Ptha 1431 - Physical Agents In Rehabilitation - Cameron Book And Stetz Lecture - Exam 3

Front 1

What is sound? ***

Back 1

propagation of vibratory motion that creates pressure changes in air or other mediums

Front 2

What is the range of human hearing? ***

Back 2

16 Hz - 20,000 Hz

Front 3

Ultrasound operates at frequencies above the upper range of human hearing (20,000 Hz)--a range considered ________. ***

Back 3

infrasound

(this doesn't make sense; if above it should be ultra--
infrasound is below 20 Hz)

Front 4

What are some medical uses of ultrasound? ***

Back 4

- radiography - imaging of internal structures
- surgery - destruction of tissue
- physical therapy - therapeutic ultrasound

Front 5

How is ultrasound generated? ***

Back 5

110V/60Hz electricity transformed (converted) to higher voltage

higher voltage = higher frequency

Front 6

Describe the crystal used in the ultrasound unit. ***

Back 6

Piezoelectric crystal within a sound head (transducer)

either
- natural (quartz) or
- synthetic (plumbum zirconium titanate--PZT or barium titanate)

most are PZT as it is the least expensive and most efficient

Front 7

What are piezoelectric properties?

Back 7

material which responds to an alternating current by expanding and contracting at the same frequency at which the current changes polarity

when the crystal expands, it compresses the material in front of it, and when it contracts it rarefies the material in front of it

Front 8

Describe conversion of energy with respect to ultrasound. ***

Back 8

electrical energy is converted to mechanical energy

mechanical energy then may, depending on settings used, be converted to heat (thermal energy) within the tissue through vibrations at the molecular levels

Front 9

Describe how rarefaction and compression of the ultrasound waves affect the crystal and the tissue. ***

Back 9

Front 10

What is rarefaction? ***

Back 10

the negative phase of the wave, during which the crystal contracts, allowing the tissue molecules to decompress or expand

(actually, it looks like the positive phase of the wave which compresses the crystal but allows the tissue to decompress, so we're speaking of rarefaction from the perspective of the TISSUE, not the crystal)

Front 11

What is compression? ***

Back 11

the positive phase of the wave, during which the crystal expands and the molecules compress

(actually, it looks like the negative phase of the wave which allows the crystal to expand, but compresses the tissue, so we're speaking of compression from the perspective of the TISSUE, not the crystal)

Front 12

What are the frequencies used in therapeutic ultrasound? ***

Back 12

either

- 1 MHz or
- 3 MHz

Front 13

How deeply does the energy penetrate for ultrasound using 1 MHz? 3 MHz? ***

Back 13

up to 5 cm (2 inches)

approximately 1-2 cm (0.4 - 0.8 inches)

Front 14

1 Hz =

1 MHz =

***

Back 14

1 cycle per second (cps)

1,000,000 cps

Front 15

Which ultrasound frequency has a more divergent beam, 1 MHz or 3 MHz? ***

Back 15

1 MHz

Front 16

Which ultrasound frequency has a more collimated beam, 1 MHz or 3 MHz? ***

Back 16

3 MHz

Front 17

What types of wave forms are available for use with therapeutic ultrasound? ***

Back 17

continuous or pulsed

Front 18

What is a continuous wave form in therapeutic ultrasound? ***

Back 18

delivery of ultrasound energy throughout the entire treatment time

Front 19

What is a pulsed wave form in therapeutic ultrasound? ***

Back 19

delivery of ultrasound energy during only a portion of the treatment time

Front 20

What is the ultrasound duty cycle? ***

Back 20

the amount of time the ultrasound is on and delivering energy out of the total treatment time

expressed as a percentage or ratio

e.g., a 20% duty cycle has the ultrasound being delivered only 20 percent of the time, usually 2 ms on, 8 ms off

Duty cycle == Time on/total time
(D = t/T or D = ON/ON + OFF)

Front 21

What is the importance of beam non-uniformity? ***

Back 21

peaks in the energy can cause stinging or burning

Front 22

What is Spatial Peak Intensity (SPI)? ***

Back 22

the greatest strength (peak) of energy anywhere within the beam

usually greatest at center of beam and lowest at the edges

Front 23

What is Spatial Average Intensity (SAI)? ***

Back 23

the average intensity of ultrasound output

Front 24

Where is SAI measured? ***

Back 24

at a short distance (about 1/2 cm) from the transducer/sound head

Front 25

What is Beam Non-uniformity Ratio (BNR)? ***

Back 25

the ratio of SPI to SAI (peak to average)

SPI:SAI

Front 26

What is the minimum acceptable BNR? ***

Back 26

6:1

Front 27

Who regulates acceptability of BNR? ***

Back 27

the FDA

Front 28

What is the maximum allowable BNR? ***

Back 28

7:1 (Ms. Stetz was a bit unsure this was absolutely correct)

Front 29

How can you determine the BNR? ***

Back 29

it should be in the manual or on the machine itself

(The FDA requires the maximum BNR for an ultrasound transducer be specified on the device.)

Front 30

The higher the BNR ratio: ***

Back 30

the less uniform the beam is

thus the beam will be less comfortable, with larger peaks to potentially sting or burn

(e.g., if your unit is 5:1 and your intensity is set at 1 W/cm sq, there could be a 5 W/cm sq spike somewhere in the field)

Front 31

Does a better ultrasound machine have a higher or lower BNR? ***

Back 31

lower is better

2:1 is better than 6:1

Front 32

What is the Effective Radiating Area (ERA)? ***

Back 32

the area of the transducer from which energy radiates

Front 33

Is the ERA the same size as the transducer? Why? ***

Back 33

no, the ERA is smaller

due to the adhesive used to hold the crystal in place

Front 34

From where does the ultrasound transducer release the most energy? ***

Back 34

from the center

Front 35

In what three manners may the ultrasound beam be transmitted? ***

Back 35

it may be

- absorbed
- refracted
- reflected

Front 36

What happens when the ultrasound beam is absorbed? ***

Back 36

the energy continues along a straight line (equal to incidence) into the tissue

Front 37

What happens when the ultrasound beam is refracted? ***

Back 37

the beam changes direction or course when it comes into contact with the tissue (it is bent)

Front 38

What happens when the ultrasound beam is reflected? ***

Back 38

the beam is redirected away from the surface of the tissue and does not enter

Front 39

Where is absorption of ultrasound energy the highest? ***

Back 39

in tissues with high collagen content

(e.g., bone, cartilage, tendon, scar tissue)

Front 40

What would cause the ultrasound energy to be reflected? ***

Back 40

bad contact or a bad medium

ultrasound is also reflected at tissue interfaces, especially where there is greatest difference between acoustic impedance of adjacent tissues (e.g., most--about 35%--occurs at soft tissue-bone interfaces)

Front 41

Is 3 MHz ultrasound considered a deep heating modality? ***

Back 41

yes, although at 1-2 cm, it does not penetrate as deeply as 1 MHz (1-5 cm)

Front 42

Which means of ultrasound delivery is considered thermal? ***

Back 42

continuous wave

Front 43

What happens physiologically when thermal ultrasound is administered? ***

Back 43

rapid vibration of molecules in the tissue produce heat

Front 44

Compare thermal effects of continuous ultrasound vs. hot pack ***

Back 44

continuous US - can increase tissue temperature 4 degrees C at depth of 3 cm

hot pack - can increase tissue temperature 0.8 degrees C at depth of 3 cm

(up to 5X more effective)

Front 45

What are the thermal effects of pulsed ultrasound? ***

Back 45

there is a small, brief heating effect during the on time of a pulse

depending on the duty cycle, this heat may or may not dissipate
(will dissipate at 20%, less so at 50%--see question, "Can pulsed ultrasound produce heat?")

