Intro to E-Stim 1 (10/10a) [Intervention]

Question 1

Some E-Stim Abbreviations

Answer 1

NMES — neuromuscular electrical stimulation

FES — functional electrical stimulation

TENS — transcutaneous electrical nerve stimulation

HPVC — high voltage pulsed current

EMS — electric muscle stimulation

NCV — nerve conduction velocity testing

Question 2

Uses of E-Stim

Answer 2

Neuromuscular dysfunction – NMES/FES

Pain - TENS

Wound/tissue healing - HVPC

Delivery of Pharmacological agents – Iontophoresis

Electric Muscle Stimulation (denervation) – EMS

Edema management

Evaluate nerve and muscle injury - NCV testing

Question 3

3 Types of Electric Currents

Answer 3

Direct current
Alternating current
Pulsatile current

Question 4

Direct Current (DC)

Answer 4

uninterrupted flow of charges

Question 5

Alternating Current (AC)

Answer 5

goes from positive to negative repetitively

Question 6

Pulsatile Current

Answer 6

there is a space between the current, could be monophasic or biphasic but would still have space/pulses

Question 7

3 Reasons to Use E-Stim

Answer 7

Sensory response
Motor response
Noxious response

Question 8

Charge (Q)

Answer 8

Clinically what carries charge:

• Electrons in metal
• Ions in solutions aka cations (+) and anions (-)

in Coulombs (C)

1 coulomb (C) = charge of 6.24x1018 electrons

Question 9

Current (I)

Answer 9

The movement of charged particles through a conductor in response to an applied electric field

How fast the electrons are moving

in Amperes ( A )
- Milliamps (mA) 10-3 → what we usually measure in

Equation → I =Q/t

1A = 1 C of charge/sec

Question 10

Voltage (V)

Answer 10

potential difference or electromotive force (EMF) that makes charged particles move

the change in electrical potential energy between two points in an electric field per unit of charge

in Volts (V), 1 Volt = 1 ampere of current in a circuit containing 1 ohm of resistance

Typical voltages in biologic tissues
Millivolt — mV 10-3
Microvolt — uV 10-6

EX: Hourglass analogy— voltage is how much sand there is, current is how fast the sand is moving

Question 11

Resistance (R)

Answer 11

Opposition to current (movement of charge particles)

Flow of current inversely proportional to resistance (I= V/R)

ρ(rho) → resistivity in biological tissues is inversely proportional to water content

Virtually all resistance at electrode-skin interface

EX: Hourglass analogy— resistance is how narrow the middle of the hourglass is

Question 12

Other Physics Terms to Know

Answer 12

Impedance (Z) — in Ohms
- fairly interchangeable with resistance

Capacitance (C) — in Farad (f)

Current Density — in mA/cm2

Ohm’s Law
- V = I*R

Question 13

In the body, main sources of resistance are ___ and ___, which act in series

Answer 13

skin and fat

NOTE: other things like nerve, muscle, and bone can provide resistance, but they are in parallel

Question 14

Resistors in Series

Answer 14

Adds the currents

V = I (R1 + R2 + R3)

Question 15

Resistors in Parallel

Answer 15

Divides the currents

1/Rt = (1/R1) + (1/R2) + (1/R3)

Question 16

Things that could affect application of e-stim

Answer 16

sweating

swelling

overused/old/dried out electrodes

Question 17

Path of Least Resistance - Electrodes touching each other

Answer 17

The current flows through one area instead of going back and forth and can create a burn

Question 18

Path of Least Resistance - Break in the skin

Answer 18

No layer of resistance, so stim tries to go through that area

Question 19

Path of Least Resistance - Dry skin or dry electrodes

Answer 19

Less water content so there is more resistance and have to increase the stim more than you usually would

Question 20

PT Use of DC

Answer 20

Iontophoresis

Administer medication transdermally via DC current

Using estim to deliver a rub (EX: dexamethasone) into the skin

Generally poor evidence

Question 21

Applying DC

Answer 21

CORRECT

• therapeutic flow of ions
• local increase in blood flow to restore pH

EXCESS

• blistering
• chemical burns
• basic reaction is more caustic to skin

Question 22

Red lead = positive (anode)

Answer 22

Caustic Hydrochloric Acid

+ Acid

+ Hardens Tissue?

+ Vasoconstriction

+ Decreases nerve excitability?

Question 23

Black lead = negative (cathode)

Answer 23

Caustic Sodium Hydroxide

• Base
• Softens tissue?
• Vasodilation
• Increases nerve excitability?

Question 24

Some contraindications for e-stim

Answer 24

Cardiac problems-pacemakers/ICDs

Pregnancy (low back/abs)

On broken/damaged skin (except wound therapy)

On chest, neck, head, ears, eyes

Cancer

Question 25

Some precautions for e-stim

Answer 25

Open skin lesions

Reduced sensation

Allergies

Metal implants

Cognitive/communication impairment

Question 26

3 Types of Electrode Configurations

Answer 26

Bipolar — 2 electrodes

Quadripolar — 4 electrodes

Unipolar — one electrode

Question 27

Electrotherapeutic Terminology

Answer 27

Target tissue — where you are targeting the body with e-stim

Electrodes — patches that go onto the skin

Leads — anode and cathode

Stimulating Unit — battery or machine