Thermal Agents: Heat Flashcards
1
Q
Mechanisms of Heat Transfer: Conduction
A
- Transfer of heat between 2 objects that
are in contact with each other - Ex: Hot packs/cold packs, movement of heat through tissue layers
2
Q
Mechanisms of Heat Transfer: Convection
A
- Transfer of heat by the movement of a
medium - Ex: Whirlpool or Air
3
Q
Mechanisms of Heat Transfer: Radiation
A
- Transfer of Energy w/out contact or the
use of a medium - Energy moves through space
- Ex: Laser or UV Light
4
Q
Mechanisms of Heat Transfer: Conversion
A
- One form of energy changed to heat
energy - Ex: Diathermy (electromagnetic energy
changed to heat energy) or Ultrasound
(acoustical energy changed to heat)
5
Q
Mechanisms of Heat Transfer: Evaporation
A
- Loss of heat by changing a liquid to a gas
(endothermic reaction) - Ex: Vapo-coolant spray
6
Q
What is Thermotherapy?
A
- The application of therapeutic heat to the
body, which increases tissue temperature
to between 104 - 115 degrees - Heat is removed from the modality and
absorbed by the body
~ Requires a heat gradient
7
Q
What are the Effects of Heat Application?
A
- Increased Cell Metabolism
- Increased Circulation
- Increased Permeability
- Decreased Tissue Stiffness
- Decreased Pain
- Decreased Muscle Tone and Spasm
8
Q
Effects of Heat Application: Increased Cell Metabolism
A
- Cell metabolism increases 2-3 times for
each increase of 18 degrees - Results of increased metabolism
~ Increased O2 consumption (Bad)
> Can increase secondary damage/
hypoxia
~ Increased Cellular wastes (Bad)
~ Increased tissue temperature (Good)
~ Increased tissue activity (Depends)
> Good during repair and
maturation phases
• Speeds up fibroblasts
> Bad during acute phase
• Inhibits WBC
9
Q
Effects of Heat Application: Increased Circulation
A
- Doubles
- Due to local vasodilation
- Results of increased Circulation
~ Increased cellular waste removal
~ Increased supply of O2, Leukocytes,
Nutrients, and Enzymes
10
Q
Effects of Heat Application: Increased Permeability
A
- Increased Potential for Venous and
Lymphatic drainage
11
Q
Effects of Heat Application: Decreased Tissue Stiffness
A
- Increased Elasticity of Collagen
- Decreased fluid viscosity
~ Ground Substance
12
Q
Effects of Heat Application: Decreased Pain
A
- Increased blood flow = Increased O2 =
Decreased Pain (chemical mediators get
flushed out) - Counter-irritant
- Removal of pain stimulating chemicals
~ Pain - spasm - stasis; removal of one,
removes all
13
Q
Effects of Heat Application: Decreased muscle tone and spasm
A
- Reduction in pain
- Decreased muscle spindle sensitivity
- Reduction of cellular metabolites
14
Q
Heating Factors: Rate of Heating
A
- Rate of Heating
~ Depends on difference between
temperature of modality and tissues
treated
> The greater the difference, the
more rapid the rate of heat
transfer
> If tissue temperature is high, it will
decrease the magnitude of the
gradient - Adipose can be a limiting factor for
heating because it insulates
~ Can be a benefit in terms of
decreasing heat loss after treatment - Pt. needs to be at a resting state or
normal temperature to apply heat
15
Q
Special Considerations for Heat Application
A
- During the first 5-6 minutes of treatment,
the body absorbs heat faster than it can
dissipate it - After 7-9 minutes the body is able to
counteract the heat by moving blood to
the area to cool it
~ Vasodilation - After 20 minutes, when the intensity of
the treatment stays constant superficial
blood vessels constrict (rebound
vasoconstriction: the body’s attempt to
save underlying tissues) - If intensity is too strong during
vasoconstriction, burns will occur
~ Mottling
16
Q
Thermotherapy Indications
A
- Decreased ROM (usually due to scar
tissue) - Subacute Inflammatory Conditions
(repair/maturation) - Pain (increased blood flow)
- Hematoma Resolution
- Edema Removal
~ Increased permeability and
vasodilation = drainage through
venous and lymphatic systems
~ Heat opens the door for osmosis:
moving water into tissues
17
Q
Thermotherapy Contraindications
A
- Acute Conditions
~ Increases Secondary Damage
~ Increases Edema Accumulation - Compromised Circulation
~ Body unable to cool area - Infection/Open Wounds
- Compromised Sensation
~ Body may not sense overheating and
will be less able to protect area
18
Q
Moist Heat Packs
A
- 1cm of effective depth
- Cover pack with a commercial cover and
at least one layer of towel
~ Keeps from burning and clean - Pt. should not be lying or sitting on pack.