Front 46

What are some non-thermal effects of pulsed wave ultrasound? ***

Back 46

- acoustic streaming
- cavitation
- microstreaming

these are thought to alter cell membrane permeability

Front 47

What is acoustic streaming? ***

Back 47

circular flow of cellular fluids induced by ultrasound

constant flow of fluid the wave travels through

(can kind of see this in underwater US)

Front 48

What is cavitation? ***

Back 48

formation, growth, and pulsation of gaseous bubbles caused by ultrasound

during compression, bubbles in the tissue are squashed, during rarefaction they expand

may be stable or unstable

Front 49

What is microstreaming? ***

Back 49

micro-scale eddying occurring near a small vibrating object (very small movement of fluid)

occurs around the gas bubbles set into oscillation by cavitation

Front 50

What are the effects of thermal (continuous) ultrasound? ***

Back 50

- increased metabolic rate
- increased circulation
- increased soft tissue extensibility
- decreased pain
- nerve conduction velocity changes
- decreased muscle spasm

Front 51

What are the effects of non-thermal (pulsed) ultrasound? ***

Back 51

- increased skin and cell membrane permeability
- increased macrophage response
- increased protein synthesis
- increased intracellular calcium levels
- decreased inflammation

Front 52

What are some indications for use of ultrasound? ***

Back 52

- soft tissue shortening (use thermal)

- pain (thermal/subacute or pulsed/acute)
- tendon and ligament injuries (thermal/subacute or pulsed/acute)

- dermal ulcers (pulsed)
- surgical skin incisions (pulsed)

- fractures (there is a special US unit that assists in detecting fractures)
- reabsorption of calcium deposits (calcific tendinitis/frozen shoulder???)

Front 53

What are some contraindications for use of ultrasound? ***

Back 53

- malignant tumor
- thrombophlebitis
- pacemaker
- plastic or cement in joint (metal OK)
- over exposed CNS tissue (e.g., post-laminectomy)
- pregnancy (distal extremities OK)
- complete relief of severe pain (nerve block???)
- over eyes or reproductive organs
- thermal on patients with impaired sensation

Front 54

What are some precautions for use of ultrasound? ***

Back 54

- acute inflammation (pulsed OK)
- over fractures (low-dose/intensity OK)
- over growing epiphyseal plates (low-dose/intensity OK)
- over bony prominences
- over breast implants

Front 55

What size transducer heads do we have available? ***

Back 55

1 cm sq (looks like a penlight)
5 cm sq (medium)
10 cm sq (large)

Front 56

What additional equipment (other than the US machine) is required for application of therapeutic ultrasound? ***

Back 56

a couplant for good contact

gel or polysonic lotion

water (submersion)

Front 57

What is the duration of ultrasound treatment? ***

Back 57

treat an area approximately twice the size of the ERA for 5-10 minutes (Cameron)

cover 1" sq every 1-2 minutes (Hayes)

Front 58

What are the intensity parameters for delivery of ultrasound? ***

Back 58

up to 3 W/cm sq

IN GENERAL:
- if using 1 MHz use about 1.0-1.5 W/cm sq
- if using 3 MHz use about 0.5-1.0 W/cm sq

of course, the above also depends upon patient comfort

Front 59

You need to keep the transducer moving, but how do you decide how fast? ***

Back 59

if using unit with good BNR (2:1 to 5:1) you can move more slowly, like 1 cm/second

if using unit with poor BNR (6:1-9:1) you need to move it more quickly due to the higher peaks which may sting or burn; use 4 cm/second

Front 60

What is phonophoresis? ***

Back 60

application of ultrasound with topical drug mixed into the medium

usually a corticosteroid such as hydrocortisone

Front 61

What are some theories behind phonophoresis? ***

Back 61

ultrasound pressure drives the drug through the skin

heating increases vasodilation and absorption

increased permeability of the stratum corneum through cavitation enhances absorption (this one is the most credible)

Front 62

Why does 1 MHz penetrate deeper? ***

Back 62

longer wavelengths penetrate deeper

Front 63

Why do you need to have skin contact with the transducer before you turn the ultrasound machine on? ***

Back 63

if you're aiming it elsewhere, the sound waves can reflect back and crack the crystal

Front 64

What variables do you control in ultrasound? ***

Back 64

- duty cycle (continuous or pulsed)
- frequency (1 MHz or 3 MHz)
- intensity (0.1 - 3.0 W/cm sq)
- time (5-10 minute treatment)
- size of transducer head

Front 65

When in doubt, what pulsed duty cycle should you use? ***

Back 65

20%

Front 66

How do the frequencies and intensities relate, in general? ***

Back 66

3 MHz is a bit more superficial, and especially if used on smaller, bonier, less fatty areas you can probably use a lower intensity (start at around 0.5-0.7 W/cm sq)

1 MHz continuous is more likely to be used on a large, muscular area and you can probably start right at 1.0 W/cm sq)

Front 67

What types of tissue is ultrasound especially good at heating?

Back 67

tissues with high collagen content, such as tendons, ligaments, joint capsules, and fascia

Front 68

Non-thermal effects of ultrasound

Back 68

- facilitate tissue healing
- modify inflammation
- enhance transdermal drug delivery

Front 69

What is absorption with respect to ultrasound?

Back 69

conversion of the mechanical energy of ultrasound into heat

highest in tissues with highest collagen content

absorption increases in proportion to the ultrasound frequency (this is why we've been starting with lower intensity on 3 MHz--it is absorbed more quickly)

Front 70

Taking into account all tissue types, what is the general relationship between absorption coefficients at 1 MHz and 3 MHz?

Back 70

by doing the math with the absorption coefficient table on page 199 (Cameron), we can see that absorption of 3 MHz ultrasound is about 3 times more efficient than 1 MHz; of course, this should be obvious as 3 is 3 times 1.

since 3 MHz comes out of the transducer faster and is absorbed about 3 times faster, we need to start treatment with a lower intensity (approximately 0.5-1.0 W/cm sq)

Front 71

BNR

Back 71

beam nonuniformity ratio

Front 72

SPI

Back 72

spatial peak intensity

Front 73

SAI

Back 73

spatial average intensity

Front 74

What is the absorption coefficient?

