Anesthesia Department

ELECTRICITY & ELECTRONICS “

For Anesthetist”

By

Prof. Gamal Elewa, MD Faculty of Medicine, Ain Shams University

I

ntended

L

earning

O

utcomes

By the end of this lecture , the post-graduate student will be able to: 1.

2.

Know types of electricity and clinical applications

Know General Electricity applications in anesthesia 3.

4.

Understand Equipment: Defibrillators, Cardiac Pace Makers, Electro-cautery (surgical diathermy), Others: computer Consider Electrical Safety and Avoid Electrocaution ©

General Electricity

• Definitions • Types of electricity: Static vs Dynamic. AC vs DC. High vs low pressure lines • SI units: currenr (A), electr. Potential (V), resist ( Ω), ..

• Classification of substances according to their electrical conductivity: conductors, semi- conductors, insulators ©

Types of electricity

• Static vs Dynamic • Clinical importance of static electricity • Direct vs AC current ©

Direct & Alternating Current

• DC: Flows in one direction • AC: Periodically reverses its direction (sine wave): -Wavelength: distance between 2 waves -Frequency: no. of waves/cycle -Velocity: wave length X Frequency ©

ELECTRICAL SI UNITS

• Frequency: Hertz (Hz)= cycle/sec • Power: Watt (W) • Electrical current: Ampere (A) • Electrical Potential (EMF): Volt (V)=W/A • Electrical Charge: Coulomb (C)=As • Electrical Resistance (Impedance, Reactance): Ohm ( Ω)=V/A (

Ohm’s Law

) • Electrical Inductance: Farad (F)=As/V • Electrical Capacitance: Henry (H) =Vs/A ©

Electrical Conductivity

• Conductors: Metals, e.g. cupper, lead, platinum, gold, silver • Insulators: glass, plastic, rubber, wood, mica, porcelin, ceramic • Semiconductors: Silicon, germanium, selenium - Used in: transistors, thermistors, diodes, some transducers - Affected by temperature, e.g. thermistors

General Electricity

• WHEAT STONE BRIDGE: R2/R1= R3/Rx Rx x R2 R 2 y R1 R3

Medical Equipment

• Defibrillators • Cardiac Pace Makers • Electro-cautery (surgical diathermy) • Others: computer

Defibrillator • Definition • Physical and Clinical Principles • Indications & uses: Cardioversion & Defibrillation • How applied?

• Precautions • Automated types

Pace Maker • Definition • Principle • Uses (Indications) • Types • Terminology • Precautions

O

V

A D

Pacemaker Identification

Chamber paced Chamber sensed O

V

A D Response of generator to sensed P or R waves Programmable O(asynchro nus) T=triggered

I

=inhibited D=dual=T+I O(fixed function) P(rate/output) M= multiprogram C=communicatin R=rate modulating O A V D Multi-site pacing (when 2 atria or ventricles are paced)

Electro-cautery (Diathermy) • Def • Principle • Types: Unipolar vs Bipolar, coagulation vs cutting • Precautions: general, with pacemaker

Electrocution

• Types: Macro-shock Micro-shock • Why?

• Prevention

Summary of important points

Definitions Types & Applications Equipment Hazards & Their Prevention Electricity

©

Examples of questions to assess the ILOs

-

Wheatstone bridge: principle and clinical applications

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Electrical cautery: precautions with pacemaker

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Physical principle of defibrillators & their types Hazards of defibrillators

-

Difference(s) between: * Direct & alternating currents, * Monophasic & biphasic defibrillators, * Static & dynamic electricity

©

• THANK YOU