Electrotherapy lecture (basic concept, electric current & Shock
PHYSICAL AGENTS & ELECTROTHERAPY
REFERENCE TEXT BOOK
Electrotherapy & Actinotherapy by P. M. Scott
Electrotherapy by Jugmohan
Lecture outline
This lecture deals about the basics of electrotherapy in the following sub-categories;
- Terminology,Introduction,Classification of electrotherapy &
- basic model of electrotherapy intervention.
- Key concepts in Electrotherapy / Electro physical agents
- Basics of Electric current / Electricity.
- Shock, types & Prevention strategies
INTRODUCTION – ELECTROTHERAPY
Electro – Electric Current / Electrical EnergyModality – Machines/ Equipments Therapy – Treatment of disease, Non surgical treatment approach
It means various forms of THERAPEUTIC applications usingElectrical Energy as primary source
Electrotherapy – Definition
Electrotherapy can be defined as the treatment of patients by electrical means.
For treatment purposes in patients we use some electrical devices –
The devices that we use – electrotherapy modalities/ equipments
Introduction – Changing nature of Electrotherapy
Electrotherapy is a long-established place in therapy practice.From the published & experimental evidence, it appears that electrotherapy can be clinically effective.
The evidence would suggest that when the appropriate modalityis applied at the right dose for the presenting problem, it can make a significant contribution to the improvement & well being of the patient.
For any therapeutic intervention to be effective there is a need for a clear assessment, a rationalization of the problems(s) & the construction of a proposed treatment plan that matches the needs of the individual taking into account their holistic circumstances, not just their presenting signs & symptoms.
The thinking therapist then re-evaluates the outcomes as the treatment progresses, modifying the treatment package in the light of these results. (+, -)
The research evidence suggests that electrotherapy can be effective as an element of treatment.
Further work is needed to evaluate the combinations or treatment packages – that are most effective.
Basic Model of Electrotherapy Intervention
A simple, but effective clinical decision making model can be utilized.
All electrotherapy modalities involve the introduction of some physical energy into a biologic system.
This energy brings about one or more physiological changes, which are used for therapeutic benefit.
ELECTRICITY – Basic concepts explained
Matter– any material that occupies space and has mass.
Elements – all matter are made of elements, over 100 elements are known.
Compounds – combination of two or more elements joined together at the atomic level.
Atom – the smallest recognized particle of matter that retains the properties of a given element. Atoms of elements are combined together to form compounds.
The atom consists of :
- A) Protons – very dense, positively charged
- B) Neutrons – dense, neutrally charged
- C) Electrons – negatively charged particles that orbit very rapidly about the nucleus of an atom.
Atomic charge balance – all atoms contain the same number of negative electrons as positive protons, thus as neutrons have no charge, then net positive charges = net negative charges (protons = electrons)
Valence electrons – the electrons present in the outer energy level that are available for atomic bonding.
Ionic Bonds – bonding in which one or more valence electrons are transferred from one atom to another.
Ions – electrically charged atoms.
positive ions – tend to lose electrons during bonding
negative ions – tend to gain electrons during bonding.
Two particles of opposite charge attract each other & two particles of the same charge repel each other.
Potential
It is electrical condition of that body when compared to the neutral potential of the earth
Bodies with an excess of electron are called negative
Bodies deficient in electrons are called positive
The Unit of potential is volt
Capacitance
It is the ability of the body to hold an electrical charge
Capacitance depends upon the material and surface area of the body. There is inverse relationship between capacitance and potential (larger the body the smaller the potential)
Difference of potential
Exists between similar bodies charged with different quantities of electricity. Electron moves from the more negative to less negative one.
The force producing the movement is called an electro motive force (EMF)
The charged body is continually seeking to attain its neutral state: if negative, by losing electrons; if positive gaining electrons.
Characteristics of charged body
These shows certain properties
The lines of force (LOF) surrounding an isolated charged body are straight.
Lines of force (LOF) repel one another.
LOF pass more easily through conductors than through insulators
LOF concentrate on that part of the surface of a charged body nearest to another object over which they can exert an influence.
Electric Fields – LOF
An electric field exists around any charged particle. If a smaller charge that is free to move is placed in the field, the paths it will move along are called lines of force.
Electromotive force – EMF
Electromotive force, or most commonly emf (seldom capitalized), or (occasionally) electromotance is “that which tends to cause current (actual electrons and ions) to flow.
More formally, emf is the external work expended per unit of charge to produce an electric potential difference across two open-circuited terminals.
The electric potential difference is created by separating positive and negative charges, thereby generating an electric field.
The created electrical potential difference drives current flow if a circuit is attached to the source of emf.
Electrical energy
Electrical energy is the energy carried by moving electrons in an electric conductor.
It cannot be seen, but it is one of our most useful forms of energy because it is relatively easy to transmit and use.
Electric Current / Electricity
An electric current is the flow of electric charge (Usually electrons) in a circuit.
Factors essential for production of electrical current are
- Potential difference (PD)
- Conducting pathway (between two points of PD)
