energy sources and electrosurgery

1. Energy devices
Abhilash

2. Energy sources in surgery
• Electrical
• Ultrasonic
• Laser
• Mechanical

3. Electrosurgery
• 1926- Cushing and Bovie
• Alternating radiofrequency current.
• 500,000 to 2 million Hz.
• Electrocautery is not same as electrosurgery.

4. Physics of electrosurgery
• Current takes path of least resistance.
• Tissue containing maximal water has least
resistance.
• Energy density – amperes/cm2

5. Ohms Law
• I= V/R
• Current = I : flow of electrons/time (amps)
• Resistance (Impedance) = R : Obstacle to the
flow of current (ohms)
• Voltage = V: force pushing current through
the resistance (volts)
• Power = V x I (watts)

6. Types of electrosurgical circuits
• Monopolar.
• Bipolar.

7. Monopolar
• ADVANTAGES
– Ease of use
– Cutting and coagulation currents
– Dissecting capability.
• DISADVANTAGES
– Larger volume of tissue injured.
– Interferes with electrical implants.
– Requires ground pad.

8. Bipolar
• ADVANTAGES.
– Small volume of tissue injured.
– Less risk of burns.
– Safe with electrical implants.
– Effective in wet fields.
• DISADVANTAGES
– More skill required.
– Coagulation only.
– No dissecting capability

9. Electrosurgical effects
• Cutting.
• Coagulation and fulgration.
• Dessication.

10. Cutting
• Non contact activity.
• Non modulated sine wave almost 100
percent of time – best for cutting.

11. Fulgration and coagulation
• Non contact.
• Short bursts of high voltage with pauses.
• Cause coagulative necrosis of tissues and
fluid.

12. Dessication
• Tissue is heated and water in the cell dries
out.
• Can use cutting or coagulation current by
contact with tissue.

15. Complications of electrosurgery
• Direct coupling – Active electrode in contact
with metal instrument.

16. • Capacitative coupling – current is
transferred from the active electrode to
nearby tissue through the intact insulation
• Insulation failure.

17. New generation
• Higher current, less voltage.
• Less thermal spread.
• Impedence feedback, end point feedback.
• Grasp, dissect, coagulate and transect.
• More efficient but costly.

18. Newer energy sources
• Advanced Bipolar devices.
– Gyrus ACMI (Olympus)
– Enseal (Ethicon Endo-Surgery)
– Ligasure (covidien) vessel sealing
• Ultrasonic scalpel
– Harmonic scalpel ( Ethicon Endo-Surgery)

19. Gyrus ACMI
• Plasma kinetic energy delivered in pulses
• Intermittent tissue cooling prevents thermal
damage and sticking.
• 2 modes
– Vapor pulse coagulator
– PK cutting

20. • Audible impedence and end point indicators.
• PK energy to tissue  forms vapor
zonescurrent passes around the vapor
zone vapor zone collapses causing tissue
sealing

21. Enseal
• Adjusts energy according to tissue
impedance.
• Smart electrode technology – millions of
nano conductive particles each with discrete
thermostatic switch.
• Each particle interrupts current flow to a
specific tissue when temperature rises.
• If temperature below fusion level particle
turns back on.

22. • Less heat required. Tissue volume reduced
by compression.
• Vessel walls fused by compression, protien
denaturation and then renaturation.
• Seals upto 7 mm vessels. Thermal spread 1
mm
• Withstands upto 7 times systolic pressures.

23. Ligasure
• “Electrosurgical collagen welding”
combination of pressure and energy 
denature collagen and elastin  permanent
seal.
• Hydrothermal rupture of collagen cross links
• 60-90 degree C.

24. • Cooling allows renaturation of entangled
unwound collagen strands.
• High uniform mechanical compression
increases entanglement/ recross linking
upon thermal relaxation.
• Permanently fuses tissue and vessels
without dessication.

25. • Average seal cycle is 2-4 sec.
• Seal can withstand upto 3 times normal
systolic pressure.
• Can ligate vessels upto 7 mm.
• Impedence feedback – adjust energy levels
according to tissue impedence.
• Feedback controlled response system to
detect end of seal cycle.

26. Harmonic Scalpel
• Converts ultrasonic energy→
mechanical energy.
• Piezoelectric crystal produces ~55000
vibrations per second.
• Lysis of H-bond → heat → denaturation of
protien → separation of tissue.
• Tissue separation at 50-60 degree C.

27. Settings on a harmonic scalpel
Higher the setting → longer excursion of the
blade --> more mechanical energy  more
cutting speed/more thermal energy

28. Advantages of harmonic scalpel
• Minimal thermal spread.
• No dessication or charring of tissue.
• No risk of electrical injury
• No smoke.
Clipless lap cholecystectomy uses a harmonic
scalpel.

29. Disadvantages of harmonic
scalpel
• inability to coagulate vessels greater than
5mm.
• Operator dependence of settings of the
blade according to tissue.
• Increased cost.

30. Types of harmonic scalpels
• ACE curved sheers
• Coagulating sheers
• Harmonic focus
• Dissecting hook

31. CUSA
• Cavitron ultrasound surgical aspirator.
• Causes cavitational fragmentation of cells.
• Ultrasonic generator at 23000 Hz.
• With coupled powerful aspiration device.
• Used in liver surgery and neurosurgery
• No coagulation or cutting.
• Only tissue gets fragmented.

33. Surg Endosc. 2009 Jan;23(1):90-6

34. Surg Endosc. 2009 Jan;23(1):90-6

35. Surg Endosc. 2009 Jan;23(1):90-6

36. • Harmonic scalpel has the least thermal
spread.
• Ligasure is the highest rated.
J Endourol. 2008 Oct;22(10):2307-12
Sealing time
(s)
Burst
pressure (hg
mm)
Smoke/visibil
ity (ppm)
Harmonic
scalpel
14.3 204 2.88 ppm
Ligasure V 10 385 12.5 ppm
Gyrus PK 11.1 290 74.1 ppm
Enseal 19.2 255 21.6 ppm

37. Argon beam coagulator
• Inert, non combustible, easily ionisable.
• Used along with monopolar electrosurgery.
• Electric current ionises argon facilitates
current flow.
• Not suitable for laparoscopy.

38. LASER
• Precise application of energy.
• Less lateral damage and stray currents.
• Energy induces molecular vibration and
thermal vibrations.
• Mediums – CO2, Argon, NdYAG.

39. Microwave ablation
• Generator probe at 2450 MHz.
• Created alternating electrical field induces
motion of polar molecules kinectic energy
converted into heat  coagulation necrosis.
• Applications – liver, prostatic hyperplasia,
endometrial bleeding, partial nephrectomy.
• Only small area ablated.

40. Radiosurgery
• Gamma knife used in neurosurgery.
• High energy gamma radiation arranged in
circular fashion.
• Focussed stereotactically

41. • THANK YOU.