OR Safety Flashcards
Four mechanisms that influence heat loss (and %’s of contribution)
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)
Optimal humidity level and why
50-55%
-Achieves minimal static and reduces microbial growth
Humidity too low/dry leads to
- Increased airborne motility of particulate matter-vector for infection
- Increased incidence of static discharges-microshocks (grounded strips on floor prevent static shocks)
Humidity to high/moist leads to
- Damp/moist supplies-loose integrity of barrier devices like cloth drapes
- Increase incidence of contamination
Air pressure in OR, how many air exchanges per hour
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
For an electrical shock to occur, body contacts occurs with ____
- 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
Ohm’s Law
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
For electrical safety, we are most interested in solving for ____
Current flow through the patient
- I = V/R
- Amps=Voltage / Resistance
Direct current (DC)
- Electron flow is always in the same direction through a conductor
- Resistance applies to this
- No leakage current is possible
Alternating current (AC)
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
Impedance
The sum of forces that oppose electron movement when alternating current is used
Capacitance
A flow of electrons, varies according to if its DC or AC
-The ability of a capacitor to store charge
Capacitor
2 parallel conductors separated by an insulator
-e.g. Defibrillator
Grounding
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
Ground fault current interrupter (GFCI)
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
Transformer
Used in the OR to electrical isolate OR power from the ground, decreases risk of shock
What happens if neutral wire becomes grounded
A circuit between the two lines and ground has been created, creates a shock risk
LIM (line isolation monitor)
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)
LIM alarms at
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
What to do if the LIM alarms
Unplug each device in the order they were plugged in
Stray capacitance
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
Macroshock
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
Microshock
Electrical current applied directly to the myocardium (10 microAmps can induce VF)
-Why temp pacers are powered by battery only
Monopolar Electrocautery
- Has one tip to deliver current
- Needs a large return/grounding pad
- Surgeons like using because you can cut and do electrocautery
Bipolar Electrocautery
- 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
Pacemakers and ICDs with cautery
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
Ionized radiation
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
Nonionized radiation
Lasers
- Excited electrons stay in molecule
- Tissues affected by heat produced by the absorbed radiation
Protection from ionized radiation
Time, distance, shielding
- 3ft from the patient
- Shielding is most reliable form of radiation protection
Lasers named for ___
Named for lasing medium in use, type of medium determines wavelength of light produced
Laser use when viruses are suspected
- Filtration masks should be worn
- Scrub tech responsible for evacuation of plume
Fire triangle and who’s responsibility
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
Fire prevention for general cases
- Laser-resistant ETT during laser surgery of upper airway (inflate cuff with saline and/or methylene blue
- Avoid N2O
Fire prevention for general and MAC cases
- 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
Fire prevention for MAC cases
- 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
Airway fire management (9 steps)
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
