New Bipolar and Hybrid Argon Plasma Coagulation Technologies Enable Improved Electrosurgical Results Daniel Friedrichs, James Gilbert, and Joe Sartor Covidien Surgical Solutions, Boulder, CO, USA daniel.friedrichs@covidien.com Abstract— A new power supply circuit significantly increases the utility of Argon Plasma Coagulation by varying patient inclusion in the plasma-forming circuit, and by supporting novel bipolar plasma instruments. This technology spans a large gap in present plasma medicine market offerings, increasing controllability and producing previously-unobtainable tissue effects. Keywords—argon plasma coagulation, electrosurgery, cautery, electrocautery, plasma medicine I. INTRODUCTION Argon plasma coagulation (“APC”) is a mature surgical technology which is used to coagulate bleeding tissue through the application of a hot ionized argon gas (plasma) [1]. Through either an open or laparoscopic instrument, plasma is formed by the application of a high potential voltage between the patient and the surgical instrument in the presence of gaseous argon. Kinetic transfer of energy from the plasma to the tissue of interest causes coagulation, protein denaturation, and hemostasis [2]. APC is utilized in certain procedures where standard (non-gas-assisted) electrosurgery risks sticking to, and potentially tearing, thin or sensitive tissues (such as the cecum or liver). Traditional APC surgical instruments consist of a single wire centered in a tube through which gas is flowed [3]. The patient is connected to a return electrode which allows completion of the electrical circuit once the instrument is brought close enough to the tissue of interest to strike an arc. The patient-connected return electrode is large in size, resulting in clinically-significant current density only appearing at the tip of the surgical instrument (which is comparatively smaller). This technology, termed “monopolar APC”, is the most mature form of APC, and is illustrated in Fig. 1. Figure 1 – Monopolar APC A recent advance in the field of APC is the use of a bipolar instrument which does not require the patient be part of the electrical circuit. The surgeon’s instrument contains both “source” and “return” electrodes and the plasma is directly formed between these electrodes. As no current is conducted through the patient, bipolar APC is argued to be safer and/or more controllable than monopolar APC. Figure 2 illustrates this configuration. Figure 2 – Bipolar APC Both monopolar and bipolar APC suffer a variety of implementation and effectiveness problems. In general, monopolar APC is somewhat uncontrollable; arcs jump between tissue sites and unexpectedly deflect due to the high applied E-field. Some implementations require a high degree of surgical skill to initiate the plasma-forming arc. Monopolar APC is also not applicable to certain procedures (such as neurological procedures) where it would be undesirable for return current to flow through the patient. Using bipolar APC avoids the return current problem, at the expense of being slower and less efficacious. While monopolar APCs utilize an operating room’s existing electrosurgical generator as a high- voltage power supply, present market offerings in bipolar APC rely on a dedicated high-voltage power supply (which has no other surgical utility); hospitals are reluctant to purchase large, specialized equipment for a limited-use instrument. This paper presents a novel alternative approach to either monopolar or bipolar APC, offering previously-unattainable tissue effects and a new degree of control freedom by varying patient inclusion in the plasma-ignition circuit, all while utilizing a common electrosurgical generator power supply for both mono- and bi-polar electrosurgical and APC instruments. Section 2 describes the design of a bipolar APC instrument which is capable of being powered by a unique but full- featured electrosurgical generator. Section 3 describes how the return electrode connection can be varied in order to produce Standard Electrosurgical Generator Gas Flow Regulator Other electrosurgical instruments Source electrode Return electrode 978-1-4799-1471-5/13/$31.00 ©2013 IEEE 386