1 Physical Therapy OBJECTIVES 1. Increasing and maintaining strength and endurance 2. Increasing coordination 3. Decreasing pain 4. Decreasing muscle spasm 5. Decreasing swelling 6. Decreasing chest congestion 7. Correcting postural deviations 8. Promoting the healing of soft tissue lesions 9. Preventing contractures and deformities 10. Increasing range of motion in joints THE PRESCRIPTION Full name, address and phone number Age Diagnosis Specific area to be treated 1 2 Dosage, frequency, duration Specific modality Past history to include contraindications EXAMPLE IF (quadrapolar) at intensity level of 27 with vector and sweep employed for 10 minutes on Low Back. US continuous at 1.5 watts for 8 minutes over R. shoulder. US pulsed at 1 watt for 10 minutes with 5% duty cycle over posterior cervical paravertebral musculature. STAGES OF HEALING Inflammatory Stage Reparative stage Toughening stage INFLAMMATORY STAGE Where white blood cells dissolve extravasated blood elements and tissue debris, characterized by swelling and local tenderness. REPARATIVE STAGE Where the network of fibrin and the fibroblasts begin the reparative process, characterized by local heat, redness, and diffuse tenderness. TOUGHENING STAGE 2 3 Often characterized by palpable thickening and induration in the area of reaction, with tenderness progressively diminishing. The greater the bleeding, the more acute and diffuse the inflammatory state, and greater induration and fibrous thickening can be anticipated. SUPERFICIAL HEAT THERAPIES Hot moist heat Paraffin dips Whirlpool Short-wave & Microwave diathermy EFFECTS OF HEAT The primary physical effect of heat is Thermal This increase in local temperature further increases the heating effects, which in turn precipitates THREE basic reactions: THREE BASIC REACTIONS 1. Analgesic effect or calming effect 2. Slight increase in local metabolism 3. Slight sedation of sensory nerves PHYSIOLOGICAL EFFECTS If heat is applied at too high of a temperature or for too long a duration , a burn may result. 3 4 The ideal situation occurs when the correct treatment time is utilized. Then, the beneficial healing effects of heat are obtained; The body responds to the application of heat according to the temperature degree produced in the tissues and the duration that the temperature is elevated. Treatments for brief periods, where there is little or no heat buildup in the tissues, seem to have little, if any, therapeutic effect. Over-utilization of heat when pain and swelling are present, especially with acute complaints, tends to aggravate the complaint and prolong healing time bv increasing local edema. Heat definitely has a beneficial effect therapeutically, but it must be used properly and only when indicated. LOCALIZED EFFECTS Heat increases the flow of blood to and from the area being treated, and it initially increases metabolism within the parts being treated, When heat is used too long, it may lead to local congestion, edema, and reduced metabolism. Heat effect upon the skin promotes sweating, which helps to remove toxic wastes. If heat is applied beyond the tolerance of the patient, a burn may result. Heat is very effective in its influence on the psyche, as it tends to relax the patient this a potential problem with heat when it is utilized for musculoskeletal complaints. Typical patients thinking is: If a little heat is good then MORE is better. Rule of thumb is: Heat should never be applied to a body part until 48 to 72 hours after the iniury, or even longer if recurrent bleeding or swelling is a danger. 4 5 REMOTE REFLEX EFFECTS OF HEATING Heat may stimulate increased blood flow, metabolism, and healing far distant from the site of application. This is especially true when short-wave diathermy is used as the modality for heat production METHODS OF HEATING Conduction Examples: Diathermy, Infrared, Microwave, UV, EMS INVERSE SQUARE LAW The closer the source of energy to the target, the greater the energy. Example: Tube-to-film distance used in taking radiographs. COSINE LAW Energy at right angles to the target has the greatest effect. Conversely, the greater the angle at which the energy strikes the target, the less the intensity. Example: An infrared lamp placed parallel to the skin exerts much less effect than one placed at a 90 degree angle. LAW of GROTHUS-DRAPER Any energy that is not absorbed by the superficial tissues is transmitted to the deeper layers of tissue. The greater