Types of electrotherapeutic current (unit 6) 1. Types of electrotherapeutic current :- There are three types of current used in electrotherapeutic purpose:- Direct current. Alternating current. Pulsed current/ pulsatile current. 2. Characteristic features of electrotherapeutic current:- Wave Form:- The shape of the single pulse or cycle phases as they appear on the graph of current (voltage) versus time is called wave form. Mainly two types of characteristics are used to describe pulsed and alternating current wave forms:- Descriptive (qualitative) characteristics. Quantitative Characteristics. 3. Current modulations:- Changes in current characteristics may be sequential, intermittent or variable in nature and are referred to as modulations. Amplitude modulation:- Variations in peak amplitude of a series of pulses. 4. Burst Current:- A finite series of pulses, a finite interval of alternation current delivered at a specific frequency over a specific time interval. Burst duration (with interruption). Inter burst interval (without interruption). Continuous mode (without interruption).

1. Dr. Prashant Kaushik
Assistant Professor
IAMR

2. 1. Types of electrotherapeutic current.
2. Characteristic features of electrotherapeutic
current.
3. Current modulations.
4. Burst.

3.  There are three types of current used in
electrotherapeutic purpose:-
(a) Direct current.
(b) Alternating current.
(c) Pulsed current/ pulsatile current.

4.  The continuous or
uninterrupted,
unidirectional flow of
charged particles is
defined as direct
current (DC),
traditionally referred
as “Galvanic current”.
 Uses :- Iontophoresis.

5.  The continuous or
uninterrupted
bidirectional flow of
charged particles is
defined as alternating
current (AC).
 Uses:- IFT

6.  The unidirectional or
bidirectional flow of
charged particles that
periodically ceases for
a finite period of time
defined as pulsed
current or pulsatile or
interrupted current.
 Uses:- Russian
current, TENS,
Faradic current etc.

8.  Wave Form:-
 The shape of the single pulse or cycle phases as they
appear on the graph of current (voltage) versus time is
called wave form.
 Mainly two types of characteristics are used to describe
pulsed and alternating current wave forms:-
(a) Descriptive (qualitative) characteristics.
(b) Quantitative Characteristics.

9. (i) Number of phases.
(ii) Symmetry of phases.
(iii) Balance of phase change.
(iv) Waveform shape.

10.  The term phase is
defined as
unidirectional current
flow on a current
intensity versus time
plot.
 There are waveforms
with three phases
called triphasic and
more than three
phases called as
polyphasic.

11.  Symmetry refers to
the exact match in size
and shape between
the two phases of the
waveform, as if one
half were reflected in
the mirror.
 Biphasic waveform
has the typical feature
of symmetry of phase.

12.  The area under 1st
phase of biphasic
waveform is equal to
the area under 2nd
phase.

13.  Varieties of waveform
shapes are available
with electrical
stimulator.
 Waveform shapes are
selected for patients
comfort and ease of
delivery of a electric
current to the tissues.

14.  Amplitude:- It is a measure of the magnitude
difference between the peaks of the two phases on a
current versus time graph. Amplitude of a current is
also called as the intensity of stimulation.
Measurement units for amplitude is mile Ampere
(mA).
(1) Amplitude dependent parameters:-
(a) Peak amplitude/ phase amplitude:- It is measured
from the baseline to the peak of either negative phase or
positive phase of biphasic pulse.

15. (b) Peak to Peak amplitude (P-P):- It is measured from the
peak of negative phase to the peak of the positive phase of
the biphasic pulse. Peak to peak amplitude is the most
commonly used to measure for amplitude.
(c) RMS (Root Mean Square) amplitude and average
amplitude:- Measures take pulse shape into account and
may more accurately reflect the stimulating power of the
waveform than do peak amplitude measures.

18. (2) Time dependent parameters:-
(i) Phase duration:- The elapsed time between the initiation and
the termination of one phase.
(ii) Pulse duration/ pulse width:- The elapsed time between the
initiation and the termination of all phases in a single pulse.
(iii) Period:- The elapsed time from a reference point on a pulse
waveform or cycle of the AC to the identical point on the next
successive pulse, the reciprocal of frequency.

19. (2) Time dependent Parameters:-
(d) Interphase Interval:- The interval time between two
successive phases of a pulse.
(e) Rise time:- The time for the leading edge of the phase to
increase in amplitude from the zero current base line to peak
amplitude of one phase.
(f) Decay time:- The time for the trailing edge of phase to return to
the zero current base line from the peak or maximum amplitude
of the phase.

20. (3) Other Parameters:-
(g) Phase Charge:- The time of current for a single phase.
That is, phase charge is represented by the area under a
single phase waveform, phase charge can be determined by
both amplitude and duration of the phase. The magnitude
of phase charge provide an indication of the relative
influence of a pulse will have in producing changes in
biological systems.
(h) Interpulse interval:- The interval time between the two
successive pulses. Inter pulse is measured in ms.

21. (3) Other Parameters:-
(i) Pulse Charge:- The time integral of the current waveform
over the entire pulse. For biphasic pulse it is the sum of the
area under each phase. For mono phasic waveform, pulse
charge is equal to the phase charge.
(j) Frequency (f):- The number of occurrences of pulses in
one second. For pulsed current frequency is expressed as
pulse per second (PPS), the number of cycles of alternating
current per second expressed in cycles per second (CPS) or
Hertz (Hz). [For clinical stimulators, it is labeled as
“rate”].

22.  Changes in current characteristics may be
sequential, intermittent or variable in nature
and are referred to as modulations.
(i) Amplitude modulation:- Variations in peak amplitude
of a series of pulses.

23. (3) Current modulation:-
(ii) Phase duration modulation:- Regular changes in the
time over which each pulse in a series acts.

24. (3) Current modulation:-
(iii) Frequency modulation:- Cyclic variations in the
number of pulses applied per unit time.

25. (3) Current Modulation:-
(iv) Ramp (surges) modulation:- Characterized by an
increase (Ramp Up) or decrease (Ramp Down) of pulse
amplitude, pulse duration or both, over time.

26. (3) Current modulation:-
(v) Timing modulation:- Systematic variations in the
pattern of delivery of a series of current pulses are referred
as “ Timing Modulation”. This includes Burst.

27.  A finite series of pulses, a finite interval of
alternation current delivered at a specific
frequency over a specific time interval.
(i) Burst duration (with interruption).
(ii) Inter burst interval (without interruption).
(iii) Continuous mode (without interruption).

28. (4) Burst current:-
(i) Burst duration:- The time interval over which the finite
series of pulses or AC cycles is delivered.

29. (3) Burst current:-
(ii) Inter burst interval:- The time period between the
bursts.
(iii) Continuous mode:- Train of pulses, train of AC or series
of bursts applied to patient without any interruptions for
the entire treatment period. Patterns of stimulation where
trains or series of bursts are intermittently or regularly
interrupted are quantitatively characterized by two time
intervals tat are:-
(a) On time.
(b) Off time.
(c) Duty cycle.

30. (a) On time:- The time during which a train of pulses of AC
or series of bursts is delivered in a therapeutic application.
(b) Off time:- The time between train of pulses or train of AC
or series of bursts is not delivered in a therapeutic
application.
(c) Duty cycle:- It is the ratio of on time the sum of on time
and off time and multiplied by 100 and expressed as
percentage.