NO 1163 AEF Topik 2 and 3 Thermal agents 2023.pptx

Topik 2 and 3: Thermal agents – Cold and Heat
NP1163: ELECTROPHYSICAL AGENT
Dr. Hafifi, Physiotherapy, FSK, UKM
1

Learning outcomes
• At the end of the lecture, students should be able to
• Identify the physical properties and the physiological responses of thermal agents.
• Analyse the physiological responses of thermal agents to promote healing.
• Assess the indications, contraindications, and precautions to use thermal agents
• Choose and use the most appropriate thermal agent to obtain desired treatment goals.
2023 NP 1163 EPA Thermal Agents 2

Principles of thermal energy
• Specific heat is the amount of energy required to raise the
temperature of a given weight of a material by a given number of
degrees.
Heat
Weight
material
Number of
degrees

• Different materials used as thermal agents and different body tissues
have different specific heats

Mode of heat transfer
• Conduction
• Heat or Cold pack
• Heat is conducted from the material at the higher temperature to the material at the
lower temperature
• Heat transfer by conduction occurs only between materials of different temperatures
that are in direct contact with each other.

• Guideline for heat transfer by conduction
• The greater the temperature difference between a heating or cooling agent the faster the rate of heat
transfer. Inflamed area response well with cold packs;
• The larger the area of contact between a thermal agent and the patient, the larger energy required to
transfer. Hot pack at the back requires larger size of hot pack
• The rate of temperature rise decrease in a proposition in proportion to the tissue thickness. Shortwave
diathermy is more suitable for thick muscle area such as gluteus maximus rather than hotpack
Therefore, conductive thermal agents are suited to heat or cooling superficial tissue but not when the goal
is to change the temperature of deeper tissue

• Convection
• Heat transfer by circulation of a medium of a
different temperature such as fluidotherapy,
whirlpool and blood circulation
• The thermal agent move to heat or cooling
the area. Ice immersion in a bowl for
inflamed ankle will cold the skin more
rapidly compare to cold pack
• Conversion
• Conversion from one type of energy to
another such as ultrasound (US) diathermy
and metabolism
• Involves the conversion of a non-thermal
form of energy such as mechanical, electrical
or chemical energy into heat.
• US cause vibration in the tissue which
generates friction between the molecules to
increase the temperature and produce heat.

• Radiation
• Heating by radiation involves the direct transfer
of energy from a material with a higher
temperature to one with a lower temperature
without the need for an intervening medium or
contact such as infrared rays (IRR)
• Evaporation
• The evaporation and changes of form from a
liquid to a gas or vapor resulting in decreae of
temperature.
• Vapocoolant spray is heated by the warm skin
of the body, it changes the liquid form to a
vapor at its specific evaporation temperature.
• Evaporation of sweat, which also acts to cool
the body when it is overheated to help the
body to normalize the normal range

The sensation test

Sensory examination
• The evaluation of sensation is highly dependent on the ability and desire of the
patient to cooperate.
• Basic testing should sample the major functional subdivisions of the sensory
systems.
• The patient's eyes should be closed throughout the sensory examination.
• Exam in this order
1.Superficial (Exteroceptive) sensation
2.Proprioceptive(deep) sensation
3.Combined cortical sensations.
• If the superficial sensation is impaired then some impairment is also seen in
deep and combined sensations.
• Sensory tests are done from the distal to the proximal direction

Sensation categories

Pain Perception
• It is also known as sharp/dull discrimination.
• To test this sensation, the sharp and dull end of any objects like a safety pin, a
reshaped paperclip, or neurological pin is used.
• The sharp and dull end is randomly applied perpendicular to the skin, should not
be applied too close to each other or in a too rapid manner to avoid the
summation of impulses.
• The patient is asked verbally to indicate sharp/dull when a stimulus is felt. All
areas of the body should be tested.
• After testing the instrument should be sterilized or disposed.
•

Temperature awareness
• Two test tubes with stoppers are required for this
examination; one should be filled with the cold
water (between 5°C to 10°C) and warm water(
40°C to 45°C).
• It should be taken care that the temperature
should remain within this range for accuracy.
• The test tubes are randomly placed in contact
with the skin area to be tested.
• All skin surfaces should be tested. The patient is
asked to respond hot and cold after each stimulus
application.
• https://youtu.be/7it5E9OBl2k
Touch awareness
• A piece of cotton, tissue, used to perceive the
light touch input.
• Needle and blunt things (pinprick test) used to
perceive the sharp and blunt sensations
• Light touch or stroke is applied in the area to be
tested. The patient is asked to indicate where
he/she recognizes that a stimulus has been
applied.
https://youtu.be/XVOVpq-41BY