Back 74

the amount of absorption that occurs in a tissue type at a specific frequency

determined by measuring rate of temperature rise in a homogeneous tissue exposed to ultrasound at a known intensity

Front 75

What is stable cavitation?

Back 75

the bubbles expand and contract, but do not burst

thought to be the mechanism for nonthermal therapeutic effects of ultrasound

Front 76

What is unstable cavitation?

Back 76

the bubbles grow, then burst, releasing free radicals (OH-, H+)

thought not to occur at the therapeutic ultrasound intensities

Front 77

To operate effectively, transducer crystals must be of an appropriate thickness to resonate with a specific frequency. How are multifrequency transducers made?

Back 77

they use a single crystal of a thickness optimized for only one of the frequencies and they operate with decreased efficiency at the other frequency (variability, reduction of ERA, increased BNR, etc.)

recently, some composite materials have been developed to more accurately and efficiently deliver ultrasound at different frequencies

Front 78

Can pulsed ultrasound produce heat?

Back 78

Yes, there is a small, brief heating effect during the on time of a pulse

Cameron cites a study consisting of a 10-minute treatment at frequency of 3 MHz; one used continuous US at 0.5 W/cm sq; the other used 50% duty cycle at 1.0 W/cm sq

they produced equal temperature change at depth of 2 cm

note the 50% duty cycle leaves less time for cooling between pulses than a 20% duty cycle

Front 79

Tissues with low ultrasound absorption coefficients generally have

Back 79

a high water content

Front 80

Is ultrasound effective for treating muscles?

Back 80

generally, no, because they have a relatively low absorption coefficient

most muscles are also larger than the transducers (or twice the transducer area), thus treatment would not be efficient

may be suitable for treating/heating small areas of scar tissue within muscles as the scar tissue will have a higher collagen content

Front 81

Does the speed at which the transducer is moved affect the increase in tissue temperature?

Back 81

no

Cameron cites a study where the transducer was moved at 2-3, 4-5, or 7-8 cm/second and all three produced the same temperature elevations

Front 82

Ultrasound at higher frequency + tissue with higher collagen content =

Back 82

higher temperature increase

Front 83

With 3 MHz ultrasound vs. 1 MHz ultrasound, depth of penetration is _______ but maximum temperature achieved is ______

Back 83

lower

higher

Front 84

An intensity ______ lower should be used when applying 3 MHz ultrasound than when applying 1 MHz ultrasound.

Back 84

3 to 4 times

Front 85

To increase the total amount of ultrasound energy being delivered, what must be increased?

Back 85

duration or intensity

Front 86

All other parameters being the same, what variable produces the greatest increase in temperature?

Back 86

(higher) intensity

Front 87

On average, soft tissue treated with ultrasound at frequency of 1 MHz and intensity of 1 W/cm sq increases in temperature _____ per minute.

Back 87

0.2 degrees Celsius

Front 88

Where is the highest thermal effect generally produced with ultrasound?

Back 88

at the soft tissue-bone interfaces where reflection is the greatest

Front 89

What is ultimately used to determine the ultrasound intensity used?

Back 89

patient's report of warmth

thus decreased sensation should be a contraindication for thermal (continuous) ultrasound

Front 90

What will the patient feel if the ultrasound intensity is too high?

Back 90

a deep ache from overheating of the periosteum

intensity must be turned down to avoid burning the tissue

Front 91

Pulsed ultrasound is particularly effective during the inflammatory phase because:

Back 91

it affects macrophage responsiveness and macrophages dominate during inflammatory phase

Front 92

There is much ambiguous information concerning the effectiveness of ultrasound, but there is one clinical use for which there is strong, high-quality evidence. What is it?

Back 92

use of low-intensity, pulsed ultrasound for healing fractures treated nonoperatively

there is strong evidence that ultrasound promotes fracture healing

Front 93

How does increasing temperature of soft tissue promote its extensibility?

Back 93

increases length gained for same force of stretch, while simultaneously

reduces risk of tissue damage

Front 94

How should stretching be used in conjunction with thermal ultrasound?

Back 94

stretching during heating and maintained 5-10 minutes after application while tissue is cooling
(plastic deformation)

Front 95

Despite conflicting studies, what seems to be the effective ultrasound treatment parameters for wound (dermal ulcer) healing?

Back 95

- 20% duty cycle
- 3 MHz frequency
- 0.8-1.0 W/cm sq intensity
- 5-10 minutes

Front 96

How are wounds treated with ultrasound?

Back 96

- around the perimeter

- directly on the wound if covered with an ultrasound coupling sheet or done underwater

Front 97

How should ultrasound be applied during the acute phase of tendon inflammation?

Back 97

- pulsed mode

- low intensity (0.5-1.0 W/cm sq)

Front 98

How should ultrasound be applied to assist in resolution of chronic tendinitis?

Back 98

- continuous

- high enough intensity to increase tissue temperature

- in conjunction with stretching

Front 99

Based on the few available studies, ultrasound parameters for tendon healing should be:

Back 99

- low-dose (0.5-1.0 W/cm sq)
and
- pulsed

interestingly, in one study (Warden, et al.) use of NSAIDs cancelled the positive effects of ultrasound on tendon repair

Front 100

What is transosseous ultrasound?

Back 100

application of ultrasound to a fracture via a metal pin inserted in the bone approximately 1 cm from the fracture or with implanted transducers

shown to decrease fracture healing time, increase bone mineral density, and improve lateral bending strength in the healing fracture

Front 101

Parameters for ultrasound facilitation of fracture healing?

Back 101

- very low dose
- 1.5 MHz frequency
- 20% duty cycle
- 0.15 W/cm sq intensity
- 15-20 minutes

Front 102

What form of ultrasound has potential benefit for carpal tunnel syndrome?

Back 102

pulsed

continuous has generally not been recommended for treating carpal tunnel because of the risk of adversely impacting nerve conduction velocity by overheating

Front 103

What advantages does transcutaneous drug delivery have over oral administration or injection?

Back 103

- higher initial drug concentration at delivery site
- avoids gastric irritation
- avoids first-pass metabolism by liver

- avoids pain, trauma and infection risk of injection
- allows delivery to a larger area than injection

Front 104

Drugs delivered by phonophoresis become ________

Back 104

systemic

and any contraindications to systemic delivery also apply

Front 105

How do you select a sound head?

Back 105

choose one that has an ERA approximately half the size of the treatment area

Front 106

Recommendations for phonophoresis

Back 106

- pulsed 20% duty cycle
- 0.5-0.75 W/cm sq intensity
- 5-10 minutes

- drug preparation should also effectively transmit ultrasound

Front 107

Reduce ultrasound intensity in areas with ______ _____ or if _______________

Back 107

superficial bone

patient complains of any increase in discomfort

Front 108

How do standing waves affect blood flow?

