PT PAP 101: Electric Currents in Physiotherapy

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Questions and Answers

What is the primary characteristic of a sinusoidal current in terms of its frequency?

100 Hz

25 Hz

10 Hz

50 Hz (correct)

What happens to the membrane potential when charged particles move across a cell membrane?

It becomes more negative.

It oscillates randomly.

It remains unchanged.

It becomes more positive. (correct)

How does sinusoidal current affect sensory nerve endings compared to faradic current?

It has no effect on nerve endings.

It completely inhibits nerve stimulation.

It has a more marked stimulation of nerve endings. (correct)

It has a lesser effect on nerve endings.

Which law correlates with therapeutic current in electrotherapy?

Ohm's law Signup and view all the answers

What is the typical resting membrane potential of a living cell?

-70 mV Signup and view all the answers

What is one of the benefits of applying direct and alternative current in physiotherapy?

It forces membrane changes. Signup and view all the answers

What distinguishes sinusoidal current from faradic current in terms of pain level?

Sinusoidal current is more painful due to longer stimulation time. Signup and view all the answers

What is a recommended method to reduce skin resistance in electrotherapy?

Apply conductive gel or lotion. Signup and view all the answers

What sensation may occur with the therapeutic effect of Direct Current?

Mild tingling or prickling sensation Signup and view all the answers

Which factor influences the intensity of current used in a circuit according to Ohm's law?

Voltage Signup and view all the answers

What is a characteristic of alternating current (AC)?

It can be used for neuromuscular stimulation Signup and view all the answers

Which of the following is NOT a method to decrease skin resistance?

Increase the distance between electrodes Signup and view all the answers

Which material is considered a high conductance material?

Copper Signup and view all the answers

In terms of spinal pain modulation, what frequency range is associated with strong pain modulation?

60-120Hz Signup and view all the answers

According to Joule's law, what does Q represent?

Produced heat Signup and view all the answers

What role do capacitors play in high-frequency current applications?

They store electrical energy Signup and view all the answers

Study Notes

PT PAP 101: Application of Direct and Alternative Current in Physiotherapy

Course: PT PAP 101
Topic: Application of Direct and Alternative current in Physiotherapy
Date: December 25, 2024

Objectives

Students will differentiate between direct and alternative currents.
Students will understand electric conduction properties in the human body.
Students will correlate Ohm's law to therapeutic current.
Students will know methods for reducing skin resistance.
Students will know the therapeutic benefits of direct and alternative currents.

Classification of Electric Currents

Direction of flow:
- Alternating current (AC): Flows in both directions.
- Direct current (DC): Flows in one direction.
Frequency:
- Low frequency: 50-100 Hz (e.g., IDC, Faradic, galvanic, sinusoidal, TENS).
- Medium frequency: 100-4000 Hz (e.g., interferential currents).
- High frequency: >1 MHz (e.g., SWD, MWD, UST).
Voltage:
- Low voltage: <100 Volts
- High voltage: >100 Volts

Concept of Electrotherapy Application

Every living cell has a membrane potential (approximately -70 mV) with the inside of the cell being negative.
Cell membrane potential relates directly with cell membrane transport mechanisms, particularly ion movement.
Changes in membrane potential influence ion movement.

Electrotherapy Application Principle

Sufficient energy can alter membrane behavior.
Smaller energy levels can "tickle" the membrane, inducing excitement and cellular excitement.
These processes are fundamental for graded and action potentials, with voltage changes across the membrane.

Low Frequency Current

Alternating current with frequency 0-1000 Hz.
Actions:
- Stimulates nerves and muscles.
- Produces muscle contractions and relaxation.

Types of Low Frequency Current

Faradic current
Galvanic current
Sinusoidal current
Dynamic current

What are Low Frequency Currents?

Used primarily to stimulate nerves and muscles.
Various currents exist in this frequency range.
Commonly used:
- Direct current: Longer duration (>10 msec), stimulates innervated muscles, repetition rate is faster (30 Hz).
- Faradic current: Shorter duration (<10 msec), stimulates denervated muscles, repetition rate is slower (50-100 Hz).

Dynamic Current

Low frequency current
Can be semi-wave or full-wave sinusoidal
50-100 Hz frequency
Combination of frequency and strength plus constant galvanic current creates modulations.
Modulations have varying effects, like analgesic effects and sympathetic blockade.

Sinusoidal Current

Alternating current with 50 Hz frequency.
10 ms pulse duration.
Sine wave form.

Effect of Sinusoidal Current

Effects are similar to faradic current (though possible differences exist).
Marked sensory stimulation; more marked improvement of circulation.
More painful, due to the longer stimulation time.

Therapeutic Effect of Direct Current

Sensory changes (tingling, prickling, mild irritation, itching).
Localized erythema (with prolonged stimulation).
Pain relief.
Acceleration of healing.
Stimulates denervated nerves.
Could lead to tissue destruction with high current densities.

Ohm's Law

Current in a circuit is directly proportional to voltage and inversely proportional to resistance.
Resistance depends on skin epidermis; larger cross-sectional area reduces resistance.

Alternating Current

Bidirectional flow of electrons.
No true positive/negative poles.
Examples: Interferential stimulation, premodulated currents, pain relief, neuromuscular stimulation.

Practical Tips to Decrease Skin Resistance

Decrease distance between electrodes.
Increase electrode size.
Minimize air electrode interface.
Use electrode gel or moisten electrodes.
Pre-warm skin.

Conductor

Substance that transports electrical charge.

Higher Conductance Materials

Silver, Copper
Electrolyte Solutions
Blood cells (high ionic content)
Inner skin layer
Nerves
Muscle fibers
Cell membranes

Low Conductance Materials

Air, Wood, Glass, Rubber
Bone
Cartilage
Tendons
Ligaments
Outer skin layer (keratinized epithelium acts as an insulator)

Frequency (in Hz)

Direct current (DC)/ Galvanic
Interrupted direct current (faradic current)
Transcutaneous electrical nerve stimulation (TENS)
High-voltage pulsed current (HVPC)
Didynamic current
Interferential current
Russian current
Shortwave diathermy (SWD)
Ultrasound (US)
Individual twitch (<20 Hz)
Spinal pain modulation (60-120 Hz)
Supra-spinal pain modulation (≤20 Hz)

Effect of Electrical Stimulation

Musculoskeletal system: Muscle excitation, contraction, increase in muscle strength/endurance, increased muscle blood flow, muscle fiber hypertrophy.
Wound healing: Increased capillary permeability and blood flow, macrophage/leucocyte and fibroblast/osteoblast activities, bactericidal effects, reduced edema.
Pain perception: Modulation of pain perception through central and peripheral mechanisms.

High Frequency Current (HFC)

Mechanism: Transformation of absorbed electrical energy into heat (Joule's law).
Heat production depends on the application method.

Mechanism of Heat Production Using HFC

Capacitors: Store electrical energy in an electric field between plates.
Induction field: Strength of magnetic field depends on current through conductor.
Eddy currents: Generated by changing magnetic fields; circulate in closed loops.

Summary

Low frequency currents for muscle and nerve stimulation.
Medium frequency currents for muscle re-education, pain relief, edema drainage.
High frequency currents for deep heat production.

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Description

This quiz covers the application of direct and alternative currents in physiotherapy, focusing on their therapeutic benefits and principles. Students will explore topics like electric conduction in the human body and the correlation of Ohm's law to therapeutic practices. Prepare to enhance your understanding of various electric currents used in physiotherapy treatments.