Cold therapy

Hemodynamic Effects
• Initial decrease in blood flow
• Cold applied to skin cause immediate vasoconstriction and reduction of blood
flow
• Persist if the duration of cold application less than 20 minutes
Karunakara RC, Lephart SM, Pincivero DM: Changes in forearm blood flow during single and intermittent cold application, J
Onhop Syons Phys Thet Mar; 29(3):177 -L80, 1999

INITIAL REDUCE BLOOD FLOW
• Cold cause vasoconstrictions
• Activation of the cutaneous cold receptors
stimulating the smooth muscle of the blood
vessel walls to contracts
• Cooling also decrease the production of
vasodilator mediators (histamine and
prostaglandins) decrease the vasodilation
• Decrease the tissue temperature also activate
the sympathetic system results in
vasoconstrictions
• Reduce the circulatory rate by increase the
blood viscosity
• Cold reduce temperature and less blood flow to
the injured area

LATER INCREASE IN BLOOD FLOW
• Prolonged cold application cause
vasodilation known as ‘Cold Induced
Vasodilation (CIVD)’
• The temperature cycling with alternating
vasoconstriction and vasodilation called
‘hunting response’
• ‘Hunting response’ mediated by axon reflex
in response to pain of prolonged cold or very
low temperature.
• CIVD likely to occur at the distal extremities
with application MORE THAN 15 minutes of
cold below 1 Celsius
• CIVD can be seen with the redness sign due
to increase the oxyhaemoglobin
concentration of the blood

Neuromuscular effects
• Decreased nerve conduction velocity (NCV)
Decrease nerve temperature results in a decrease of nerve conduction velocity
after 5 minutes of superficial cooling
However, after 20 minutes of cooling NCV take 30 minutes or longer to
recover due to too much reduction in temperature caused by longer duration of
cooling
Cold decrease the NCV for sensory and motor nerves
A- delta fibers shows greatest decrease in cindcution after cold application

• Increased pain threshold
• Decrease the sensation of pain via gate control mechanism, reduction of muscle spasm, or
postinjury oedema
• Cold may provide sufficient sensory input or partially along the spinal cord or decrease pain
sensation
• Reducing oedema can alleviate the pain that results in from the compression of nerves or
other pressure-sensitive structures

• Decreased spasticity
• Due to a decrease of gamma motor neuron
• After prolonged cooling for 10 – 30 minutes due to a decrease in the discharge from
the afferent spindles and Golgi’s tendon
• Decreased metabolic effects
• Cold decrease the rate of all metabolic reactions, including those involved in
inflammation and healing
• The activity of cartilage degrading enzymes, collagenase, elastase, hyaluronidase and
protease is inhibited by decreases in joint temperature
• Cryotherapy is recommended to prevent the reduction of collagen destruction in
inflammatory joint diseases such as osteoarthritis and rheumatoid arthritis

Benefits and uses of cold therapy
Briefly describes the effects of cold therapy on the following conditions
• Control of inflammation
• Control of oedema
• Control of pain
• Spasticity modification

Contraindication
of cold therapy

Cold hypersensitivity
• Causes the patients to develop skin reaction
• Skin shows more pale or redden compare to
surrounding area
Cold intolerance
• Causes severe pain, numbness and color
changes to patients
Please describes and explain why cryotherapy is
contraindicated for the following conditions?
• Paroxysmal cold cryoglobinuria
• Regeneration of peripheral nerve
• Peripheral vascular diseases

• Uncommon aggregation of serum proteins in the
distal circulation when exposed to cold
• Causing local ischemia and then gangrene
• May associate with Systemic Lupus Erythematosus
(SLE), Rheumatoid Arthritis (RA)
Therefore, should check with physician

Raynaud diseases
• Digital Cyanosis due to systemic disorder
• Characterized by sudden pallor, sudden cyanosis and
follow by redness
• Maybe associated with thoracic outlet syndrome (TOS)
or Carpal Tunnel Syndrome (CTS)