Back 108

they can cause blood cell stasis (lack of flow)

the plasma and RBCs will separate and band in the vessels, this reverses with cessation of ultrasound

however, the endothelial lining of the blood vessels is also damaged, and the damage remains even after treatment stops

Front 109

How are standing waves prevented?

Back 109

keep the transducer moving

Front 110

When using continuous ultrasound with the goal of heating tissues, the patient should feel it within ______

Back 110

2-3 minutes

but should not feel increased discomfort at any time

Front 111

If using continuous ultrasound in an area with superficial bone, how does that affect the intensity?

Back 111

a slightly lower intensity should produce warmth, as the ultrasound reflected by the bone will cause a greater increase in temperature

Front 112

What intensity is most often used when applying ultrasound for nonthermal effects?

Back 112

0.5-1.0 W/cm sq

Front 113

What is the maximum treatment area for ultrasound?

Back 113

approximately 4 times the ERA of the transducer

anything larger than that (like an entire lower back) will have areas cooling while other areas are still being treated or have yet to be treated

Front 114

What is electromagnetic radiation? ***

Back 114

- electric and magnetic fields oriented perpendicular to each other

[electromagnetic energy is one of the 5 forms of energy in nature (along with chemical, mechanical, nuclear, and thermal)]

Front 115

How is the electromagnetic spectrum categorized? ***

Back 115

according to frequency and wavelength

Front 116

What is the relationship between frequency and wavelength? ***

Back 116

they are inversely proportional

(i.e., the higher the frequency, the shorter the wavelength, and vice versa)

Front 117

Between infrared, ultraviolet, and visible light, which has the longest wavelength? The highest frequency? ***

Back 117

- infrared

- ultraviolet

Front 118

At what speed does visible light move through a vacuum? Ultraviolet light? ***

Back 118

trick question

they both move at the same speed (the speed of light) through a vacuum, as does the rest of the energy in the electromagnetic spectrum

Front 119

What is the speed of light in a vacuum? ***

Back 119

299,792,458 metres per second
186,282 miles per second

Front 120

What does LASER stand for? ***

Back 120

Light
Amplification by
Stimulated
Emission of
Radiation

Front 121

What are the two broad types of medical laser? ***

Back 121

hot or cold

Front 122

What is a hot laser? ***

Back 122

a laser which is capable of destroying tissue and has surgical applications

Front 123

What is a cold laser? ***

Back 123

a non-thermal laser which is capable of enhancing tissue

Front 124

What are some other names for cold laser therapy? ***

Back 124

LLLT - low-level laser therapy
LPLT - low-power laser therapy

(also soft laser, therapeutic laser, biostimulating laser, medical laser, and laser acupuncture)

Front 125

What types of lasers are used with LLLT? ***

Back 125

LLLT devices include:

- gallium arsenide (GaAs)
- gallium aluminum arsenide infrared semiconductor (GaAlAs)
- helium neon (HeNe)

Front 126

What type of laser is ours? ***

Back 126

gallium aluminum arsenide infrared semiconductor (GaAlAs)

Front 127

Why are lasers given a classification number? ***

Back 127

it tells how much eye damage the laser could potentially cause

Front 128

What laser classification numbers did we discuss? ***

Back 128

1, 1M, 2
3A - eye damage w/prolonged exposure
3B - eye damage with brief use
4

1 = CD player
2 = low-level pointers, etc.

Front 129

What classification is our laser? ***

Back 129

3B

eye damage with brief use

Front 130

What are the key properties of LLLT? ***

Back 130

- monochromatic
- coherent
- collimated

Front 131

Monochromatic =

laser light is _____ color and has _____ wavelength. ***

Back 131

one

one

Front 132

Coherent =

all waves are __ _______ ***

Back 132

in phase

Front 133

Collimated (Directional) =

the laser beam is ________ ***

Back 133

non-divergent

Front 134

What is SLD? ***

Back 134

super luminescent diodes

(a.k.a. supraluminous)

Front 135

What is LED? ***

Back 135

light-emitting diodes

Front 136

What are the differences in light between SLD and LED? ***

Back 136

SLD - high-intensity light

LED - low-intensity light

Front 137

Which operates at a lower frequency, SLD or LED? ***

Back 137

SLD

Front 138

Are SLD and LED monochromatic? ***

Back 138

no

Front 139

Which beam is more collimated, SLD or LED? ***

Back 139

SLD (the beam is narrower than LED, but wider than laser)

Front 140

Which beam is coherent, SLD or LED? ***

Back 140

neither

Front 141

Which is more powerful, SLD or LED? ***

Back 141

SLD (more powerful than LED, but less than laser)

Front 142

What are the levels of tissue penetration for laser, SLD, and LED? ***

Back 142

5 cm
2.5 cm
0.5 cm

Front 143

Which has a longer wavelength, SLD or LED? ***

Back 143

SLD penetrates deeper, thus must have the longer wavelength

Front 144

What type of tissue is SLD used to treat? ***

Back 144

superficial tissue

Front 145

What type of tissue is LED used to treat? ***

Back 145

very superficial tissue due to its 0.5 cm penetration

Front 146

What is a cluster probe? ***

Back 146

a laser diode combined with SLDs and/or LEDs to form a cluster

Front 147

For what type of treatment is a cluster probe used? ***

Back 147

for treating larger areas

Front 148

How is laser power represented? ***

Back 148

rate of energy flow/production (mW)

(usually fixed and set by manufacturer)

Front 149

How is laser power density represented? ***

Back 149

mW/cm sq

power/cm sq

the amount of power per unit area

Front 150

How can one reduce the preset, fixed manufacturer's power setting on a laser? ***

Back 150

use it in a pulsed mode

Front 151

What is dosage with respect to laser? ***

Back 151

energy delivered per unit area

energy (Joules) = Power (Watts) * Time (sec)

J = Ws

Front 152

What is energy density with respect to laser? ***

Back 152

amount of power per unit area

J/cm sq

Front 153

What power and dosage settings do we use for laser? ***

Back 153

we use the manufacturer's preset parameters

manufacturer also sets treatment time

Front 154

What percentage is used for pulsed laser treatment? ***

Back 154

90%

it cannot be further adjusted

Front 155

At what level does cold laser and light energy work? ***

Back 155

photons (light energy) are absorbed at the macroscopic or microscopic level

Front 156

What is a chromophore? ***

Back 156

at the microscopic level, it is the part of a molecule that absorbs light and gives it color

Front 157

What are the effects of cold laser and light therapy? ***

Back 157

- promotes collagen synthesis
- promotes ATP production
- decreases inflammation
- inhibits bacterial growth
- promotes vasodilation
- alters nerve conduction velocity (NCV)--some say it increases it, some say decreases
- increases production of endogenous opiates, reducing pain (endorphins, enkephalins, etc.)
- increases cell proliferation (some WBCs, fibroblasts, osteoblasts, and chondrocytes)
- repairs tissue

