Principles of Electrosurgery, feat. Dr. Gary Frishman

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A 45-year-old woman in the postoperative recovery unit develops dyspnea. Her serum sodium is 130 mEq/L. Which of the following was the most likely distending medium used during her hysteroscopic monopolar fibroid resection?

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Today we welcome Dr. Gary Frishman to the podcast. He is a clinical professor of obstetrics and gynecology at the Warren Alpert Medical School of Brown University, and has served in varying leadership capacities at Brown as a residency program director and in other organizations, such as for MIGS Fellowship at ABOG, and within ASRM, SRS, and AAGL. While we were residents at Brown, Dr. Frishman used to share his wisdom with us on electrosurgery and we have wanted to put this podcast together for a long time! It’s more than just cut and coag!

What is electrosurgery?

  • Delivery of radio frequency waves that heat up tissue, which then causes tissue desiccation.

    • Cautery: not a specific term for this!

    • Electrosurgery represents alternating current where the body is part of the conductive circuit.

      • Modulating the delivery of this electricity is how we can get differing tissue effects.

Monopolar and Bipolar

  • Bipolar: movement of electricity from one point to another direct point.

    • i.e., bipolar forceps, LigaSure device (has two ends)

    • More precise delivery of energy, less smoke.

  • Monopolar: movement of electricity from one point (in dispersive fashion) to a return point.

    • i.e., the “grounding pad” when you are using a Bovie / electrosurgical instrument.

      • Energy still goes through body, to a second electrode and back to the machine!

Modifying the Delivery of Energy

  • Waveforms:

    • Think about energy delivered as a garden hose with a spray nozzle at the end.

      • The amount of energy delivered is your watts setting on the machine (i.e., 35W).

        • This you can adjust linearly — you can go up to 40W, or down to 30W, but it’s a linear adjustment — less efficient.

      • If you adjust your spigot at the end of the nozzle, that is another way to adjust your energy delivery. Like if you get a dispersed spray (sprays all over the wall) versus a fine spray (that gives you a directed, straight line of water).

        • Cut: the directed, fine, straight line of water spray

        • Coag: the dispersed spray that goes everywhere

          • The energy is still our original 35W, it’s just differently applied!

      • Importantly, the cut and coag settings also are different in the time energy is applied.

        • Cut: energy is constantly applied — so, for example, 100W of energy delivered over 100 seconds.

          • Clinically, this delivers good cutting, but poor hemostasis.

        • Coag: energy is applied in bursts, and it’s only on 6% of the time — so 100W of energy delivered over 6 seconds.

          • It’s an uncontrolled, massive burst!

          • Clinically, this delivers a lot of lateral spread, and you get good hemostasis, but not great cutting.

        • Blend curve: tries to get you both: excellent cutting, excellent hemostasis, little thermal damage.

  • Spot size:

    • You can also adjust the spot size of energy delivery by changing the tip of delivery instrument (i.e., Bovie)

      • By flattening the tip, you make the spot size larger — much larger surface area to deliver energy across.

      • By using the fine point of the tip, your spot size is much smaller — delivers energy to more concentrated area (i.e., needle tip electrodes).

Complications of Electrosurgery

  • Direct coupling

    • Accidentally touch something metal with your electrosurgery device

      • i.e., touching a retractor or a laparoscope, which is in turn touching something else

      • Good news — just like with the “spot size,” if you touch a retractor, it’s such a large surface area it’s unlikely to cause damage. However, with smaller instruments, this can modify injury and cause injury.

        • Plastic trocars help prevent this in laparoscopic surgery.

  • Insulation failure

    • Tiny cracks in an instrument that can cause insulation to fail — as you might get inadvertent direct coupling from the device if electricity is leaking out through the insulation.

      • Fortunately this is very uncommon.

      • If there are gross breaks — don’t use the instrument.

      • Limit the use of coag (i.e., use cut exclusively) to prevent this kind of injury.

  • Capacitive coupling

    • Two conductors separated by an insulator

      • Energy is stored in the separated conductor, and can then deliver energy.

        • Less likely to occur with cut than coag

        • Jewelery and electrosurgery - a possible (though rare) complication of wearing jewelry in surgery.

Role of Tissue Resistance

  • Electricity heats up water in the cell

    • Cut: heats up water in the cell very rapidly, and it explodes.

    • Coag: heats up water in cell more slowly, and energy dissipates laterally.

  • Electricity follows path of least resistance

    • As tissue dessicates (water removed), it becomes harder for electricity to pass through.

    • Think about a car on cruise control, set to a speed of 30W:

      • If you’re going uphill, you’re going slower unless car adjusts — higher tissue resistance.

      • If you’re going downhill, you’re going faster unless car adjusts — lower tissue resistance.

  • Newer generators measure tissue resistance and can adjust your energy appropriately!

    • Newest bipolar instruments also take surgeon out of equation entirely — and automatically adjust energy to resistance and shut off automatically when resistance is so high energy can’t pass.'

  • Importantly, if you’re using monopolar — electricity will go around high-resistance areas! This is how you can get capacitive coupling to jewelry and other areas.

    • A “grounding pad” is usually very large to help accommodate for this and prevent this injury.

      • It’s also in two halves, and both must be connected to make the machine work.

      • Bipolar instruments reduce this risk significantly.

Fulguration

  • Taking the tip of the device and placing it close to, but not on the tissue — may have heard of this as “arcing” the device.

    • Use coag on this because you want a huge burst of energy to leap across the space.

    • This energy “follows the blood” back to the original bleeder.

Cutting on Skin??

  • You can! But you need to know how to deliver energy — need a small spot size and to use cut.