The Use Of Physical Agent Modalities In A Clinical Setting

Physical agent modalities (PAM) may be used by occupational therapists as adjuncts to or in preparation for purposeful activities. Both heat and ice are useful in reducing pain and muscle spasms of musculoskeletal and neurologic pathologies. Paraffin and fluidotherapy, along with other modalities such as hydrotherapy, whirlpools, and heat lamps are examples of superficial heat that could be used to increase local metabolism and circulation. The use of heat is indicated in the treatment of subacute and chronic traumatic and inflammatory conditions such as muscle spasms, arthritis of small joints of hands and feet, tendonitis, and bursitis. In a clinical setting, heat is used to increase motion, decrease joint stiffness, and aid in the reabsorption of exudates and edema in a chronic condition. In general, the use of heat is contraindicated in circumstances where clients have the following conditions: acute inflammatory conditions, cardiac insufficiencies, malignancies, or peripheral vascular disease. In addition, heat should not be applied to clients that have no sensation.

Fluidotherapy

Fluidotherapy is a commonly used physical agent modality. Fluidotherapy is rooted in the concept of convection. Convection supplies heat to the tissue by fluid motion and around tissues. Fluidotherapy involves a machine that agitates finely ground cornhusk particles by blowing warm air through them. The device is similar to a whirlpool, but corn particles are used instead of water. The temperature is maintained with the therapeutic range extending up to 125 degrees. Treatment time, temperature, and treatment area should be carefully documented. This modality is an excellent choice for raising tissue temperature in the hands and feet. An additional benefit is its effect to desensitization irritable scar tissue. The agitator can be adjusted to increase or decrease the flow of corn particles, thus controlling the amount of stimulation to the skin. This modality is effective as a warm-up before exercises, dexterity tasks, functional activities, and work simulation. Fluidotherapy is a commonly used treatment modality for individuals suffering from complex regional pain syndrome to minimize pain. Patients with this condition should be asked to perform active range of motion exercises while the limb is in the machine and temperature should be lowered to 98 degrees inside the machine. When working with patients suffering from complex regional pain syndrome, it is important to be cautious not to overstimulate hypersensitive areas, and therefore, if patients have a warm, reddened limb, using ice packs and monitoring patient closely is advised. Fluidotherapy should be cautiously used in the presence of open wounds. Open wounds must be covered with a plastic barrier to prevent cellulose particle from entering the wound.

Paraffin

Conduction is the transfer of heat from one object to another through direct contact. Paraffin, along with hot packs, provide heat through conduction. Paraffin is stored in a tub that maintains a temperature between 125 and 130 degrees Fahrenheit. The client repeatedly dips his or her hand into the tub until a thick, insulating layer of paraffin is covering the extremity. The hand is then wrapped in a plastic bag and towel for 10-20 minutes. This technique is ideal for use in hands and digits to treat patients with chronic arthritis. Partial hand coverage is possible. The paraffin transfers its heat to the hand, and the bag and towel acts as an insulator against heat escaping into the air. Special attention must be provided to protect insensate parts from burns. Paraffin should not be applied when moderate to severe edema is present to prevent excessive vasodilation.

Paraffin and Ultrasound are two physical agent modalities commonly used for burn scars. Paraffin combines the benefits of heat and skin lubrication, which are useful before exercise. Dense scar burns are best heated by ultrasound. As a precaution though, extreme care must be taken with paraffin and ultrasound treatments due to the possibility of decreased sensation and heat tolerance of scar tissue. Paraffin and ultrasound are never to be used on open wounds or broken skin. Additionally, paraffin is a useful tool to a therapist because it is relatively inexpensive, easily found at many department stores or pharmacies, and easily incorporated into a home education program as a mode of pain relief to facilitate improved occupational performance.

Ultrasound

Ultrasound is rooted in the concept of conversion where heat is generated internally by friction. Ultrasound uses sound waves to penetrate the tissue, causing vibration of the molecules, and the resulting friction generates heat. The sound wave energy is converted to heat. The soundwaves are applied with a transducer, which glides across the skin in slow, continuous motions at 90 degree angles to the skin. Gel is used to improve the transmission of the sound to the tissues. Ultrasound is considered a deep heating agent. At 1MHz (1 million cycles per second), it can heat tissues to a depth of 5 cm. Many therapeutic ultrasound machines provide a 3 MHz option for treatment of more superficial structures. Ultrasound at frequencies higher than recommended standards can destroy tissue. When using ultrasound, parameters include intensity, frequency, treatment time, and waveform. Typical intensity ranges from 0. 75-1. 5 W/cm squared. As mentioned, frequency set to 1 MHz for deep penetration or 3MHz for less deep penetration. Treatment time is between 5-10 minutes. Waveform should be set to continuous for thermal effects or pulsed for primarily non-thermal effects. When applying ultrasound to increase ROM, position the client for simultaneous stretching if possible. Clients should not perceive heat, and if it becomes excessively warm, the clinician should add additional gel and maintain good skin contact. If the problem persists, the unit should be checked. Signs of overdose is the client complaining of sudden and sharp pain in the treatment area. Some clients complain of a gradually increasing ache. Ultrasound is contraindicated in areas of decreased circulation or impaired sensation, over the reproductive organs or eyes, on a pregnant uterus, pacemaker, bone growth plates of children, joint replacements, an unprotected spinal cord, and freshly repaired structures such as tendons and nerves or in the presence of cancer.