Front 158

What is the Arndt-Schultz law? ***

Back 158

states that:
- a certain stimulus is needed to initiate a biological process
- a slightly stronger stimulus may produce greater effects
- beyond a certain point, a stronger stimulus will have a progressively less positive effect
- higher levels will become inhibitory

(somewhat akin to the law of diminishing returns)

Front 159

What are some indications for use of lasers and light? ***

Back 159

- wounds and fractures
- musculoskeletal disorders (bursitis, tendinitis, etc.)
- neurological conditions (neuropathy, neuralgia, etc.)
- pain control
- arthritis
- lymphedema

Front 160

Where should you position the laser to treat for pain control? ***

Back 160

at the acupuncture points

(thus the name "laser acupuncture")

Front 161

What can be done with the laser head if contamination is a concern? ***

Back 161

cover it with saran wrap

the laser can penetrate it and the treatment will still be effective

swab the head with alcohol before and after treatment as well

Front 162

What is gridding with respect to laser treatment? ***

Back 162

using laser to treat (an open wound) 1 to 1.5 cm sq sections @ 15 seconds each

Front 163

What is sweeping with respect to laser treatment? ***

Back 163

using laser to treat (an open wound) along the periphery and within

Front 164

What are some contraindications for laser and light? ***

Back 164

- malignancy
- after recent radiotherapy (within past 4-6 months)
- over hemorrhaging regions
- over eyes
- over thyroid or other endocrine glands
- over abdomen or low back during pregnancy
- over epiphyseal plates in children or fontanels of a baby
- in photo-sensitive patients

Front 165

How is laser treatment usually administered? ***

Back 165

8-10 treatments, typically

QD (every day) or
QOD (every other day

Front 166

Name some sources of electromagnetic radiation. ***

Back 166

natural and manufactured sources

- sun
- earth's magnetic field
- some electrical appliances
- radio, TV, lights

Front 167

What is the inverse square law? ***

Back 167

states that the intensity of waves varies inversely with the square of the distance between the radiant source and the absorbing tissue

at 2X the distance, intensity is 1/4; at 3 feet intensity is cut to 1/9

Front 168

What is the cosine law? ***

Back 168

states that maximum absorption of radiant energy occurs when the source and target are at right angles to each other

Front 169

What is the Bensen-Roscoe Law of Reciprocity? ***

Back 169

states that intensity and duration of dose are inversely proportional

(the machine will have preset power; with a lower-power unit, treat longer and with a higher-power unit, treat shorter)

Front 170

How is the velocity of electromagnetic energy measured? ***

Back 170

V = frequency X wavelength

Front 171

What is the Law of Reflection? ***

Back 171

the phenomenon of throwing back a ray of radiant energy from a surface

Front 172

What is the Law of Refraction? ***

Back 172

the bending of light rays when the beam passes from one medium into another

Front 173

What is absorption of electromagnetic energy? ***

Back 173

the taking in and assimilation of the energy

energy must be absorbed before any physiologic changes can take place

Front 174

Describe UV use in physical therapy. ***

Back 174

use of ultraviolet light (electromagnetic energy) for
treatment

light source, not a heat source

was used some time back, but fell out of favor; is now making a comeback

Front 175

What are some indications for UV therapy? ***

Back 175

- skin disorders (psoriasis, vitiligo, eczema, acne)

- wound healing

Front 176

What are the UV bands? ***

Back 176

UVA - long wave
UVB - medium wave
UVC - short wave

Front 177

Describe UVA. ***

Back 177

- long wave
- penetrates deepest
- safest and produces less erythema
- use with psoralen to increase intensity, but not to the point of UVB

Front 178

Describe UVB. ***

Back 178

- middle wave
- produces most erythema

Front 179

Describe UVC. ***

Back 179

- short wave
- ionizing (can deform cells)
- germicidal
- too strong for use in PT

Front 180

What is the most common UV treatment modality? ***

Back 180

UVA with psoralen (a.k.a. PUVA)

Front 181

Is psoralen used with UVB? ***

Back 181

no, the combination would be too strong and produce burns

Front 182

What are some of the effects of UV radiation? ***

Back 182

- erythema production
- tanning
- epidermal hyperplasia
- vitamin D synthesis
- bactericidal effects

Front 183

What are some contraindications for UV treatment? ***

Back 183

- skin cancer
- most systemic disorders (SLE, TB, renal and hepatic pathology, diabetes)
- fever
- irradiation of eyes

Front 184

What are some precautions for UV treatment? ***

Back 184

- photosensitivity (very pale skin)
- recent X-ray therapy
- photosensitizing medications or supplements (e.g., St. John's Wort)
- if previous dose has not disappeared (skin is still pink or red)

Front 185

What are some of the adverse effects of UV? ***

Back 185

- cancer
- eye damage
- premature aging of skin
- burning

Front 186

What is a strip test? ***

Back 186

used to determine minimal erythemal dose (MED)

strip with 4 holes put on patient's arm, arm under lamp

1st hole uncovered for 120 seconds, then 2nd hole for 60 seconds, then 3rd and 4th for 30 seconds each (total exposure will be 240, 120, 60 and 30 seconds)

patient observes for 24 hours to see which area turns pink or red within 8 hours but disappears within 24 hours--this will be the MED

Front 187

What is SED? ***

Back 187

sub-erythemal dose - no change within 24 hours per the strip test

Front 188

What is MED? ***

Back 188

minimal erythemal dose - the smallest dose producing erythema within 8 hours and disappearing within 24 hours

Front 189

What is a first-degree erythemal dose (E1)?
Second-degree (E2)?
Third-degree (E3)? ***

Back 189

MED * 2 1/2

MED * 5

MED * 10

Front 190

What factors affect UV penetration of skin? ***

Back 190

- wavelength
- intensity of radiation
- power of radiant source
- distance between source and skin
- angle
- thickness of skin

Front 191

Parameters of UV treatment ***

Back 191

- usually begin with lamp approximately 30 inches from skin

- time may be as low as 15 seconds, can increase to 15 minutes

- must wear goggles

Front 192

Describe infrared treatment. ***

Back 192

- superficial, dry heat
- no contact
- effects same as hot pack

Front 193

What types of infrared are available? ***

Back 193

- luminous (red, amber, or white bulb)

- non-luminous (carborundum core)

Front 194

What are some of the effects of IR treatment? ***

Back 194

- increased temperature
- increased vasodilation
- increased metabolism
- decreased muscle spasm

Front 195

What are the indications for IR treatment? ***

Back 195

- seeping wounds
- some skin conditions
- sub-acute/chronic musculoskeletal conditions (strains, sprains, etc.)

