As one of the oldest treatment modalites, the therapeutic effects of heat have been experienced for several hundred years. In order to use heat in the treatment of deep muscle injury, diathermy treatment is the therapy of choice. Diathermy uses high-frequency electrical currents to heat deep muscular tissues. This heating results in pain relief, increased blood flow, and increased flexibility. Research has demonstrated evidence both for and against the effectiveness of diathermy treatment. Attention must be given, however, to risk factors predisposing some patients to serious adverse effects due to diathermy treatment.
Diathermy: Uses, benefits, and risks
Diathermy refers to the use of high-frequency electrical currents to heat deep muscular tissues. This heat increases the flow of blood to the area, which in turn, speeds up recovery. The term diathermy is a derivative of the Greek words therma, meaning heat, and dia, meaning through. Therefore, the term diathermy literally means heating through.
The therapeutic effects of heat have been recognized for thousands of years, and the practice of diathermy has its roots in therapies utilized in ancient Rome. More than 2000 years ago, Romans built hot-spring bathhouses in order to take advantage of the healing effects of heat. Various methods of heat related therapy have evolved since then. A French physiologist by the name of Arsene d'Arsonval began studying the medical application of high frequency currents in the early 1890s. German physician Carl Franz Nagelschmidt coined the term diathermy and developed a prototype apparatus in 1906. American doctor J.W. Schereschewsky commenced the study of the physiological effects of high-frequency electrical currents in animals in 1925. However, this was only a start, and it took several years for the fundamentals of diathermy to be understood and put into practice.
As one of the oldest modalities of pain relief, heat decreases muscle spasm and improves function. Superficial heat can be provided through the use of hot packs, hot water bottles, hot-moist compresses, electrical heating pads, or chemical/gel packs. Heat can also be provided through immersion in water. All these modalities for the provision of heat convey heat by convection or conduction. These types of superficial heat elevate the temperature of tissues provides the greatest therapeutic effect at 0.5 cm or less from the surface of the skin. On the other hand, the deep heating provided by diathermy is achieved by converting electrical energy to heat. Diathermy increases temperature to depths of 3 to 5 cm. The physiological effects produced by heat include analgesia or relief from pain, increased flexibility of collagenous tissues, reduction of muscle spasm, increase in blood flow, and mental relaxation.
Diathermy is used to treat conditions involving stiff, painful joints, such as arthritis and bursitis. It is also used to treat some pelvic infections and sinusitis. Diathermy is also sometimes used in surgical procedures, where electrically heated probes are used to seal blood vessels in order to prevent excessive bleeding. Physicians can also use diathermy to destroy abnormal growths, like tumors, warts, and infected tissues.
A benefit of diathermy is that is a painless procedure that can be quickly administered in a clinic setting. Another benefit of diathermy is that the treatment relieves pain, which may allow some patients to discontinue pain killers, thus avoiding high costs and adverse side effects.
Diathermy works to alleviate pain and discomfort by heating deep muscular tissue. When heat is applied to the area of concern, blood flow increases and cellular metabolism speeds up. This in turn accelerates tissue repair. The heat created by diathermy also reduces nerve fiber sensitivity, which increases the patient's pain threshold.
There are three general methods of diathermy: shortwave diathermy, ultrasound diathermy, and microwave diathermy. In each method, energy is delivered to the deep tissues, where it is converted to heat. In shortwave diathermy, the body part to be treated is placed between two capacitor plates. High-frequency waves travel through the body tissues between the plates, heat is consequently generated, and inflammation is reduced. This type of diathermy is most often used to treat areas covered with a dense tissue mass, like the hip, and it is also used to treat sinusitis and pelvic infections. The frequency allowed for shortwave diathermy treatment is regulated by the Federal Communications Commission, and most machines function at 27.33 megahertz. In ultrasound diathermy, heat is generated in deep tissues through the use of high-frequency acoustic vibrations. Microwave diathermy uses radar waves to heat the tissue to be treated. This form of diathermy is the easiest to use, but the microwaves cannot penetrate deep muscle tissue.
