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Shortwave. Definition. 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 is one of the diathermy family.
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Definition 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 is one of the diathermy family. • Other modalities that can also heat the tissues are microwave and ultra sound. • Shortwave, microwave and ultrasound can heat the tissues up to a very deep layer. • The electromagnetic spectrum has a wild range of shortwave.
Shortwave Has Three Main Frequencies: 27.12 MHz, wavelength 11 M (most common used one). 13.56 MHz wavelength 22 M. 40.68 MHz 7.5 M.
Shortwave Diathermy Machine • Picture is on page 279 of Low and Reed book. • First we have the power supply. • Inside the machine there is a high frequency generator + an amplifier + oscillator coil + resonator coil + variable capacitor. • Outside the machine we have two electrodes + the part being treated
There Are Two Circuits Here: Machine circuit : composed of a high frequency generator, amplifier, oscillator coil. Patient circuit: composed of a resonator coil, variable capacitor, electrodes and the treated tissue.
Shortwave produces both electric and magnetic fields. The amount of electric field to magnetic field is dependent on: • The characteristic of the machine itself (dependent on the manufacturer). • The type of electrodes that we use.
Shortwave Can Be Used in Two Modes: Continuous (energy is emitted all the time). Pulsed (energy is emitted part of the time). When using the pulsed shortwave, there are certain parameters that we need to know: Pulse width: measured by micro seconds. Pulse frequency: how many pulses we have per second measured by Hz or pulses per second (PPS)
Peak power output: usually is a set value that is determined by the manufacturer. • Mean power output: is variable and is determined by factors such as the pulse width and the pulse frequency.
How could we produce energy into the body without causing heat production? • The off time with pulsed shortwave is longer than the on time which allows the dissipation of heat. • The interpulse period gives time for the heat to dissipate. • If the interpulse is short heat will develop, because there is no time for the effect to dissipate within the body.
Continuous shortwave is always thermal. • Pulsed shortwave can be thermal or non thermal. • High parameters usually gives thermal effect. • If we use long pulse duration, high pulse frequency, heat will develop. • The mean power is affected by the parameters chosen and the time of treatment.
Pulsed shortwave can only be non thermal if short pulses, low pulse repetition rate and short treatment duration is being used.
Wrong Terminologies Used For Pulsed Shortwave • Pulsed electromagnetic energy (PEME) • Pulsed electromagnetic energy treatment (PEMET) • Pulsed electromagnetic field (PEMF) • Pulsed electromagnetic therapy (PEMT) Do Not Use Them!
Recent attention has been paid to the shortwave in the last 5-7 years. • More studies has been one to establish its efficiency. • Equipments now are safer than before. • User friendly.
Advantages of Shortwave • The deep penetration, it goes deep to 5cm. • You can use it while attending to another patient, which allows you to manage your time in the clinic. • It covers large areas. • It can heat the deeper tissue without heating the superficial tissue • It can be used with sensitive tissues because it doesn’t need to be in contact with the treated tissue.
Types of Electrodes: Flexible plates Space electrode Monode Minod Diplode Coil Minode and monode are called “drums”
Shortwave Can Be Applied In Two Ways: • Capacitance (the electric field is more than the magnetic field) : Can be achieved by using two space plates together, or one space plate and a flexible ,or diplodes. • Inductance (the magnetic field is more than the electric field) : Can be achieved by using the coil or the drums.
Effects of Shortwave on The Molecules and Ions of Tissues: • If it is charged there will be vibration. • If it is dipole it will rotate. • If it is not charged it won’t be affected.
Air Space Electrodes • They come in different sizes. • Can be used in almost every part of the body, but because they are rigid they will not fit every contour. • It can be put on either side of the limb, or can be used in the same side. • If the electrodes are placed on the same side there should be a distance between the electrodes, because if there is no distance there would be a shock, so we need to put a distance equal the diameter of the electrode.
Skin-electrode distance: is the distance between the electrode and the skin. • If we place to electrodes at the same distance there will be even heating. • If we placed one electrode closer to the skin than the other, the heating won’t be even, it will be more near the closer electrode. • If we used a large electrode and a small one the heating will be more near the small.
Flexible Electrodes • When using them you should insure it is in full contact. • We have to rap it in towel that is 2 cm thick, less than that could cause a burn, more than that will affect the amount of heating created in the body. • Distance between the electrodes should be equal the diameter of the electrode, if it is less than that there will be a shock.
Coil • Usually used for limbs • Used in two ways: • wrapped around the part being treated. • Pancake (usually used on the back). • When wrapping, the space between one turn and the other should be 5 to 10cm and it is insure by felt spacers (comes from the manufacturer). • It is known to heat the deeper tissue without heating the superficial tissue.