Front 196

What are some contraindications for IR treatment? ***

Back 196

- cancer
- acute inflammatory conditions
- fever
- active bleeding
- cardiac instability
- recent X-ray therapy

Front 197

Parameters of IR treatment? ***

Back 197

- lamp approximately 24-36 inches from patient
- perpendicular
- treat for approximately 20 minutes
- patient feedback important

Front 198

What is radiation? ***

Back 198

process by which energy is transferred from a material with a higher temperature to one with a lower temperature without the need for an intervening medium or contact

Front 199

What is compression? ***

Back 199

a mechanical force that increases external pressure on the body or a body part

Front 200

Name three types of compression ***

Back 200

- static (e.g., compression garments)
- intermittent (mechanical)
- sequential (distal to proximal, mechanical)

Front 201

What are some indications for external compression? ***

Back 201

- edema (due to venous insufficiency or lymphedema)
- risk of DVT
- venous stasis ulcers
- post-amputation
- risk of hypertrophic scarring

Front 202

How does compression help resolve edema? ***

Back 202

it increases extravascular hydrostatic pressure, reducing outflow from vessels and causing fluid in the interstitial space to return to vessels

Front 203

What are some causes of edema due to venous insufficiency? ***

Back 203

- obstruction by tumor
- venous valve degeneration
- lack of physical activity
- phlebitis

Front 204

What are some causes of lymphedema? ***

Back 204

- obstruction by tumor
- degeneration of valves
- lack of physical activity
- removal of lymph nodes
- radiation therapy damage

Front 205

Who is at risk of DVT? ***

Back 205

- immobilized patients
- post-surgical patients
- over 50% of all DVTs occur within hospitalized or nursing home patients

Front 206

What is a venous stasis ulcer? ***

Back 206

a tissue breakdown caused by impaired venous circulation

for unknown reasons, frequently occurs on the medial malleolus, accompanied by swelling

not necessarily painful

Front 207

How does compression aid a post-amputation patient? ***

Back 207

prevents stretching of soft tissue due to fluid accumulation and

allows shaping of the residual limb

Front 208

Compression can help prevent _______ scarring after severe burns or injuries. ****

Back 208

hypertrophic

Front 209

What are some contraindications for use of intermittent or sequential compression pumps? ***

Back 209

- heart failure or pulmonary edema
- recent DVT, thrombophlebitis, or embolism
- obstructed lymphatic or venous return
- severe peripheral artery disease or ulcers from arterial insufficiency
- acute local skin infection
- acute trauma or fracture
- significant hypoproteinemia (low protein/malnutrition)
- post vascular surgery
- skin graft

Front 210

What are some precautions for use of intermittent or sequential compression pumps? ***

Back 210

- uncontrolled hypertension
- impaired sensation/mentation
- stroke
- cancer

Front 211

What is one potential adverse effect of external compression? ***

Back 211

too much pressure can impair arterial circulation, causing ischemia

this can impair healing or cause tissue death

Front 212

Name some compression garments. ***

Back 212

- antiembolism stockings
- Thrombo embolic deterrent (TED) hose
- velcro-closure devices (adjustable)

Front 213

Setup for intermittent pneumatic compression pump ***

Back 213

appendage covered with stockinette and placed into an inflatable sleeve

elevate limb

Front 214

For how long and how often may a patient be treated with an intermittent pneumatic compression pump? ***

Back 214

treat for 1-4 hours

treat 3X/week to 4X/day

Front 215

What is the on:off cycle for treatment with an intermittent pneumatic compression pump? ***

Back 215

either 3:1 or 4:1

Front 216

What pressure levels are used for the upper/lower extremities when using an intermittent pneumatic compression pump? ***

Back 216

UE = 30 - 60 mmHg

LE = 40 - 80 mmHg

these are only a guide, however, patient comfort should dictate

Front 217

What should the patient not feel during treatment with an intermittent pneumatic compression pump? ***

Back 217

- tingling
- throbbing
- numbness
- their own pulse

Front 218

Frequency and wavelength are _______ ________

Back 218

inversely proportional

Front 219

Lower-frequency EMR, including ELF waves, shortwaves, microwaves, IR radiation, visible light and UV has what characteristics?

Back 219

- non-ionizing
- cannot break molecular bonds
- cannot produce ions

thus can be used for therapy

Front 220

Higher-frequency EMR such as X-rays and gamma rays has what characteristics?

Back 220

- ionizing
- can break molecular bonds
- can form ions
- can inhibit cell division

therefore is usable only in small doses for imaging or in larger doses for tissue destruction

Front 221

The intensity of any type of EMR reaching the body is greatest when:

Back 221

- the energy output is high
- the radiation source is close to the patient
- the beam is perpendicular to the surface of the skin

Front 222

Clinical effects of EMR are determined primarily by:

Back 222

the radiation's frequency and wavelength range

Front 223

Frequencies of EMR used clinically can be in the _______ range.

Back 223

- shortwave
- microwave
- IR
- visible light
- UV

Front 224

Sunlight includes EMR in the ______ ranges

Back 224

- IR
- visible light
- UV

Front 225

Most light is ______

Back 225

polychromatic (made up of light of various wavelengths within a wide or narrow range)

Front 226

How does laser light differ from other forms of light?

Back 226

it is monochromatic (made up of light that is only a single wavelength)

Front 227

Who introduced the idea of stimulated emission and proposed the possibility of making a powerful light amplifier?

Back 227

Albert Einstein

Front 228

What is a maser?

Back 228

stimulated emission of radiation in the microwave range

Front 229

What are the advantages of hot lasers? (Just FYI, as we use cold laser for therapy.)

Back 229

- narrow beam
- selectively absorbed by chromophores, generating heat in and destroying only tissue directly in the beam
- doesn't damage surrounding tissues
- sterile
- allows fine control
- cauterizes as it cuts
- produces less scarring

Front 230

When and by whom were the first indications of non-thermal effects of tissue healing by low-level HeNe laser discovered?

Back 230

late 60s, early 70s

Endre Mester

Front 231

Gas-tube lasers were eventually superceded by

Back 231

semi-conductor-technology-based photodiodes

Front 232

What types of diodes are available in laser light therapy probes (applicators)?

Back 232

- LEDs
- SLDs
- laser diodes

Front 233

LEDs, SLDs, and laser diodes produce light in the ____ or _____ range of the EM spectrum

Back 233

- visible
- IR

Front 234

What is a cluster probe?

Back 234

use of more than one diode in a probe (applicator)

usually they contain various diodes of different types, wavelengths, and power

Front 235

How is light generated?

Back 235

electricity is applied to excite electrons and move them to a higher valence level

the electrons then spontaneously fall back down to their original level, and as they do, they emit photons of light at various frequencies, depending on how far they fall

Front 236

How are photodiodes constructed?

Back 236

two layers, with P-type material in one layer and N-type material in the other

electrons fall from the N-type to the P-type, photons of various frequencies are emitted

if the diode has mirrored ends, it can also be engineered to produce monochromatic laser light

Front 237

What is the difference between spontaneous emission of light (such as with a light bulb) and stimulated emission of light (such as with a laser)?

