Surgery: precise incisions with microwave plasma

Gentle surgical techniques support a faster patient recovery process. This also includes high-frequency surgery, where electric current passes through the body via the scalpel. This makes tiny, precise surgical cuts (incisions) possible and promotes vascular closure in the wound area. However, this technique is not without risk for the patient. The microwave plasma scalpel could offer an alternative in the future.

In this interview with COMPAMED-tradefair.com, Prof. Holger Heuermann talks about the newly developed plasma scalpel and its advantages over high-frequency surgery (HF surgery).

Prof. Heuermann, how does your plasma scalpel work?

Prof. Holger Heuermann: It generates an argon beam with a 0.2 diameter. The argon is highly ionized. The beam cuts at an energy density of 80 kilowatts per square centimeter and transfers decreasing energy with increasing distance to the source. Our plasma is generated at 2.5 gigahertz, in the microwave range. This means in less than 0.2 nanoseconds, the electrons oscillate in one direction. In common plasmas, they oscillate approximately one microsecond, meaning in a thousand-fold period. This is also why these electrons penetrate far deeper into tissue sections than they do with our plasma.

Our plasma is brand-new and unique: when it comes to energy density, we range between lasers and existing arc thermal plasma.

What are the benefits of these types of plasma scalpels compared to electric scalpels used in high-frequency surgery?

Heuermann: In HF surgery, current flows through the patient's body at high density. The advantage here is that wound edges close immediately because they coagulate. This speeds up the wound healing process and patients are ultimately discharged much faster from the hospital. Having said that, the current flow also entails some risks: the patient has to be integrated into the electric circuit via an electrode such as a metal plate, through which the current can leave the body again. If this connection is not set up properly, it can result in severe burn injuries in the electrode region. There have even been some fatal accidents.

No current flows through the body with the plasma scalpel. In this case, we only work with energy on the surface where we plan to make incisions. This also enables us to perform surgery on patients on a regular operating table. In turn, surgeons are also able to perfectly control the depth of the cut because the energy density of the plasma decreases as the distance to the source increases.

What happens at the wound area during surgery from a physical perspective?

Heuermann: We do not make the surgical incision by applying thermal energy. Instead, the plasma instantly heats the water-bearing vessels in the tissue, which causes them to burst in a manner of speaking. This results in a similarly precise incision as is the case in HF surgery. The wound coagulates and essentially does not bleed. The result is a thin, minor incision.

For which types of surgical interventions will the plasma scalpel be best suited?

Heuermann: The microwave plasma scalpel is essentially intended for all types of surgeries were electric scalpels are being used. We are working on matching its specifications and incision quality with today’s electric scalpels.

What development steps do you now have to complete before you have a prototype available or before you are able to conduct a clinical trial?

Heuermann: Like I said, we are working on optimizing the incision quality to produce a precise cut that is comparable to cuts performed in HF surgery. And although we are still not quite there yet, remember there have also been decades of research in the HF surgery area. Compared to where we started, we already see major improvements.

Next will be device development and clinical testing. However, this is done by the device manufacturer, BOWA-electronic.