the energy that was concentrated at the treatment site is evenly dispersed over the return or grounding pad, it is able to exit the patient’s body safely to return to the generator to complete the electrical circuit.
While a published report of an electrosurgical pad burn during a flexible endoscopic procedure is unknown, it is still wise to take advantage of the inexpensive, well studied safety advantages of using "split/dual/sensing" grounding pads and the corresponding generator software. These systems are known as REM, CQRM, PPS and other names. When using any of these systems the pads are able to communicate with the generator and both visual and audible warnings can alert the operator that the pad is sensing an impedance level that if not corrected, could result in a temperature rise on the patient’s skin under the pad and might produce a burn.
To make sure that all the energy leaving the patient’s body is evenly dispersed it is important to place the dispersive pad carefully. Open sealed pads just before use to avoid dried adhesive gel. Pads should be placed on patients to promote the best possible dispersion of energy over the pad surface. For nearly all GI procedures, placement on the upper thigh or the flank will meet guidelines for most patients. Avoid placing pads over excessive hair, scar tissue, implants or bony prominences such as a hip bone.
The first patent for dual (split) grounding pad safety using microprocessor control was US Pat. No. 4,416,276 by David Newton for ValleyLab, 1983. The first patent describing the use of a microprocessor to control output characteristics was filed in 1986 by Michael Manes of Aspen Labs. US Pat No. 4,574,801.
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Best Practices for the Use of Dispersive (Grounding) Pads:
- Place grounding pads in the most suitable position that is closest to the treatment site. Refer to the instructions on the pad label for each manufacturer’s advice.
- Choose a site that is muscular (not overly fatty) and well vascularized. Make sure that the entire area of the grounding pad is smoothly and reliably in contact with the patient’s skin.
- Current will follow a path of least resistance directly toward the pad. In gastroenterology procedures placement on the flank or the upper thigh are preferred sites, but some individual consideration is often necessary.
- Make sure that the grounding pad remains properly attached throughout the procedure. Check the pad if the patient has been moved or repositioned. If the pad must be removed mid procedure for any reason, consider discarding it in favor of a fresh disposable pad.
- Never attach the pad over implants, metal, bony protuberances, broken skin or scar tissue. Circumstances may require the skin to be cleaned or shaved in order to get even contact.
- If possible, avoid placing pads over tattoos.
- Don’t overlap the pad.
- Never use pads with a damaged or dried gel layer. Never cut pads in an attempt to resize them.
- If reusable grounding pad cables are used be sure they are properly attached. Be sure that the attachment clip covers the gel free connecting lugs or tabs so that they do not make contact with the patient’s skin. Replace cables when worn.
- Extend the grounding pad connecting cables away from the patient and do not align or entwine the cable with other cables such as the active cord or cables leading to patient monitoring equipment.
(Nelson G, Morris M. Electrosurgery in the Gastrointestinal Suite: Knowledge is Power.
Gastroenterology Nursing; 38(6), 430-39).
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Helpful Tips for Dispersive (Grounding) Pad Use
Don’t open individually packed pads until needed. When pads are purchased in multi packs try not to remove them from the package in advance as this helps prevent the gel from drying out. Follow the manufacturer’s recommendation about storing, opening and use.
A common problem in endoscopy is ESU safety lights that won’t give the green light (Go) signal quickly with some patients. An understanding of how dual/sensing/split pads work can help with trouble shooting. These sensing pads send a signal to the generator that gives a baseline reading of the impedance at the pad site on that individual patient. Working with the tissue sensing software in the generator, the pad continues to monitor the impedance safety limits during the entire procedure. Generators are programmed not to give the "green" light until the impedance is within an acceptable limit at the start, and to alarm if this limit is exceeded at any time during the procedure.
The baseline impedance at the start is dependent on several factors. Skin smoothness, dryness, excess hair, oil or lotions can all interfere. Pads are made with a high water content gel and it is important that this gel has not dried out because it must adhere to the skin to transmit an acceptable baseline impedance to the generator.
In busy GI practices users often don’t have advance warning that a pad will be needed. The quick rush to apply the pad in typical endoscopic settings sometimes doesn’t give the pad enough time to adequately establish its connection with the ESU software. It helps to use the overall good pad safety advice to avoid placing pads over scars or excessive hair on a muscular area with good blood flow. Remove excess skin lotion. If the pad light does not turn green quickly in spite of this careful placement, rub the surface of the pad gently for a moment.
