# Short wave diathermy Short Wave Diathermy n Diathermy

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Short wave diathermy

Short Wave Diathermy n Diathermy Shortwave means the application of high frequency electrical energy to the body tissues in order to bring physiological and therapeutic effects, these effects can be achieved by thermal or non thermal effect.

Shortwave Diathermy n To apply SWD we have two main circuits, the machine circuit which produce high frequency current coupled with the patient circuit through inductors to transfer the electrical energy to the patient.

Electromagnetic Phenomena n n Electromagnetic phenomena can be considered from three different aspects: 1 - Electrostatic concerns the electric force between the electric charges. . These forces act between any charges and their strength and direction can be described by drawing lines called lines of electric force. The area in which this force acts is called an electric field.

Electromagnetic Phenomena 2 - When charges move it is referred to as an electric current. An inevitable consequence of constantly moving charges is the formation of magnetic force at right angles to the direction of the charge motion. The area in which the magnetic force is evident, called the magnetic field. n

Electromagnetic Phenomena n If an electric charge is accelerated it causes the production of an electromagnetic radiations which radiates away from the moving charge and once generated is independent of the charge. These radiations include radio waves (SWD), visible light and X-rays.

J Shortwave produces both electric and magnetic fields. The amount of electric field to magnetic field is dependent on: 1) The type of electrodes that we use.

Types of SWD applications n n n Capacitor (Condenser) Electrodes Create Stronger Electrical Field Than Magnetic Field Ions Will Be Attracted Or Repelled Depending on the Charge of the Pole

Capacitor Electrodes n n Electrical Field Is The Lines of Force Exerted on Charged Ions That Cause Movement From One Pole To Another Center Has Higher Current Density Than Periphery

Capacitor Electrodes Patient Is Between Electrodes and Becomes Part of Circuit n Tissue Is Between Electrodes in a Series Circuit Arrangement n

Electrical Field n The Tissue That Offers The Greatest Resistance To Current Flow Develops The Most Heat – – – n Fat Tissue Resists Current Flow Thus Fat Is Heated In An Electrical Field Precaution: electrical field may overheat area with large fat content Heating= Current 2 X Resistance

Capacitor Electrodes (Air Space Plates) Two Metal Plates Surrounded By Plastic Guard n Can Be Moved 3 cm Within Guard n Produce High. Frequency Oscillating Current n

Induction Method Creates A Stronger Magnetic Field Than Electrical Field n A Cable Or Coil Is Wrapped Circumferentially Around An Extremity Or Coiled Within n Electrode n

Induction Electrodes n Passing Current Through A Coiled Cable Creates A Magnetic Field By Inducing Eddy Currents (small circular electrical fields) That Generate Heat

Induction Electrodes n n Patient In A Magnetic Field Not Part Of A Circuit Greatest Current Flow Through Tissue With Least Resistance – – n Tissues react like a parallel circuit Fat does not provide as much resistance to electromagnetic energy Tissue High In Electrolytic Content Respond Best To A Magnetic Field – Muscle and blood n Precaution: Not as much superficial sensation of heat with electromagnetic

Biophysical and biochemical effects of SWD Effects of an electrostatic field: 1 - Free ions in the tissues give minimal movement due to high frequency leading to friction between ions and produce heat. n

Biophysical and biochemical effects of SWD 2 - The dipolar molecules (as water) move to the opposite charge on the condenser plates, charge change rapidly, friction between molecules leads to heat in the tissues. 3 - The non-polar molecules (as fat)…. . the electrode cloud become distorted but negligible heat is produced.

J If it is charged there will be vibration. J J If it is dipole it will rotate. If it is not charged the electrode cloud become distorted

Biophysical and biochemical effects of SWD n n n Effects of electromagnetic field: Electromagnetic field produces circular currents at right angles to the line of force giving eddy currents which leading to friction of tissue particles and produce heat. The heat will concentrate in the tissues of low resistance (blood and muscles).

