← All decks
Anaesthesiology
Electrical Safety and Fires in the Operating Room
Built from Barash Clinical Anesthesia, 9th Edition
What’s inside
24 sections · 194 slides
Overview
- Scope of this topic
- Key points
- Key points continued
Fundamental Principles of Electricity
- Mechanical analogies for electrical quantities
- Ohm's law and its terms
- Electrical power and work
- Direct current versus alternating current
- Alternating current as a sine wave
- Capacitance
- Capacitance and current behaviour in electrolyte solution
- Impedance and fields outside the circuit
Electrical Shock
- Microshock and macroshock compared
- Hazardous shock and what determines its severity
- Proximity to the heart and reading the current threshold table
- Effects of 60-Hz current on an average human for a 1-second contact
- Let-go current and the effect of frequency on shock
Causes of Electric Shock
- Hot and neutral lines in an alternating current circuit
- Short circuit
- Completing a circuit through the body to earth
- Meanings of the term ground
- Earth as an electrical reference
Grounded Electrical Power
- Three-wire household outlet
- Three-wire electrical cable
- Neutral grounded power distribution to a building
- Where current returns and what the ground wire does
- Shock from an ungrounded faulty device
- Protection by an intact equipment ground wire
- Separate roles of the neutral and ground wires; fluid intrusion
- Class I and Class II appliances
Common Safety Features of a Grounded Electrical System
- Circuit overload and maximum current draw in the operating room
- Common operating room current draw
- Circuit labelling on operating room receptacles
- Circuit breakers and the limits of their protection
- Ground fault circuit interrupter outlet
- Trip characteristics and nuisance tripping of GFCIs
Power Receptacles
- NEMA 5-15 and NEMA 5-20 receptacles
- NEMA standards and receptacle orientation
- Hospital-grade plug and receptacle
- Splash-resistant power strips off the floor
Ground-Isolated Electrical Power
- Electrical risk profile of the operating room
- Grounded and isolated power systems
- Isolation transformer and isolated power panel
- Line 1 and line 2 on the isolated side
- Voltage relationships in a grounded house supply
- Single-point contact with an isolated power system
- Behaviour of faulty equipment on an isolated system
- The second fault
The Line Isolation Monitor
- Leakage current in alternating current systems
- The line isolation monitor and its hazard current reading
- Line isolation monitor alarm thresholds
- Two causes of a rising hazard current
- First fault as a cause of LIM alarm
- Leakage current alarms and what the technician needs to know
- Responding to a line isolation monitor alarm
- Managing a first fault and code limits on GFCIs
- The silent first fault and managing loss of isolation
- Ground fault circuit interrupters in the operating room
Microshock
- Current density, the microshock threshold and electrical susceptibility
- Reported fibrillation thresholds in electrically susceptible patients
- Sources of hazardous current in equipment
- Protection of the electrically susceptible patient by an intact ground wire
- Consequence of a broken equipment ground wire
- Behavioural precautions and the insidious nature of microshock
Safety Features within Monitors
- Optical isolators and paediatric electrocution from lead wires
- Current standard for patient lead wire connectors
Electrosurgery
- Hazards associated with electrosurgical units
- Operating principle of the electrosurgical unit
- Radiofrequency current and fibrillation attributed to electrosurgery
- Correctly applied electrosurgical return plate
- Incorrectly applied electrosurgical return plate
- Contact quality monitoring return pads
- The return pad is not earthed, and isolated unit power supplies
- Remaining alternate return pathways
- Metal jewellery and piercings during electrosurgery
- Interference with pacemakers and its management
- Perioperative management of an implanted defibrillator
- Team communication about electrosurgical safety
Electromagnetic Interference
- Two forms of electrical interference with medical devices
- Electromagnetic radiation and the spread of wireless devices
- Large studies of interference with implanted devices
- Interference rates in implantable cardioverter defibrillators