the amount of energy that is absorbed, the less is 5 6 transmitted and penetrates. ARNOLD-SCHULTZ PRINCIPLE No reaction will occur unless there is sufficient energy to stimualte the absorbing tissues. Example: In the use of a subthreshold electrical current. Such current does not produce any effect on neurologic tissues and cannot produce a sensory response or muscle contraction. GENERAL INDICATIONS HEAT THERAPY Enhance local nutrition Produce general sedation and local analgesia Relaxation of spasticity Enhance the absomtion of exudates Increase lymph flow CONTRAINDICATIONS Over localized edema Bleeding tendency Patients with high fever Over acute skin conditions Deficient vascularity due to organic disease of the blood vessels 6 7 THERAPEUTIC ULTRASOUND Therapeutic ultrasound is that which is used for therapeutic (rather than diagnostic) purposes and is usually produced at 1 megacycle or 1 million cycles per second US has replaced diathermy for many types of conditions because it is less time consuming and penetrates tissues well. Many of the newer US units use an additional frequency range of 3.3 MHz. This higher frequency allows US to be applied in areas that previously were not sonated, such as TMJ. US energy is produced by a process involving the conversion of electrical energy into mechanical energy in the form of sound waves. This is accomplished by passing an electrical current through a crystal, either Quartz or lead zirconium-titanate. The electrical current causes the crystal to alternately expand and contract. The resulting expansion and contraction of the crystal transforms the electrical energy into mechanical energy in the form of sound waves, a process known as the "Piezoelectric effect." The resulting mechanical vibration passes into the target tissue and creates a molecular vibration. This vibration creates friction between the molecules and the mechanical sonic energy and is converted once again into thermal energy, which results in heating of the deeper tissues. The therapeutic effect of ultrasound varies among various tissues. US waves have an affinity for tissues that are highly organized, such as ligaments and tendons. Consequenuy, these structures are selectively heated, whereas, other less organized structures are affected to a lesser degree. 7 8 Those tissues containing a high water content, such as fat and muscle, are not significanUy warmed by the US waves. Other tissues, such as the periosteum, may be adversely affected by an accumulation of US energy. CONDUCTION OF THE SOUND WAVE To transmit the energy into the tissues of the body, some type of fluid material must be used between the sound head and the body. The fluid material is referred to as a coupling agent The therapeutic effects of US are compromised if the transducer is not properly coupled to the skin Prolonged periods with inadequate coupling may seriously affect the integrity of the crystal and shorten the life of the US unit. To minimize these problems, many of the newer US units have sensing devices in the transducer that detect when the contact is not adequate and stop the flow of current to the crystal. PENETRATION US waves are generally thought to penetrate as deep as 4 to 6 cm into the tissues. Tissues with a high fluid content, such as blood and muscle, transmit sound waves much better than less hydrated tissues. The energy is best absorbed in tissues that are highly organized particularly the ligaments and tendons, which make US very beneficial in treating injuries to these areas. ULTRASOUND VS DIATHERMY There is less danger of burning 8 9 It takes only 8-10 minutes vs. 20 minutes for diathermy. It is capable of penetrating 4 to 6 cm into the tissues. ULTRASOUND Continuous US causes a thermal effect. The friction caused by the vibration within the patient's tissues will produce heat. Because US is transmitted by skin and fat, the heat can be directed to the deeper muscle layers where it is needed. PULSED ULTRASOUND The energy is on for a short period of time, then off, alternating so that the "on time" or duty cycle is approximately 550% of the total time. The "off time" allows the tissues to disperse the heat created, thereby minimizing or eliminating the thermal effect. With the 5% duty cycle, there is virtually no heating With the 50% duty cycle, some heating occurs. Pulsating US is advantageous when the thermal effect may be detrimental. Generally speaking, the more intense and painful