Therapeutic Effects of SWD 1 - Pain relief: of traumatic pain and rheumatic conditions affecting muscles, ligaments and joints. 2 -Muscle spasm: may be reduced directly by SWD. 3 - Inflammation: resolution of inflammation as a result of increase blood supply.

Therapeutic Effects of SWD 4 - Accelerate wound healing: by increase coetaneous circulation. 5 - Infection: increase circulation and increase white blood cells and antibodies. 6 - Fibrosis: increase extensibility of fibrous tissues such as tendons, joint capsule and scars.

Indications and Therapeutic Uses 1 - Musculo-skeletal disorders: -– Tendonitis. -Bursitis. - Strain. – Sprain. – Capsule lesion. - Sub-acute and chronic arthritis - Tenosynovitis. - Bursitis. – Carbuncles. – Abscesses. -

Indications and Therapeutic Uses 3 - Chest disorders: - To relieve muscle spasm in some forms of bronchial asthma. - Sub-acute and chronic bronchitis. 4 - Neurological disorders: - Neuritis. – Sciatica. –-

Indications and Therapeutic Uses 5 - gynecologic disorders: n - Congestive cervicitis. –Endometritis. –– Ovaritis. 6 - Ear, nose and throat disorders: - Sinusitis. – Laryngitis. - 7 - respiratory condition

Contraindications of SWD 1 - Malignant and ischemic tissues. 2 - Moderate and excessive edema. 3 - Metallic implants. 4 - Pacemakers. 5 - Tendency of hemorrhage; during menstruation, pregnancy, peptic ulcer and varicose veins. 6 - Impaired thermal sensation.

Contraindications of SWD 7 - Unreliable patient. 8 - Recent radio-therapy. 9 - Acute infection or inflammation. 10 - Analgesic therapy. 11 - Severe cardiac condition and blood pressure abnormalities.

Application of SWD Six main variations in electrodes are commonly available: n Flexible pads: consist of metal electrode encased in rubber and produce an electrostatic field. n

Application of SWD n Space plates: consist of a rigid metal electrode encased in a Perspex cover electrostatic field.

Application of SWD n Coil: or cable electrode consists of a wire with plugs at either end electromagnetic field.

Application of SWD n The monode: flat, rigid coil encased in Perspex cover electromagnetic field.

Application of SWD The minode: conical rigid coil encased in Perspex cover electromagnetic field. n The diplode: or drum electrode, consists of a flat coil electrode encased in a Perspex cover with two wings electromagnetic field n

FACTORS INFLUENCE FIELD DISTRIBUTION IN S. W. D 1 - Spacing: allows the lines of force in the electrostatic field to diverge before entering the tissues. This prevents concentration of heat in the super-facial tissues and ensures more heating through the part. n Spacing provided by: 1 - wrapping flexible pads in towel. 2 -flat felt spacing between pad electrode and skin. 3 -air when using space plates.

FACTORS INFLUENCE FIELD DISTRIBUTION IN S. W. D a- Normal spacing even field distribution. n b- Increased spacing deep field concentration. n c- Decreased spacing superficial concentration. n

FACTORS INFLUENCE FIELD DISTRIBUTION IN S. W. D It has been suggested that for most short wave sources at maximum output spacing of about 4 cm to the maximum that will give the greatest absolute heating of the deep tissues. n Conversely the minimum skin electrode distance is about 2 cm. n Note: the spacing refers to the distance of the metal electrode, not the plastic cover, from the skin. n

FACTORS INFLUENCE FIELD DISTRIBUTION IN S. W. D 2 - Air in cavities: as sinuses or uterus, the lines of force deviate to avoid air as it offers a high resistance. As a result only the sides of air cavity will be heated.

FACTORS INFLUENCE FIELD DISTRIBUTION IN S. W. D 3 - Electrode size: if the electrodes are too small than the diameter of treated part line of force will be concentrated superficially. n -If the electrodes are markedly larger the line of force will be lost in the air. n

FACTORS INFLUENCE FIELD DISTRIBUTION IN S. W. D 3 - Electrode size: n -Ideally, the electrodes should be slight larger than the area treated.

