Electricity Flashcards
1
Q
What is electricity?
A
is the change in potential energy caused by the movement of electrons from an area of high concentration to an area of low concentration.
2
Q
The flow of electricity is from a surplus of ______ to a deficit of the same.
A
electrons
3
Q
What is important to know about the OR?
A
has many electrical safety hazards, you must be able to identify and avoid them
4
Q
What is the SI unit for electric charge?
A
coulomb (C)
5
Q
Describe the relationship of coulomb’s law.
A
One coulomb is the amount of electric charge transported in one second by a steady current of one ampere.
6
Q
What is the equation for coulomb’s law?
A
1 C = 1A x 1 s
7
Q
What is the electrical potential energy unit?
A
Volt
8
Q
What is a volt?
A
represents electrical ”pressure” or the gradient of charges that could potentially flow
9
Q
What is coulomb’s law?
A
like charges repel each other and opposite charges attract each other inversely to the square of their distance
10
Q
Coulomb’s Law: Opposite charges ______ more when closer together
A
attract
11
Q
Coulomb’s Law: Like charges _____ more when closer together
A
repel
12
Q
What is Ohm’s Law?
A
For electricity to flow, there must be a completed circuit.
13
Q
What is the formula for Ohm’s Law?
A
V = I x R V = Electrical Potential (in volts) I = Current (in ampere) R = Electrical Resistance (in ohms)
14
Q
What does ohm’s law form?
A
The basis for the physiologic equation: BP = CO x SVR
BP = Pressure (analogous to voltage) CO = Cardiac output (analogous to current) SVR= Systemic vascular resistance (resistance)
15
Q
What is electrical potential?
A
the difference in the concentration of electrons on one side compared to the other
16
Q
What is the measurement for electrical potential?
A
The difference in the concentration of electrons on one side compared to the other
17
Q
What is current?
A
Current is a measure of the amount of electric charge passing a given point per unit of time or in other words the amount of electrons that move through the conductor (electrical wire) per second.
18
Q
What is the measurement for current?
A
Ampere (A)
19
Q
What is resistance?
A
Resistance in a measure of the opposition to the flow of electrons in an electric circuit.
20
Q
What does resistance determine?
A
How much current can flow in relationship to electrical potential
21
Q
What is resistance measured in?
A
Ohm (Ω)
22
Q
How do electrons flow in an electrical current?
A
From a surplus of electrons to a deficiency of electrons
23
Q
What must happen for electrical flow to occur?
A
Electricity must have a complete circuit
24
Q
What are three components of a simple circuit?
A
A positive side (live, hot), a negative side (neutral), and a ground
25
What effect does the ground have in electrical flow?
A conductor that is connected to the earth (ground) and provides a low, resistive, alternate route for electricity to flow through in the case of an electrical surge
26
What are the the different types of electrical flow?
Direct current (DC) or alternating current (AC).
27
What is DC circuits?
the flow of electrons is always in one direction
28
What is AC circuit?
the flow of electrons reverses direction (alternates) at a set frequency
29
What type of electricity is delivered by the power company?
AC because its voltage can easily be maintained while traveling long distances to customers via the power grid
30
What type of electricity is present in the operating room equipment and most residential equipment?
AC
31
What is the difference between AC and DC circuit?
Except resistance is more complex with AC circuits, and the positive side alternates between both wires
32
What is resistance referred to in AC circuits?
Impedance and is the total of all forces that impede electrical flow
33
What contributes to AC impedance?
To the inherent characteristics of the conductive material, capacitance and inductance
34
What is capacitance?
the capacity to store charge
35
What is a capacitor?
Composed of two parallel conductive plates separated by an insulator
36
What will occur when a capacitor is exposed to a voltage source in an open circuit?
One plate will store a positive charge, and the other will store a negative charge
37
Capacitors have useful applications in electronic devices, but can leak stray _______-.
capacitance
38
What can be created from stray capacitance?
There are no absolute insulators, and stray capacitance may create an unintended charge in the casing of electrical equipment.
39
What is electromagnetic inductance?
The transfer of an electric current between circuits without physical contact, using induced magnetic waves
40
Any conductors carrying an electric current will also carry a ________ field.
Magnetic
41
What is important about the charge in AC circuits?
the charge is alternating, and so the magnetic field will change too
42
What can occur as a result of a changing magnetic field?
May induce a small electric current in nearby conductive materials such as equipment metal casings, even in the absence of physical contact between the circuit and the casing.
43
What can stray capacitance and inductance cause?
may contribute a low risk of shock, because they are low-current flows
44
What constitutes a high risk of electric shock?
