Microwave Diathermy .
Microwave Diathermy can be defined as the therapeutic use of microwaves for the treatment of various diseases and disorders. Microwave diathermy is also called Microthermy. Microwaves are electromagnetic waves with wavelength in between one centimeter and one meter. For physiotherapeutic purpose, high frequency current of 2,450 MHz and wavelength 12.25 cm or 433.92 MHz and 69 cm are used. Considering the electromagnetic spectrum, one can very well note that the wavelength of microwaves lies between infrared and short waves.
Production of Microwave Diathermy .
Principle .
It is not possible to produce microwaves by mechanical means and hence, they are produced from magnetron, which is a special type of thermionic valve.
Apparatus of Microwave Diathermy .
Microwave diathermy apparatus consists of the following functional parts; power supply, magnetron oscillator circuit, magnetron oscillator, intensity control, coaxial cable and emitter. Power supply unit supplies high voltage pulsed direct current and magnetron oscillator circuit control adequate heating and cooling of magnetron .
The primary function of magnetron oscillator is to produce high frequency current required for the production of microwaves. Magnetron is a special type of thermionic valve characterized by centrally placed cathode, which is surrounded by circular type metal anode. The anode has circular cavities that allow the production of circulating or alternating current.
Coaxial cable carries high frequency currents from magnetron and feeds it to the antenna of the emitter. Now the emitter is also known as director or applicator. The emitter consists of antenna and reflector. Antenna is mounted in front of a metal reflector. Reflector is a metal plate, which directs the waves in only one direction.
Emitters are available in various sizes and shapes. The emitter can be kept in contact with the body, if there is internal spacing in it, otherwise it should be kept at a distance of 10 to 20 cm from the body surface to be treated. Intensity knob controls output of the microwave by varying the power supplied to the magnetron.
Indications of Microwave Diathermy .
- Sprains .
- Strains .
- Capsular lesions .
- Degenerative Joint disease .
- Chronic Rheumatoid arthritis .
- Stiffness in Superficial joint .
- Haematoma .
- Contusions .
- Tendonitis .
- Tenosynovitis .
- Bursitis .
- Contractures .
- Myofascial trigger points .
- Abscesses .
- Infected Surgical infections .
Dosages of Microwave Diathermy .
Dosages of microwave diathermy are, in acute conditions 5 to 10minutes and in chronic conditions 20 to 30 minutes with an output, which will produce just perceptible and comfortable warmth. It can be measured and up to 200 watts can be given so as to raise the body tissue temperature in therapeutic range of 40 to 45°C.
Physiological and Therapeutic Effects of Microwave Diathermy .
Physiological and therapeutic effects of microwave diathermy are same as that of short wave diathermy. Microwave diathermy is useful more in local conditions rather than in the generalized conditions. The amount of heat production is more in muscles as compared to short wave diathermy since the heat production by the microwaves depends on the watery content of the tissues.
The depth of penetration of microwaves in the tissues is less and is ranges between 3 mm and 3 cm, while short wave can penetrate as deep as 6 cm. Other therapeutic effects are the same as of short wave diathermy. It can be used in traumatic and inflammatory conditions, degenerative arthropathies, enthesopathies, arthritis of joints etc.
It is useful in the treatment of soft tissues and superficial joints because it is generally possible to irradiate only one aspect of the body at a time. Microwave diathermy is more useful in the treatment of superficial tissues those with high fluid content.
Physiological Effects of Microwave Diathermy .
1. Increased Blood Flow .
Microwave diathermy can cause vasodilation (expansion of blood vessels) in the treated area. This results in an increased blood flow, which can help deliver more oxygen and nutrients to the tissues. Improved circulation also aids in the removal of metabolic waste products.
2. Tissue Temperature Elevation .
The primary goal of microwave diathermy is to raise the temperature of deep tissues. This increase in temperature can have several effects, including enhanced tissue extensibility (stretchiness) and reduced muscle stiffness. It can also help in pain relief by reducing muscle spasms and increasing the pain threshold.
3. Muscle Relaxation .
The heat generated by microwave diathermy can promote muscle relaxation, helping to alleviate muscle tension and reduce muscle spasms. This can be particularly beneficial in conditions involving musculoskeletal pain and stiffness.
4. Promotion of Collagen Extensibility .
The application of microwave diathermy can influence the collagen structure within connective tissues, such as tendons and ligaments. This can lead to increased extensibility of these tissues, facilitating better flexibility and range of motion.
5. Analgesic Effect .
The thermal effects of microwave diathermy contribute to an analgesic (pain-relieving) effect. Heat can help to decrease the sensitivity of pain receptors, providing relief from pain and discomfort.