Drum Electrodes • It is known to heat the deeper tissue without heating the superficial tissue. • Penetration to 3cm. • Make sure that the fat layer of the patient is not more than 2cm, because the penetration will be limited and the absorption of heat will accumulate in the fat layer which might cause a burn. • The tissues that are heated are blood vessels, muscles and sweat.
Methods of Applying The Electrodes • Contraplanar electrodes are placed on opposite sides of the part, to treat deeply placed structures. • Coplanar: electrodes are placed on the same side of the part to treat more superficial structures. • Cross-fire: half the treatment is given with the electrodes in a diagonal way, the other half of the treatment is put on the opposite way. This method is usually used for sinuses and body cavities such as the uterus. • Longitudinal: one flexible electrode is used with a space electrode.
Factors Influencing The Field • Spacing between the electrodes. • Electrode size. • The technique applied. • Metal (If the patient has a metal implants, or if the bed is metal).
Spacing The Electrodes • When using flexible electrodes a 2cm thick towel ensures the spacing between the electrode and the body part. • When using coil electrode “felt spacers” ensures the distance between the turns. • When using space electrodes the space between the electrode and the body part is 2-2.5cm.
The Size • If electrodes are smaller than the diameter of the part treated there will be superficial heating. • If the electrode is larger than the part being treated there will be wasted energy. • When using unequal electrodes size concentrates the field on the small electrode side.
Spacing more than 2.5cm should be used on the side where no concentration of the field is required.
When Choosing The Size of Electrode We Should Consider: • The size of the area treated. • Location of the area to be treated. • The depth of the targeting tissue. • Treatment goals. • The contraindications.
Modes of Heat Transfer In Shortwave • Conduction (with the capacitance) • Conversion (with the inductance) Heat production depends on the amount of resistance present inside the tissue.
Physiological Effects of Shortwave (Thermal) • Increase of tissue temperature by 1 degree increase metabolism (good for healing). • Increase of tissue temperature by 2-3 degrees effective for pain and muscle spasm. • Increase of tissue temperature by 3-4 degrees good for tissue extensibility (when we need to do stretching).
Patient’s Feeling • Continuous (Thermal) shortwave Tell the patient that they will feel mild gentle warmth. • Pulsed, Non thermal shortwave the patient will feel nothing. • Pulsed, Thermal shortwave Tell the patient that they will feel mild gentle warmth.
Important Rule • Chronic cases you can treat it with thermal or non thermal shortwave. • Acute only use non thermal shortwave
Metal implants Pregnancy During menses Cardiac pacemaker Radiation therapy Malignant tissue After analgesic therapy Blood pressure abnormalities Vascular diseases Hemorrhage Fever Inflammation Wet dressing Tuberculoses Impaired thermal sensation Contraindications
Indications • Sprain • Strain • Muscle and tendon tear • Capsule lesion • Degenerative joint disease • Joint stiffness • Hematoma • Synovitis • Bursitis • Abscess
Effects of Thermal Shortwave • Increase blood flow • Promote tissue healing • Decrease inflammation • Decrease pain • Increase tissue extensibility • decrease muscle spasm • Control infection
Dosage with the shortwave Includes: • Time of application. • Parameters chosen (mode, frequency, type of electrodes, etc…). • How much do we apply the treatment.
Duration • Average of 15 minutes depending on the site of the area and the patient’s response • Can increase to 30 minutes. • Longer treatment duration may result in reflect vasoconstriction noticed clearly in the toes and fingers
When increasing the intensity wait 2-3 minutes to allow the temperature to build in the tissue before moving to the next stage.
How To Set The Parameters When Using Pulsed Shortwave If we want to set the pulsed shortwave: • In acute conditions, the mean power output should be 3 and the treatment time is 10 minutes. • In sub acute, the mean power output should be 2-5 and the treatment time 10 to 15 minutes. • In chronic conditions, the mean power output is from 5-7 and the treatment can go up to 30 minutes.
Mean power output = peak pulse power / percentage of on time On time = pulse duration / pulse period Pulse period = peak pulse power / pulse repetition rate
When Using Thermal Shortwave • Adjust the machine. • Ask the patient. • If the temperature is too hot decrease it. • The patient is not feeling heat increase it. • Dosage with the continuous shortwave depending on the thermal sensation reported from the patient. • Use your clinical judgment in administering the dosage .
Frequency of The treatment • Daily or every other day. • Depends on the patient’s response. • If the condition is very acute, daily treatment will give better results. • Chronic condition, every other day treatment. • If it didn’t improve do it everyday.