Back 237

With spontaneous emission, the electrons rise to and fall from various levels, emitting photons of light of various frequencies

with stimulated emission, all electrons are stimulated to move up to the same level, thus when they fall they emit photons all with the same wavelength

Front 238

Laser diodes produce light that is _______, ______, _______, and ____-_____

Back 238

- monochromatic
- coherent
- directional
- high-intensity

Front 239

LEDs produce light that

Back 239

- may appear to be one color
- is not coherent
- is not directional (spreads widely)
- low-intensity

Front 240

How does the low power of LED affect treatment time?

Back 240

treatment time is longer

and often there are many (>30) LEDs on the applicator

Front 241

SLDs produce light that

Back 241

- is almost monochromatic
- is not coherent
- is not directional (spreads more than laser, but less than LED)
- high-intensity

Front 242

How deeply does IR light penetrate soft tissue? Red light?

Back 242

- 2-4 cm

- only a few millimeters (just through and below skin)

Front 243

How is light intensity expressed?

Back 243

watts or milliwatts

Front 244

What is power density?

Back 244

the amount of power per unit area, expressed as milliwatts per centimeter squared

(mW/cm sq)

Front 245

Laser and other light therapy applicators generally have fixed power, but how can it be reduced?

Back 245

pulsing

Front 246

The power of most laser diodes used for therapy is between ___ and ____ mW and are thus classified _______

Back 246

between 5 and 500 mW

classified 3B

Front 247

When a laser or light therapy applicator includes a number of diodes, the power of the applicator is equal to _______ and the power density is equal to _______

Back 247

the sum of the power of all its diodes

the total power divided by the total area

Front 248

Which laser application has more pronounced effects:
short-duration, high-power doses, or long-duration, low power doses
if they deliver the same total amount of energy?

Back 248

short-duration, high-power doses seem to have a more pronounced effect

Front 249

How is energy expressed?

Back 249

in Joules

energy = power X time
J = W * s

Front 250

What is energy density?

Back 250

a.k.a. fluence

amount of power per unit area

Front 251

How is energy density expressed?

Back 251

in Joules per centimeter squared

J/cm sq

Front 252

What treatment dose measurement is preferred for use in laser/light therapy?

Back 252

energy density

J/cm sq

Front 253

Why do we generally not have to select the treatment time for laser/light therapy?

Back 253

it is already included when the therapist selects either
- energy (W * s) or
- energy density (J/cm sq)

J = power (W) X time (sec)

so energy density =
W * s/cm sq

Front 254

What is a chromophore?

Back 254

the light-absorbing portion of a molecule that gives it color and that can be stimulated by light energy to undergo chemical reactions

Front 255

There is evidence that light has a wide range of effects at cellular and subcellular levels, including:

Back 255

- stimulating ATP production
- stimulating RNA production
- promoting collagen production
- altering synthesis of cytokines involved in inflammation
- initiating reactions at the cell membrane by affecting calcium channels and intercellular communications

Front 256

What is thought to be the primary contributor to the clinical benefits of laser and light therapy, particularly in tissue healing?

Back 256

increased ATP production

Front 257

How is laser and light therapy thought to promote collagen production?

Back 257

by stimulating production of mRNA that codes for procollagen

Front 258

What is important to remember about use of goggles with laser light treatment?

Back 258

the goggles used need to be opaque to the wavelength of the light emitted from the laser being used

goggles need to be marked with the wavelength range they attenuate and their optical density within that band

goggles suitable for one wavelength should not be assumed to be safe at any other wavelength

Front 259

Do eye/retinal damage concerns extend to LED and SLD?

Back 259

no, as these nonlaser light sources are divergent and thus diffuse the light energy so that concentrated light energy would not reach the eye

Front 260

Why is laser/light therapy contraindicated within 4-6 months after radiotherapy?

Back 260

because radiotherapy increases tissue susceptibility to malignancy and burns

Front 261

Although photosensitivity is a concern with laser/light treatment, is really only applies to the ____ range.

Back 261

UV

since increased skin sensitivity to light is generally limited to the UV range of the EM spectrum, only UV irradiation must be avoided in sensitive patients

Front 262

What are some noted adverse affects of laser/light treatment?

Back 262

- transient tingling
- mild erythema
- skin rash
- burning sensation
- increased pain or numbness

Front 263

Since the mechanism of therapeutic action of laser and light therapy is not thermal, why do we have to be concerned with possible burns of patient skin?

Back 263

the diodes used to apply laser or other light therapy will get warm if used for prolonged periods of time

this is more likely to occur with low-powered LEDs that take a long time to deliver a therapeutic dose of energy

Front 264

How do you treat an area that does not have intact skin, is painful to touch, or otherwise doesn't tolerate contact with laser/light therapy?

Back 264

applicator may be held slightly above skin but with the light beams still perpendicular to the tissue surface

Front 265

How is laser/light treatment applied if the treatment area is larger than the applicator?

Back 265

repeat the dose to areas approximately 1 inch apart throughout the entire treatment area

Front 266

How do you select a particular type of diode for treatment?

Back 266

there is much controversy, since there are few studies directly comparing the effects of coherent (laser) and noncoherent (LED and SLD) light

it is not clear if the differing wavelengths, or degree of coherence or collimation have a clinical impact

Front 267

For what types of treatment might LED be most suitable?

Back 267

since they have the most diffuse light with the widest frequency range and are low power individually they are probably most suitable for treating larger, more superficial areas

Front 268

For what types of treatment might SLD be most suitable?

Back 268

since they provide light that is less diffuse and of narrower wavelength than LEDs and are more powerful, they are probably most suitable for treating superficial or moderately deep areas, depending on wavelength

Front 269

For what types of treatment might laser diodes be most suitable?

Back 269

since laser diodes provide light of a single wavelength that is very concentrated, they are probably most suitable for treating small areas and deeper tissues in that small area

Front 270

Laser light wavelengths:

Back 270

- red (600-700 nm)
- IR (700-1,100 nm)

longer wavelength (IR) will penetrate deeper (30-40 mm)
while shorter wavelength (red) will not go as deep (5-10 mm)

also now blue light which has shorter wavelength than red, and is suitable for surface tissue or exposed soft tissue

Front 271

Laser light diode power:

Back 271

each diode somewhere between 5 mW and 500 mW

Front 272

LED power:

Back 272

each diode generally somewhere between 1-5 mW but can be as high as 30-40 mW

one probe (applicator) generally will have 20-60 diodes, but may be up to 200+

Front 273

SLD power:

Back 273

each diode somewhere between 5-35 mW, but may be as high as 90 mW or more

one probe (applicator) generally will have 3-10 diodes

Front 274

In general, low energy densities are thought to be ________, while too high an energy density can be ________ or ________

Back 274

stimulatory

suppressive or damaging

Front 275

Laser/light treatment of acute and superficial conditions should use ______ doses, and for chronic/deeper conditions use ______ doses.

Back 275

lower

higher

Front 276

Why is intermittent compression thought to improve circulation more effectively than static compression?

