Thermal Agents Flashcards
Define specific heat
The amount of energy required to raise the temperature of a given weight of a material by a given number of degrees
Define conduction and a few examples
Heat transfer resulting from energy exchange by direct collision between molecules at different temperatures
Examples: hot pack, cold pack, ice massage, contrast bath, paraffin bath
Define Convection and a few examples
Heat transfer through direct contact of a circulating medium with material of a different medium
Examples: whirlpool, fluidotherapy, cold packs that must be struck in order for the chemical reaction to occur
Define Conversion and a few examples
Heat transfer by conversion of a non-thermal form of energy (ex., mechanical, electrical or chemical) into heat
Examples: ultrasound, diathermy
Define Radiation and a few examples
Transfer of energy from one material to another without the need for direct contact or an intervening medium
Examples: infrared lamps, laser, UV lights
How do you calculate the rate of transfer by conduction?
= (area of contact) x (thermal conductivity) x (temperature difference) / tissue thickness
The greater the temperature difference between a heating/cooling agent and the body part it is applied to, the ____ the rate of head transfer.
faster
Materials with high thermal conductivity transfer heat _____ than those with lower thermal conductivity.
faster
The larger the area of contact between a thermal agent and the patient, the ____ the total heat transfer.
greater
The rate of temperature rise ______ in proportion to tissue thickness.
decreases
Is more heat transferred by convection or conduction over the same period of time?
Convection
How does blood circulating in the body transfer heat? Describe how…
Convection
Vasodilation increases the rate of circulation therefore increasing the rate at which the tissue temperature returns to normal
When it comes to conversion what does the rate of heat transfer depend on?
the power of the energy source
4 things that rate of tissue temperature increase depends on
1) The size of the area being treated
2) The size of the applicator
3) The efficiency of transmission from the applicator to the patient
4) The type of tissue being treated
Does conversion require direct contact between the thermal agent and the body?
No
What does the rate of radiation temperature increase depend on?
- The intensity of the radiation
- The relative size of the radiation source
- The relative size of the area being treated
- The relative size of the distance of the source from the treatment area
- The relative size of the angle of the radiation to the tissue
What are the 2 hemodynamic effects of cold?
- Vasoconstriction
- Cold-induced vasodilation
What are 5 neuromuscular effects of cold?
- Decreased nerve conduction velocity
- Increased pain threshold
- Altered muscle strength
- Decreased spasticity
- Facilitation of muscle contraction
Cold _____ metabolic rate.
decreases
Indications for cryotherapy
- Inflammation Control
- Edema Control
- Pain Control
- Modification of Spasticity
- Symptom Management in MS
- Facilitation of Motor Patterns
- Cryokinetics and Cryostretch
7 Contraindications of Cryotherapy
- Cold Hypersensitivity
- Cold Intolerance
- Cryoglobulinemia
- Paroxysmal Cold Hemoglobinuria
- Raynaud’s Disease and Phenomenon
- Regenerating peripheral nerves
- Circulatory compromise or PVD
What is cryoglobulinemia?
Aggregation of serum proteins in distal circulations that form a gel that car impair circulation
What is Paroxysmal Cold Hemoglobinuria?
Hemoglobin from lysed RBCs released into the urine
What is Raynaud’s Disease?
A form of paroxysmal digital cyanosis
What are the precautions of cryotherapy?
- Superficial main branch of a nerve
- Open wound
- Hypertension
- Poor sensation
- Decreased mental ability
- Very young or very old patients
How can cold cause hypertension?
It can cause transient increases in systolic or diastolic BP
Adverse effects of cryotherapy
- Tissue death (most severe)
- Temporary or permanent nerve damage
How does tissue death occur?
By prolonged vasoconstriction, ischemia, or thromboses in smaller vessels
Tissue damage can occur when skin temperature reaches __ degrees F
59
Frostbite occurs when skin temperature drops to below __ degrees F
39
In order to prevent nerve damage, it is important to limit cold application to under __ minutes and above __ degrees F
45
59
Cold packs should be between _ - _ degrees C (32-41 F)
0 - 5
Cold pack cooling units should be __ C (23o F)
-5
Cold pack should be cooled for at least __ minutes between uses and for _ hours or more before initial use
30
2
Which provides more aggressive cooling, cold pack or ice pack at the same temperature? Why?
Ice pack
Ice has a higher specific heat than most gels and it absorbs a large amount of energy when it melts
What is the slush recipe?
3 cups water and 1 cup rubbing alcohol
What is the most important thing to remember when performing an ice massage?
You MUST keep ice cup/ice popsicle moving when in contact with patient’s skin
What is the temperature of the water set to in Controlled Cold Compression Units?
between 10 to 25 degrees C (50 - 77 degrees F)
When it comes to vapocoolant sprays, “_____ is the action, ____ is the distraction”
stretch
spray
What is the purpose of vapocoolant sprays?
to provide a counterirritant stimulus to the cutaneous thermal afferents overlaying muscles to cause a reflex reduction in motor neuron activity and thus a reduction in resistance to stretch
When are cold whirlpools indicated?
in acute and subacute conditions in which exercise of the injured part during cold treatment is desired
What are contrast baths used to treat
Subacute swelling, gravity-dependent swelling, and vasodilation-vasoconstriction response
How does cryokinetics work?
The injured part is numbed to the point of analgesia and then work toward achieving normal ROM through progressive active exercise
Cryokinetic exercises should include what 4 things?
- performed during periods of numbness
- should be pain-free
- progressive in intensity
- concentrate on both flexibility and strength
What is the hemodynamic effect of heat?
Vasodilation
What are the 3 neuromuscular effects of cold?
- Changes in nerve conduction velocity and firing rates
- Increased pain threshold
- Changes in muscle strength
Heat ____ metabolic rate
increases
heat ____ collagen extensibility
increases
5 indications of superficial heat
- Pain Control
- Increased ROM
- Decreased Joint Stiffness
- Accelerated Healing
- Infrared radiation for Psoriasis
6 Contraindications for Thermotherapy Use
- Recent or potential hemorrhage
- Thrombophlebitis
- Impaired sensation
- Impaired mental ability
- Malignant tumor
- Infrared irradiation of the eyes
Precautions for Thermotherapy Use
- Acute injury or inflammation
- Pregnancy
- Impaired circulation
- Poor thermal regulation
- Edema
- Cardiac insufficiency
- Metal in the area
- Open wound
- Where topicals have recently been applied
- Demyelinated nerves
4 Adverse Effects of Thermotherapy
- Burns
- Fainting
- Bleeding
- Skin and eye damage from Infrared irradiation
Excessive heat can cause ______ denaturation and ___ death
protein
cell
When does protein denaturation occur?
at 45 degrees C (113 degrees F)
Cell death occurs when cells maintains __ degrees C for __ minutes or __ degrees C for __ minutes
43 for 60
46 for 7.5
Hot packs are stored in hot water kept at about __ - __ degrees C
70-75
Hot pack should be reheated for at least __ minutes between uses and for _ hours or more before initial use
30
2