Superficial main branch
• Applying cold directly over the superficial
main nerve at the lateral knee or the
radial nerve at the posterolateral elbow
may cause nerve conduction block
• Therefore, one should monitor for the
sign and symptoms such as numbness,
tingling or to discontinue therapy
Open wound
• Should not apply to open
wound because it can
delay the wound healing
reducing the circulation or
metabolic rate
• Inspect the skin closely for
deep wound, cuts or
abrasions

Hypertension
• Cold can cause increases in systolic or diastolic blood pressure, patient with
hypertension should be careful
• Discontinue therapy if the blood level beyond the safe levels
Patients with poor sensations
• The patient cannot report the discomfort the face. The clinicians should
monitors effectively discontinue therapy if the blood level beyond the safe
levels
When treating very young and very old patients
• Be careful as the young and older one frequently impaired thermal regulations

APPLICATION
TECHNIQUES
OF COLD
THERAPY

Cold pack VS Ice pack
COLD PACK
• Filled with gel composed of silica or mixture of saline and
gelatin and covered with vinyl
• Should be cooled for 30 minutes between uses
• Should be cooled for 2 hours or longer before initial uses
• Equipment required
• Various shape of cold pack for different areas of body
• Freezer or specialized cool unit
• Towels or pillow cases for hygiene or insulation
ICE PACK
• Made up of crush ice place in plastic bag
• More aggressive cooling than cold packs because ice has
higher specific heat because ice absorbs a large amount
of energy when it melts and changes from a solid to
liquid
• More insulation should be used when applying an ice
pack due to aggressive cooling
• Equipment required
• Plastic bag
• Ice chip
• Ice chip machine or freezer
• Towels or pillow cases for hygiene or insulation

Ice and cold pack therapy
ADVANTAGES
• Easy to use
• Inexpensive materials and equipment
• Short use of clinician time
• Low level of skill required for application
• Covers moderate to large areas
• Can be applied to an elevated limb
DISADVANTAGES
• Pack must be removed to visualize the
treatment area during treatment
• Patient may not tolerate of the pack
• Pack may not be able to maintain good
contact on small or contoured areas

Procedure to apply cold/ice pack
1. Assess the patient if indicated or contraindicated
2. Remove all the jewellery and clothing from the area to be treated and inspect the area
3. Perform the sensation test
4. Wrap the cold pack with towel
5. Position the patient comfortably, elevating the area to be treated if edema is present
6. Place the wrapped pack on the area to be treated and secure it well with elastic bandages or towel
to ensure the good contact with the patient's skin
7. Leave the pack in place for 10-15 minutes to control pain, inflammation and edema
• 10 minutes is the most effective
• 30 minutes for spasticity control
8. Check every 10 to 15 minutes for any sign of adverse effects
9. Provide the patient with bell or other means to call for assistance
10. When the treatment is completed, remove the pack and inspect the treatment area for any signs
of adverse effects such as rash. It is normal for the skin to be red or dark pink after icing
11. Cold or ice pack application can be repeated every 1 to 2 hours to control pain inflammation.
12. Assess the outcome of treatment

ICE PACK VS COLD PACK
COLD PACK ICE PACK
Ice pack provides more intense training
Ice pack is less expensive
Cold pack is quicker

Ice massage
• Ice cups or frozen water popsicles
• Frozen ice cups made by freezing small paper or
Styrofoam cups of water. To use these, the therapist
holds on to the bottom of the cup and gradually peels
back the edge to expose the surface of the ice and puts
it in direct contact with the patient’s skin.
• Wate popsicles are made by placing a stick or tongue
depressor into the water cup before freezing. When
frozen, the ice can be completely removed from the
cup and the stick used as a handle for applying the ice
• Patients can easily make ice cups or popsicles for home
use

Ice massage
Advantages
• Treatment area can be observed
during application
• Can be used for small and
irregular areas
• Short duration of treatment
• Inexpensive
• Can be apply to an elevated limb
Disadvantages
• Too time consuming for large
areas
• Requires active participation by
the clinician pr patient
throughout the application

Procedure of ice massage application
1. Assess and check if the patient indicated or contraindicated for the treatment
5. Place towels around the treatment area to absorb any dripping water and to wipe away water on
the skin during treatment
6. Rub the ice over the treatment area using small, overlapping circles. Wipe away any water as it
melts on the skin
7. Continue ice massage application for 10-15 minutes or until the patient experiences analgesia at
the site of application. The ice is either rubbed with pressure for 3 to 5 seconds or quickly stroke
over the muscle bellies to be facilitated. This technique is known as quick icing
8. When the treatment is completed, inspect the treatment area for any signs of adverse effects
such as rash. It is normal for the skin to be red or dark pink after icing

