Passive Care Exam 2

What is ultrasound?

acoustical energy that uses sound waves at high frequencies

Higher frequency ultrasound absorbed more rapidly and therefore is used on _ skin

superficial (3.3 mHz)→ ankle, elbow, wrist

Lower frequency ultrasound absorbed slower and is used on _ skin

Deep→1mHz→ quadricep or paraspinals

Acoustic energy uses _ to penetrate the skin

heat

Crystal used in ultrasound is _mm thick (very thin and fragile)

2-3mm

What type of ultrasound is this?

continuous

What type of ultrasound is this?

Pulsed ultrasound

Ultrasound has alternating current that passes through the crystal, this is called _

Reverse Piezoelectric effect (indirect)→ produces high frequency sound waves that result in ultrasound

High pressure wave causes tissue to compress and expand which results in friction and leads to _

heat

What is continuous ultrasound?

100% duty cycle

heat tissues

bone, tendon, ligament, joint, dense so most absorbed

skin and fat are least absorbed

What is an example of continuous ultrasound use?

chronic muscle spasm

What is pulsed ultrasound?

50% and 20% duty cycle

mechanical effect

NO HEAT

What is an example of pulsed ultrasound being used?

Acute ankle sprain

What are the treatment areas for ultrasound?

1. Near field/ fresnel zone→ MAIN TX effect

2. Far field/fraunnofer zone (deeper) increased circulation

What is intensity/amplitude of ultrasound?

Spatial peak intensity→ peak intensity or maximum intensity (watts per cm² )

How do you calculate average intensity?

Isp x duty cycle

What is effective radiating area?

area of sound head that produces energy (size of crystal)

always smaller than size of ultrasound head

What is beam nonuniformity ratio?

variability of beam, ratio of peak intensity/average intensity

Ideal 1:1→2:1- 8:1 is acceptable

lower BNR, the more uniform the intensity

decreased hot spots, comfort/safety

underwater (indirect)

What is conducting media?

air is a poor conductor of ultrasound

gel and gel pads preferred

keep sound head flat against skin (90 degree angle of sound waves)

What is direct vs indirect ultrasound?

Direct→ head in direct contact with patient

Indirect→ uses medium between head and patient

What is the distance for underwater ultrasound?

0.5-3.0 cm

What are the parameters of ultrasound treatment?

1. amplitude of sound waves→ amount of sound energy being emitted by sound head (watts)

dosage is based on amount of energy in a square centimeter

more watts= more heating not greater penetration

2. Frequency→ typically 1-3 mHz

3. Duty cycle→ can be interrupted or continuous

Frequency affects _ at which the greatest amount ultrasound energy is absorbed

DEPTH

What is reflection vs refraction?

Reflection→ reversal of direction of propagation of the ultra sound wave

Refraction→ change of ultrasound wave from straight path when passing obliquely from one medium to another

What benefits can occur at 1 degree celsius?

increased metabolic activity (heating/repair/proliferation) NOT ACUTE!

What are the benefits of 2-3 degrees celsius?

decreased muscle spasm

increased blood flow (repair/proliferation/remodeling) NOT ACUTE

What are the benefits of 4 degrees Celsius?

increased elasticity of collagen (scar tissue)

Which modality is best for muscle spasms?

Russian, biphasic, ultrasound

What is tissue cooling?

Temporary

superficial cools faster than deep

What are the non-thermal effects of ultrasound? TQ

affect tissue healing and later cellular activity via

1. Nano motion or acoustical streaming

2. Stable cavitation

What is acoustic streaming?

movement of fluids along cell membranes due to mechanical pressure exerted by sound waves

increases cell membrane permeability

What is stable cavitation?

rhythmic expansion and contraction of bubbles during repeated pressure changes over many acoustic cycles

facilitates fluid movement and membrane transport

What are the contraindications of ultrasound?

1. Malignancy

2. Hemorrhage

3. Ischemia

4. Thrombus

5. infection

6. gonads

7. eye

8. pelvic, abdominal, and lumbar areas of pregnant women

9. spinal cord after laminectomy

10. plastic and cemented implants

11. near or over electronic implants

12. unknown etiology

What are the risks for ultrasound?

1. bony prominences

2. epiphyseal plate

For ultrasound intensity, do not exceed _

8.0 W/cm²

What is treatment time for ultrasound?

5-8 min

NO more than 15 min

Why does ultrasound emitter need to be moving during entire treatment?

prevents burns

What is phonphoresis?

sonophoresis

sound energy to drive medication into tissue

What is a combination therapy?

1. Ultrasound

2. Electrical stimulation

used for trigger points, epicondylitis, superficial pain areas, decrease adhesions

What is low intensity pulsed US?

LIPUS

stimulation of fracture healing

What is diathermy?

high frequency electromagnetic energy

short wave frequency

What is the more common form of diathermy?

pulsed short wave diatherm

Operator of diathermy must remain _ ft from device

3-6 ft

What are the thermal effects of diathermy?

1. Dipole rotation

2. Ionic oscillation

3. Kinetic energy of rotation

cause friction and heat

What are the physiologic effects of diathermy?

1. Pain relief

2. wound management

3. joint contractures

What are the two types of electrodes and effect for diathermy?

1. Capacitor electrodes produce electrical field

2. Induction electrodes produce magnetic field

What is the capacitive technique?

tissues placed in electric field

greatest absorption in tissues with low water content/fat

areas of low subcutaneous fat

knee, foot, hand, shoulder

plates/pads

What is the inductive technique?

tissues placed in magnetic field

deeper, more fat/obese

muscle, tendon, joint

patients with more subcutaneous fat

drum, cables, garment

What are the indications for diathermy?

1. OA

2. Neck/back pain

3. Ankle pain

4. Dermal wounds

5. MSK injuries

What are the contraindications for diathermy?

1. Loss of sensation

2. electronic implants

3. surgically implanted metal

4. metal in contact with skin

5. COPPER IUDS

6. cancer

7. pregnant

8. hemorrhagic areas

9. ischemic

10. testes

11. eyes

12. open growth plates

What are the risks for diathermy?

pregnant operators need to be 3 ft from device

other patients 10 ft from device

What needs to be done before diathermy treatment?

1. test cold/warm sensation

2. 2-3 cm lay of towels for spacing

3. NO JEWLERY

What are the 4 laws of diathermy?

1. Arndt-Schultz law

2. Grotthuss-Draper law

3. Inverse square law

4. Cosine law

What is the arnold-schultz law?

Dose vs response→ small dose stimulate, high dose inhibit

What is the grotthuss-draper law?

“common sense law”

absorption vs therapeutic effect→ absorption is critical for treatment effect

What is the inverse square law?

Dose vs divergence

distance between bulb and skin

10 cm to 20 cm= 2x distance

inverse of 2= ½
square of ½ = ¼

therefore ¼ as much heat with 2x perpendicular distance

What is cosine law?

lambert’s law

decreased energy if angle is increased

decreased with change from perpendicular

T/F Continuous short wave diathermy is more common than PSWD

false→ PSWD is MC