Random A
A transmission medium must be used due to what aspect of attenuation?
Reflection. 100% of US waves are reflected unless a medium such as US gel is used.
List the modes of thermal transfer. (5)
Conduction, Convection, Conversion, Radiation, Evaporation.
T/F. Thermotherapy should be always used on patients with acute rheumatory inflammatory disorders
False. Can use heat but with caution.
How deep have temperature changes been reported during the application of cryotherapy.
1-4 cm.
Adipose tissue will also affect depth.
What are modalities of conduction?
Ice packs, hot packs, paraffin baths, etc.
When would you use pulsed vs continuous ultrasound?
What percent duty cycle should be used with pulsed US?
Pulsed: to increase/accelerate tissue healing. 20% duty cycle.
Continuous: to increase tissue temperature and soft tissue extensibility.
Give an example of evaporation. What modality uses thermal transfer of evaporation?
Sweating.
Vapocoolant sprays.
State the recommended use for cryotherapy for pain control. How long will it last?
10-15 minutes on ice, will give 60+ minutes of pain relief.
Discuss evaporation.
A material must absorb energy to change from liquid to gas. Evaporation of sweat cools the skin.
State the correct paraffin application protocol.
Stored at 126 degrees F.
Remove jewelry, wash hands.
With fingers apart, dip 5x, not touching bottom.
Wrap with cellophane, towel.
15 minute treatment.
What are the three contraindications for cryotherapy.
Cold hypersensitivity/cold intolerance.
Area over a regenerating peripheral nerve.
Area of compromised circulation or PVD.
Why is it required to move the US head, rather than keep it on one spot?
Nonuniform Heating/Nonuniform Output Ratio (peak intensity to average intensity - 1:6)
Thickness of tissue layers and variability of absorption.
May cause cavitation.
What are the contraindications of US? (5)
Malignant tumor, Pregnancy, Joint cement or Plastic components, Pacemaker, Thrombophlebitis
What thermal agent is an example of radiation?
Infrared light.
T/F. Both heat and cold increase pain threshold through the pain gate theory.
True.
What is radiation?
Transfer of heat energy without contact or intervening medium.
State the correct moist heat application protocol.
Canvas covered silicone gel pack heated to approx.175 degrees F
Inspect area to be treated, remove jewelery
Position for comfort and support
6-8 layers between pack and pt.
Give call BELL, check on patient in 5 minutes
20 minute treatment
Contact PT prior to application if:
D/C cryotherapy if:
There is skin irritation from previous session, patient had hypersensitivity to cold with previous application, or health status has changed.
Skin blanches or blisters during treatment, or rash appears during treatment.
What is the sequence of sensation when applying cryotherapy? (5)
Intense cold
Burning
Aching
Analgesia
Numbness
What are the two frequency options for US? Give the correct units. What depths do these frequencies reach?
1.0 MHz will reach up to 5cm.
3.0 MHz will reach up to 1-2cm.
Can sometimes be preset to 3.3 MHz on certain machines.
What intensity is used for pulsed ultrasound? Use correct units.
Between 0.5 and 1.0 W/cm2. US for tissue healing is most effective at 0.5 W/cm2.
What are the precautions of US? (4)
Breast implants, fractures, acute inflammation, epiphysial plates.
What is conversion?
Conversion of nonthermal energy such as mechanical, electrical or chemical to thermal energy.
Not reliant on temperature of physical agent, but instead on the power of the energy source.
Discuss the hemodynamic affect of heat.
Vasodilation occurs where heat is applied and also, to a lesser degree, to distal areas
This distant effect may be used to increase blood flow to areas where it would otherwise be unsafe. Ex. Over an ulcer
How long do you apply ice to reduce spasticity? How long will the ice decrease spasticity for?
10-30 minute application. 60-90 minutes relief from spasticity.
Our core body temperature is regulated by what center of the brain?
Hypothalamus.
What intensity is used for continuous US? Use correct units.
Between 0.5 and 2.0 W/cm2. Depends on the frequency. The higher the frequency, the lower the intensity must be.
Discuss contrast bath.
A systematic review of research found evidence that contrast bath may increase superficial blood flow in order to increase flexibility and decrease pain without increasing edema.
