Ultrasound/Laser/cryo (wk 3) Flashcards
What is ultrasound?
high frequency sound waves are transmitted through a wand or probe into the body and lead to vibrations of the molecules in the body
Expansion and compression of what in the ultrasound produces the sound waves?
Crystal
T/F The crystal creates a uniform intensity of the beam.
False, not perfectly uniform, and does not expand and contract uniformly leading to nonuniformity of intensity of the beam
How do you reduce the standing waves created by reflection of the ultrasound head?
Keep sound head moving
Where is absorption of ultrasound highest?
in tissues of greater density (lig/tendons)
What is attenuation of ultrasound energy?
measure of decrease in sound energy as the sound wave travels through different tissues
What frequency do you use if you are treating a superficial tendon or ligament?
3 MHZ = up to 2.5 cm deep
What frequency do you use when you are treating a deeper quad muscle?
1 MHz = up to 5 cm deep
What is the duty cycle of US?
– fraction of time the US energy is on over one pulse period (time on + time off)
What is the duty cycle for continuous US?
100%
What is the duty cycle for pulsed US?
20%, 50%, 100%
What are the proposed mechanism for use of US?
a. Modulate pain
b. Increase connective tissue extensibility
c. Reduce muscle spasm
d. Increase tissue temperature
e. Increase blood flow
f. Facilitate healing
Contraindication or precaution of US:
Impaired circulation
Contraindication
Contraindication or precaution of US:
impaired cognitive function
Contraindication
Contraindication or precaution of US:
breast implants
precaution
Contraindication or precaution of US:
absent sensation
Contraindication
Contraindication or precaution of US:
cancer
Contraindication
Contraindication or precaution of US:
healing fracture
precaution
Contraindication or precaution of US:
joint cement
Contraindication
Contraindication or precaution of US:
open epiphyseal plates (growth plates)
precaution
Contraindication or precaution of US:
directly over plastic components
Contraindication
Contraindication or precaution of US:
over vital areas (brain, eyes, heart, ear, reproductive organs)
Contraindication
Contraindication or precaution of US:
acute inflammation
precaution
Contraindication or precaution of US:
pregnancy
Contraindication
What is the goal of thermal (continuous) us?
Increasing tissue temperature through friction (aka vibration) between molecules (1-5cm depth dependent on frequency)
Proposed impacts of US? (5)
- Increased pain threshold
- Increased collagen extensibility
- Alteration of nerve conduction velocity
- Increased enzymatic activity
- Increased tissue perfusion
Excessively high temperatures may produce sudden strong ache caused by overheating of periosteal tissue causing what type of pain?
Periosteal pain - reduce intensity, increase treatment surface, add more coupling gel, or remove soundhead
Nonthermal (pulsed) US causes cavitation, what is that?
alternating compression and expansion of small gas bubbles in tissue fluids due to the mechanical pressure waves of the acoustic waves
Do we want stable or unstable cavitation?
we want stable cavitation
unstable cavitation - severe collapse of gas bubbles during compression phase of pulsed US which can results in local tissue damage due to high temperatures
Nonthermal (pulsed) US also causes acoustic streaming, what is that?
forward movement of fluid and ions along boundaries of cell membranes
If criteria for direct contact of US soundhead can not be safely met, what would you do?
immersion technique - for irregular surfaces, sensitive or broken integument
What 4 things do you document when doing intervention?
- Treatment area
- Patient position
- Parameters
- Outcome measure
If you have soft tissue shortening or pain, what parameters of US would you set? duty cycle? frequency? intensity? time?
thermal 100% duty 3 MHZ, 0.5-1.0 W/cm2 1 MHz, 1.5-2 W/cm2 5-10 min
If you have delayed tissue healing and prolonged inflammation, what parameters of US would you set? duty cycle? frequency? intensity? time?
non-thermal 20%,50% 3 MHz, 0.5-1.0 W/cm2 1 MHz, 1.5-2 W/cm2 5-10 min
The amount of laser light energy, light amplification by stimulated emission of radiation, absorbed by biological tissues depends on what?
the wavelength of light
If the laser power is greater than 500mW, what type of laser is it>?
High-intensity laser (hot laser)
Laser Physiological Effects?
- Improved mitochondrial function
- Promotes collagen production- through mRNA production
- Modulate inflammation- through Interleukin and Prostaglandin production
- Inhibit Bacterial growth of biological pathogens
- promotes vasodilation of microcirculation
- Increased nerve conduction velocities
What are the contraindications of laser?
a. Direct eye exposure
b. Pregnancy
c. Malignancy
d. Following acute injury where hemorrhage is possible or suspected
e. Open growth plates
f. Over the thyroid or other endocrine gland
What are some examples that research has shown laser to be weak-moderately beneficial in?
i. Carpal tunnel syndrome
ii. Reducing pain and muscle spasm in patients with fibromyalgia
iii. Myofascial/trigger point disorders
iv. Knee OA
v. Rheumatoid arthritis
vi. Migraine headaches
vii. Myofascial pain syndrome
viii. Tennis elbow
What is the heat/cold transfer from a one object to a another by direct physical contact; effective 1-3cm depth?
conduction
What is the heat/cold transfer by movement of air or fluid moving past a body part; affective 1-3cm depth?
convection
What is the heat/cold transfer from one object to another object by transmission of electromagnetic energy?
radiation
What are the goals of heat (thermo therapy)?
i. ↓ pain and stiffness
ii. Alleviate muscle spasm
iii. ↑ ROM and tissue extensibility
iv. Improve tissue healing by ↑ blood flow
Describe the increased physiological response to local heat on blood flow:
dilation of arteries/arterioles
Describe the increased physiological response to local heat on capillary permeability:
increased capillary pressure
Describe the increased physiological response to local heat on elasticity of nonelastic tissues:
increased extensibility of collagen tissue
Describe the increased physiological response to local heat on metabolism:
every 10 degree celsius increase in tissue temp = 2-3x increase cellular oxidation rate
Describe the increased physiological response to local heat on vasodilation:
release of vasoactive agents