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38 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Who regulates Electricity Safety in the OR?
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JCAHO- equipment standards.
NFPA- National Fire Prevention Safety--safety requirements for electrical construction |
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What makes up a simple electrical Current.
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1. Source of Electromotive Force.(EMF)
2. Device that uses electricity to do work and produce resistance. 3.conductor (wires) to carry from source to device and back in a circle.(circle must be complete for electricity to flow) |
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What is amperage?
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-denoted by "I"
-- electric current --the flow of electrons through a conductor -measured in amps. |
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What is voltage?
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-denoted by "E"
--electromagnetic force --potential difference in charge that causes te flow of electrons -measured in volts. |
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What is resistance?
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-denoted by "R"
--the force resisting the flow of electrons in a circuit --measured in Ohms. |
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What is Ohms Law?
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E = I x R
Voltage = Amps x Resistance (Volts = Current x resistance) Amps = Voltage/Resistance |
BP analogy:
Pressure drop = CO x SVR increase in voltage = increase in amps increase in resistance = decrease in amps |
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What is electric power?
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an electric current measured in Watts.
*Watts = Voltage x Amps (W = E x I) Amps = Watts/ Voltage |
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What is current electricity?
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High current at Low voltage.
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What is static electricity?
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Low current at High voltage
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accumulation of excess energy and separation of a charge can create a spark.
OSHA requires 50% humidity in OR. |
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What is capacitance?
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Measures a substance's ability to store a charge
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two parallel conductors separated by an insulator.
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What is a conductor?
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A substance which has loosely attached and easily lost electrons
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metals, human tissue
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What is a nonconductor?
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A substance that has tightly bound electrons. An insulator.
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glass, rubber, plastic.
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What are the two types of electric current?
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Direct Current and Alternating current
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DC & AC
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What is the frequency at which an alternating current repeats cycle....measured in cyles/second
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Hertz
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in US 120v = 60 Hertz
60 cycles/sec = 120 times it changes direction. |
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What is resistance in AC Current?
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Impedence
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What is Inductance in AC Currents.
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A Property of AC circuits in which opposing electromagnetic fields are generated.
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Causes electricity to leak from a device.
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What is a capacitor?
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A device that stores a charge in direct proportion to the potential.
Current flow decreases as the charge on the capacitor increases. |
Charging a defirillator
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Describe properties of electricity
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1. electricity flows in a circle.
2. follows a gradient from high to low voltage. 3. seeks path of least resistance 4. injury occurs when a person becomes part of the current pathway. |
- Electric shock occurs when touching 2 points (wire and ground) to complete the circle.
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List Electrical shock injury variables:
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1. Duration of exposure
2. Amount of voltage 3. Type of current (AC more dangerous than DC) 4. Density of current (size of area) --Density= amps/area 5. Tissue resistance and susceptibility |
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What are the tolerable levels of electric shock?
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1 ma/sec = mimally noticed
5 ma/sed = maximum harmless level 10-20 ma/s = "can't-let-go-current" 50-100 ma/s = pain, fainting, 100+ ma/sec = VFib/VT |
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What is a microshock?
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Minimal shocks- imperceptible level
- 10 mcgA (0.01 mA) = maximum allowable leakage in the OR |
Pacing wires, PA catheter, EKG
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What is macroshock?
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Perceptible electrical shock
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1 mA/s tingling sensation
5 mA/s pain felt- pull away 10 mA/s Can't let go |
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How is Equipment grounded?
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A third wire connects the metal case of the equipment to the grounding prong in the wall socket.
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provides a low resistance pathway for current during faults.
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What is grounded power?
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One of the wires delivering electricity is in contact with earth (ground).
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What are the three Electrical power options in the OR?
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1. Standard grounded power
2. Standard power with Ground Fault Circuit Interruptor (GFCI). 3. Isolated power (best) |
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What are the disadvantages of standard grounded power in the OR?
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1. electricity follows path of least resistance--Patient, surgeon,...
2. Fluid conducts electricity 3. Current seeks to return to ground... via fluid, patient, etc... |
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What is the pros and cons of Standard power w/ GFCI?
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1. Current is shut off if a fault is detected.
2. cons: shuts off vital equipment 3. Protects user from microshock, but shuts off equipment. |
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What is the advantages of isolated power in the OR?
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1. Contact with either of the lines and the earth does not complete the circuit- so no shock.
2. Faulty equipment is detected and an alarm is tripped- but equipment stays on --but system is now a grounded system, so the next faulty equipment could cause a shock. 2. Primary power is separated from secondary power by an Isolation transformer. |
LIM: Line Isolation Monitor
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Does a LIM protect against microshock?
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No- just macroshock. (Equipment grounding protects against microshock)
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Will electricity still work after the LIM alarms?
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Yes, but the system is now a grounded system, so the second faulty equipment that occurs will produce a macroshock and injury.
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LIM alarms with- faulty equipment, wet cords, malfunctioning power outlet.
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What is Inductance?
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- small amounts of current tat is present even when there are no direct electrical connections.
--Max allowable: 10 microamps |
Leakage
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What is an electrical fault?
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an unintentional connection between a nongrounded conductor and ground.
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What is the amount of current flowing through the body divided by the cross-sectional area of tissue through which the current flows.
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Current Density
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what are some of the properties of an Electrosurgical Unit. (Bovie)
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- Use high voltage (3000 v)
- produce 400 watts of power Heat is produced at the tip to cauterize blood vessels or cut tissue. |
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Risks of the ESU?
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Current is dispersed through a grounding pad and completes circuit back to patient. If pad is not properly placed- current will seek other ways to ground. (surgeon, patient,)
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How do ESU cause burns?
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1. small return plate connection. (larger the area covered, the lower the current density)
2. inadequate or improper application of the pad 3. Disruption of the return wire. 4. Insufficient conductive gel |
dispersive plate placement guides:
-close to operative site -as far away from EKG pads -not placed over scars, implants, skin -ensure adequate skin contact |
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What is a unipolar vs a bipolar ESU?
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the Bipolar has 2 elctrodes that look like forceps, one is active and one is collecting the current. (no dispersive pad)
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What is the Argon Beam ESU used for?
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Coagulation when large expected blood loss surgery. (unipolar)
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