ELECTRICITY & ELECTRONICS

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2 Νοε 2013 (πριν από 4 χρόνια και 9 μέρες)

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ELECTRICITY & ELECTRONICS


For Anesthetist”

By

Prof.
Gamal

Elewa
, MD

Faculty of Medicine,
Ain

Shams University



Anesthesia Department

©

I
ntended

L
earning

O
utcomes

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

1.
Know types of electricity and clinical applications

2.
Know General Electricity applications in
anesthesia

3.
Understand Equipment: Defibrillators, Cardiac
Pace Makers, Electro
-
cautery

(surgical
diathermy), Others: computer

4.
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 (

), ..


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

x

R
2

R
1

R3

Rx

R2

y


WHEAT STONE BRIDGE: R2/R1= R3/Rx



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

Pacemaker Identification

Multi
-
site
pacing (when
2 atria or
ventricles are
paced)

Programmable

Response
of generator
to sensed P
or R waves

Chamber
sensed

Chamber
paced

O

A

V

D

O(fixed function)

P(rate/output)

M=
multiprogram

C=
communicatin

R=rate modulating

O(
asynchro
nus
)

T=triggered

I
=inhibited

D=dual=T+I

O

V

A

D

O

V

A

D

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

Electricity

Definitions

Types & Applications

Equipment

Hazards & Their Prevention

©

Examples of questions to assess the ILOs

-
Wheatstone bridge: principle and clinical applications

-

Electrical
cautery
: precautions with pacemaker

-
Physical principle of defibrillators & their types

-

Hazards of defibrillators

-
Difference(s) between:

* Direct & alternating currents,

*
Monophasic

& biphasic defibrillators,

* Static & dynamic electricity



THANK YOU