OR Safety

Question 1

Four mechanisms that influence heat loss (and %’s of contribution)

Answer 1

Radiant: 50%
-Heat rays from surrounding objects, walls of room
-Room temp!
Convection: 25%
-Temp gradient between body and ambient air
-Bear hugger!
Evaporation: 20%
-Transfer of heat from a liquid to gaseous state
Conduction: <10%
-Direct contact with cooler things (IVF, OR table)

Question 2

Optimal humidity level and why

Answer 2

50-55%

-Achieves minimal static and reduces microbial growth

Question 3

Humidity too low/dry leads to

Answer 3

• Increased airborne motility of particulate matter-vector for infection
• Increased incidence of static discharges-microshocks (grounded strips on floor prevent static shocks)

Question 4

Humidity to high/moist leads to

Answer 4

• Damp/moist supplies-loose integrity of barrier devices like cloth drapes
• Increase incidence of contamination

Question 5

Air pressure in OR, how many air exchanges per hour

Answer 5

Positive, 25 air volume exchanges per hour per the National Fire Protection Agency

• 80% of air is recirculated from OR room with rest fresh air
• Recirculated air is filtered, 90% of particles are removed

Question 6

For an electrical shock to occur, body contacts occurs with ____

Answer 6

• 2 conductive materials at different voltage potentials, complete a circuit
• Current flows from hot wire (positive wire) through victim to the ground, then to the neutral wire to complete a circuit

Question 7

Ohm’s Law

Answer 7

V or E = I x R

• V/E=Voltage, propels electrons through the circuit, electron storage place
• I=Amps, amount of electrons traveling through the circuit
• R=Resistance, in opposition to electron flow

Ohm’s Law also applies to how BP is calculated: CO x SVR

Question 8

For electrical safety, we are most interested in solving for ____

Answer 8

Current flow through the patient

• I = V/R
• Amps=Voltage / Resistance

Question 9

Direct current (DC)

Answer 9

• Electron flow is always in the same direction through a conductor
• Resistance applies to this
• No leakage current is possible

Question 10

Alternating current (AC)

Answer 10

Electron flow switches directions at regular intervals

• 60 Hz wall current (50 in Europe), switches 120 times per second
• Impedance applies only to this
• More dangerous than direct current

Question 11

Impedance

Answer 11

The sum of forces that oppose electron movement when alternating current is used

Question 12

Capacitance

Answer 12

A flow of electrons, varies according to if its DC or AC

-The ability of a capacitor to store charge

Question 13

Capacitor

Answer 13

2 parallel conductors separated by an insulator

-e.g. Defibrillator

Question 14

Grounding

Answer 14

Electrical power
-Grounded: Home, increased risk of electrical shock
-Ungrounded: OR, current is isolated from the ground, decreased electrical hazard
Electrical equipment
-Grounded: Home, OR-all electrical equipment is grounded
-Ungrounded: Home

Question 15

Ground fault current interrupter (GFCI)

Answer 15

Immediately cuts off circuit to a device if it becomes grounded to decrease risk of shock

• Provides better shock protection than LIM (line isolation monitor, used in OR), but can’t be used in OR because it stops power to all devices
• Would interrupt life support equipment

Question 16

Transformer

Answer 16

Used in the OR to electrical isolate OR power from the ground, decreases risk of shock

Question 17

What happens if neutral wire becomes grounded

Answer 17

A circuit between the two lines and ground has been created, creates a shock risk

Question 18

LIM (line isolation monitor)

Answer 18

Designed to detect whether the electrical power system is still isolated from the ground

• Continuously monitors the integrity of a IPS (isolated power system)
• Readings indicate the amount of leakage in the system (not amount of current flowing, but amount that would flow in the event of a first fault)

Question 19

LIM alarms at

Answer 19

2 or 5 mA

• At this point the system isn’t totally isolated from the ground
• A second fault would still be needed to create a dangerous situation

