Heating Modalities (infrared modalities)
From almost the beginning of mankind, heat has been used in the treatment of aches and pains. The use of warm fires, hot coals, warm compresses, hot baths and similar modalities has been passed down through the ages as helpful he A L I Ng tools.
Heating moda1ities fall within two sections of the electromagnetic spectrum (inftared and diathermy), as well as in the acoustic spectrum (ultrasound). The major difference between these types of heating modalities is the depths of penetration. Remembering back to the lecture on wavelengths and frequencies, we note that the infrared modalities have extremely short wavelengths and thus have only superficial penetration and their effects limited to the superficial blood vessels and cutaneous nerve receptors. The diathermies have much longer wavelengths, which are capable of penetrating further into the tissues, and are thus considered to be deep penetrating heat. Ultrasound is also considered to be deep penetrating and, as discussed earlier, is the deepest penetrating modality.
Superficial Heat
The inftared modalities, which transfer heat through convection, conduction and radiation.
Deep Heat
Modalities, which penetrate deeper into the tissues where there energy is converted to heat through the resistance of the tissues.
Heat is defined as the type of energy stored in matter as kinetic energy or the energy of movement of the particles. Temperature is defined as the heat energy possessed by matter.
Three Sources of Heat
Chemical exothermic reactions such as instant hot packs, or the burning of coal, wood or gas. Mechanical sources such as fiiction, or ultrasound (soundwaves)
Electrical currents moving against resistance (Joules Law). Electrical energy is converted to heat as it moves through a conductor.
Four Forms of Heat Transmission
Conduction. Conduction occurs when two or more adjacent objects (media) of unlike temperatures are placed in contact and a state of energy exchange occurs. Heat is transferred (conducted) from the warmer to the cooler object by the process of conduction. Examples: hot packs (hydrocollator type, chemical gel packs, instant chemical hot packs, hot water bottles, heating pads, Kenny Packs and paraffin baths.
Convection. Convection involves the exchange of heat between a surface and a fluid (liquid or gas) moving over the surface. In general, a fluid medium is used and the body part is immersed. Examples: whirlpool baths, fluidotherapy, Hubbard tank, sitz bath, and contrast baths.
Radiation. Radiation is the transmission of heat without the intervening medium being warmed. Examples: longwave (non-luminous) IR and shortwave (luminous) IR.
Conversion. Heat energy can be generated by the conversion of one form of energy into heat such as an electric heater where electrical energy is passed through a wire with high resistance, through fiiction where mechanical energy is converted to heat, vibration where mechanical energy converted to heat (ultrasound), and in electrical current modalities where high tTequency currents are used to convert electrical energy into heat (diathermy- shortwave, longwave and microwave).
Physiologic Effects of Heat
The primary effect of the use of heat is considered thermal. This increase in local temperature further increases the heating effects, which in turn precipitates three basic reactions: an analgesic or calming effect, an increase in local metabolism, and some sedation of sensory nerves. As local metabolism increases this further increases local temperature and gives rise to the release of histamine and histamine-like substances, which results in arteriolar vasodilation. The overall effects of heat application vary according to the intensity (temperature), concentration of application, duration, wavelength and the vascularity of the area. Short periods of heat, where there is little or no build up of heat, seem to have little, if any, therapeutic effect.
Effects of local Heat Application
Increased superficial local temperature
Increased local metabolism
Vasodilation of arterioles and capillaries
Increased local blood flow and hyperemia (increased blood in part of the body)
Increased leukocytosis and phagocytosis
Increased capillary permeability
Increased lymphatic and venous drainage
Increased metabolic wastes
Increased axon reflex activity
Increased elasticity of soft tissue (muscle, ligaments, joint capsules)
Analgesia through increased threshold of pain receptors, the pain gate, and local Enkeph**** production
Increased formation of edema
Decreased muscle tone
Decreased muscle spasm through decreased muscle spindle
Perspiration
Systemic Effects of Heat Application
Increased oxidation
the rate of oxidation
Increased circulation
Increased heart rate- for every 1°F of temperature increase there is a corresponding increase in pulse rate of 10 beats.
Hypotension- as more blood flows to the area of heat application, overall blood pressure levels drop.
Increased perspiration Increased urine production
Indications for Heat
Heat is indicated in subacute and chronic conditions where the following are desired:
-Thermal effects
-Pain relief or sedation
-Decrease myospasm as the heat increases the stimulus threshold of the muscle spindle -Lengthen muscle tissue
-Increase joint motion
-Assist in resolution of the inflanunatory stage through increased blood flow, fi leukocytes, fi phagocytes, and fi lymphatic and venous drainage, however, care must be taken not to heat for so long as to increase edema formation, or increase metabolic wastes, as this would be counterproductive.
-Or where increased phagocytosis is indicated, as in skin abscess or boil. Inflanunation is the normal response of the tissues to the presence of bacteria. The' principle features are vasodilation, exudation of fluids into the tissues, and increase in the concentration ofWBC's and antibodies in the area. Heating the tissues augments these changes and reinforces the body's normal mechanism for de****g with the infected organisms. (Clayton's Electrotherapy)Consensual heat vasodilation (increased blood flow in areas remote to application site) such as the use of deep heat over the low back to increase circulation in the lower extremities of a patient with peripheral vascular disease. Note: This increased circulation is transient.
Specific Conditions: Heat may be used on the following conditions: subacute or chronic; sprain/strain, contusion, fractures; subacute or chronic inflanunatory conditions such as: arthritis, capsulitis, bursitis, tendonitis, tenosynovitis, neuralgia, neuritis, radiculitis, myalgia, myositis, or myofascitis; Catarrhal (head/throat mucus membrane inflanunation) sinusitis, bronchitis; urogenital/gynecological: prostatitis, epididimitis, pelvic inflammatory disease, menstrual cramping; and in skin conditions such as foIliculitis, boils, and abscesses. Bells Palsy, Raynaud's.
Whether or not a patient has responded positively to heat application cannot always be determined immediately. Most patients like the feel of heat. However, how the patient feels several hours after heat application gives us a better indication of the overall benefit of heat application. Common usage of heat in the chiropractic setting is prior to the adjustment, pre*stretching, or pre ROM exercise, where we desire to reduce pain, soften soft tissues, and relax the patient.
Contraindications for Heat Modalities
-Deficient vascular system either peripheral vascular diseases due to organic disease or advanceC cardiovascular disease
-Areas of diminished sensation (over scars, diabetic neuropathies)
-Malignancy in the area (increased metabolism may increase tumor activity)
-Patients with bleeding tendencies (hemophilia, peptic ulcers, heavy bleeding of menstruation) -Active tuberculosis
-Over the low back or pelvis during pregnancy
*-Over deep inflammatory processes especially when suppuration exists -Acute stage of injury, or edema
-The very old, young or debilitated individuals
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Originally Posted by Doc.Sust