Direct contact with exposed electrical wiring because of higher voltages
45
What are three mechanisms that electrical shock could occur to patients and operating room personnel?
- Direct wire contact with metal casing due to insulation damage or faulty construction
- Inductance due to the magnetic field of the AC, producing a small electrical flow in the surrounding metal casing despite no direct contact
- Stray capacitance from the buildup of electrical potentials with an AC circuit despite no closed circuit electrical flow
46
Potential Shock OR:
| _____________ with metal casing due to insulation damage or faulty construction
Direct wire contact
47
Potential Shock OR: _________ due to the magnetic field of the AC, producing a small electrical flow in the surrounding metal casing despite no direct contact
Inductance
48
Potential Shock OR: _________ from the buildup of electrical potentials with an AC circuit despite no closed circuit electrical flow
Stray capacitance
49
What must happen for shock to occur?
a complete circuit must be made
50
What is a complete circuit?
If a patient or a member of the operating room personnel makes contact with both a live wire and the ground, they may complete an electric circuit and receive a shock.
51
What types of electric shock are there (2)?
macroshocks or microshocks
52
What is a macroshock?
refers to large amounts of current conducted through the patient's skin and other tissue
53
What type of injuries can occur in macroshock?
Injuries may be minor or severe
54
What two factors effect the injury obtained for a macroshock (2)?
The amount of current and the duration of exposure
55
Describe the flow of electrical current within the body.
Electric current seeks the path of least resistance, and is often dissipated throughout the body tissues.
56
What effect do macroshocks have on the heart?
The amount that reaches the heart is often insufficient to cause arrhythmias
57
What is microshock?
The delivery of small amounts of current directly to the heart
58
What can increase the injury obtained from microshocks?
Conductive materials in a patient's body may place that patient at greater risk by providing a low resistive path for electricity to flow to the heart.
59
What range of electrical currents can induce VF?
20 – 100 (microamperes) μA
60
What are two objects that can increase the intensity of a microshock?
pacemaker leads or invasive monitoring catheters
61
What causes injury in electrical shock?
Occurs from a release of thermal energy from the ES and disruption of nervous, muscular and cardiac function
62
Effects of Macroshock: 1 mA
Threshold of perception
63
Effects of Macroshock: 5 mA
Maximum harmless current
64
Effects of Macroshock: 10-20 mA
"Let go" current before sustained muscle contraction
65
Effects of Macroshock: 50 mA
Pain, LOC and possible mechanical injury
66
Effects of Macroshock: 100-300 mA
Ventricular Fibrillation
67
Effects of Microshock: 20-100 uA
Ventricular Fibrillation in humans (100)
68
Effects of Microshock: 10 uA
Recommended maximum leakage current
69
What is a transformer?
is used to isolate the electrical supply systems from one another.
70
How does a transformer work?
uses the principle of magnetic inductance to transfer electricity from one system to another system without having physical contact
71
What relationship do transformers and OR power have in common?
Allows the operating room power supply to be ungrounded, preventing a circuit from being completed when a person contacts one live wire and reducing the risk of shock
72
In many modern hospitals, the OR power supply is isolated from ground by an ____________
isolation transformer
73
What impact does having an ungrounded OR power supply have?
Preventing a circuit from being completed when a person contacts one live wire.
74
Can a shock still occur in the OR even though the power supply is ungrounded?
If a person contacts both wires in a circuit, shock may occur as the path of electricity flows through the person from one line to the other.
75
What is electrocautery?
devices use high-frequency electric currents to cauterize, cut, and destroy tissue
76
What type of electrocautery (2)?
Unipolar or bipolar
77
What is bipolar electrocautery?
Bipolar electrocautery devices have two tips: one to supply the electric current, and
the other to return the current
78
Bipolar devices do not require a _____________
return electrode
79
Which type of electrocautery is less likely to cause burns or injuries apart from the local area of use?
Bipolar
80
What surgery uses bipolar electrocautery?
Abdominal surgery, the technique is required when ovary or fallopian tube electrocautery is needed to avoid possibly fatal bowel injury
81
What is unipolar electrocautery?
Unipolar devices have only one tip to deliver an electric current, and a large surface area return electrode with good conductive contact must be placed on the patient
82
What is important to know when working with unipolar electrocautery?
The path of current flow from the unipolar device to the return electrode should not cross the patient's heart.
83
For unipolar electrocautery, where should the return be placed?
Placement of the return path should be away from bony prominences and metal objects to minimize the risk for burns
84
What is important to known about electrocautery and anesthesia?
The high current flows used in electrocautery units may cause electromagnetic inductance, which in turn may cause artifact in other electrical equipment such as ECG monitors
85
What can unipolar electrocautery device may cause during surgery?