This will increase the likelihood of burns
19
Q
Paraffin
A
- For use of small irregularly shaped areas:
fingers and toes - The body part needs to be cleaned first
in order to limit the spread of infection - Post-treatment, the wax will leave the
skin slippery - Immersion Bath
~ Dip the body part up to 12 times, then
immerse - Pack/Wrap Method
~ Dip body part 6-12 times, then wrap
in plastic wrap and a towel
> The first layer should be the
highest to avoid leakage and burns
20
Q
Warm Water Immersion/Whirlpool
A
- 100 - 108 degrees for whole body
- 105 - 112 degrees for extremities
~ The extremities are able to keep cool
more than the body because cool
blood can reach them - Containers should be clean and sanitized
~ Iodine can should added to the water
if an open wound is present - This modality is gravity dependent (body
part lower than the heart) which can
cause swelling to go down
21
Q
Fluidotherapy
A
- Unit contains fine cellulose particles in
which warm air is circulated - The particles will mimic water and form
to the body part simultaneously applying
heat, pressure, and massage
22
Q
Diathermy
A
- Used mostly to heat tissues, but there’s
some non-thermal effects:
~ Microwave Diathermy
> 300 MHz - 300 GHz
> Not used very much
~ Shortwave Diathermy
> 1.8 - 30 MHz
> Mostly used
~ Main difference between the two is
frequency of electricity
23
Q
Downside of Microwave Diathermy (MWD)
A
- Main downside is that it’s much more
likely to cause tissue burns
~ Metal can reflect MWD back towards
tissues
~ Does not penetrate deeply so more
energy is absorbed superficially
~ Increased reflection at tissue
interfaces
24
Q
Production of Diathermy
A
- When electricity flows through a
conductor, a magnetic field is formed
perpendicular to the flow of electricity - SWD generator coverts alternating
current from outlet to SWD frequency
~ Electrical current enters the coil
contained in the drum of the unit and
a magnetic field is produced in the
tissues
25
Q
Thermal Effects of Diathermy
A
- The magnetic field in the tissues causes
charged ions and molecules within the
tissues to oscillate and move
~ The motion causes friction resulting
in heat and increased tissue
temperature
~ Tissues w/ the highest amounts of
water means they have a higher
concentration of electrolytes and
therefore heat the most
> Hamstrings
> Quads
26
Q
Thermal Ultrasound vs. SWD
A
- Ultrasound
~ Can heat tissues 3-5 cm deep
~ Heats small areas
~ Short stretch/thermal window
~ Can sometimes cause pain if area
gets heated too much due to lack of
movement of probe - SWD
~ Can heat tissues 3-5 cm deep
~ Heats large areas
~ Long stretch/thermal window
~ Stays warmer longer
27
Q
Thermal Effects of SWD
A
- Can increase muscle temperature to 104
degrees in 15 minutes - Decay rate is 2-3 times slower than
Ultrasound
28
Q
Non-Thermal Effects of SWD
A
- Not well understood, no sound theories
- Most theories stem from the relationship
between magnetic and electrical fields
~ Thought is that the magnetic field
affects the electricity driven functions
of the cells
> Possibly allows membranes to
repolarize so cell function is
restored
> Fibroblasts, osteoblasts, WBC
29
Q
Advantages of SWD
A
- Stationary Drum: no hot spots and even
heating - No mess
- Can be applied over clothing
- Doesn’t require clinician to be present
the whole time
30
Q
SWD Indications
A
- Pain
- Spasm
- Decreased ROM
- Subacute Inflammation
- Edema
31
Q
Continuous vs. Pulsed SWD
A
- Continuous SWD
~ Not used very much due to the fact
that it tends to heat tissues too fast
causing discomfort and possible
burning - Pulsed SWD
~ Mostly used
~ Alternates between on and off
32
Q
Pulsed SWD Parameters
A
- Pulse width (duration)
~ On time
~ Measured in milliseconds - Pulse Rate
~ Number of pulses per second - Power/Intensity
~ Measured in Watts
~ Function of both pulse width and
pulse rate
> Higher pulse widths and rates
produce more power/intensity =
more healing
33
Q
SWD Contraindications
A
- Not over the eyes, genitals, and
epiphyseal plates in children - Pace maker: effects electrical current
- Pregnancy
- Cancer
- Infection
- Metal implants for MWD
- Diminished sensation
- Circulatory Impairment: won’t be able to
cool down area post-treatment
34
Q
Considering the inflammatory response, when would heat application be most appropriate?
A
- During the repair and maturation phases
because it will speed up the process =
speed up healing - Least appropriate acutely because it will
increase swelling, bleeding, and
secondary damage which will increase
WBC and Hypoxia