the condition the less intense the treatment. ULTRASOUND EFFECTS Tissue temperature rise Decreased nerve conduction velocity Increased circulation Increased tendon extensibility 9 10 Reduced adhesion formation Decreased pain Muscle relaxation ULTRASOUND INDICATIONS Neuromuscular, musculoskeletal disorders Sprains and strains; adhesive capsulitis Arthritic conditions - acute and chronic Bursitis, tendinitis, including calcific tendinitis SPECIFIC ULTRASOUND INDICATIONS Neuromas, scars, dupuytrens contracture Plantarwarts Hematomas Adhesions PRECAUTIONS Over heating of the cutaneous tissues may occur if: The intensity is set too high Transducer is moved too slowly Transducer surface is not kept parallel to the skin surface 10 11 Over heating of the periosteum may occur if: The transducer is held too close to the bone The intensity is set too high The transducer is moved too slowly CONTRAINDICATIONS 1. Epiphysis of growing bones 2. Over reproductive organs 3. Over a gravid uterus 4. Over the heart 5. Over the eye; over anesthetic areas 6. Over ischemic areas; directly over the spinal column or brain. 7. Over a fracture (until well healed) 8. Deep vein thrombosis 9. Arterial disease, hemophilia, malignancy 10. TB of the lungs or bone 11. Over the thoracic region of a patient with a pace maker APPLICATION OF ULTRASOUND 11 12 Apply coupling medium to the part being treated and place the transducer against the coupling medium. The unit should never be turned on without coupling medium because the crystal may over heat. Keep the transducer moving slowly Turn the intensity up to the desired level Avoid bony prominences and keep the transducer parallel to the skin as possible The patient may get a mild sense of warmth. If the patient gets too hot, or uncomfortable, the wattage should be reduced to a tolerable level Treatment guidelines: Acute - 4-6 minutes, Chronic - 6-8 minutes US IMMERSION METHOD Good for treating hands, wrists, feet and elbows Place the transducer and the treating part in a container of water Keep the transducer moving slowly and within 1-2 inches of the part being treated. Duration: acute 3-4 minutes; chronic 5-8 minutes Most patients will experience a greater sensation when US is used with the underwater technique. During the acute stage of the injury involves immersing the injured part in a bucket of ice water. During the chronic phase of treatment, the body part to be treated is immersed in a container of warm water. COMBINATION THERAPY Combining US and electrical stimulation provides a very effective treatment modality. 12 13 This is accomplished by simultaneously directing both sound waves and electrical current through the transducer head. In addition to emitting acoustic energy, the sound head becomes the active electrode in an electrical stimulator The combined effect of these two modalities allows the unit to warm the deeper tissues, improve cellular transport mechanisms, to soften connective tissues, and improve circulation. At the same time, the electrical stimulation reduces pain by closing the pain gate and it improves muscle tone, function, and circulation by producing muscle contraction. This has a dramatic effect on many chronic conditions such as myofascial trigger points. Although patients do not feel US, they do feel a tingling sensation or ~pins and needles" that results from the electrical current. In addition, if the intensity of the ES is adequate, they will experience muscle twitching. SHORT-WAVE DIATHERMY The term diathermy means deep heat Uses high frequency currents to heat the body tissues (13.56 MHz and 27.12 MHz) The heat results from the resistance offered by the tissue to passage of the electric current. The patient's sensation is an important guide as the regulation of dosage, as it should produce only a mild comfortable sensation of warmth and not a sensation of heat NOTE: It is imperative that the sensory perception of the patient be normal in the use of diathermy. SWD is one of the few modalities that is used for many conditions other than musculoskeletal aches and pains (e.g., bronchitis, prostatitis, and sinusitis). 13 14 There are two types of treatment applicators (electrodes) used in SWD. 1.Condensor 2. Inductor 1. CONDENSOR APPLICATORS Also known as capacitors provide an energy field that is mostly electrical, whereas the inductor type primarily provides a magnetic field. Uses two separate pads or metal plates with an airspace between them. The current passes from one plate to the other. 