Electrical Modalities Background/Terminology

Question 1

2 Purposes of Electrical Modalities

Answer 1

1) Provide sensory input to sensory receptors (a different stimulation to receive)
2) Excite a motor unit (make muscles work harder)

Question 2

Flow or movement of ions or charged particles from one point to another in order to equalize the charge: often from + to -

Answer 2

Current

Question 3

Used clinically to facilitate the ionization of medication through the skin (iontophoresis)

Answer 3

DC - Direct Current (unidirectional) also called galvanic current.

Question 4

Periodically changes the direction of flow

Answer 4

AC- Alternating current. Clinically this could be interferential or Russian Stim

Question 5

Used in TENS, NEMS, FES. Electron flow in one direction however it is interrupted.

Answer 5

PC- Pulsatile Current

Question 6

PC Current which the two phases deviate equally from the baseline

Answer 6

Symmetrical Biphasic- pulse is bi-directional (more comfortable)

Question 7

PC Current which the two phases are not identical. Creates greatest nerve excitation under the negative electrode

Answer 7

Asymmetrical Biphasic- pulse is bi-direction (less comfortable) it is used when unable to elicit a response with symmetrical.

Question 8

The pressure or force that moves the electrons

Answer 8

Voltage (this is built into the device)

Question 9

Determines the magnitude of the response

Answer 9

Amplitude- Intensity. This is the knob we turn up slowly on the device. Most are measures in millamps (mAmp)

Question 10

Factors that prevent or reduce the ability of the current to pass through the tissue

Answer 10

Resistance: (adipose, scar, dry skin, hair, not adequate medium) effect the comfort level of the unit.

Question 11

Ohms Law

Answer 11

I = V/R Intensity (amplitude) = Voltage/Resistance

Question 12

The amount of time that a stimulus (pulse) is on

Answer 12

Pulse Duration - Measured in mili-seconds. (often called width) May be fixed on the unit to 200-400 m-sec.

Question 13

Pulses delivered per second: Expressed as pps (pulse per second) Can also be expressedin Hz (Hertz)

Answer 13

Pulse Frequency also called rate: Effects the rate of fatigue

Question 14

1-25 pps

Answer 14

may get twitch generally used for increased blood flow or sensory input .

Question 15

30 pps and up

Answer 15

Need at least 30 for tetanic contraction

Question 16

50 pps and up

Answer 16

For much larger muscles - generally relates in fatigue

Question 17

Gradual build up or amount of time it takes to reach the amplitude.

Answer 17

Ramp-Rise time.
Slower ramp time provides increased comfort.
Also affects spastic response, stretch reflex (important for pts. who may be guarding or who have tone issues)

Question 18

Amount of time it takes for current to return to off

Answer 18

Fall time

Question 19

Cycle of work vs. rest time

Answer 19

Duty Cycle- On/Off Time.

Effects the fatigue of muscles. Recover time needed to benefit from next contraction.

Question 20

Adequate Ratio for a duty cycle

Answer 20

1: 2 ratio.

i. e. 10 seconds on and 20 off, -> ramp on 2 seconds, 6 second hold, ramp of f2 seconds

Question 21

7 Contraindication for electromodalities

Answer 21

1) Demand Pacemaker
2) Over Carotid Artery/Anterior neck triangle
3) Trans-cerebral electrode placement - seizures
4) Undiagnosed pain- unknown etiology
5) Over pregnant uterus
6) Infection (except when used in wound healing)
7) Cancer

Question 22

10 Precautions for electromodalities

Answer 22

1) Polio, MS, Peripheral Vascular Disease
2) Seizure
3) Decrease Sensation
4) Over bony area
5) Over excess adipose tissue/obesity
6) Over superfical metal implants
7) Skin irritation or wounds
8) Use of machinery or sleep while unit on
9) Around microwave or cell phone use
10) Cognitive, esp. when planning home use