Cold compression/Cryocuff unit
• Controlled cold compression units alternately pump cold water and
air into a sleeve that is wrapped around a patient’s limb
• Normal cryocuff don’t have the pump, but have air vent instead to
drain water into sleeve
• Equipment required:
• Controlled cold compression unit/cooler
• Sleeves for appropriate targeted treatment

Cold compression/Cryocuff unit
Advantages
• Allows simultaneous of cold and
compression
• Temperature and compression
force are easily and accurately
controlled
• Can be applied to large joints
Disadvantages
• Treatment site cannot be
visualized during treatment.
• Expensive
• Usable only for extremities
• Cannot be used for trunk or
digits

Cold Compression Unit

The procedure to apply cold
compression/cryocuff
1. Assess the indication and contraindication of the patient
4. Prepare the cold compression device
6. Cover the limb with a stockinette/towel before applying the sleeve
7. Wrap the sleeve around the area to be treated
8. Elevate the area to be treated
9. Apply cooling for 15 minutes every 2 hour for acute swelling
10. Provide the patient with bell for assistance
11. When the treatment is completed, remove the sleeve and inspect the treatment area

Classroom activities:
Please demonstrates the application of
cold therapy for people with joints swelling
(ankle, knee, elbow, wrist and shoulder)

Heat Thermotherapy

Effects of
heat

Superficial heat
• Uses
• Pain control
• Increase ROM
• Decreased joint stiffness
• Accelerated healing

Contraindication
• Acute injury or inflammation
• Recent or potential
haemorrhage
• Thrombophlebitis
• Impaired sensation
• Infrared radiation of the eyes
• Pregnancy
• Impaired circulation
• Poor thermal regulation
• Edema
• Cardiac insufficiency
• Metal in the area
• Over an open wound
Precaution

Adverse effects
• Burns
• Fainting
• Bleeding
• Skin and eye damage

Classroom activities
please explain the following based on
the notes given:
1) Heat effects
2) Uses
3) Contraindication
4) Precaution
5) Adverse effects

Application technique of heating therapy

Heat therapy
• Hot packs
• Paraffin
• Infrared lamps

Hot pack

Procedure of hot packs application
4. Position the patient comfortably
5. Wrap the hot pack in six to eight layers of dry towels. Towel should not removed during the treatment
6. Apply the wrapped hot pack and cover it well for 20 minutes. After 5 minutes, check and inspect the area
being treated for excessive redness, blistering, or other signs of burning
7. Provide the patient with bell for assistance
8. After 20 minutes, remove the hot pack and inspect the treatment area. lt is normal for the area to appear
slightly red and to feel warm to the touch

Hot packs
Advantage
• Easy to use. Inexpensive materials
(packs and towels)
• Short use of clinician's time
• Low level of skill needed for
application
• Can be used to cover moderate to
large areas
• Safe, as packs start cooling on
removal from the water cabinet
• Readily available for patient purchase
and home use
Disadvantage
• Hot pack must be moved to observe
the treatment
• Patient may not tolerate the weight of
the hot pack
• Pack may not be able to maintain
good contact with small or contoured
area
• Active motion not practical during
treatment
• Moderately expensive equipment

Paraffin wax

Procedure application of paraffin wax
1. Assess and check if the patient indicated or contraindicated for the
treatment
2. Remove all the jewellery and clothing from the area to be treated and
inspect the area. Thoroughly was and dry the area to be treated to
minimize contamination of the paraffin
5. Applied the wax via either one of these techniques 1) Dip immersion wrap
2) Dip immersion method 3) Paint method

Dip immersion wrap
1. With fingers apart, dip the hand into the paraffin as far as possible and remove . Advise the patient to avoid
moving the fingers during the treatment because this will crack the paraffin coating. Also, advise the patient
to avoid touching the sides or bottom of the tank because these may be hotter than the paraffin
2. Wait briefly for the layer of paraffin to harden and become opaque
3. Redip the hand, keeping the fingers apart, repeat steps 2 through 5 six to ten times.
4. Wrap the patients 'hand in a plastic bag, wax paper or treatment table paper and then in a towel. The plastic
bag or paper prevents the towel from sticking to the paraffin, and the towel acts as insulation to slow the
cooling of the paraffin. Caution the patient not to move the hand during dipping or during the rest period
because this may crack the coating of paraffin, allowing air to penetrate and the paraffin to cool more rapidly
5. Elevate the extremity
6. Leave the paraffin in place for 10 to 15 minutes or until it cools
7. When the treatment is completed, peel the paraffin off the hand and either replace the paraffin in the
container to melt or discard it