2. INDUCTOR FIELD Is usually some type of drum, either a hinged drum or a single drum. Induction coils are used with this method. The induction type of applicator produces a magnetic field that passes through the superficial tissues and is absorbed best in tissues with a high electrolyte content, such as muscle and blood. It is the preferred method for heating the deep layers of muscle. PRECAUTIONS Remove metallic pins, buttons Metallic objects must not contact the patient as they will concentrate the heat and could cause bums. keys, jewelry, watches and buckles. Should not be used at the same time as any other form of electrical modality. TEN MAJOR EFFECTS 14 15 1. Thermal 2. Stimulation 3. Increased Blood flow 4. Hypotonicity 5. Increase in visceral circulation ea :, MAJOR EFFECTS 6. Endocrine changes 7. Oxidation 8. Phagocytosis 9. Detoxification 10. Increase in capillary pressure DOSAGE LEVEL 1 For patients who have no apreciable specific pain or in the treatment of visceral conditions, gradually increase temperature to where the patient just perceives a comfortable yet distinct sensation of "velvety~ warmth". DOSAGE LEVEL II For patients who have pain, the temperature is decreased to a point just below the level of Dosage I. No detectable sensation of warmth should be perceived by the patient. GENERAL RULE 15 16 The more acute the condition to be treated, the less temperature elevation and the shorter the treatment duration. ELECTRODE POSITIONS The three common electrode positions are: 1. Transverse 2. Longitudinal 3. CO-planar GENERAL RULE The thicker the bodv Dart to be treated, the GREATER should be the electrode -skin distance, which is provided by air spacing or towels. INDICATIONS 1. URI 2. Chronic osteoarthritis CONTRAINDICATIONS 1. Over pregnant uterus 2. Over wet skin 3. Patients with pacemaker 4. Peptic ulcers 5. Rheumatoid arthritis 16 3. Prostatitis 17 6. Malignancy 7. Patients on anticoagulant therapy SW DIATHERMY APPLICATION Condenser field application uses two separate pads or metal plates with an airspace between them. The pads are placed directly on the patient with a single layer of toweling on the skin to absorb moisture. The metal plates are placed at a distance of 2-3 cm from the skin, with an airspace between the plates and the patient. Inductive field applicator is usually some type of drum. The applicator is placed directly over the target area, which is covered by a single layer of toweling. PULSED DLATHERMY Many manufactures of diathermy units provide a pulsed mode, believing that the pulsations reduce the amount of heat generated. That the nonthermal method of applying SWD yields a variety of therapeutic effects that are somehow different. The current literature does not support this contention, and there does not appear to be any specific advantage in using pulsed diathermy. TREATMENT DURATION Treatment times vary between 10 and 30 minutes. The time is based on the condition and the patient. MICROWAVE DIATHERMY 17 18 Microwave diathermy is the easiest to apply of the forms of deep heating. The area which can be treated at any given time is limited to a comparatively small field. Depth is limited to subcutaneous tissues and the more superficial musculature. Microwave diathermy is ineffective in treatment of the deeper and larger joints. Involves the production of an electromagnetic at a frequency of 2450 MHz. On application, check skin sensation, thoroughly dry skin prior to application Remove any metal in or near the field. Do not treat over dressings, bandages, etc.. Do not use toweling between the director and the skin. Do not treat over or near the eyes Use great care over bony prominences. INDICATIONS Whenever mild heat build up or associated reflexes are desired in a specific site that is localized and not too deep, microwave is the treatment of choice. 