- Studying interference and the frequencies devices are sensitive to
- Rising wireless frequencies and magnets in accessories
- Practical recommendations on electromagnetic interference
Emergency Backup Power and Regulations
- Emergency backup power and red outlets
- Causes of power loss and preparation for failure
- Three regulatory questions about operating room wiring
- Flammable anaesthetics and the 1984 code revision
- NFPA 99 requirement for special protection
- Isolated power system versus GFCI as protective means
- NFPA 99 wet procedure wording and the stakeholders in the debate
Operating Room Fires
- From flammable anaesthetics to modern fire risks
- Incidence of operating room fires
- Fire statistics and fires as sentinel events
- American Society of Anesthesiologists fire prevention practice advisory
- Fire safety algorithm
- The fire triangle
- The fire tetrahedron
- Examples of operating room fire triangle components
- Ownership of the fire triangle within the operating room team
Flammability and Oxygen Concentration
- Oxygen enrichment, flammability and carbon dioxide insufflation
- Ignition times at rising oxygen concentrations
- Flammability of surgical materials
- Interpretation of the flammability data
- Density of oxygen and accumulation under drapes
- Nitrous oxide as an oxidiser and how to handle it
Assessing Fire Risk during the Presurgical Timeout
- Purpose of the presurgical fire-risk assessment
- Fire-risk assessment
- Drying time for alcohol preparation and team acknowledgement
- Precautions with an open oxidiser source above the xiphoid
Lessons from Closed Claims and Reviews
- Recurring aetiology identified in the closed claims
- Mannequin simulation of a drape fire during surgery
- Speed of fire development in the simulation
- Conditions under which no fire occurred in the model
Supplemental Oxygen and Fire Risk
- Alveolar oxygen concentration versus concentration at the face
- Excess oxygen around the head and high-flow devices
- Advice from the ASA and the APSF on delivered oxygen
- Nasal cannula connected to the anaesthesia machine
- Impact of air:oxygen flow ratios on delivered oxygen concentration
- Impact of air:oxygen flow ratios on delivered oxygen concentration (continued)
- Working examples of air to oxygen ratios
- Titrating supplemental oxygen down
- Drape material and oxygen distribution
- Securing the airway when high oxygen is required
On-Patient versus In-Patient Fires
- On-patient fires and the persistence of oxygen
- Washout of oxygen from the breathing circuit
Airway Fires
- Definition and consequences of an airway fire
- Breathing circuit fires and carbon dioxide absorbents
- Lasers used around the airway
- Eye protection requirements by laser type
- Mechanism of laser-induced endotracheal tube fire
- Burning endotracheal tube
- Immediate management of an endotracheal tube fire
- Unintended laser strikes and lasering via bronchoscope
- Tube-free lasering techniques and model-based recommendations
- Risk factors quantified in a laser airway model
- Laser-resistant endotracheal tube
- Precautions during laser airway surgery and saline-filled cuffs
- Laser airway management in young children
- Tracheostomy fire risk and precautions with a natural airway
- High-flow nasal oxygen during tracheostomy
- Changing airway state during tracheostomy in an intubated patient
- Managing the vulnerable moment of tracheal entry
- Fire during tonsillectomy
- Precautions during tonsillectomy and adenoidectomy
Fires in Other Surgical Settings
- Fires during periocular surgery
- Room air eye fires and fires in oculoplastic surgery
- Prevalence of fire experience among eye surgeons
- Abdominal and colonoscopy fires and the insufflation gas
- Fires during thoracic surgery and with lung isolation
- Electrical equipment fires
Fire Prevention and Response
- Communication as the basis of fire prevention
- Role-specific fire mitigation plans
- Fire risk changes during a case
- The ERASE fire response sequence
- Team preparedness and extinguishing an operating room fire
Summary and References
- Summary of electrical safety principles
- Summary of microshock and electrosurgery
- Summary of operating room fire safety
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Barash, Cullen, and Stoelting's Clinical Anesthesia, 9th Edition