May cause electrical interference that could be interpreted by an AICD as a VT.
86
What could happen if the AICD interprets electrical interference as VT during Unipolar electrocautery?
This would trigger a defibrillation pulse to be delivered to the patient and would likely cause an actual episode of VT or VF.
87
During unipolar electrocautery, what is the safest approach when some has an AICD?
The safest approach is to disable the AICD’s ability to defibrillate.
88
What is the best approach for a pt who has an AICD?
Manufacturers vary in ability disable AICD with a magnet so the manufacturer representative should be contacted prior to surgery for consultation and to interrogate the AICD post-operatively.
89
What is electromagnetic radiation?
is thought to travel as photons or packets of energy, and can be observed as both a particle and a wave, depending on how scientists study and measure it
90
What is unique about EMR?
Dual nature of behaving as both a particle and a wave
91
When is EMR called a photon?
exhibits particle-like behavior
92
What are important characteristics about EMR (2)?
They have no mass and are pure energy
93
What influences the energy of EMR?
Frequency
94
EMR components: Higher frequencies correspond to ________ energies
Higher
95
EMR components: Lower frequencies correspond to ________ energies
Lower
96
How is the velocity of EMR in a vacuum?
Remains constant and does not change depending on the frequency
97
EMR exists independently of _______.
Matter
98
Sound (pressure) waves do not exist without _______ through which their energy is transmitted.
Matter
99
What are the possible interactions of EMR (4)?
Reflected, refracted (scattered), diffracted (redirected), or absorbed (interfered) by matter
100
What can EMR be converted into (3)?
other forms of energy such as electricity (gas discharge), heat (incandescence), and chemical energy (photoluminescence)
101
What must be obeyed when EMR is converted?
Law of conservation of energy.
102
What happens when matter is exposed to EMR?
it may change form
103
Why is EMR's interaction with matter important?
The analysis of EMR's interaction with matter is the underlying principle of x-ray fluoroscopy, anesthetic gas measurement, pulse oximetry, and lasers.
104
What are X-Rays?
A form of electromagnetic waves or radiation not different from visible light except for the wave length
105
What is the characteristics of X-Rays?
A very short wavelength equating to higher frequency
106
How are X-Rays classified?
Penetrating abilities
107
What impact do higher frequencies have, according to X-Rays?
Higher penetrating abilities and are less affected by the atmosphere
108
What is an important component of higher frequencies?
More difficult to contain and harsher to life
109
What can X-rays cause (2)?
Damage to DNA and be mutagenic (lead to cancer)
110
What is needed when working with X-Rays?
Proper protection
111
What three factors are important for X-Rays?
distance from source, barriers, and exposure time
112
What explains how energy intensity significantly decreases when getting further away from X-rays?
Inverse Square Law
113
What is the minimum recommended distance from a x-ray source?
6 feet
114
Where is the greatest intensity of an x-ray?
directly in front of the beam generator
115
Standing at least 6 feet away and behind or to the side of the beam direction ______ Xray exposure.
lessens
116
What are lead barriers and why are they important?
Efficient absorbers of x-ray energy
117
X-ray technicians often wear badges that measure ________ to x-rays over a period of time.
total exposure
118
What is the relationship between X-ray exposure and risks?
Greater exposure to x-rays is associated with greater risks.
119
What would increase the chance of maximum exposure to X-ray?
Unless practitioners are exposed to radiographic procedures frequently, the doses received usually fall well below established limits for maximal allowable exposure.
120
What are the two most important factors that reduce X-ray exposure?
Shielding and distance from the x-ray source
121
Where do lasers get their name?
acronym Light Amplification by Stimulated Emission of Radiation
122
How do lasers work?
When many atoms of a particular matter are continually energized by incident photons while their electrons are already in a higher energy state, then photons of the same frequency and direction will be emitted as the electrons are forced down to their natural resting state. When this process is channeled through a series of mirrors in a tube, the result is a very powerful energy source (laser) emission.
123
What can excite a medium in a laser?
Powerful electric source, effectively pumping electrons into a higher orbital sphere (stimulated absorption).
124
Medical Lasers: What is the wavelength of He-Ne?
633 nm
125
Medical Lasers: What is the wavelength of CO2?
10,600 nm
126
Medical Lasers: What is the wavelength of Argon?
488 nm/514nm
127
Medical Lasers: What is the wavelength of KTP?
1060 nm
128
Medical Lasers: What is the wavelength of YAG?
1064-2940 nm
129
Medical Lasers: What is the degree of tissue penetration for He-Ne?
none
130
Medical Lasers: What is the degree of tissue penetration for CO2?
less than 0.5 mm
131
Medical Lasers: What is the degree of tissue penetration for Argon?