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With bipolar accessories (sometimes referred to as multipolar or MPEC devices) the electric circuit does not require a remote dispersive (grounding) pad. The accessory itself contains both the active (outward flowing) and the return electrode within the device.
The energy flows only through a limited amount of tissue at the treatment site. This can have some advantages in certain situations such as the presence of sensitive implanted devices. Bipolar power settings are often lower since it is not necessary to compensate for the higher impedance present in a longer distance monopolar circuit. Currently in flexible endoscopy there is only one overall style of bipolar instrument aside from specialty applications such as BARXX dedicated RF catheter systems.
Bipolar endostasis probes are available from many manufacturers and while they differ in materials, price, size and configurations of handles, they often have common elements. All have a two color spiral or pie shape pattern at the tip which indicate the two electrode dual function. Most have a lumen through the accessory with a connector for the attachment of a lavage washing source and a few have an integrated injection needle for adding various solutions such as epinephrine to the therapy. These probes are widely used for staunching large upper gastrointestinal bleeding and for treating other types of less intense bleeding. They can also serve an ablative function but since they are usually paired with low voltage continuous narrow power curve outputs, the ablation action may be depth limited.
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Electrosurgery with Implanted Cardiac Devices
Implanted cardiac pacemakers and cardioverter defibrillators (ICDs) are designed to sense and react to electric signals from the heart. This makes them vulnerable to interference from electrical signals that are not cardiac in origin, and it has long been known that extra care must be taken when using electrosurgery for treating these patients. Patients with these implanted devices can safely undergo electrosurgery as long as certain precautions are taken.
Newer pacemakers have been engineered to be resistant to electric interference and alteration in function from electrosurgery is extremely rare in gastroenterology. However the risk exists. Interference with the device can have several different effects. In all cases every institution should have a protocol in place that will be followed with any patient with any implanted device.
Especially for patients that are dependent on an implanted cardiac device, (estimated to be about 20%) it is important to use best efforts to identify the device and its manufacturer. Stay up to date on announcements from device makers. In January 2014, St. Jude Medical announced a new finding that some of their oldest pacemakers, when exposed to electrocautery (sic), “may exhibit a temporary change in function that could persist for 30 seconds or longer after the electrocautery exposure has been terminated.” Devices of concern are the Affinity, Entity, Integrity, Identity, Sustain, Frontier, Victory and Zephyr models. “The most clinically significant observation has been loss of capture due to a transient reduction in the pacing output voltage. Placing a magnet over the device or programming to an asynchronous pacing mode will not prevent this temporary reduction in this pacing output.” Special caution and/or the avoidance of electrocautery (electrosurgery) in patients with these older models is advised. Please note that more recent families of St. Jude pacemakers—Accent and Anthem—and all ICDs, are not subject to this higher concern. The usual guidelines would be appropriate for these devices. For questions, clinicians may call St. Jude Technical Services at 800-722-3774” (St. Jude 2014).
An up to date, exhaustive treatment of this subject is available in Nelson G, Morris M. Electrosurgery in the Gastrointestinal Suite: Knowledge is Power.
Gastroenterology Nursing; 38(6), 430-39
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Other Implanted Devices
New implanted devices are constantly being introduced. Some devices are used to treat Parkinson’s disease and other movement disorders and there are many others. User materials posted for these devices warn that system damage or operational changes can occur during the use of electrosurgery. Sometimes bipolar applications are recommended. Many of these devices are not directly life supporting and can be turned off long enough for electrosurgical treatment. Since they are so varied, it is wise for the GI nurse to simply be aware that they exist and to plan ahead to get further information on how best to care for individual patients affected.
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Electrosurgery with Jewelry
It is always a good idea for patients to remove (and leave at home!) as much of their jewelry as possible. There is always a risk of loss, tissue tearing, or swelling. Many years ago, electrosurgery generators were plagued by ‘stray’ (leaky) currents and there was fear that this unseen energy could concentrate on jewelry and cause patient burns. This hazard has been removed due to improvements in technology. Nevertheless, metal objects, including jewelry, in the direct path of current flow can concentrate electrosurgical energy. This is one reason that staff should not place grounding pads over metal implants.
Never place the dispersive pad directly over any piece of metal (jewelry or a gown snap). In monopolar electrosurgery, the current flows from the treatment site, following a path of least resistance to the grounding pad to be collected and returned to the generator to complete the circuit. In the case of a colon polyp with a grounding pad placed on the thigh, ear or finger rings would not be in the current path and would be of no concern. A genital or a new style dermal piercing, however, may have at least a theoretical risk of being in the current path and at risk of heating although no burns are known to have been reported from this cause. If it is not possible to remove such items, staff may use careful watching and reporting by a conscious patient to help mitigate the minor risk. Choose the lowest generator setting possible to successfully complete the procedure. It may be of benefit to interrupt the application of energy periodically to allow for tissue cooling if the procedure is lengthy.