6. Accelerated Metabolic Rate .
The increased temperature induced by microwave diathermy can stimulate cellular metabolic processes. This acceleration in metabolic rate may enhance tissue repair and regeneration, promoting faster healing of injured tissues.
Therapeutic Effects of Microwave Diathermy .
1. Pain Relief .
One of the primary therapeutic effects of microwave diathermy is pain relief. The heat generated by the microwaves can help alleviate pain by reducing muscle spasms, increasing blood flow, and promoting relaxation in the treated area. This can be particularly beneficial for conditions such as arthritis, muscle strains, and other musculoskeletal injuries.
2. Muscle Relaxation .
Microwave diathermy induces vasodilation and increases the temperature of deep tissues, leading to muscle relaxation. This effect is useful for reducing muscle stiffness, improving flexibility, and enhancing range of motion. It is often applied to areas with muscle tightness or tension.
3. Improved Blood Circulation .
The electromagnetic waves used in microwave diathermy can stimulate vasodilation, leading to increased blood flow in the treated area. Improved circulation helps deliver more oxygen and nutrients to the tissues, promoting healing and reducing inflammation.
4. Enhanced Tissue Extensibility .
The heat generated by microwave diathermy can increase the extensibility of collagen fibers in tendons, ligaments, and other connective tissues. This can contribute to improved flexibility and range of motion in the joints.
5. Reduction of Joint Stiffness .
Microwave diathermy can be beneficial in reducing stiffness in joints, especially in conditions like osteoarthritis or rheumatoid arthritis. The heat helps to increase the suppleness of joint structures and may contribute to improved joint function.
6. Acceleration of Metabolism .
The increased temperature induced by microwave diathermy can accelerate metabolic processes at the cellular level. This may enhance tissue repair and regeneration, potentially speeding up the healing process for injuries.
7. Promotion of Relaxation and Comfort .
The warmth generated during microwave diathermy treatment can induce a feeling of relaxation and comfort. This can be particularly soothing for individuals with chronic pain conditions or those recovering from injuries.
Dangers and Contraindications of Microwave Diathermy .
1. Burns .
Microwave diathermy can cause burn on the superficial tissues. Skin must be kept dry to avoid burns. Water is heated more rapidly by microwaves because of high degree of absorptive power of these waves. The patient’s perception of heat is the only guide of the treatment. The patient must be asked for comfortable warmth. In all cases of diminished sensations, microwave diathermy should be avoided.
2. Metal implant .
Microwave diathermy should not be applied in cases of metals in the tissues because diathermy currents may get concentrated in the metals.
3. Dangers to hearing aids or cardiac pacemakers .
Such patients those who are using hearing aids or cardiac pacemakers should not be treated with microwave diathermy and should not be allowed to come in close proximity of the apparatus.
4. Eyes .
Treatment on eyes should be avoided. There may be concentration of heat in the intraocular fluid.
5. Circulatory defects .
Patients with hemorrhage, vascular disease, thrombosis or thrombophlebitis must not receive microwave diathermy.
6. Menstruation .
Diathermy should never be applied to the abdomen during menstruation because hemorrhage may further increase.
7. Pregnancy .
Diathermy should never be applied to the abdomen or pelvis during pregnancy.
8. Tumors .
Diathermy should not be applied to the area of tumor growth because the temperature could accelerate the growth of the tumor. Further, due to increased circulation metastasis, i.e. spreading of tumor may occur.
9. Deep X-ray or cobalt therapy .
Due to deep X-ray or cobalt therapy the devitalization of tissues occurs, which could lead to further damage due to the application of microwave diathermy.
10. Patient at particular risk .
Treatment should be avoided in children, mentally retarded patients, uncooperative patient or epileptic patient because these patients cannot appreciate the amount of heat required for the treatment and thus cannot report for the overheating.
Oudin current .
Oudin current is rarely used nowadays due to the recognition of shortwave diathermy by most of the physiotherapists across the world. In general, it is mono-terminal high frequency current in the range of long-wave band. It is often marketed as Heal-O-Ray or just by the name high frequency unit. It fascinates the therapist as well as the patients. This current may be preferred sometime in those patients who do not respond to other forms of treatment. These patients like the sparking sound that occurs during the treatment and the pinkish color in the glass electrode. This current is applied through the glass vacuum electrode.
In administering this current, the glass electrode is held close to the body part that is to be treated. When the current is applied through the electrode, it produces sparking. This produces counterirritation and hyperemia. This current may be considered in neuralgias, sprains, strains, myositis and sluggish non-infected wounds and ulcers. One should use this modality with caution, since literature about the treatment parameters is not readily available. If this current is applied with high intensity, high frequency and with very close proximity to the body, it can produce electrodessication.
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