Following completion of this chapter, the student will be able to:
Explain why cryotherapy and thermotherapy are best classified as thermal energy modalities.
Differentiate between the physiologic effects of therapeutic heat and cold.
Describe thermotherapy and cryotherapy techniques.
Categorize the indications and contraindications for both cryotherapy and thermotherapy.
Select the most effective conductive energy modalities for a given clinical diagnosis.
Explain how the clinician can use the conductive energy modalities to reduce pain.
Of the therapeutic modalities discussed in this chapter, perhaps none are more commonly used than heat and cold modalities. As indicated in Chapter 1, the infrared region of the electromagnetic spectrum falls between the diathermy and the visible light portions of the spectrum in terms of wavelength and frequency. There is confusion over the relationship between electromagnetic energy and conductive thermal energy associated with the infrared region. Traditionally, it has been correct to think of the infrared modalities as being those modalities whose primary mechanism of action is the emission of infrared radiation for increasing tissue temperatures.1,2 Warm objects emit infrared radiation. But the amount of infrared energy that is radiated from these objects is negligible. These modalities operate by conduction of heat energy, so they are better described as conductive thermal energy modalities. The conductive thermal energy modalities are used to produce a local and occasionally a generalized heating or cooling of the superficial tissues.
Conductive thermal energy modalities are generally classified into those that produce a tissue temperature decrease, which we refer to as cryotherapy, and those that produce a tissue temperature increase, which we call thermotherapy. Cryotherapy treatment techniques include ice massage, cold hydrocollator packs, ice packs, cold whirlpools, ice immersion, cold spray, cold compression, cryokinetics, and whole- or partial-body cryotherapy. Thermotherapy treatment techniques include warm whirlpool, warm hydrocollator packs, paraffin baths, Fluidotherapy, and ThermaCare wraps.
Luminous infrared and nonluminous infrared lamps are classified as electromagnetic energy modalities. While the wavelength and frequency of the energy emitted by these modalities are similar to the other thermotherapy and cryotherapy modalities, the mechanism by which the infrared lamps produce a tissue temperature increase involves a completely different type of energy. Their mechanism of energy transfer is through electromagnetic radiation, thus explaining why they are classified as electromagnetic energy modalities. However, since they are used for increasing superficial temperature and have wavelengths and frequencies similar to the other cryotherapy and thermotherapy techniques, they will also be discussed in this chapter.
MECHANISMS OF THERMAL ENERGY TRANSFER
Easy application and convenience of use of cryotherapy and thermotherapy modalities provide the clinician with the necessary tools for primary care of injuries. Heat is defined as the internal vibration of the molecules within a body. The transmission of heat occurs by three mechanisms: conduction, convection, and radiation. A fourth mechanism of heat transfer, conversion, is discussed ...