Warm: 105 degrees
Cold: 55 degrees
Warm 3 minutes, Cold 1 minute, 5 times and then end with warm.
Through what mechanisms does our body maintain homeostasis/constant core temperature??
Vasodilation / vasoconstriction
Shivering
Sweating
What is conduction?
Result of energy exchange by direct contact between two materials at different temperatures.
Heat is conducted from the material at the higher temp to the lower until temperatures become equal.
State the four contraindications of thermotherapy.
Recent or potential hemorrhage: is it bruised, warm?
Thrombophlebitis: blood clot/is the calf swollen or unusually tender?
Impaired sensation or mentation
Malignancy: cancer presentHow does cryotherapy decrease inflammation? How long is the recommended interval?
Cryotherapy can control acute inflammation through decrease in metabolic reactions.
15 minutes.
What is attenuation? What are the three things that cause attenuation?
Attenuation is a measure of the decrease in ultrasound intensity as the ultrasound wave travels through the tissue.
It is the result of: Absorption (conversion of sound waves to heat/makes up about half of attenuation), Reflection, Refraction (occurs at tissue interfaces and where there are changes in density of tissue)
What thermal agents are examples of conversion?
Ultrasound, diathermy, chemical ice pack.
Does nerve firing rate increase or decrease with elevated muscle temperature of 108.
Decrease. Contributes to a decrease in muscle spasm, but also decrease in muscle strength.
Discuss convection. Give examples.
Heat transfer occurs with direct contact between a circulating medium and another material of a different temperature. Because of the circulation, different particles are constantly warming the area so transfers more heat in the same period.
Ex. Whirlpool, Fluidotherapy
Discuss benefit of increase collagen extensibility.
Soft tissue heated before stretching maintains a greater increase in length after stretching force.
Maximum increase is achieved when tissue is maintained at 104-113 degrees F for 5 to 10 minutes of stretching.
What are the five precautions of cryotherapy?
Over superficial main branch of nerve.
Over an open wound.
Hypertension.
Poor sensation or mentation.
Very young or very old due to impaired thermal regulation/communication.
Why are different heat agents used at different temps?
Specific heat.
The amount of energy required to raise the temperature of a material a set number of degrees. Thermal agents with high specific heat are administered at lower temperature than air based agents.
What is cavitation and why can it occur with US?
Is a non-thermal affect of ultrasound, is a stimulated response of expansion and shrinking of micron sized gas bubbles in a sound field. Can be helpful or harmful.
Stable cavitation, the ebb & flow of small changes may contribute to increased cell permeability.
Unstable cavitation, due to high intensity for a long time, causes greater fluctuations; the gas bubbles to grow too large where they violently collapse causing tissue damage. May be due to intensity, or not moving sound head.
Why could new towels or jewelry on a patient effect a treatment?
Metal has high thermal conductivity. Heat will transfer rapidly to and from the metal and could burn the pt.
New towels will be fluffy and likely trap extra air which has poor thermal conductivity. Pt may not feel the heat as much as they should.
Discuss the guidelines for conduction.
The greater the temperature difference between an agent and body part, the faster the rate of transfer.
> area = > total heat. Superficial areas are affected most.
High thermal conductivity transfers heat more rapidly. Metal vs. ice vs. water vs. air. We are looking for a moderate rate of transfer from physical agent.
Ice has higher thermal conductivity than cold water. Ice massage vs. different ice packs with varying levels of water content.
List precautions for heat application. (10)
Acute injury or inflammation. Pregnancy. Impaired circulation/venous return. Poor thermal regulation. Edema. Cardiac insufficiency. Metal in the area. Open wound. Over topical irritants. Demyelinated nerve conditions.
Explain the Hunting Response.
Later reflexive cycling of blood flow is called Hunting Response or cold-induce vasodilation (CIVD).
Most likely to occur in the distal extremities with > 15 minutes at 35 degree F
Inconsistent, Protective response to stabilize core temp.
Blood circulation used which principle of thermal transfer?
Convection. There is a greater risk of thermal injury if blood circulation is impaired.
What is a piezoelectric material?
A material that has the ability to change shape in response to an electrical current or mechanical force.
*The crystal in the US head is a piezoelectric material, but so is bone!*