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Definition

Heat treatments are therapeutic applications of superficial or deep-heating agents to areas of the body.

Purpose

Thermal agents are used therapeutically to:

• decrease pain
• decrease muscle spasm
• decrease muscle tightness and increase flexibility
• prepare joints and muscles for exercise
• increase local blood flow to the area, thus promoting tissue healing

Precautions

Therapeutic heat treatments should not be used in individuals who have bleeding or recent hemorrhage, an acute inflammatory process, or local infection near the point of application. Furthermore, heat treatments should not be used over areas of malignancy, decreased sensation, or vascular disease. Heat treatments also should be used with caution on individuals with heart, lung, or kidney diseases. Deep heat treatments should not be used on areas above the eye, heart, or on a pregnant patient. Deep heat treatments over areas with metal surgical implants should be avoided in case of rapid temperature increase and potential for injury.

Description

There are two type of heat treatments: superficial and deep. Superficial treatments are applied to the skin over the involved area. Depth of heat depends on types of tissue and ranges from 0.19 in (0.5 cm) to 0.39–0.78 in (1–2 cm). Heat depth also depends on amount of fat in the area, as fat is an insulator. There are four different ways to convey heat:

• Conduction is the transfer of heat between two objects in direct contact with each other.
• Conversion is the transition of one form of energy to heat.
• Radiation involves the transmission and absorption of electromagnetic waves to produce a heating effect.
• Convection occurs when a liquid or gas moves past a body part creating heat.

Hot packs, water bottles, and heating pads

Hot packs are a very common form of heat treatment using conduction as a form of heat transfer. Moist heat packs are readily available in most hospitals, physical therapy centers, and athletic training rooms. Treatment temperature should not exceed 131°F (55°C). The pack is used over multiple layers of toweling to achieve a comfortable warming effect for approximately 30 minutes. More recently, several manufacturers have developed packs that may be warmed in a microwave prior to use.

Hot-water bottles are another form of superficial heat treatment. The bottles are filled half way with hot water between 115–125°F (46.1–52°C). Covered by a protective toweling, the hot-water bottle is placed on the treatment area and left until the water has cooled off.

Electrical heating pads continue to be used as a home treatment, but safety and convenience issues limit their use in healthcare settings.

Paraffin

Paraffin, a conductive form of superficial heat, is often used for heating uneven surface of the body such as the hands. It consists of melted paraffin wax and mineral oil. Paraffin placed in a small bath unit becomes solid at room temperature, and is used as a liquid heat treatment when heated at 126–127.4°F (52–53°C). The most common form of paraffin application is called the dip and wax method. In this technique, the patient will dip eight to 12 times and then the extremity will be covered with a plastic bag and a towel for insulation. Most treatment sessions last about 20 minutes.

Hydrotherapy

Hydrotherapy is used in a form of heat treatment for many musculoskeletal disorders. The hydrotherapy tanks and pools are all generally set at warm temperatures. Because the patient often performs resistance exercises while in the water, higher water temperatures become a concern as the treatment becomes more physically draining. Because of this, many hydrotherapy baths are now being set at 95–110°F (35–43.3°C). There are also units available with moveable turbine jets that provide a light massage effect. Hydrotherapy is helpful as a warm-up prior to exercise.

Fluidotherapy

Fluidotherapy is a form of heat treatment developed in the 1970s. It is a dry heat modality consisting of cellulose particles suspended in air. Units come in different sizes and some are restricted to only treating a hand or foot. The turbulence of the gas-solid mixture provides thermal contact with objects that are immersed in the medium. Temperatures of this treatment range from 110–123°F (43.3–50.5°C). Fluidotherapy allows the patient to exercise the limb during the treatment and also massages the limb, increasing blood flow.

Ultrasound

Ultrasound heat treatments penetrate the body to provide relief to inner tissue, thus it is a deep heating agent. Ultrasound energy comes from the acoustic or sound spectrum and is undetectable to the human ear. By using conducting agents such as gel or mineral oil, the ultrasound transducer warms tissue by conversion of sound waves to heat. Some areas of the musculoskeletal system absorb ultrasound better that others. Muscle tissue and other connective tissue such as ligaments and tendons absorb this form of energy very well, but fat absorbs to a much lesser degree. Ultrasound has a relatively long lasting effect, continuing up to one hour.

Diathermy

Diathermy is another deep heat treatment. An electrode drum is used to apply heat to an affected area. It consists of a wire coil surrounded by dead space and other insulators such as a plastic housing. Both short-wave and microwave frequencies have been used in therapeutic deep-heating devices. Prior to ultrasound technology, diathermy was a popular heat therapy of the 1940s–1960s.

Preparation

Before administering any form of heat treatment, nurses and allied health professionals need to assess a patients sensation and sensitivity to heat. The skin over the area to be heated should be clean. When a patient is undergoing any form of heat treatment supervision should always be present, especially in the treatment of hydrotherapy.

Aftercare

Once the heat treatment has been completed, any symptoms of dizziness and nausea should be noted and documented along with any skin irritations or discoloring not present prior to the heat treatment. A one hour interval between treatments should be adhered to in order to avoid restriction of blood flow.

Complications

All heat treatments have the potential of tissue damage resulting from excessive temperatures. Proper insulation and treatment duration should be carefully administered for each method. Overexposure during a superficial heat treatment may result in redness, blisters, burns, or reduced blood circulation. During ultrasound therapy, excessive treatment over bony areas with little soft tissue (such as hand, feet, and elbow) can cause excessive heat resulting in pain and possible tissue damage. Diathermy may produce hot spots, and is contraindicated for patients with metal implants.

Health care team roles

Nurses and allied health care professionals must realize that there are metabolic, vascular, and connective tissue effects secondary to therapeutic heat treatments. When heat is required to deep structures such as deep into a joint, deep heat is appropriate. Superficial heating is variable and depends on area and goal of the heat treatment.

Patient education

Nurses and allied health care professionals may need to provide patients with instructions on home therapeutic treatments. There are many heating agents available commercially which operate either electrically, heated in a microwave, or heated in hot water. Nurses and allied health care professionals need to educate patients on precautions, heating times per day, duration of heating, proper positioning, and any specific instructions related to pathology.

Mark Damian Rossi