Anesthesia and Electrical Safety – D. John Doyle Insulator – does not allow the flow of electrons (or current) // conductors allow flow Direct current – electrons flow in one direction / alternating current – electron current switches direction at regular intervals(120x per second for 60 Hz wall current) V= IR // P = QR Power (W) = V x I Electrical energy – watt-sec (Joule) Capacitance – stores charge – two parallel conductors separted by insulator // in contrast to DC circuits, capacitor in an AC circuit permits current flow // C= Q/V Stray capacitance / Capacitative coupling -- inherent in all electrical equipment, generally undesirable;; not designed into the system Electrical shock --- hjgh freq current has low tissue penetration and does not excite contractile cells (but can still cause burns) // DC is less dangerous; AC (at 60Hz) is more dangerous Macroshock – large current flows that can cause harm / Microshock – small amts of current flow – dangerous only to susceptible pts (ex – pacing wires, central line in situ) 100microA – Vfib 10microA – recommended maximum 60Hz leakage current (in OR) MACROSHOCK -- <1mA = imperceptible // 10mA = skeletal muscle contraction, but can let go // 100mA – Vfib 2 prong plugs=no ground;; 3 prong = grounded // allows a low resistance path for stray current to travel GFCI (ground fault circuit interrupter) – monitors whether there is same current in hot and neutral wires // if there is faulty piece of equipment and there is a ground, it shuts it down // Unequaol currents in sensor coil activates trip coil to interrupt circuit //
Anesthesia and Electrical Safety D. John DoyleInsulator does not
allow the flow of electrons (or current) // conductors allow
flowDirect current electrons flow in one direction / alternating
current electron current switches direction at regular
intervals(120x per second for 60 Hz wall current)V= IR // P =
QRPower (W) = V x I Electrical energy watt-sec (Joule)Capacitance
stores charge two parallel conductors separted by insulator // in
contrast to DC circuits, capacitor in an AC circuit permits current
flow // C= Q/VStray capacitance / Capacitative coupling -- inherent
in all electrical equipment, generally undesirable;; not designed
into the system
Electrical shock --- hjgh freq current has low tissue
penetration and does not excite contractile cells (but can still
cause burns) // DC is less dangerous; AC (at 60Hz) is more
dangerousMacroshock large current flows that can cause harm
/Microshock small amts of current flow dangerous only to
susceptible pts (ex pacing wires, central line in situ)100microA
Vfib 10microA recommended maximum 60Hz leakage current (in OR)
MACROSHOCK --