1. DJD 2. RA 3. Calcific bursitis 4. Tendinitis 18 19 CONTRAINDICATIONS General contraindications to heat should be observed. Never over edematous tissues Over adhesive tape Near metallic implants PHYSIOLOGIC EFFECTS The configuration of a pattern is determined and controlled by the distance that it is placed from the patient and the shape of the reflector. The power output of the microwave unit is adjusted in accordance with the size and shape of the body part treated. The smaller heat output of a microwave unit warms tissues in a much more local area. There is little penetration into deeper organs. Most of the effects of microwave radiation are due to heating of tissues by conversion. The heat build up occurs mainly because of the resistance offered by tissue constituents to high frequency current, and a specific temperature distribution results within body tissues. MICROWAVE DIATHERMY Contact is not necessary, and smaller confined areas can often be treated more effectively. The field that can be heated at any one time is relatively small. Microwave has little, if any effect on deep joints or viscera MICROWAVE DIATHERMY PRECAUTIONS 19 20 If vigorous heating effects are desired, the applicator must be brought close to the surface of the skin. The applicator should not be brought into contact with the skin. Avoid sweat droplets forming on the skin that can be selectively heated. During treatment near the head, the eyes should be shielded with special goggles. Watches must be kept away from the high frequency field, Hearing aids must be placed at least 4 feet from the treatment field. NOTE: The director should be placed from 1-7 inches from the patient, depending on the type that is used. TREATMENT DURATION A treatment duration exceeding 20 minutes is inadvisable INTERFERENTIAL THERAPY The name Interferential therapy stems from the concept of two currents interfering with each other This becomes readily apparent when one views the four electrodes that are necessary to produce the standard interferential effect in a patient IF is one of a number of electrical stimulation techniques used in modem physiotherapy. The common feature of all modalities is the ability to facilitate healing in damaged tissues However, IF has a number of advantages INTERFERENTIAL CURRENT ADVANTAGES Reduces skin impedance and makes the current very comfortable. 20 21 Reduction in skin resistance and the combined effect of the two currents allows greater current penetration to the deeper tissues. IFC is best used to reduce pain and muscle spasm, particularly with acute conditions. INTERFERENTIAL CURRENT DISADVANTAGES The IFC stimulators are designed to be used on a continuous mode only. Consequenuy , they tend not to be as versatile when it comes to rehabilitation procedures that require an interrupted, surged, or reciprocating mode. IFC stimulators typically are more expensive than other types of ES devices. INTERFERENTIAL THERAPY Modalities which are very different, for example, SW diathermy, US, and IF, may all achieve the same result, but use different mechanisms in so doing. SW diathermy, the mechanism of healing is largely?, US achieves facilitation of healing by utilizing a? mechanism. In contrast, IF facilitates healing by utilizing a bioelectrical effect. Thus, three different modalities, SWD, US, IF, can achieve similar results, using a different mode of action in each case. The major problems with the standard low frequency currents lie with the resistance offered by the skin and the relatively long pulse duration. Normal human skin has a very high resistance to the passage of a low frequency current. When the skin resistance is high, a larger potential difference (voltage) has to be applied to the skin in order to achieve an adequate current flow in the tissues. 21 22 The larger the applied voltage, the more likely it is that the stimulus will become uncomfortable for the patient. If the skin resistance is lowered, then a smaller applied voltage will be required to produce a given current flow in the tissues. Little resistance is offered to a higher frequency alternating current The net result is that if the applied current has a higher frequency, the skin resistance will be low, with all the advantages of a more comfortable and efficient stimulation. In addition, the higher frequencies will mean shorter pulse duration's and this will lead to a more comfortable stimulus Problems arise, however, that in order to gain the advantages of lowered skin resistance, the frequency of the current used needs to be approximately 4,000 Hz, At this medium frequency the current is well outside the usual biological range of between 0.1 and 200 Hz. If however two medium frequency alternating sine waves that are slightly out of phase with each other are applied to the skin and tissues in such a way that there is a difference in frequency between the two currents, then a rather interesting effect occurs. This is the basis of the production of IF currents. IF currents are produced by the interfering of the two medium frequency, alternating currents. Two such medium frequency currents, one at 4,000Hz and the other at 4,100 Hz. When these two currents are superimposed on one another, it can be seen that the effect of the blending of these two medium frequency sine waves is a variable increase in amplitude (intensity) of the resultant current. 