Operating Room Hazards

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Operating Room Hazards
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Types of Hazards

• Electric
• Inhalation
• waste anesthetic gases
• chemicals
• airborne diseases

3
More Hazards

• Blood-Borne
• Herpes
• Hepatitis
• HIV

4
More Hazards

• Radiation
• Fire
• laser
• other

• Noise
• Stress
• substance abuse
• suicide

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Ohms Law

• E I x R
• E electromotive force (volts)
• I current (amperes)
• R Resistance (ohms)
• note similar to BP CO x SVR

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ELECTRICAL HAZARDS
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Watt

• Measure of electrical power
• W E x I
• E volts
• I current

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Wattage

• Measure of electrical work
• May also apply to heat production
• Wattage square root of current times the
  resistance
• W I squared x R

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Joule

• Unit of electrical work
• Joule watt seconds
• large units Kilowatt hours

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Calculating I (current)

• When wattage and voltage are known, amperes and
  resistance can be calculated
• I W
• E
• I amperes W watt E volts

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Example

• 60 watt light bulb
• 120 volt current
• I 60
• 120
• I 0.5 amperes

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Calculating R

• Ohms law R E
• I
• R resistance
• E volts
• I amperes

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Example

• Using the same light bulb
• R 120 volts
• 0.5 amperes
• R 240 ohms

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Types of Current

• Direct current -
• electrons flow in the same direction
• Alternating current-
• electron flow reverses direction at regular
  intervals
• rate of flow reversal is the frequency

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• Conductors facilitate the flow of electrons
• Insulators oppose the flow of electrons

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Impedance (Z)

• The sum of all forces that oppose electron
  movement in AC current

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Capacitance

• Two parallel conductors separated by an insulator
• Has the ability to store a charge
• Capacitance is the measure of the stored charge

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Current characteristics

• AC - permits flow even if the circuit is not
  completed
• DC - only momentary current flow

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The effect of capacitance on impedance varies
directly with the frequencythe higher the
frequency, the lower the impedance
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Stray Capacitance

• Not intended in design of equipment
• Occurs in all equipment
• Electric wires have capacitance even if equipment
  is not running
• Metal housing of equipment has capacitance

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Inductance

• When electrons flow in a wire, a magnetic field
  is formed around the wire
• Inductance is a property of AC circuits in which
  opposing EMF is generated in the circuit

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Inductance

• Inductance increased impedance
• Increased frequency increases impedance
• Impedance within a coil is greater than simple
  resistance

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Electric Shock

• When current passes through the body, shock
  occurs
• Shock may be beneficial or detrimental

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Beneficial Shock

• Cardiac Pacemakers
• Electrical Convulsive Therapy
• Tens units
• EMG

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For Shock to occur, a completed circuit must be
present
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For Shock to Occur

• Completed circuit
• Current flow
• Voltage sufficient to drive the current through
  the existing impedance

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Typical Power Cord

• Source 120 volts
• Cord has 2-3 wires
• hot wire carries current to the impedance
• neutral wire returns current to the source
  (ground)
• Ground wire connects to ground

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Typical Power Cord

• High impedance / low current flow
• Short circuit zero impedance

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For You to be Shocked

• You must complete the circuit
• contact at 2 points is necessary
• Current must flow through you

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Physiologic Effects of Shock

• Altered cellular function
• heart / brain
• Disruption of normal electrical activity
• Thermal injury

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Severity of shock depends upon the amount of
current (amperes) and length of exposure
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Types of Shock

• Macroshock - large amounts of current which could
  cause harm or death.
• Microshock - smaller amounts of current only
  dangerous if applied directly to electrically
  susceptible tissue (heart / brain)

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The frequency of the current and current density
will determine the effect on the body
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In the United States, standard current frequency
is 60 Hz

• What are the implications of 60Hz current?

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Effects of 60 Hz current

• 1 mA threshold of perception
• 5 mA maximum harmless current
• 10-20 mA let go current
• 50 mA pain, mechanical injury.
• Heart and respiratory function continue

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Effects of 60 Hz current

• 100-300 mA Vent. Fibrillation
• respiratory center remains intact
• 6000 mA sustained myocardial contraction
  followed by normal heart rhythm. Temporary resp.
  paralysis. Possible thermal burn.

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Effects of 60 Hz current

• Note These values are only for 60Hz current
• At very high frequencies, more amps are safe
• Very high frequencies do not excite muscle tissue
  and do not cause arrhythmias

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Microshock

• 100 uA - ventricular fibrillation
• 10 uA - maximum allowed 60 Hz current leakage
  from electronic equipment in the operating room

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Actual shock depends upon

• Skin resistance
• Duration of contact
• Current density
• Cardiac cycle at the time of the shock

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Current Density

• Amount of current applied per unit of area of
  tissue

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Grounding is the basis for electrical safety
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Grounding

• Power may be grounded or ungrounded
• Equipment may be grounded or ungrounded

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Grounded Power

• Electric potential of earth is zero
• One wire supplying power to your home is
  connected to the earth
• prevents power buildup
• protection in storms
• Power source may be grounded even if the outlet
  is not

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Three Wires

• Hot (black) 120 v above ground potential
• Neutral (white) connects to ground
• Ground (green or bare) connects to ground
• Both neutral and ground are connected to a cold
  water pipe

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Breaker Box

• Power enters main breaker box
• Source connects to power bars
• Breakers connect to bars
• each breaker has specific amp rating
• Circuits distributed throughout the house /
  building

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Breakers and Fuses

• Limit the current flow through wires
• Prevent wire melt down
• When current exceeds ampere rating of the breaker
  / fuse, circuit is interrupted

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Electrical Power in the Operating Room