0.5-2.0 mm
132
Medical Lasers: What is the degree of tissue penetration for KTP?
0.5-2.0 mm
133
Medical Lasers: What is the degree of tissue penetration for YAG?
2-6 mm
134
What is the characteristics of He-Ne?
Aiming beam for invisible lasers
135
What is the characteristics of CO2?
Highly absorbed by water
136
What is the characteristics of Argon?
Selectively absorbed by hemoglobin
137
What is the characteristics of KTP?
Highly absorbed by hemoglobin
138
What is the characteristics of YAG?
Used to ablate and destroy tissue
139
What is the function of laser surgery?
Enable very precise excision, produce minimal edema and bleeding, and are favored by surgeons for resection of tumors and other obstructions of the airway
140
What type of surgeries is the CO2 laser frequently used?
For operations in and around the larynx, used because of its shallow depth of burn and extreme precision
141
What type of surgeries is the holmium: yttrium-aluminum-garnet (Ho:YAG) laser frequently used?
Excellent absorption in water-rich tissues, and in otolaryngology it has been used for nasal surgeries and for tonsillectomies
142
Why are laser light beams useful in surgery?
Thermal effect and can be used to cut, coagulate, or vaporize tissue
143
What type of surgery has the greatest risk for surgical fires?
Head and neck surgery, due to the presence of oxygen and use of lasers
144
Use of Laser mandates certain ______.
safety precautions
145
What type of eye protection is mandatory when a Nd:YAG laser is used? Why?
Green-lensed, stray or reflected beams of the Nd:YAG laser are capable of traversing the eye to the retina
146
What type of eye protection is mandatory when a CO2 laser is used? Why?
clear glass or plastic that surrounds the face
147
What type of eye protection is mandatory when a potassium titanyl-phosphate (KTP) laser is used? Why?
Orange-red eye glasses
148
What type of eye protection is mandatory when a argon laser is used? Why?
Orange glasses
149
What are some examples of combustible OR material (3)?
Drapes, dressings, and linens
150
Lasers are often used for ______ surgeries.
Otorhinolaryngologic, endotracheal tube fires can occur during these cases.
151
What should be available to extinguish a ETT fire?
Source of saline
152
What should be done if an ETT fire occurs?
Stop oxygen flow, stop ventilation, extubate the patient, extinguish the fire, mask ventilate, and reintubate the patient
153
What must be done after a ETT fire?
The patient will require airway assessment and medical treatment, including bronchoscopy, lavage, and steroids.
154
Why should nitrous oxide be avoided when working with lasers?
Combustible
155
What could the laser tube cuff be inflated with to help easily detect a cuff perforation?
Methylene blue dyed saline
156
What three components can cause a surgical fire (3)?
Ignition, Fuel and Oxidizer
157
What is an example of ignition source?
Electrosurgical units, lasers, and fiberoptic light sources
158
What is an example of Fuel source?
Surgical drapes, alcohol-based skin preparation agents, the patient
159
What are examples of oxidizers?
Oxygen, nitrous oxide, room air
160
What is a laser plume?
When tissues are cut by a laser, the smoke and vapors that are formed
161
What effect does a laser plume have on OR personnel?
Environmental concern and potentially toxic
162
What could potential further make the laser plumes more dangerous?
When the tissues vaporized by the laser are malignancies or viral papilloma, the concern arises as to whether these vapors are even more dangerous
163
What should be used at the site of laser vaporization? Why?
Smoke evacuators, actual environmental transmittance of these pathogens is low the risk still exists
164
What is the primary concern of laser safety?
Prevention of combustion within the airway
165
What is the rate of fire occurrence in the airway?
Relatively uncommon (0.4%), and it is usually the result of penetration of the laser through the ETT, which exposes the beam to a rich oxygen supply
166
What effect could positive pressure ventilation have on an airway fire?
Presence of intraluminal combustion produces a blowtorch effect that causes serious damage to the respiratory tract of the unfortunate patient.
167
What safety measures should be taken during a oropharyngeal surgery (Tonsillectomy) to reduce chance of fire?
- scavenge deep within the oropharynx with a metal suction cannula to catch leaking O2 and nitrous oxide (N2O).
- Moisten gauze or sponges and keep them moist, including those with uncuffed tracheal tubes
168
What safety measures should be taken during a Tracheostomy to reduce chance of fire??
Do not use electrosurgery to cut into the trachea
169
What safety measures should be taken during a Bronchoscopic surgery to reduce chance of fire??
If the pt requires supplemental oxygen, keep it below 30%. Use inhalation and exhalation gas monitoring (With O2 analyzer) to confirm proper concentration