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Argon Assisted Coagulation (APC, ABC, or ArC)
Electric current is a flow of electron charges. Most substances are not good conductors: their electrons are so tightly bound that they are not easily torn loose to flow from atom to atom in a current. The process of forcing electrons from their home atom is called ionization
. Unlike most substances, cheap, safe, argon gas is quite easily ionized. In its ionized state, argon, like all ionized gases, is called a gas plasma
. In the plasma state, argon provides a bridge that allows high frequency electric current to flow across a gap between the endoscopic accessory and the patient tissue. Once across, the current does its job of therapeutic heating.
The eschar that results is fairly consistent in depth and quite soft and pliable so that it tends to heal quickly. Argon medical use was first patented by McGreevy in 1988 (US Pat. No. 4,781,175 for C.R. Bard) and it was used extensively in open surgery cases. In 1997 Erbe introduced its use to flexible endoscopy in the United States. Argon plasma coagulation is now routinely used throughout the gut for non-contact hemostasis and tissue ablation. ArC is also increasingly being used in the lung for the same indications.
Argon as used in flexible endoscopy today is a monopolar application and requires the use of a dispersive (grounding) pad. This has implications for the beam length which is impacted by the total resistance in the entire circuit which includes not only the gap of mixed air between the accessory probe tip and tissue, but the patient’s total tissue resistance from the application site to the dispersive pad, and the resistance of all cables in the pathway as the energy completes the circuit with the ESU. This is why there may be variation in the beam length created by any argon system from patient to patient and day to day if only one power setting is available.
In various widely distributed marketing materials, the Erbe ICC/APC300 argon capable system is referred to in the United States as the first generation argon system for flexible endoscopic use. Second generation systems are the Erbe VIO/APC2 and the KLS Martin/Conmed BeamerMate/Beamer Plus. The third generation is considered the Genii gi4000
all in one unit.
The character of the argon beam has varied with each generation/system model. It is important to recognize that the manufacturer’s recommendation for power setting also varies with each system. Argon assisted coagulation is a form of electrosurgery and is NOT a laser.
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Argon Coagulation: Clinical Tips
- Argon systems are not all the same. Users should be sure to use power settings recommended by the manufacturer for the system in use.
- All systems are equipped with buttons for the automatic activation of a purge function. Purging (filling with argon) the connector and argon probe with argon gas at least once is universally recommended.
- In addition to the initial purge, it may be helpful to add a second short purge once the probe has been inserted in the scope and is near the target site (be sure tip of the probe is not touching tissue). This helps to ensure the gas covers the ignition electrode which is located at the end of the probe and makes sure an adequate non ionized argon cloud is surrounding the target site.
- Approaching the tissue with the probe in a tangential position can be useful both for positioning and for encouraging ignition. An additional option is to carefully ‘lay down’ the probe tip and then pull back without delivering energy to help gauge the distance from the tissue.
- Working close gives better control so it is best not to extend the probe too far out of the scope. About 2 to 5 cm is adequate if you see the tip of the probe extending beyond the tip of the endoscope.
- There are three popular application techniques: “spot welding”, “painting”, and “ignite and drag”. Each has different uses and slightly different techniques. It helps to practice on ex vivo or animal models. Depress the pedal long enough to get ignition started. For the painting technique, move the scope, not the probe.
- Increasing the TIME of application increases the penetration depth.
- Applying the dispersive (grounding) pad as close as possible to the treatment area can shorten the impedance path and help make the beam longer.
- Turning up the gas to a higher flow rate will NOT make the beam longer. This will only push the ionized argon species farther apart and increase the risk of distension.
- 1 liter per minute flow rate is sufficient for most applications.
- The patient must be monitored for distension during the procedure. Applying suction frequently is advised, especially for lengthy procedures. Argon gas is flowing when the foot pedal is depressed even if the beam has not ignited.
- Special ceramic tips argon probes do not make it safe to touch the tissue.
- Do not use argon coagulation to treat varices, hemorrhoids or other lesions requiring tamponade or coaption.
