THS521: MACHINES PT 1

What are the four major categories of therapeutic modalities?

Electricity, heat transfer, mechanical vibration, and electromagnetic spectrum therapies.

What is electricity?

The movement (flow) of electrons.

What is mechanical circulation used for in therapy?

To improve circulation and transfer heat.

What are the primary purposes of heat transfer modalities?

To change tissue temperature for therapeutic benefit.

What is the electromagnetic spectrum composed of?

Photons.

What are sound waves?

Mechanical longitudinal waves that require a medium to travel.

Do sound waves require a medium?

Yes.

What is electricity dependent on to flow?

Atoms with easily movable electrons (conductors).

What particles make up electromagnetic radiation?

Photons.

Do photons have mass?

No.

Do photons require a medium to travel?

No.

What type of wave is a sound wave?

Longitudinal mechanical wave.

What type of wave is electromagnetic radiation?

Transverse wave.

True or False: Radio waves are sound waves.

False.

Name the seven general categories of the electromagnetic spectrum.

Gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves.

As wavelength increases, what happens to energy?

It decreases.

As wavelength increases, what happens to frequency?

It decreases.

Longer wavelengths primarily produce what effect?

Heat.

Shorter wavelengths primarily produce what effect?

Ionization and tissue destruction.

What happens when an atom absorbs a photon?

An electron moves to a higher energy orbit.

What happens when the excited electron returns to its original orbit?

It releases electromagnetic energy.

What should clinicians remember about therapeutic modalities?

Most have low-quality evidence supporting efficacy.

Why should clinicians be cautious about manufacturer claims?

Marketing claims often exceed the available evidence.

What is a conductor?

A material that allows electrons to move easily.

What is an insulator?

A material that resists electron flow.

What are the two major types of electrical current?

Direct current (DC) and alternating current (AC).

Describe direct current (DC).

Electrons flow in one direction (monophasic).

Describe alternating current (AC).

Electrons oscillate back and forth (biphasic).

Which current flows from cathode to anode?

Direct current.

What is voltage?

The electrical push or force moving electrons.

Voltage is measured in what units?

Volts.

What is current (amperage)?

The rate of electron flow.

Current is measured in what units?

Amperes (amps).

One amp equals how many milliamps?

1,000 mA.

One amp equals how many microamps?

1,000,000 μA.

One milliamp equals how many microamps?

1,000 μA.

What is electrical resistance?

Opposition to current flow.

Resistance is measured in what units?

Ohms.

What is electrical power?

Voltage multiplied by amperage.

Power is measured in what units?

Watts.

Formula for electrical power

Watts = Volts × Amps.

What determines frequency in electrotherapy?

Pulses per second (pps) or Hertz (Hz).

What is another name for pulses per second?

Hertz (Hz).

What does intensity refer to in electrotherapy?

The strength (amplitude) of the electrical current.

What is amplitude?

The height or strength of the waveform.

What is waveform modulation?

Changes in pulse shape, ramp, surge, or pulse duration.

What determines the path electricity follows in the body?

Path of least resistance.

What largely determines tissue conductivity?

Water content.

Which tissue has the lowest conductivity?

Bone.

Approximate conductivity of bone

5%.

Approximate conductivity of skin

5%.

Approximate conductivity of fat

15%.

Approximate conductivity of tendon

20%.

Approximate conductivity of fascia

20%.

Approximate conductivity of neural tissue

68%.

Approximate conductivity of muscle

75%.

Why is muscle highly conductive?

High water content.

Which tissues are directly excited by electrical current?

Nerves and muscles.

Name three common electrode pad types.

Silicone carbon fiber, metal sponge pads, self-adhesive disposable pads.

Proposed tissue-level effects of electrotherapy

Muscle contraction, increased circulation, tissue remodeling, reduced viscosity, increased lymphatic flow.

Proposed systemic effects of electrotherapy

Descending analgesia, endogenous opioid release, improved circulation, organ modulation.

Which endogenous opioids may increase with electrotherapy?

Endorphins, enkephalins, dynorphins.

Proposed cellular effects of electrotherapy

Increased ATP, metabolism, protein synthesis, enzyme activity, fibroblast activity, osteoblast activity.

What are the four intensity levels of electrotherapy?

Subsensory, sensory, motor, nociceptive.

What is subsensory stimulation?

No sensation perceived.

What is sensory stimulation?

Tingling or pins-and-needles sensation.

What is motor stimulation?

Visible muscle contraction.

What is nociceptive stimulation?

Deep ache or superficial burning sensation.

At 0-10 pps what muscle response occurs?

Individual muscle twitches.

At 40-60 pps what muscle response occurs?

Summation or weak tetany.

At 80-150 pps what muscle response occurs?

Strong tetanic contraction.

What are common indications for electrotherapy?

Pain, inflammation, edema, tissue healing, circulation, muscle spasm.

List the major contraindications for electrotherapy.

Electronic implants, anterior neck, brain, heart, pregnancy, hemorrhage, infection, malignancy, DVT, impaired sensation.

Why is electrotherapy contraindicated over pacemakers?

It may interfere with device function.

Why avoid electrotherapy over the anterior neck?

It may stimulate the vagus nerve, carotid sinus, or airway muscles.

Why avoid electrotherapy through the heart?

It may cause arrhythmias.

Why avoid electrotherapy through the brain?

Risk of unwanted neural stimulation.

Why avoid electrotherapy over a pregnant uterus?

Potential fetal risk.

What does the mnemonic HIM stand for?

Hemorrhage, Infection, Malignancy.

List important precautions for electrotherapy.

Pregnancy, eyes, chest, poor circulation, CVA/TIA, epilepsy, MS, edema, skin disease, varicose veins.

What sensory-level settings are commonly used for acute pain?

80-150 pps.

What sensory-level settings are used for acute edema?

1-15 pps.

What motor-level settings are used for neuromuscular reeducation?

40-60 pps.

What motor-level settings help increase muscle strength?

40-60 pps.

What motor-level settings exhaust musculature?

80-150 pps.

What nociceptive-level settings are used for chronic pain?

1-15 pps.

What nociceptive-level settings provide combined gate/opioid pain modulation?

80-150 pps.

Name five common types of electrical stimulation machines.

TENS, Low-Volt Alternating, Low-Volt Galvanism, High-Volt Pulsed Current, Microcurrent, Interferential.

Describe low-volt alternating current.

Biphasic sinusoidal waveform; versatile in-office modality.

Typical voltage of low-volt alternating current

Less than 150 volts.

Typical amperage of low-volt alternating current

Less than 50 mA.

Typical frequency of low-volt alternating current

Up to 1,000 pps.

What does TENS stand for?

Transcutaneous Electrical Nerve Stimulation.

Typical waveform of TENS

Biphasic rectangular.

Typical voltage of TENS

40-60 V.

Typical amperage of TENS

1-120 mA.

Typical frequency of TENS

1-250 pps.

Primary use of TENS

Pain management, especially home use.

Describe low-voltage galvanism

Monophasic continuous or pulsed direct current.

Primary use of galvanic stimulation

Iontophoresis.