Dip immersion method
1. With fingers apart, dip the hand into the paraffin and remove.
2. Wait 5 to 15 seconds for the layer of paraffin to harden and become
opaque.
3. Redip the hand, keeping the fingers apart.
4. Allow the hand to remain in the paraffin for up to 20 minutes and then
remove it.
5. The temperature of the paraffin should be at the lower end of the range
for this method of application because the hand cools less during
treatment than with the dip-wrap method.
6. The heater should be turned off during the treatment so the sides and
bottom of the tank do not too hot.

Paint method
1. Paint a Iayer of paraffin onto the treatment with a brush.
2. Wait for the layer of paraffin to become opaque.
3. Paint on another layer of paraffin no larger than first layer.
4. Repeat steps 3 through 5 six to ten times
5. Cover the area with plastic or paper and then with towel
6. As with the dip-immersion method, plastic or paper is used to prevent the towel
sticking to the paraffin and the towel acts as insulation to slow down the cooling of
the paraffin
7. Caution, the patient not to move the area during treatment as this may crack the
coating of paraffin allowing air to penetrate and the treatment area cool more rapidly.
8. Leave the paraffin in place for 20 minutes or until cools.
9. When the treatment is completed, paraffin and either replace it in the melt or discard
it.

• For All Methods:
• When the treatment is complete. Peel off the paraffin and either
replace it in the container to melt or discard it
• Paraffin may be sterilized by heating it to 80 'C ',176 'F) and then
allowing it to cool overnight. Its temperature should be allowed to
return to between 45' and 50 'C (773' to 122'I) before it is used again
for treatment

Paraffin wax
Advantages
• Maintains good contact with highly
contoured areas.
• Easy to use.
• Inexpensive.
• Body part can be elevated if using
the dip-wrap method
• Oil lubricates and conditions the
skin.
• Can be used by patient at home
Disadvantages
• Messy and time-consuming to
apply.
• Cannot be used over an open skin
lesion as it may contaminate the
lesion
• Risk of cross-contamination if
reused.
• Part in dependent position for
method

Infrared lamp
5. Allow the IR lamp to warm-up for 5 to 10 minutes so it will reach a stable level of output
6. Position the patient with the surface of the area to be treated perpendicular to the infrared (IR) beam and
about 45 to 60cm away from the source. e. Remember that the intensity of the IR radiation reaching the
skin decreases, with an inverse square relationship, as the distance from the source increases, and in
proportion to the cosine of the angle of incidence of the beam. Adjust the distance from the source and
wattage of the lamp output so that the patient feels a comfortable level of warmth. Measure and record the
distance of the lamp from the target tissue
7. Apply the IR for 20 minutes. Set the time at the machine. After 5 minutes, check and inspect the area being
treated for excessive redness, blistering, or other signs of burning

Continue..
8. Instruct the patient to avoid moving closer to or farther from the
lamp and to avoid touching the lamp since movement toward or away
from the lamp will alter the amount of energy reaching the patient
9. After 20 minutes, remove the IR and inspect the treatment area. lt is
normal for the area to appear slightly red and to feel warm to the touch
10. When the treatment is completed, tum off lamp and dry any
perspiration from the area

Infrared lamp
Advantage
• Does not require contact of the
medium with patient. This reduces
the risk of infection and possible
discomfort of the weight of a hot
pack.
• Also avoids the problem of poor
contact when in highly contoured
areas.
• The area being treated can be
observed during the treatment
Disadvantage
• Infrared radiation is not easily
localized to a treatment area.
• It is difficult to ensure consistent heat
in all treatment areas because the
amount of heat transfer affected by
the distance of the skin from radiation
source and the angle of the beam the
skin, both of which vary with tissue
and may be inconsistent between
sessions

Classroom activities:
Please demonstrates the application of
heat therapy for people with muscle pain
(neck, shoulder, upper back, lower back,
hamstring, calf)

References
Cameron, M.H (2003). Physical Agent in Rehabilitation From Research To Practice. Saunders

NO 1163 AEF Topik 2 and 3 Thermal agents 2023.pptx

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