There are two general categories of diathermy: monopolar and bipolar. In Monopolar diathermy, an electrical plate is placed on the patient and acts as an indifferent electrode. The electrical current passes between the instrument and the indifferent electrode, and localized heating is produced at the tip of the instrument, while minimal heat is produced at the indifferent electrode. Bipolar diathermy involves the use of two electrodes that are combined in the instrument, such as forceps. The current passes between the two electrodes, and not through the patient.
In preparation for treatment, patients are asked to remove clothing from the body part being treated, to prevent sweating. If sweating occurs, electrical currents may pool in the moist area, which causes burns. Any clothing or jewellery containing metal must also be removed. In addition, watches and hearing aids must also be removed because the electrical waves may interrupt their functions.
Certain precautionary measures must be taken into account before diathermy is used on a patient. Patients with metal implants should not undergo diathermy treatment because the metal can act as a heat conductor, and this can result in severe internal burns. Moreover, females with metallic uterine implants, like an IUD, should avoid diathermy treatment in the pelvic area. Furthermore, diathermy should not be used in joints that have been replaced with prosthesis or in patients with sensory impairment who may not be able to sense if they are burning. Diathermy should also not be used during pregnancy, as it can result in abnormal fetal development. In addition, patients with hemophilia should avoid diathermy treatment because the increased blood flow caused by the treatment could result in haemorrhaging. Also, channelling effects can occur if diathermy is used on appendages, such as on a finger during surgery.
There are some side effects related to the use of diathermy treatment. Some patients may experience superficial burns at the treatment site. Therefore, extra care must b taken to avoid burns, especially in patients who have sustained injuries that have caused decreased sensitivity to heat. Diathermy has also been found to affect pacemaker function. Also, female patients who receive diathermy treatment in the lower back or pelvic area may experience increased menstrual flow.
Research has proven the beneficial therapeutic effects of diathermy. Peres et al. (2002) conducted a study to compare the effects of three treatments on ankle dorsiflexion range of motion. The three treatments under study were prolonged long-duration stretching, pulsed shortwave diathermy followed by stretching, and pulsed shortwave diathermy, stretching, and ice combined. The dependent variable in the study was the range of motion change triceps and flexibility. Results indicated that after 14 days of treatment, the range-of-motion increase was greater after heat and stretching than after stretching alone. After 6 additional days of rest, the heat and stretching range-of-motion increase was greater than that of stretching alone. The researchers concluded that pulsed shortwave diathermy application before prolonged static stretching was more effective than stretching alone in increasing flexibility throughout a 3-week period. Furthermore, after 14 treatments, prolonged long-duration stretching combined with pulsed shortwave diathermy followed by ice application resulted in greater immediate and total range-of motion increases than prolonged long-duration stretching alone.
Goats (1989) explained how continuous shortwave diathermy is the best available technique when uniform elevation of temperature is required in deep tissues. This type of diathermy permits superficial structures to be heated selectively. Sub-acute and chronic conditions have been found to respond best to continuous shortwave diathermy, which works as effectively as ultrasound. Continuous shortwave diathermy can help to relieve muscle spasm and pain, resolve inflammatory states and reduce swelling, increase the compliance of connective tissue, promote vasodilation, and increase joint range and decrease stiffness of joints.
On the other hand, some research has demonstrated that diathermy does not result in significantly improved results. A study by Draper et al. (2002) compared the effects of low-load, short duration stretching with and without high-intensity, pulsed shortwave diathermy on hamstring flexibility. The three independent variables in the study were treatment mode, pretest and posttest measurements, and day. The treatment mode of the study had 3 levels: diathermy and stretching, stretching alone, and control. The dependent variable in the study was range-of-motion. Hamstring flexibility was tested using a sit-and-reach box before and after each treatment. The results indicated that the average increases in hamstring flexibility over the 5 treatment days for the diathermy and stretching group was 6.06 cm (19.6%), the stretching-only group was 5.27 cm. (19.7%),…