22 23 The two currents are modified so that they "beat" together from 1 to 200 times per second. The intensity of the current rises and falls this is described as a "beating of the two frequencies. The "beat" frequency is the number of times in each second that the current rises and in intensity to the maximum and falls away to its minimum value The beat frequency in Hz is simply the difference in frequency between the two medium frequency currents. This "beating" is the actual "interferential effect" The beat frequency relates solely to the number of times per second the intensity increases and decreases. The medium frequency (4,000 Hz) is called the carrier frequency The current flowing in the tissues is approximately 4,000 Hz but its INTENSITY is increasing and decreasing (beating) within the range of about 0.1 to 200 times per second. INTERFERENTIAL THERAPY PRE-MODULATED It is possible to deliver IF currents to a patient using two, instead of the conventional four electrodes. In this system, the two currents are "mixed" in the machine and delivered to the Patient via two electrodes. The average treatment time for most applications being 20 to 30 minutes On the first treatment session, it is wiser to halve this, in order to ensure that there are no abnormal responses from the patient. If the overall treatment program has been carefully designed and delivered, then good results should be expected fairly quickly. In most cases, six to ten sessions of IF, together with other measures should produce considerable improvement in the patient. 23 24 If the patient's condition is unchanged after one or two treatments, then the situation needs reassessing. INTERFERENTIAL THERAPY SUMMARY Two medium frequency currents of slightly different frequencies are applied in a crisscross fashion to produce a beat frequency. This therapeutic beat frequency is produced internally to the tissue treated. The beat frequency is determined by the difference of the frequencies applied. Since the therapeutic beat frequency is developed at the intersection of the treatment currents, only a small area is treated. To enlarge the treatment area the vector can be incorporated to effectively spread the area of treatment to include the total area between the pads.19 INTERFERENTIAL THERAPY INDICATIONS 1. Pain Relief - acute and chronic 2. Relief of muscle spasm 3. Arthritic conditions 4. IVO lesions INTERFERENTIAL THERAPY CONTRAINDICATIONS 1. Thrombosis 2. Pacemaker patients 24 25 3. Cardiac conditions, over the heart 4. Malignancy NOTE: Within 20 feet of an operating SWD unit. INTERFERENTIAL THERAPY APPLICATION The single most important factor in successful treatment is proper electrode contact with the patient. 1. Clean the skin area, but do not use alcohol 2. Apply self adhesive disposable/reusable electrodes. Do not use "snap on" type electrodes 3. Apply electrodes over the area in a criss cross manner. 4. Turn machine on (on back of unit) 5. Time is preset (can be changed) 6. Choose frequency 7. Press start 8. Increase intensity to patients tolerance 9. Press vector 10. Sweep is already engaged on some machines. If not press sweep also. RUSSIAN STIMULATION Dr. Y.M. Kots, a Russian physiatrist, has been credited with the development of Russian Stim during the late 1960's. Presented seminars in the U.S. on the use of EMS to augment strength gain 25 26 The stimulators developed in the U.S. after Dr. Kots presentations were termed Russian current generators. These stimulators deliver a medium frequency (2,000 to 10,000 Hz) The peak current intensity stimulates muscle very well and is comfortable. The initial uses of Russian Stimulation in the U.S. were for rehabilitation following surgical procedures such as ACL repair. Strengthening of the quadriceps muscle to correct atrophy of disuse has become a standard, effective treatment procedure. AC medium frequency 2500 Hz Primary purpose is for muscle rehab/re-education RUSSIAN STIMULATION PHYSIOLOGICAL EFFECTS 1. Muscle strengthening and re-education 2. Decrease edema 3. Increase blood flow 4. Reduces