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Avoid using any electrosurgery if the patient is uncooperative with the endoscopy procedure or uncontrolled. Operators should try to avoid activation if it is impossible to visualize the active electrode. It is extremely important not to use any
electrosurgery device (including APC) with an improper bowel preparation. Catastrophic bowel explosions are a real risk if naturally occurring gases present in some patients, such as hydrogen and methane, are mixed with oxygen during sigmoidoscopy and colonoscopy. Complete, full length, colon cleansing using approved preparation protocols is required even if the electrosurgery is to be performed only in the sigmoid or rectum.
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References and Further Reading
- AORN. Recommended practices for electrosurgery. Perioperative Standards and Recommended Practices. Denver, CO; AORN, Inc. 2010; 105-125
- ASGE Technology Status Evaluation Report: Electrosurgical Generators, ASGE Technology Committee, Sarah A. Rodriquez, Committee Chair. Gastrointest Endosc 2013; 78(2) 197-208
- Fiek M, Dorwarth U, Durchlaub I, Janko S, Von Bary C, Steinbeck G, Hoffmann E. Application of radiofrequency energy in surgical and interventional procedures: are there interactions with ICD's? Pacing Clin Electrophysiol 2004; 27(3):293-8
- Ginsberg G, Barkun AN, Bosco J, et al. Technology status evaluation report: the argon plasma coagulator. Gastrointestinal Endoscopy 2002; 55(7):807-810
- Goulet CJ, Disario JA, Emerson L, et al. In vivo evaluation of argon plasma coagulation in a porcine model. Gastrointest Endosc 2007;65(3):457-62.
- Kwan V, Bourke MJ, Williams SF, et al. Argon plasma coagulation in the management of symptomatic gastrointestinal vascular lesions: experience in 100 consecutive patients with long-term follow up. Am J Gastroenterology 2006; 101(1:58-63
- Laine L, Long GL, Bakos GJ, et al. Optimizing bipolar electrocoagulation for endoscopic hemostasis: assessment of factors influencing energy delivery and coagulation. Gastrointest Endosc 2008; 67:502-8
- Manner H, Plum N, Pech O, et al. Colon explosion during argon plasma coagulation. Gastrointest Endosc 2008; 67:1123-7
- Morris ML. Electrosurgical Principles. In Ginsberg G, Kochman M, Norton I, Gostout CJ (eds): Clinical Gastroenterologic Endoscopy, WB Saunders/Elsevier , Chapter 6, 2005
- Morris ML, Norton ID. Electrosurgical Principles. In Ginsberg G, Kochman M, Norton I, Gostout CJ (eds): Clinical Gastroenterologic Endoscopy, WB Saunders/Elsevier, Second edition. Chapter 6. 2012
- Morris, ML, Hwang, JH. Electrosurgery in Therapeutic Endoscopy. In Clinical Gastroenterologic Endoscopy, WB Saunders/Elsevier, Third edition. Chapter 6. IN PRESS
- Morris Marcia L, Tucker Robert D, Baron Todd H, Wong Kee Song, Louis M. Electrosurgery in Gastrointestinal Endoscopy: Principles to Practice. Am J Gastroenterol 2009; 104(6); 1563-74
- Morris, M L. Electrosurgery in the Gastroenterology Suite: Principles, Practice, and Safety. Gastroenterology Nursing 2006; 29(2), 126-134
- Morris, ML. Electrosurgery, Jewelry and GI: The Real Story. Endonurse 2012; 12(4): 20
- Munro MG, Abbott JA, Vilos GA, Brill AI. Radiofrequency Electrical Energy Guidelines for Authors: What’s in a name? Journal of Minimally Invasive Gynecology 2015;22(1)1-2.
- Nelson G, Morris M. Electrosurgery in the Gastrointestinal Suite: Knowledge is Power. Gastroenterology Nursing 2015;38(6) 430-39.
- Norton ID, Wang MD, Levine SA et al. In vivo characterization of colonic thermal injury caused by argon plasma coagulation. Gastrointest Endosc 2002;55(6):631-636.
- Rey J.F, Bellenhoff U, Dumonceau J. M. ESGE Guideline: the use of electrosurgical units. Endoscopy 2010; 42:764-771
- Wong Kee Song LM. Modalities for tissue coagulation or ablation : electrocoagulation. In: Tytgat GNJ, Classen M, Waye JD, Nakazawa S, eds. Practice of therapeutic endoscopy. London: WB Saunders:59-74, 2000.
- Wong Kee Song LM, Wallace M. Electrosurgical Principles for endoscopy. In: Practice of Therapeutic Endoscopy, 3rd edition. London: WB Saunders: IN PRESS
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