Question 20

What to do if the LIM alarms

Answer 20

Unplug each device in the order they were plugged in

Question 21

Stray capacitance

Answer 21

Leakage present in all electrical equipment as a result of

1: Capacitance coupling stray current
2: Induction between internal electrical components
3: Defective insulation

What causes electrical shock-macro and micro

Question 22

Macroshock

Answer 22

Shocks applied to the outside of the body
-Maximum leakage current allowed in the OR equipment is 10mA
1mA-minimum perceptible macroshock
10mA-involuntary muscle contractions
100mA-VF

Question 23

Microshock

Answer 23

Electrical current applied directly to the myocardium (10 microAmps can induce VF)
-Why temp pacers are powered by battery only

Question 24

Monopolar Electrocautery

Answer 24

• Has one tip to deliver current
• Needs a large return/grounding pad
• Surgeons like using because you can cut and do electrocautery

Question 25

Bipolar Electrocautery

Answer 25

- Has 2 tips, one delivers current and one is return - No need for return pad - Better to avoid fire, burn - Safer to use with open oxygen (MAC cases), pacemakers, AICDs - Surgeons prefer to use monopolar

Question 26

Pacemakers and ICDs with cautery

Answer 26

Have magnet available -Will put most pacemakers into asynchronous mode -Will suspend arrhythmia detection in ICD (won't put into asynchronous mode) - if pt is pacer dependent recommend reprogramming before surgery to turn off arrhythmia detection and put into asynchronous mode with magnet Contact manufacturer and determine what magnet placement will do for that model Pacer pts should have interrogated within 12 months prior to procedure, ICD pt 6 months. And ICDs always interrogated after

Question 27

Ionized radiation

Answer 27

Fluroscopy, xrays - Creates free radicals and ionized molecules in tissues by driving electrons out of stable orbitals - Can destroy tissue or change chromosomes that can stimulate malignant growth

Question 28

Nonionized radiation

Answer 28

Lasers - Excited electrons stay in molecule - Tissues affected by heat produced by the absorbed radiation

Question 29

Protection from ionized radiation

Answer 29

Time, distance, shielding - 3ft from the patient - Shielding is most reliable form of radiation protection

Question 30

Lasers named for ___

Answer 30

Named for lasing medium in use, type of medium determines wavelength of light produced

Question 31

Laser use when viruses are suspected

Answer 31

- Filtration masks should be worn | - Scrub tech responsible for evacuation of plume

Question 32

Fire triangle and who's responsibility

Answer 32

Fuel source: Drapes, sponges, ETT, LMA, suction catheters, hair, bowel gas -OR staff responsible Oxygen source: O2, N2O -Anesthesia responsible Ignition source: ESUs, fiberoptic light source, laser -Surgeon responsible

Question 33

Fire prevention for general cases

Answer 33

- Laser-resistant ETT during laser surgery of upper airway (inflate cuff with saline and/or methylene blue - Avoid N2O

Question 34

Fire prevention for general and MAC cases

Answer 34

- Let flammable skin prep dry before draping patient - Moisten sponges near ignition source - Save saline ready to douse fire - Collaborate with team throughout procedure to minimize oxidizer-enriched environment near ignition source

Question 35

Fire prevention for MAC cases

Answer 35

- Use air with low O2 <30% if patient can tolerate, otherwise intubate - Tent surgical drapes to avoid O2 buildup - Discontinue O2 if possible 1 min before laser head/neck procedures

Question 36

Airway fire management (9 steps)

Answer 36

1: D/c laser 2: Simultaneously: Stop ventilation, turn off O2, Disconnect and pull out ETT, call for help 3: Douse fire with NS 4: Remove burning material, save it 5: Mask ventilate with 100% O2, consider bronch (remove debris, lavage with NS), reintubate with smaller ETT (tissues may be edematous, thermally injured) provide high humidity environment and leave intubated if laryngeal edema 6: Labs (ABG, CoHgb) 7: CXR 8: Meds (Steroids, antibiotics) 9: Provide for observation in ICU regardless of degree of burn