What is the Difference Between Faradic and Galvanic Current

Madhu

2 years ago

The key difference between faradic and galvanic current is that faradic current is a short duration interrupted direct current having a pulse duration ranging from 0.1 to 1 ms and a frequency of 50 to 100 Hz, whereas the galvanic current is a long duration interrupted direct current.

Electric currents are able to create severe burns in the body. However, if the nature of the current beam is regulated, it can be used in the medical field to cause contraction and relaxation in innervated muscles of patients. Faradic current and galvanic current are two such types of currents.

1. Overview and Key Difference
2. What is Faradic Current
3. What is Galvanic Current
4. Faradic vs Galvanic Current in Tabular Form
5. Summary – Faradic vs Galvanic Current

What is Faradic Current?

Faradic current is a short-duration interrupted current having a pulse duration ranging from 0.1 and 1 ms and a frequency of 30 – 100 Hz. The waveforms of Faradic current come in four types:

Induced asymmetrical alternating current
Biphasic, asymmetrical, unbalanced, and spiked current
Positive portion (has a short duration, high amplitude, and spiked)
Negative portion (long duration, low amplitude, and curved)

Faradic currents are usually surged for treatment purposes in producing a near normal tetanic contraction and relaxation of the muscle. Moreover, current surging means the gradual increase and decrease of peal intensity.

Effects of Faradic Currents

The effects of faradic currents can be shown as below:

Stimulation of sensory nerves (it is not very marked due to the short duration, and it causes reflex vasodilatation of the superficial blood vessels that leads to slight erythema)
Stimulation of the motor nerves (this occurs when the current has a sufficient intensity that causes contraction of the muscles that is supplied by the nerve distal to the point of stimulus. Usually, a suitable faradic current that is applied to the muscle elicits a contraction of the muscle itself and can also spread to the neighbouring muscles)
Stimulation of the nerve is due to the production of a change in the semi-permeability of the cell membrane, which can be achieved by altering the resting membrane potential.
Faradic current will not stimulate denervated muscles
Reduction of swelling and pain (this occurs when an alteration of the permeability of the cell membrane leads to acceleration of fluid movement in the swollen tissue and arterial dilatation)
Chemical changes

What is Galvanic Current?

A galvanic current is a unidirectional direct current. This type of current is very painful for patients due to its unidirectional nature. However, constant direct current is useful in iontophoresis and denervating muscle stimulation. This direct current is used to activate muscles directly without activating the peripheral nerve. It requires a pulse of phase durations of at least 1 ms. More often, it uses longer durations. The recommended dosage of galvanic current for a patient is a regular 20 – 30 contractions with an average of 90 – 200 contractions per muscle per day.

Figure 02: A Galvanic Cell Produces a Galvanic Current

Galvanic direct current is useful for iontophoresis, modified direct current is useful in stimulating denervated muscles, it maintains the properties of muscle, it retards the denervation atrophy, and it helps the muscle to use all the substances and to maintain the nutrition. Moreover, it improves the absorption and activates the pumping function of muscle, and prevents venous and lymphatic stasis.