1. Technological Sciences for the Operating Room
Electricity for the Surgical Technologist

2. Introduction W.T. Bovie developed first spark-gap tube generator
Electrical burn is a serious risk to patients
Patient Safety Depends on
Knowing basic electrical terminology
Principles of electricity
Proper applications in O.R.
Surgical technologists must learn theories of electricity and usage for 21st century medicine

3. Surgical Applications of Electricity
Electrosurgical Unit (ESU)
Generates current to cut tissue
Direction of current flow:
Generator → active electrode → dispersive (inactive) electrode → generator (Figure 6-6, Pg 115)

4. Surgical Applications of Electricity
X-ray Machine
Utilizes electromagnetic radiation
Uses of X-rays
View internal body structures
Determine presence of foreign bodies
Find retained sponges, sharps, or instruments
Verify presence of fluid or air
Assist in bone realignment

5. Surgical Applications of Electricity
Endoscopes
Instrument inserted in patient through abdomen, chest wall, or orifice
Flexible or rigid
Camera and light cord attached
Used with ESU, laser or robotic arm
Applications
Diagnosis, obtain biopsy, repair, retrieve foreign object, hemorrhage control

6. Surgical Applications of Electricity
Lasers
Utilized in almost all surgical specialties
Energy converted into light energy
Laser light does not spread
Choice of beam criteria
Power, wavelength, color, duration of exposure, type of tissue
Laser classification
Gas, solid, liquid, semiconductor crystals

7. Surgical Applications of Electricity
Robotics
Extend and enhance human capabilities
Components
Robotic arm (manipulator), computers to operate the robotic arm and interpret commands, voicecard, video system and microphone
Advantages
Eliminates hand tremor (holding endoscope); promotes faster recovery, improves visualization of surgery site; enable telesurgery; reduces costs.

8. Principles of Electricity
Electron Theory
All electronic effects caused by movement of electrons
Serves as basis for design of electrical equipment
Atoms, Electrons, Matter
Matter has mass and occupies space; consists of atoms

9. Principles of Electricity
Atoms, Electrons, Matter
Atoms
Composed of protons, electrons, neutrons
Nucleus is center; contains positive charged protons and neutral charged neutrons
Negative charged electrons travel in orbits around nucleus
Atoms held together by opposite charges of protons and electrons
Different elements have varying numbers of protons and electrons

10. Principles of Electricity
Atoms, Electrons, Matter
Electrons
Revolve in shells or orbits
Close to nucleus – strong attraction; outer orbits – less attracted
Free electrons located in outer orbits; movement creates electric current
Electricity: term actually describes movement of free electrons moving from orbit of one atom to another (principle based on Bohr’s Theory)

11. Principles of Electricity
Atoms, Electrons, Matter
Electrons con’t.
A conductor is a material that allows flow of free electrons
The greater the number of electrons in a substance, the better the conductor
Copper is the most commonly used material for a conductor. Silver, zinc and brass are also used.
Devices in O.R. that use copper as a conductor: surgical lamps, ESU, power drills
Water is a conductor; humidity in O.R. should be maintained at 50%-60%

12. Principles of Electricity
Insulators
Materials with small number of free electrons; inhibit flow of electrons
Basically poor conductors
Used to wrap conductors to preserve current and prevent leakage of electrons
Types of insulators
Rubber cord, plastic around ESU or X-ray machine

13. Principles of Electricity
Electrical Charge
Can be either positive or negative
Defined as too many or too few electrons orbiting an atom
Law of Electric Charge: like charges repel each other; unlike charges attract each other; opposites attract

14. Principles of Electricity
Electrical Current
Movement of electrical charge
Current moves through conductors by movement of free electrons migrating from atom to atom inside conductor

15. Magnetism Magnetic Fields
Electrons create a magnetic field or electric charge while orbiting the nucleus
In some materials electrons travel in the same direction, combining magnetic fields
Natural magnetic substances include iron, nickel, cobalt, even the earth
Electrical generators depend on the close relationship of electricity and magnetism

16. Magnetism Magnetic Fields con’t. Two poles, north and south
Earth
Two poles, north and south
Magnetic field is lines of magnetic force between poles
Magnetic field causes metal objects to be attracted to the magnet; needle in a compass

17. Magnetism Electromagnets
Metals that become magnetic when encircled by a conductor
Magnetic field created by current traveling through conductor
Magnetic field used to create electricity
Electricity does not create power; only means for transporting it
Interaction between wires and magnets produces power

18. Magnetism Electromagnets con’t.
Example: Power plant
Water from dam heated  forms steam  turns turbines (generators)  turbines spin magnets  electricity is created for use

19. Volts – Named after Alessandro Volta, a 17th Terminology
Volt is electrical potential
– Voltage is potential energy of electrons
– Named after Alessandro Volta, a 17th
century scientist who invented the battery
Electric system: battery creates voltage to move electricity
Circuit is the path electricity travels

20. Current Measured in amperes (amps) Rate of flow of electrons
Current flow is the movement of free electrons
Free electrons attracted from point of excess electrons to a point with fewer electrons