• Ungrounded
• Isolated system

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Isolated Power Sources

• Isolation transformer
• no direct contact with outside power
• coils in close proximity
• Inductance power is transferred
• Power is isolated from the ground

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Isolated System

• 120 volt potential between wires only
• Neither wire is hot or neutral with respect to
  ground
• Touching 1 wire and ground will not cause shock

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Advantages of Isolated System

• Touching 1 wire will not cause shock
• Grounding equipment adds second protection
• Faulty equipment may not trip the circuit breaker
• Equipment, not power, is grounded

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What is the difference between a first fault and
a second fault?
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First Fault

• Converts faulty equipment from an isolated back
  to a grounded system

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Second Fault

• Faulty equipment is grounded system and will
  cause a shock when touched

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Line Isolation Monitor

• Monitors the integrity of the system
• Detects current leak
• Audible and visual alarm when faulty equipment
  converts system to grounded condition
• indicates presence of first fault

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Line Isolation Monitor

• Equipment continues to function
• There may be a risk of shock to patient or HCW

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Can the line isolation monitor alarm if all the
equipment is working properly?
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Causes of LIM trigger

• Faulty equipment
• Normal leak from many properly working pieces of
  equipment
• Most LIM allow up to 5 mA
• If leak gt 5 mA, equipment is usually faulty

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What should be done when the line isolation
monitor triggers?
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LIM Trigger Procedure

• Check monitor to see the level of leak
• Identify the faulty piece of equipment and remove
  it
• unplug in reverse order until alarm stops

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Ground Fault Circuit Interrupter

• Has a red test button
• Monitors both sides of the circuit for equality
  of current flow
• Interrupts current when flow is unequal
• Disadvantage - equipment stops

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Electrocautery

• First used in 1926
• Dangerous in the presence of explosive gases
• Causes interference on the other monitors

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Electrocautery

• Frequency 500,000 - 1,000,000 Hz
• Entry point small
• Exit through large area
• Frequency too high to cause heart problems
• May disrupt pacemaker

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Inhaled Hazards

• Anesthetic gases
• no scavenger until mid 60s
• reported problems
• headache
• fatigue
• memory loss
• ECG changes

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Anesthetic Gas Pollution

• Studies found
• infertility/spontaneous abortion
• congenital abnormalities
• cancer/tumor
• hematopoetic disease
• liver disease
• neurologic disease
• psychomotor/behavior changes

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Pollution Related To

• Function of the scavenger
• Fresh gas flow rate

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NIOSH Standard (1977)

• Nitrous Oxide 25 ppm
• Halogenated Agent
• with nitrous 0.5ppm
• without nitrous 2.0ppm

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Inhaled chemicals

• methylmethacrylate
• cement for prosthetic joints
• may cause problems
• cutaneous
• respiratory
• genitourinary
• Allowable level
• 8-hour time weighted average of 100 ppm

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Airborne-Diseases

• Laser vapor
• formaldehyde
• intact viral DNA
• viable viruses
• Use suction/filter device
• Wear high filtration mask

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Infectious Hazard

• Respiratory Viruses
• Influenza
• Respiratory Syncytial Virus
• Rhinovirus
• tuberculosis

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More Infectious Hazards

• Herpes Virus
• Vericella-Zoster Virus
• Herpes Simplex
• Type I
• Type II
• Herpetic Whitlow

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More Infectious Hazards

• Cytomegalovirus
• Rubella
• Measles

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Viral Hepatitis

• Type A
• Self-limited
• Oral/Fecal Spread
• Handwashing and gloves for protection

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Hepatitis (continued)

• Type B
• Blood-borne
• May end your career as CRNA
• 90 recover
• 1 fulminant hepatitis
• 10 carriers
• Chronic active hepatitis may develop liver
  failure or liver cancer
• prevent with Hep B vaccine

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Hepatitis (continued)

• Non A/Non B Hepatitis
• Hepatitis with negative serologic findings
• Related to transfusions
• Now termed Hepatitis C

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HIV Infection

• Spread by body fluids
• Universal precautions are essential
• OSHA standards
• Fines for violation of standards
• Barash table 4.4 found on page 82

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More on HIV Infection

• 1990 study
• 24 reported cases of HCWs infected by patients
• Reported exposure immediately

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Radiation Hazards

• Many forms of Radiation
• x-rays
• fluoroscopy
• May have genetic effects
• if pregnant, stay away
• ALWAYS WEAR LEAD

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Fire Hazard

• Sources
• laser
• cautery
• defibrillator
• Requirements for fire
• fuel
• oxidizing agent
• source of ignition

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Reducing The Laser Fire Hazard

• Protect the tube
• metallic wrap
• wet gauze
• Reduce the FIO2 below 40
• use helium

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In Case of Airway Fire

• Disconnect at y-piece and remove tube
• Turn off oxygen
• Irrigate site if still smoldering
• Ventilate by mask, attempt to reintubate
• maintain oxygenation and stabilize vital signs

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Airway Fire (continued)

• Perform laryngoscopy and bronchoscopy to evaluate
  extent of damage
• Secure the airway with intubation trach
• Admit to ICU and monitor (intubated) for at least
  24 hours. Follow ABGs.

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Airway Fire (continued)

• Use ventilator, steroids and antibiotics as
  needed
• Pray

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Noise Pollution

• OSHA standard 90db for 8 hours
• adding 5db cuts time in half
• Operating rooms usually at 75-90db
• Noise reduces attention to detail, increases
  stress/fatigue and errors

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Stress

• High Stress for many reasons
• some real
• some imaginary
• Stress leads to
• behavior changes
• breakdown of the family
• suicide
• substance abuse

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SUBSTANCE ABUSE