Back 276

the varying pressure is thought to milk fluids from the distal to the proximal vessels

Front 277

How is it thought that compression helps control scar tissue formation?

Back 277

it is proposed that the warmth produced by compression garments increases the activity of temperature-sensitive enzymes that break down collagen, such as collagenase

Front 278

How is normal balance of fluids maintained in tissues?

Back 278

hydrostatic and osmotic pressure remain in proportion (with hydrostatic pressure just slightly higher)

Front 279

What is hydrostatic pressure?

Back 279

the pressure that pushes fluids out of the blood vessels

Front 280

What is osmotic pressure?

Back 280

the pressure that keeps fluids inside the vessels

Front 281

What determines hydrostatic pressure?

Back 281

blood pressure and effects of gravity

Front 282

What determines osmotic pressure?

Back 282

concentration of proteins inside and outside the vessels

Front 283

Why, under normal circumstances, is hydrostatic pressure slightly higher than osmotic pressure?

Back 283

to produce the small amount of fluid leakage into the tissues that eventually becomes lymph

Front 284

What variables help ensure appropriate amount of leakage into tissues to produce lymph?

Back 284

- healthy diet
- healthy vascular system
- muscular contraction

Front 285

What are the major causes of edema?

Back 285

- venous or lymphatic obstruction
- venous or lymphatic insuffficiency
- increased capillary permeability
- increased plasma volume due to sodium and water retention

Front 286

Edema may also occur following what events?

Back 286

- exercise
- trauma
- surgery
- burns
- infection

Front 287

Why may edema also occur after exercise, trauma, surgery, burns, or infection?

Back 287

acute inflammation associated with these events causes increased vascular capillary permeability

Front 288

Why may pregnancy cause edema?

Back 288

- increased blood volume
- altered venous smooth muscle tone
- increased pressure within veins caused by gravid uterus reducing venous return from the lower body, leading to venous insufficiency

Front 289

What other diseases and medical conditions can cause edema?

Back 289

- congestive heart failure
- cirrhosis
- acute renal disease
- diabetic glomerulonephritis
- malnutrition
- radiation injury

Front 290

Should edema caused by congestive heart failure, cirrhosis, acute renal disease, diabetic glomerulonephritis, malnutrition, or radiation injury be treated with compression? Why or why not?

Back 290

no

in these cases compression is not likely to reduce the edema and may in fact worsen the overall health of the patient

Front 291

What is the primary factor propelling both lymphatic and venous flow?

Back 291

muscle contraction

healthy skeletal muscle activity such as with walking or running or rhythmic isometric muscle contraction provides a milking action to propel blood in the veins back to the heart

Front 292

What can cause venous insufficiency?

Back 292

- lack of physical activity
- dysfunction of venous valves
- mechanical obstruction of veins by tumor or inflammation

Front 293

What is the most common cause of venous insufficiency?

Back 293

phlebitis

Front 294

If limbs are in a dependent position, edema will ______

Back 294

worsen further because of increased hydrostatic pressure caused by gravity

Front 295

Where are lymph nodes concentrated?

Back 295

- axillary
- throat
- groin and
- paraaortic areas

Front 296

Why does fluid flow into the lymphatic system?

Back 296

because concentration of proteins inside lymphatic vessels is generally higher than in the interstitial space

Front 297

Upon what does flow of lymphatic fluid depend?

Back 297

as with other fluids, it depends on muscle activity

Front 298

What factors can cause lymphedema?

Back 298

- decreased levels of plasma proteins (especially albumin)
- mechanical obstruction in the lymphatic system
- abnormal distribution of lymphatic vessels or nodes (e.g., some removed after surgery)
- reduced physical activity

Front 299

How does decreased levels of plasma protein cause lymphedema?

Back 299

the osmotic pressure that normally keeps fluid in the lymphatic vessels is reduced

Front 300

What are normal plasma protein levels?

Back 300

6-8 gm/dL

3.3 gm/dL for albumin

Front 301

When lymphedema is caused by hypoproteinemia, what should be done?

Back 301

the underlying problem needs to be addressed first to prevent further edema

Front 302

Lymphedema can be _____ or ______

Back 302

primary

secondary

Front 303

What is primary edema?

Back 303

congenital disorder of the lymphatic vessels

(e.g., Milroy's disease in which the lymphatic vessels are hypoplastic, aplastic, or varicose and incompetent)

Front 304

What causes secondary lymphedema?

Back 304

- blockage or insufficiency of the lymphatics
- infection
- neoplasm
- radiation therapy
- trauma
- surgery
- arthritis
- chronic venous insufficiency
- lipedema

Front 305

What are the most common causes of secondary lymphedema worldwide? In the U.S.?

Back 305

- filariasis - filarial worms

- result of cancer treatment with lymph node removal or radiation, both of which can cause fibrosis

(also mechanical obstruction, dysfunction of valves, accidental damage during surgery)

Front 306

What are some of the adverse consequences of edema (of any origin)?

Back 306

- impaired ROM
- limitations of function
- pain

Front 307

Persistent chronic edema, particularly lymphedema, can cause

Back 307

collagen to be laid down in the area, leading to subcutaneous tissue fibrosis and hard induration of the skin

this may eventually cause disfiguring and disabling contractures and deformities

Front 308

Chronic edema also increases the risk of ______ because________.

Back 308

infection

tissue oxygenation is reduced

this risk is further elevated with lymphedema because of the protein-rich environment for bacterial growth

Front 309

Advanced chronic lymphatic or venous obstruction may result in:

Back 309

- cellulitis
- ulceration
- partial limb amputation if unmanaged

Front 310

When are the more serious sequelae (cellulitis, ulceration, partial amputation) of chronic lymphatic/venous obstruction more likely to occur?

Back 310

if the pressure of the excess fluid accumulated in the interstitial extravascular spaces causes arterial obstruction

Front 311

Chronic venous insufficiency often causes:

Back 311

- itching due to stasis dermatitis
- brown pigmentation due to hemosiderin deposition

these are commonly seen on the medial lower leg

Front 312

Blood flowing slowly can:

Back 312

coagulate and form a thrombus

Front 313

Which has been found to be more effective in preventing DVTs, heparin or intermittent pneumatic compression?

Back 313

compression has been found to be at least as effective as heparin, if not more so

combining the two may be best of all

Front 314

What is postthrombotic syndrome?

Back 314

characterized by pain, swelling and skin changes in the area of the thrombus

Front 315

What are venous stasis ulcers?

Back 315

areas of tissue breakdown and necrosis that occur in areas of impaired venous circulation

Front 316

What is the mechanism for causing venous stasis ulcers?

Back 316

it is unknown, but possible that the elevation in venous pressure caused by impaired venous circulation leads to endovascular and inflammatory changes which provide the setting for ulcer formation

skin changes associated with inflammation can then cause fibrosis, impaired wound healing, and ulceration

tissue oxygen levels in the area are typically normal

Front 317

What is the treatment of choice for venous stasis ulcers?

Back 317

compression