Key points

A case presentation of electrocautery for ESD accompanies this article

Introduction

The rapid advancement of endoscopic treatment for gastrointestinal tumors that has occurred recently has quickly transformed the era of traditional polypectomy and endoscopic mucosal resection into the era of endoscopic submucosal dissection (ESD). Accordingly, to perform safe and effective treatment while minimizing complications, one must fully understand the principles and features of the electrosurgical units (ESUs) that are used for ESD, and choose the appropriate, case-dependent settings for each surgical instrument, depending on the equipment, lesions, and organs.

This article describes the optimal settings for the ESU VIO300D (ERBE Elektromedizin GmbH, Tubingen, Germany) ( Fig. 1 ), and how its features can be fully used for safe and effective ESD.

VIO300D (ERBE Elektromedizin GmbH, Tubingen, Germany).

Introduction

The rapid advancement of endoscopic treatment for gastrointestinal tumors that has occurred recently has quickly transformed the era of traditional polypectomy and endoscopic mucosal resection into the era of endoscopic submucosal dissection (ESD). Accordingly, to perform safe and effective treatment while minimizing complications, one must fully understand the principles and features of the electrosurgical units (ESUs) that are used for ESD, and choose the appropriate, case-dependent settings for each surgical instrument, depending on the equipment, lesions, and organs.

This article describes the optimal settings for the ESU VIO300D (ERBE Elektromedizin GmbH, Tubingen, Germany) ( Fig. 1 ), and how its features can be fully used for safe and effective ESD.

VIO300D (ERBE Elektromedizin GmbH, Tubingen, Germany).

ESU description

An ESU is an apparatus for performing incisions and coagulation through applying Joule heat, generated by a high-frequency current (high-frequency alternating current: 300 kHz to 5 MHz), onto tissue without neuromuscular stimulation. The higher the current density is (ie, more current per unit of area), the greater the Joule heat. To incise tissue requires a steam explosion (spark). During incision, electrical resistance is continually changing, depending on many factors, such as the shape of the surgical instrument, contact area, movement speed, and the electrical conductivity of the target tissue. Therefore, with the conventional ESU, which is an output control type, the incision and depth of coagulation is not constant because of changes in voltage that accompany changes in resistance.

The solution to this problem is a voltage-control type of ESU, which is based on the principle that the discharge distance (coagulation depth) is proportional to the voltage. Thus, by sensing the voltage between the active electrode and the tissue in real time through an internal high-speed sensor circuit and continuing to maintain the correct voltage setting through instantaneous feedback, consistent incision and coagulation depth can be maintained with high reproducibility. In particular, using this voltage-control type of ESU for ESD, which demands precision, is recommended.

Differences between cut output and coagulation output

Output of the ESU includes incision output and coagulation output, as described earlier. Incision output is needed to generate a steam explosion (spark) by quickly raising the intracellular fluid temperature through continuous application of Joule heat generated by the high-frequency current (unmodulated pulse: continuous wave). On the other hand, coagulation output is applied to dehydrate and dry tissue by slowly raising the intracellular and extracellular fluid temperature through intermittently applying Joule heat (modulated pulse: intermittent wave). ESUs are known to act differently above and below a borderline of 200 peak voltage (Vp). Because a spark is generated when more than 200 Vp is applied, an incision effect can be created even from the coagulation output when the current density is high and the contact area is narrow. This effect is dependent on the status of the current density at the tip of the device and the surface area of tissue contact. That is, ESD can be performed using coagulation output because the requirements are fulfilled. Conversely, only dehydration and drying of the tissue occur without spark generation when the voltage is less than 200 Vp, even with continuous wave; this is called SOFT COAG mode , and it plays an important role in contact coagulation when treating vessels for hemostasis during management and prevention of bleeding in ESD. Therefore, the waveform, such as continuous or intermittent, is selected only for the pace of Joule heat generation.

Features of VIO300D

VIO300D is an evolutionary outcome of the conventional intelligent cut and coagulation (ICC) series. The main features are as follows:

• 1.
  

  Conventional ENDO CUT has improved and evolved to ENDO CUT I and Q.

  
  
• 2.
  

  DRY CUT and SWIFT COAG, new incision, and dissection output settings are provided for ESD.

  
  
• 3.
  

  The power peak system (PPS) works on all cut outputs (see next section).

  
  
• 4.
  

  The amount of current is doubled and the amount of heat generated is improved 4-fold compared with the ICC 200 series.

  
  
• 5.
  

  Voltage control or arc control is possible for all cut/coagulation outputs.

The basic output philosophy of the VIO300D is an unmodulated (continuous wave) or pulse-modulated sine wave (burst wave) with the frequency of 350 kHz, regardless of whether it is for incision or coagulation. In other words, the waveform that repeats the amplitude 350,000 times per second (continuous wave) or the intermittent waveform using only a few percent of amplitude that repeats 350,000 times (burst wave) is applied for incision and coagulation. The belief is that a large difference can result in incision and coagulation depth when the Vp is different, and that there can be differences in incision and coagulation ability when the duty cycle is different because of pulse modulation, even if the frequency and conduction time are the same.