SINUSOIDAL CURRENT Dr. Amal Abd El Baky, LOGANATHAN CHANDRASEKAR 353 RHPT – 1435 – 1436H – 1 st SEM

Lecture outline 6/23/ RHPT Sinusoidal Current 2  Physics and principles of sinusoidal current  Characteristics, Physiological & Therapeutic effects of sinusoidal current  Uses and dangers of sinusoidal current  Parameters &technique of application of sinusoidal current

Lecture objectives 6/23/ RHPT Sinusoidal Current 3 At the end of lecture the student is able to  Define and outline the principle & production of sinusoidal current.  List the Characteristics, physiological &Therapeutic effects, uses & dangers of sinusoidal current.  Select the appropriate sinusoidal current dose.  Demonstrate the Parameters & application of sinusoidal current.

Definition & Physics 6/23/ RHPT Sinusoidal Current 4 Definition:  A sinusoidal current is an evenly alternating sine wave low frequency current with a frequency of 50 HZ  It can be produced from the mains by reducing the voltage to V with a step down transformer.  Patient feel tingling sensation

6/23/ RHPT Sinusoidal Current 5 Sine waves are characterized by the amplitude and period. The amplitude is the maximum value of a voltage or current; the period is the time interval for one complete cycle. Sine waves The amplitude (A) of this sine wave is 20 V The period is 50.0  s A T

6/23/ RHPT Sinusoidal Current 6  It can be used as surged or unsurged currents.  It is usually surged to cause a RHYTHMICAL MUSCLE CONTRACTION. Sinusoidal current Surged sinusoidal current

6/23/ RHPT Sinusoidal Current 7 Characteristics of a Sine Wave The length of time it takes to complete one cycle or conversely the number of cycles that occur in one second. Period Frequency The maximum and minimum voltage or current swing Amplitude Peak-to-peak amplitude

6/23/ RHPT Sinusoidal Current 8 Period, T The period of a sine wave can be measured between any two corresponding points on the waveform.

6/23/ RHPT Sinusoidal Current 9 Frequency, f 3.0 Hz Frequency ( f ) is the number of cycles that a sine wave completes in one second. Frequency is measured in hertz (Hz). If 3 cycles of a wave occur in one second, the frequency is 1.0 s

6/23/ RHPT Sinusoidal Current 10 Amplitude, A  Peak amplitude  Peak-to-Peak amplitude The amplitude of a sine wave is only measured from the center to the maximum point.

6/23/ RHPT Sinusoidal Current 11 Sinusoidal voltages are produced by ac generators and electronic oscillators. Generation of a sine wave A BC D When a conductor rotates in a constant magnetic field, a sinusoidal wave is generated. A - When the conductor is moving parallel with the lines of flux, no voltage is induced. B - When the loop is moving perpendicular to the lines of flux, the maximum voltage is induced

Physiological & Therapeutic effects of sinusoidal current 6/23/ RHPT Sinusoidal Current 12 Tetanic muscle contraction and tingling sensation due to motor & sensory nerve stimulation Rhythmic muscle contraction by surged mode helps in edema reduction Pain relief via sensory stimulation by the same mechanisms of TENS Enhance blood flow and intramuscular Reduction of edema and inflammatory exudate by unsurged mode

Dangers 6/23/ RHPT Sinusoidal Current 13  Burn: a. Overdose( high intensity, long duration) b. Bare metal electrode on the skin. c. Metal in the path of the current.

6/23/ RHPT Sinusoidal Current 14  Shock: Sudden Increase or decrease of the current intensity.

6/23/ RHPT Sinusoidal Current 15  Pain : a. Overdose. b. Small raised edge. c. Tiny cut not insulated.

Technique of application 6/23/ RHPT Sinusoidal Current 16  Sinusoidal current can be applied in the same way as other low-frequency currents by means of electrodes and pads.  However, because of the marked sensory stimulation this current is often applied to large areas and rarely used for local muscle stimulation.  So it is applied either through large pads or water baths.

6/23/ RHPT Sinusoidal Current 17 For pain it can be used in continuous mode at intensities close to the limit of tolerance and increase the current with accommodation. Application will be done for 5 min and repeated with insufficient response. For reduction of oedema and to increase the limb circulation surged sinusoidal current is suggested. causing regular rhythmical muscle pumping actions.

Application – Procedure / Method 6/23/ RHPT Sinusoidal Current 18  Put the patient in a comfortable position.  Explain the patient the purpose of the treatment.  Select the setting on the machine for a sinusoidal current with a pulse duration of 10 ms, and a frequency of 50 Hz.

6/23/ RHPT Sinusoidal Current 19  Connect the leads to the metal electrode and to the machine.  The pads should be moistened evenly.  Explain the sensation to the patient “ tingling sensation ”  Examine the area under both active and indifferent electrodes for any cut and if insulate with Vaseline.

6/23/ RHPT Sinusoidal Current 20  Bandage the active electrode on the target tissue with indifferent one on the foot.  Increase the intensity gradually till the patient experiences tinging sensation under the active electrode. The response decreases slowly after sec then increase the intensity gradually.

6/23/ RHPT Sinusoidal Current 21  Continue this. After 4 minutes see if the stinging is adequate there is immediate marked numbness to touch and pressure, and all pain in the treated area is lost.  If there is no numbness or partial, repeat for 4 min.  The erythema and numbness persists for about 1 h.