FACTORS INFLUENCE FIELD DISTRIBUTION IN S. W. D 4 - Metal: metal causes the lines of force to concentrate on the metal

Shortwave Can Be Used in Two Modes: 1) Continuous (energy is emitted all the time). 2) Pulsed (energy is emitted part of the time). n When using the pulsed shortwave, there are certain parameters that we need to know: J Pulse width: measured by micro seconds. J Pulse frequency: how many pulses we have per second measured by Hz or pulses per second (PPS)

J Peak power output: usually is a set value that is determined by the manufacturer. J Mean power output: is variable and is determined by factors such as the pulse width and the pulse frequency.

Pulsed Shortwave Diathermy • -Is short wave at the frequency of 27. 12 MHz, which is pulsed at a rate, selected by therapist. • -The pulse frequency range is from 15 to 200 Hz. • -The maximum intensity is 1000 watts. • -The pulse duration is constant at 0. 4 ms in square pulse. • -The advantage of pulsed S. W. D. is that a very high intensity of power can be administered with minimal effect.

How could we produce energy into the body without causing heat production? J The off time with pulsed shortwave is longer than the on time which allows the dissipation of heat. J The interpulse period gives time for the heat to dissipate. J If the interpulse is short heat will develop, because there is no time for the effect to dissipate within the body.

Pulsed Shortwave Diathermy Biological Effects 1 -Increased metabolism. 2 -Relief of pain. 3 -Stimulated wound healing. 4 -Relaxed muscle spasm. 5 -Accelerated wound healing. 6 -Decreased haematoma formation.

Pulsed Shortwave Diathermy 2 - Indications 12345 - Sprains. Contusions. Haematoma. Bursitis. Sinusitis.

Pulsed Shortwave Diathermy 3 -Contraindications 1234 - Pacemakers. High fever. Tumour. Metal.

Therapeutic Technique of Application 1 - Shortwave machine with chosen electrodes and its test tube to ensure the machine is working. 2 - Test tubes for skin test. 3 - Cotton towels or felt pads for spacing. 4 - Ensure that there are no contraindications for SW application. 5 - Put the patient in a comfortable position and well support, allow the area to be treated to be completely uncovered.

Therapeutic Technique of Application 6 - Inspect the area will be treated. 7 - Ensure there is no metal (jewellery or hairpin) within 300 mm of treatment area. 8 - Explain the procedure and feeling to the patient. 9 - If using flexible pad electrodes, wrap them in several layers of towelling or place them between felt pads to ensure the required amount of spacing.

Therapeutic Technique of Application 10 - If using space electrodes adjust the distance according to the concentration needed. 11 -Instruct the patient not to move during treatment and warn her/him from uncomfortable heat feeling. 12 - If the machine has a patient safety switch instruct the patient to switch the machine off if he feel

Therapeutic Technique of Application 13 - Check the machine controls at the zero position, then switch the power on. 14 - Switch the intensity on and wait 2 -3 minutes on the minimum intensity and ask the patient about her/his feeling, then adjust the timer to the required treatment time. 15 - After treatment time has finished, turn the intensity switch to zero and remove the electrodes. 16 -Inspect the area after treatment and ask the patient to stay few minutes for rest and to regain

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION 1 - Application using two flexible pads or space plates: A- The electrodes should be slightly larger than the area treated and spaced from the skin by approximately 25 mm. B- To concentrate heat on one aspect of the part the electrode should be unequal in size (smaller one placed over the area where concentration of heat is required).

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION C- You can produce concentration of heat by using equal size electrodes but with unequal spacing (25 mm over concentrated area and more than 30 mm on other electrode).

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION D- Coplaner application to treat structures on one aspect of the body. If the spacing is less than 25 mm more concentration in the superficial tissue. If spacing increases more depth achieved. The distance between adjacent ends (x) must be greater than the sum of skin electrode distance (A+B) otherwise the line of force will pass directly between electrodes rather than tissues.

