PART II: THERMAL AGENTS
Chapter 7: Thermotherapy
Test Bank
1. Which electrophysical agent is capable of generating moist heat?
A. Fluidotherapy
B. Ultrasound
C. Shortwave diathermy
D. Hot pack
2. A proposed physiologic effect on soft tissues resulting from paraffin bath use is a decrease in:
A. Cellular metabolism
B. Vasodilation
C. Joint viscosity
D. Soft-tissue elasticity
3. Fluidotherapy transfers heat to the body by:
A. Conduction
B. Convection
C. Conversion
D. Evaporation
4. Compared with soft tissues other than bone, __________ has the lowest specific heat capacity and
thermal conductivity.
5. The greater the amount of heat within a thermal agent, the higher its __________.
6. Temperatures of a paraffin bath should range from __________ to __________.
7. A clinician elects to use the paraffin dip immersion with wrapping method for a patient with hand
stiffness due to osteoarthritis. The patient notices that the temperature on the paraffin unit thermometer is
54°C (129°F) and is worried that dipping will cause severe pain and possibly a burn. Explain why
immersion in a paraffin bath at a given temperature is unlike immersion in water at the same temperature.
8. Why is application of a hot pack an example of heat transfer by conduction?
9. What is Fluidotherapy?
10. What factors determine the thermal dose when applying a hot pack?
11. Why is it important to measure the temperature differential between a thermal agent (ag) and the
exposed skin (s) prior to treatment?
12. What are the benefits of fluidization in Fluidotherapy?
13. Why is the use of a hot pack contraindicated in an area of thrombophlebitis?
14. A patient presents with wrist stiffness following immobilization of a distal radius and ulna fracture.
Impairments include wrist pain, decreased wrist passive range of motion, and decreased wrist and hand
strength. Discuss the justification for the use of paraffin bath therapy in this case.
15. A patient presents with subacute low back pain secondary to a lumbar muscle strain. Impairments
include lumbar pain, bilateral paravertebral muscle spasm, and decreased active thoracolumbar range of
motion. The patient is overweight at 136 kg (300 lb) for his height of 1.72 m (5 ft 9 in) and is
uncomfortable in prone-lying or side-lying positions or with prolonged sitting. Discuss your considerations
with regard to using a hot pack in this case.
Answer Key Chapter 7
1. D
2. C
3. B
4. Subcutaneous fat
5. Temperature
6. 51° to 54°C (124° to 129°F)
7. Specific heat capacity is the ability of a substance to store or hold heat at a given temperature. Thermal
conductivity is the ability of a substance to conduct or transmit heat. Paraffin has much lower specific heat
capacity and thermal conductivity than water. Because water has a greater ability to store and conduct
heat, it will feel much hotter than a paraffin bath.
8. Conduction is defined as thermal energy exchange between materials of different temperatures by
direct molecular collision. In this example, heat transfer occurs when there is direct contact between the
hot pack, the warmer agent, and the cooler tissues. Energy exchange continues until the temperature and
speed of movement of the materials is equal, or the hot pack has cooled and the tissues have warmed.
9. Fluidotherapy is actually a trademark name of a system designed in 1973 by Ernest Henley. The
device consists of a cabinet containing fluidized finely ground cellulose particles designed for therapeutic
heat delivery. The heated air is circulated through the particles, creating a fluid-like medium. The device
provides dry heating and mechanical sensory stimulation.
10. Factors that determine dose include the size or mass of the hot pack, temperature differential
between the hot pack and the skin before the application, application duration, coupling thickness, and
thermal conductivity of the exposed tissues.
11. Measuring the difference between the thermal agent and the exposed skin (T°ag-s) will provide
information regarding the thermal agent potential to cause a thermal change in the tissues. The larger the
temperature difference between the skin surface and the thermal agent, the greater the capacity of the
agent to either add or subtract heat to and from the tissues will be.
12. The fluidization, or agitation, of cellulose particles around the part provides a massaging effect and
sensory stimulation. It is suggested that this micromassage may help to desensitize hypersensitive skin
areas. The activation of A-beta mechanoreceptors through agitation may also serve as a counterirritant,
lessening pain through spinal gating.
13. Thrombophlebitis is an inflammation in a vein due to a blood clot. It occurs most often in the lower
extremities and may involve superficial or deep veins. A dislodged clot in a deep vein may travel to vital
organs, leading to serious morbidity or death. Pulmonary embolism is a life-threatening example of a clot
that travels to the lungs and blocks blood flow. Heat generated by the hot pack will increase tissue
temperature, vasodilation, and the rate of circulation. Increasing the circulatory rate may cause a clot to
become dislodged.
14. There is evidence to support that a thermal agent such as paraffin bath can reduce joint stiffness and
improve range of motion. The proposed mechanism is an increase in tissue extensibility and decrease in
joint viscosity when combined with passive and active mobilizations and stretching. Heat may also act as
a counterirritant, modulating pain transmission by activating cutaneous thermoreceptors and thus
improving the patient’s ability to function. Paraffin can cover the irregular surfaces of the wrist,
transmitting heat to the entire surface, and can be used at home in conjunction with a home therapy
program.
15. While moist heat pack may be indicated in this case to reduce lumbar pain and muscle spasm, other
concerns are apparent. Subcutaneous fat acts as a thermal barrier with low heat capacity and poor
conduction. Adipose tissue is an insulator and prevents heat from reaching deeper soft tissues such as
muscle; thus, the effect of tissues under the adipose would be minimal. If the patient lies supine and rests
on the pack, higher pressure is created between the pack and tissues. Body weight will accelerate heat
transfer, and local circulation may be reduced through compression, impairing the body’s ability to
dissipate heat. If additional toweling beyond the recommended five to eight layers is used, the patient’s
lumbar position may be so altered by the bulk that the spine will be poorly positioned. When the skin is
inspected after 5 minutes, the patient’s position will be disturbed. It appears that the disadvantages of
using a hot pack, including the safety risk of overheating, will outweigh the benefits in this case.