muscle spasm RUSSlAN STIMULATION INDICATIONS 1. Chronic back pain 2. Post-injury muscle atrophy and/or wasting 3. Post~casting 4. Muscle spasms 26 27 RUSSlAN STIMULATION CONTRAINDICATIONS 1. Pacemakers 2. Malignant lesions 3. Upper thorax 4. Pregnancy RUSSIAN STIMULATION APPLICATION 1O/5Opre-set Start with low on times and long off times with long ramp times As strength begins to return, increase on times and decrease off times with shorter ramp RUSSIAN STIMULATION PAD PLACEMENT Bipolar technique Origins and insertions RUSSIAN STIMULATION SUMMARY 1. When an electrical stimulation is applied to muscle or nerve tissue, the result will be tissue membrane depolarization, provided that the current has the appropriate intensity, duration, and waveform to reach the tissue's excitability threshold. 2. Muscle contraction will change according to changes in current. 27 28 3. As the frequency of the electrical stimulus increases, the muscle will develop more tension as a result of the summation of the contraction of the muscle fiber through progressive mechanical shortening. 4. Increases in intensity spreads the current over a larger area and increases the number of motor units activated by the current. 5. Increases in the duration of the current also will cause more motor units to be activated. 6. Electrically stimulated muscle contractions are used clinically to: Help with muscle re-education Muscle contraction for muscle pumping action Reduction of swelling Prevention or retardation of atrophy Muscle strengthening Increasing range of motion in tight joints. NOTE: It does appear that the intensity of contraction is positively correlated to strength gains. The stronger the contraction, the greater the gain. 10/10 PRE-SET Physiological effects are as follows: 1. Decrease edema via pumping effect 2. Break spasms by fatigue of muscles 28 29 3. Increase blood flow INDICATIONS Muscle spasms Edematous situations 10/10 PRE-SET PAD PLACEMENT Bipolar technique Origins and insertions Polarity not important VIBRATORY THERAPY May be applied manually or mechanically, superficially with relatively horizontal oscillations, or to deeper tissues via percussion strokes. EFFECTS The primary action is kinetic Causes an increase in circulation and lymphatic flow Decrease in systemic nervous tension and general or local muscle spasm INDICATIONS A large number of musculoskeletal ailments can be effectively treated with vibratory therapy. See Table II for listed indications 29 30 VIBRATORY THERAPY TREATMENT DURATION Because of the G-5/G-3's strong effect and deep penetration, it is not advisable to use the unit too long over an isolated site. Overuse can produce tissue inflammation and symptoms of soreness. As with most therapies, proper therapy duration depends on the patient's condition and tolerance to the modality General guidelines for treatment time are shown in table IV. If the patient reports a strong "itchy" sensation the treatment should be stopped. This sensation is invariably due to excessive stimulation of cutaneous and subcutaneous receptors, often with progressively adverse vasomotor consequences VIBRATORY THERAPY PRECAUTIONS Prior to application, be sure that the attachments are securely fastened to the applicator head so that they will not disconnect during therapy, and assure that the cable does not become kinked. Because the unit is designed to operate against pressure, it should not be allowed to run extensively when not applied. Avoid sliding the applicator back and forth over the spinal column or bony prominences, and don't move the applicator too fast. Always work toward the heart, in the direction of venous and lymph flow, when the extremities are being treated. Because of the deep penetration produced by the unit, there is no need to apply heavy pressure while moving the applicator. Excessive pressure or moving the unit too fast may cause patient discomfort and/or bruise thepatient's skin. 30 31 Use of a dry towel at the applicator - skin interface prevents body oils and perspiration from contaminating the attachment and prolongs the life of the attachment The towel also contributes a dispersive cushioning factor. It is not a good procedure to allow excessive vibration to the operator's hand over prolonged periods, day after day. There has been cases of unilateral hypertrophic arthritis in barbers who routinely used a small hand-attached vibrator to stimulate customers scalps after shampooing. 31