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION b- Application using a combination of flexible pad and space plate: - Use a space plate over the top of the foot, because there is less soft tissue around the ankle joint than elsewhere in the lower leg, the line of force concentrates at the ankle and the sensation of heat is felt by the patient in the region.

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION c- Application using a coil electrode: 1 - The coil wound evenly firmly 2 - Pancake application heat superficial tissues.

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION d- Application using a flexible pad and coil: 1 - Useful for the treatment of hip and shoulder to localise heating to the joint, the proximal end of the cable is attached to the machine electrostatic field is produced between the pad and the proximal loop of coil, electromagnetic field is produced

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION 2 - To treat hip joint with referred pain down the thigh, the distal end of the coil is attached to the machine and the proximal end of coil is insulated. An electrostatic field is produced between the pad and the proximal loop and electromagnetic field is produced around all loops of the coil.

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION e- Application using diplode: n Adjust wings of diplode parallel to the skin of the treated area, electromagnetic field will produce. n

Application Using Diplode

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION f- Applications to two limbs: Two flexible pads, two space plates or flexible pad with a space plate are used. It is essential to put a cotton towel between the two limbs to absorb any perspiration.

THERAPEUTIC VARIATION IN THE FIELD DISTRIBUTION g- Cross-fire application: For the treatment of sinuses, space plates positioned diagonally, after half of treatment time the positions are alternate. This ensures that all aspects of the sinus membrane are heated. Care must be taken to avoid direct placement over the eye. For the treatment of uterine disorders such as dysmenorrhoea. n n n

Dangers and Precautions in SWD 1 - Burn can be avoided by: n -Checking all contra-indications and area to be treated. n -Test of thermal skin sensation. n -Taking care during application over a bony prominence. n -Never apply S. W. over clothing. n -Making sure that the skin is dry.

Dangers and Precautions in SWD n -If you apply over two skin surfaces in contact, they must be separated by absorbent material towel. n -Making sure that there is adequate spacing between the electrodes and the skin. n -Allowing 2 or 3 minutes on each intensity setting maximum heat.

Dangers and Precautions in SWD 2 - shock can be avoided by: n -Not increasing intensity unless the leads and electrodes are connected to machine. n -Making sure that the machine is earthed. n -Not touching the machine. n -Making sure that there is no metal within the range of 300 mm. n -If the patient is wearing a hearing aid switch it off.

Heating With Continuous SWD n Patient Sensation Provides Basis For Recommendations Of Continuous SWD n Dose I (Lowest) (<38 W) - No Sensation of Heat Dose II (Low) (~80 W)- Mild Heating Sensation Dose III (Medium) (80 -300 W) - Moderate or Pleasant Heating Sensation Dose IV (Heavy) (>300 W) -Vigorous Heating Within Pain Threshold n n n

PSWD Mean Power Calculations n Pulse Period (Pulse on + off time) = – Peak Pulse Power (W) / Pulse Rep Freq (Hz) n Percentage On Time = – Pulse Duration (msec) / Pulse Period (msec) n Mean Power = – Peak Pulse Power (W) / Percentage on Time

Example Peak Pulse Power = 800 W n Pulse Duration =. 4 ms n Pulse Frequency = 200 Hz n Pulse Period = 800 W / 200 Hz = 4 ms n % on time =. 4 / 4 =. 10 or 10% n Mean Power = 10% of 800 = 80 W n – End Result = thermal effect – < 38 W = no heating

Microwave Diathermy MWD Has Higher Frequency and Shorter Wavelength Than SWD n Advantage: better focus wave on body, thereby more local heating affects n Disadvantage: Depth Of Penetration Is Minimal In Areas With Subcutaneous Fat > 1 cm n

n 1 - electromagnetic radiation with very short wavelength and high energy represent the ionizing range ( ) n 2 - The wave length of red visible light is more than 1 mm ( ) n 3 - Infrared and short wave travel through vacuum at the same speed ( ) 4 - infrared is visible light ( ) 5 - infrared indicated for acute and chronic inflammation ( ) n n