PT9111 - Lecture 19 (Modalities 3)

Question 1

Electrons

Answer 1

Negatively charged ions that are part of atoms

Question 2

Electrical current

Answer 2

Flow of electrons from one area to another ([high] to [low])

Question 3

Amperes

Answer 3

Rate of current

Question 4

Voltage

Answer 4

Potential difference between high and low concentration areas of electrons

Question 5

Ohm’s Law

Answer 5

Rate of current (I) is directly proportional to strength of driving force (V) and inversely proportional to resistance (R)
I=V/R

Question 6

Name materials of high conductance

Answer 6

metal and water

Question 7

Name materials of high resistance

Answer 7

Air, wood, glass

Question 8

Tissues with high conductance

Answer 8

1. High water content
2. Blood
3. Granulation Tissue

Question 9

Tissues with high resistance

Answer 9

1. Skin
2. Bone
3. Necrotic Tissue

Question 10

What 3 factors increase skin impedance

Answer 10

1. Cooler skin temp
2. Hair and oil present
3. Increased skin thickness

Question 11

What 3 factors decrease skin impedance

Answer 11

1. Remove excess hair
2. Warming skin
3. Washing skin

Question 12

Describe the cathode and anode in terms of electric current

Answer 12

Cathode is black and is the negative pole that causes nerve depolarization and sends signal to positive/red anode where hyperpolarization then occurs down the nerve fibre so signal stays local

Question 13

Name 6 characteristics that are different between anodes and cathodes

Answer 13

Question 14

Cathode results in a [blank] reaction

Answer 14

Basic

Question 15

Anode results in a [blank] reaction

Answer 15

Acidic

Question 16

Name 3 types of currents

Answer 16

1. Direct Current
2. Alternating Current
3. Pulsed Current

Question 17

Direct Current

Answer 17

Continuous unidirectional movement of charged particles = net charge has polarity

Question 18

Alternating Current

Answer 18

Uninterrupted bidirectional movement of electrically charge particles = no net charge

Question 19

2 primary differences between direct and alternating current

Answer 19

Direct = flow of e- is unidirectional and polarity is constant
Alternating = Flow of e- reverses and no polar effects

Question 20

Pulsed Current

Answer 20

Pulses of current flow interrupted by short periods

Question 21

Name the 2 types of pulsed currents

Answer 21

1. Biphasic
2. Monophasic

Question 22

Monophasic Pulsed Current

Answer 22

Isolated unit of unidirectional movement of charged particles separated by a finite period from another unit of charged particles = net charge has polarity

Question 23

Biphasic Pulsed Current

Answer 23

Isolated unit of bidirectional movement of charged particles separated by finite period from another unit of charged particles = no net charge

Question 24

Name two types of standard currents

Answer 24

1. Household current = changes polarity
2. Batteries = direct current

Question 25

Name 6 characteristics of waveforms

Answer 25

1. Duration 2. Amplitude 3. Frequency 4. Bursting 5. Rate of rise and decay (ramping) 6. Waveform shape

Question 26

Name 3 types of duration

Answer 26

1. Pulse 2. Phase 3. Cycle

Question 27

Pulse

Answer 27

Single waveform that may have one or more phases

Question 28

Phase

Answer 28

Portion of pulse which rises above or below baseline and returns to baseline

Question 29

Cycle

Answer 29

2 phases that each return to baseline

Question 30

Amplitude

Answer 30

Magnitude of electromotive force driving e-

Question 31

T or F: The greater the amplitude the stronger the current

Answer 31

T

Question 32

Frequency

Answer 32

Number of pulses or cycles per second

Question 33

At what frequency do we get tetanic muscle contraction

Answer 33

>50 Hz

Question 34

At what frequency do we get only muscle twitching

Answer 34

<50 Hz

Question 35

T or F: As frequency increases, duration increases

Answer 35

F as frequency increases, duration decreases

Question 36

Bursting

Answer 36

Train of pulses follow by short period of time with no activity to decrease accommodation by nerves of stimulus and elicit a strong muscle contraction

Question 37

Ramping

Answer 37

Waves rising gradually to full amplitude and the falling gradually to zero current to allow muscle to warm up to stimulus and not cause too strong of a contraction immediately

Question 38

T or F: Different waveform shapes can cancel each other out to cause no charge

Answer 38

T

Question 39

Do biphasic, symmetrical currents have a charge?

Answer 39

No charge

Question 40

Do biphasic, asymmetrical currents have a charge?

Answer 40

It depends, but yes, if they are not balanced

Question 41

Do monophasic currents have a charge?

Answer 41

Yes

Question 42

Why do we have to worry about a charge?

Answer 42

Build up of charge leads to acidic or basic chemical reactions so it is important to know the current used and if the phases are balanced (if biphasic)

Question 43

What are the 3 most important characteristics to delivering a sufficient current

Answer 43

1. Duration (usec) 2. Amplitude (mA) 3. Frequency (Hz) **Combination of these values can result in subsensory stimulation, appropriate treatment, or noxious stimulation

Question 44

Accomodation

Answer 44

Overtime, with a constant amplitude, frequency or duration of electrical energy, a nerve will become unexcitable

Question 45

How to modulate so accommodation does not occur

Answer 45

Modify intensity, frequency (eg. bursting), duration or a combination of these

Question 46

What are 8 contraindications to using electrical modalities

Answer 46

1. Pacemaker/arrhythmia 2. Over carotid sinus or excitable areas like chest, eyes and head 3. Thrombophlebitis 4. Impaired sensation, altered mental state, or poor communication skills 5. Over pelvis, abdomen, trunk when pregnant 6. Severe peripheral vascular disease (only with NMES because works body too hard and can cause damage) 7. Over superficial metal implants 8. Cancer

Question 47

Name 3 precautions of electrical modalities

Answer 47

1. Turn machine off before checking leads 2. Be aware of ON:OFF cycles when adjusting amplitude 3. Application of electrodes (evenly against skin with constant pressure)

Question 48

Name 3 adverse reactions of electrical modalities

Answer 48

PSS: Pain (P)-> requires good therapist Skin reactions (s) -> burns due to build of ions (increased risk from long treatment, sweating, jewelery, creams) Risk of Surge (S) -> Could be electrocuted