BME Seminar Series: Michael Sealander
Tissue Bioeffects of Pure Argon Plasma - Thermal Diffusion and Possible Cell Signaling Mechanisms for Influencing the Inflammation Cascade and Wound Healing
Most surgical procedures involve the dissection of tissue using a combination of cutting and coagulation, often with
specialized energy sources. Many different devices are available, but they all divide and coagulate tissue by converting
various types of energy into heat. The vast majority of such devices are electrosurgical and achieve their thermal tissue
effect by passing electrical current through the tissue, which can be uncontrolled and unpredictable. Complications specific
to electrosurgery relate to unrecognized energy transfer, commonly referred to as
stray current, often occurring outside
the surgical field beyond the notice of the surgeon.
The PlasmaJet® surgery system (Plasma Surgical, Roswell, GA, USA) uses a low flow of argon gas excited to the plasma state using a low voltage DC arc generated within a set of electrodes internal to the device as the source of thermal energy for cutting, vaporization or coagulation of the target tissues. The resulting thermal plasma emerges from the tip of the handpiece in a focused jet, and gives up its energy when it contacts the tissue surface in three forms; heat that is used to cause the intended surgical effect when directed to the tissue, light that illuminates the surgical field, and kinetic energy that clears the surgical site of fluid as well as facilitates the dissection of tissue planes. In addition to being purely thermal with no current passing through the patient, the resultant tissue necrosis is minimal relative to electrosurgery, and is especially beneficial in surgical procedures requiring the selective removal of unwanted disease tissue overlying otherwise healthy or desirable tissue.
In addition to the relatively well-established benefits of having minimal thermal effect and thus being tissue-sparing, there is some reason to believe that thermal plasma may positively impact inflammation signaling mechanisms, with implications for wound healing and postoperative peritoneal adhesion formation. The high-temperature of the plasma can result in an uncatalyzed endothermic reaction between O2 and N2, creating small amounts of Nitric Oxide (NO). NO is a free radical signaling molecule in variety of biological processes and, depending on its redox state and source, may be toxic or protective. Studies on the role of NO in adhesion formation in rat models potentially indicate that Nitric Oxide Synthase (NOS) inhibition causes severe peritoneal adhesions following surgery (Galili et al. 1998) and that increased levels of nitric oxide can result in reduced adhesion formation (Ozden et al 1999). It has also been hypothesized as an important mediator in normal wound repair (Schaffer et al 1996).
Plasma Surgical is considering proposals from researchers interested in collaboratively investigating bioeffects of pure plasma. A PlasmaJet console and handpiece will be present at the talk for live demonstration and audience use.