21. Ohm’s Law Scientific law of electricity
– Mathematical equation showing how voltage,
current, and resistance interrelate
– Ohm’s Law: V = I x R
Resistance
Restricting flow of current; measured in ohms
Ohm’s Law
– More voltage will increase current if resistance
is constant; higher resistance causes
decreased current if voltage is constant

22. Power Rate at which work is completed Measured in watts (W)
Rate of movement of electrons or current flow
Product of voltage & current is power
P = I x V
Measured in watts (W)
Converted to kilowatts (KW): 1 KW = 1,000 W
Example: DC Circuit is 12V & 20A, Power is
P = 20 x 12 = 240W or 0.24KW

23. Load Device that uses electricity to perform a function
Can change amount of energy from power source
Examples: surgical lamps, ESU, power drills, video monitors
Resistive energy loads: conductor has high resistance to flow of electricity
Example: filament (conductor) in light bulb; electricity has to force way thru resistance to cause filament to glow

24. Switch Device used to open or close circuit Example: Flashlight
Controls flow of electricity
Example: Flashlight
Batteries (power)
Wires (conductors) connected to battery that is connected to switch activated by user
Bulb (load) must have voltage
Voltage carried by conductors and switch controls flow of current to load; open switch – no flow, closed switch bulb lights up

25. Wires Hot Wire Neutral Wire Ground Wire
Wire that connects to switch; colored red
Neutral Wire
Pathway for electrons to return to energy source; complete the circuit; colored green
Ground Wire
Sends leaking electrons to ground to prevent shock; colored black

26. Resistors Devices made of materials that are purposely resistive
Designated with letter R

27. Direct Current (DC)
Electrical current flows in one direction – negative to positive pole
Example: Batteries
Serve as storage device; keep electricity until needed
Negative (-) and positive (+) terminals
When switch is closed, current flows from one terminal to the other

28. Direct Current (DC) Batteries con’t. Four components of DC circuit
Battery: source of electricity
Wire (battery to load): conductor
Switch: control device
Load: bulb

29. Alternating Current Current that periodically reverses direction
Complete cycle is current that moves in one direction, then reverses direction
Hertz (Hz): one AC cycle
Frequency: number of AC cycles in a second; symbol ƒ
Most common AC in U.S. is 60 cycle AC
Typical voltage is 110V or 120V

30. Alternating Current AC Can Change Voltage
AC delivered as high voltage, then “stepped down”
Example:
Transformers “step up” exiting voltage
Power lines (transformer) deliver electricity at high voltage
Voltage is stepped down before use

31. Radio Frequency (RF)
Frequency is number of wave cycles (one cycle is a hertz) per second
Radio and TV signals are electromagnetic waves
Radio transmitter delivers signal to antennae system
Electromagnetic signals travel through cable, air or optical fiber to receiving antennae
RF spectrum begins at 9 kHz (or less) to over 3 GHz

32. Isolated Circuit Cause of electrical shock
Secondary circuit contains hazardous current due to isolated circuit
Transformer insulation isolates secondary circuit
Person touches both poles of non-insulated isolated circuit and experiences an electrical shock and/or burn

33. Isolated Circuit Secondary Circuit con’t.
Two methods of prevention:
Solid insulation placed as total barrier to prevent complete access to circuit
Conductive barrier of insulation between isolated circuit and conductive barrier

34. Electrosurgery
Application of electrical current through tissue to coagulate bleeding or cut tissue
Electrosurgical Unit (ESU): Device that provides power for electric current
Electrosurgery: Electrical currents applied directly to tissue; utilizes AC current
Electrocautery: Uses heated wire to burn tissue; no electricity enters body; utilizes DC current

35. Electrosurgery ESU Circuit: Current Flow
Generator  thru conductor cord  active electrode (Bovie tip)  surgical site (energy converted to thermal energy to cut or coagulate)  thru patient  dispersive electrode (grounding pad)  conductor cord  generator

36. Bipolar Electrosurgery
Used for delicate procedures, presence of moisture, prevent nerve damage
Two prongs of forceps: active and inactive electrodes
Current travels through one tip, passes thru tissue, disperses to other tip
No dispersive electrode required

37. Monopolar Electrosurgery
Flow of current is as described.
Dispersive Electrode (grounding pad)
Placement is critical to avoid electrical burns to patient
Pad must be in complete contact with patient’s skin
Pad pulled up or portion not in contact, may result in second or third degree burns to patient

38. Electrosurgery Shock and Burn
Patient
Burns usually deep; tissue necrosis; thrombosis
Debridement
Sterile Surgery Team Members
RF Capacitive Coupling: AC travels from active electrode, through intact insulation, burns skin; apply active electrode beneath Crile held by surgeon to prevent burns

39. Electrosurgery Shock & Burn con’t.
Sterile Surgery Team Members
Dielectric Breakdown: High voltage breaks down insulating material, such as sterile glove; produces hole in glove – surgical team member sustains small burn

40. Electrosurgery Vaporized Tissue Plume
Occurs during procedures involving electrosurgery, lasers, power drills
Plume is vaporized tissue
Contains hazardous bioparticles that are carcinogenic, mutagenic, and they may carry bloodborne pathogens
Surgical technologists utilize suction to “suck smoke” from wound when using electrosurgery or smoke evacuators for lasers

41. SUMMARY
THE END