Ultrasound has a plethora of uses. It can be used to treat a variety of conditions such as: compartment syndrome, dysfunctions of the elbow, hand osteoarthritis, impingement syndrome, radial nerve compression, tendon disorders, joint contractures, scarring with its associated adhesions, muscle spasms, and wrist dysfunction. Continuous wave ultrasound works to increase tissue extensibility and permeability, improve blood flow, and decrease the pain felt by an individual by increasing the pain threshold which makes this modality a good choice for patients who have pain radiating from under the skin. Continuous wave ultrasound therapy can be used in patients with Dupuytren’s approximately 3 weeks after surgery. Ultrasound therapy is a good option for this condition because it works to enhance soft tissue mobility and reduce stiffness. In addition, pulsed ultrasound has been found to facilitate the resolution of the inflammatory phase of healing. Finally, ultrasound may be used to drive anti-inflammatory medication into tissues in a process called phonophoresis. This modality is believed to increase membrane permeability for greater symptom relief and may also be used after corticosteroid injections.

Iontophoresis

Iontophoresis is defined as the use of direct current to introduce topically applied ionized medication to underlying inflamed and scar tissue, which produce the effects of reducing edema and altering pain perception. This technique uses an electrode filled with the medication of choice. The medicine is transferred by applying an electric field that repels the ions into the tissues. Dosage is expressed in milliamps-minutes (mA-min). For example, a dosage of 20 mA-min may be provided with an intensity of 4mA applied for 5 minutes. The same dosage maybe achieved with an intensity of 2mA for 10 minutes. Typically, dosages range from 20 to 40 mA-min with dosages dependent on the ion being transferred. Many treatment protocols exist. The clinician should gradually increase intensity and remain within the patients’ tolerance. The client should only experience a mild tingling. The client should be instructed to report any delayed posttreatment skin irritation immediately.

Iontophoreses is best applied to specific localized, and relatively superficial target tissues such as tissues of the rotator cuff tendons, common wrist/finger/hand flexors and extensor origins, patella ligament, achilles tendon, etc. Iontophoresis with saline has been shown to minimize excessive scar formation and can also be used at 3 weeks after surgery in Dupuytren’s clients where saline acts as a sclerosing agent when delivered with iontophoretic current. The saline (1. 5 mL in 2. 5% aqueous solution) is delivered via the cathode. Iontophoresis is contraindicated in areas with bruises, cuts, or otherwise broken skin. It is also contraindicated in acute injuries and over sites of active hemorrhage. Iontophoresis should be very cautiously applied in areas of impaired sensation.

Electrical Stimulation

Electrical modalities are used to decrease pain, decrease edema, increase motion, and reeducate muscles for the purpose of increasing a client’s functional abilities within the realm of occupational therapy. Electrical modalities are contraindicated with clients who have pacemakers or cardiac conditions. Transcutaneous electrical stimulation (TENS) is a noninvasive pain relief measure that uses cutaneous stimulation via electrical current. TENS is an effective technique for control of pain without the side effects of medication. TENS is safe to use and clients can be educated in independent home use. A TENS unit consists of a battery-powered generator that sends a mild electrical current to peripheral nerves through electrodes placed on the skin at or near the pain site. The therapist can control several attributes of the waveform such as the frequency, amplitude, and pulse width. When TENS is applied at a low-firing setting, endogenous opiates, naturally occurring substances within the body that reduce pain sensation, are released. The effects of high-frequency TENS are based on the gate control theory of pain which essentially describe how TENS applied to peripheral nerves block the transmission of pain signals to the brain. TENS can be applied for acute and chronic pain, and is often used after surgery when it is mandatory that motion be initiated within 72 hours. As an example, this modality would be used when it is important to maintain tendon gliding through the injured area after fractures. It also is especially useful for clients who have a low threshold for pain because it makes exercising easier. TENS can additionally be used to decrease pain from an inflammatory condition such as tendonitis or nerve impingement with additional education on tendon and nerve protection and a proper home program of symptom management, positioning, and ADL and work modification.

TENS can be used to treat flaccidity, along with other methods such as high-frequency vibration, tapping, and quick stretch among other techniques. Occupational therapists trained in neuromuscular electrical stimulation can quicken recovery of range of motion and strength in the hands by placing electrodes on the wrist extensors and extensor digitorum communis while the client actively performs wrist and finger extension. Another suggested electrode placement would be on the biceps and supinator muscle where the negative electrode would be placed on the supinator and the positive electrode on the biceps utilizing an asymmetric waveform while encouraging active movement.

Neuromuscular electrical stimulation (NMES) provides a continuous interrupted current. It is applied through an electrode to the motor point of innervated muscles to provide a muscle contraction. The current is interrupted to enable the muscle to relax between contractions, and the durations of the on and off times can be adjusted. Adjustments can also be made to control the rate of the increase in current (ramp) and intensity of the contraction. NMES is used to increase ROM, facilitate muscle contractions, and strengthen muscles. Active ROM provides an internal stretch against resistant scar tissue, and if a client is unable to achieve active motion because of scar adhesions or weakness, the use of a battery-operated NMES may assist to increase the motion. It may be used after surgery to provide a stronger contraction for released tendon gliding. It also may be used later in the tendon repair protocol, once the tendon has healed sufficiently to tolerate stress, usually at a minimum of 6 weeks. NMES may be used to lengthen a muscle that has become weakened because of disuse. During the reinnervation phase after a nerve injury, this technique may be used to help stimulate and strengthen a newly innervated muscle. Other techniques that use an electrical current include high-voltage galvanic stimulation (HVGS) and inferential electrical stimulation to treat pain, inflammation, and edema. Some hand therapists use high-voltage direct current as an intervention to increase motor activity of denervated muscles. High-Volt Pulse Current is a consideration for specifically subacute and chronic edema and there is evidence that supports HVPC in conjunction with splinting yields a reduction in edema. Interferential Current (IFC) uses two wave kilohertz frequencies and creates interference between them resulting in a unique current. At times, the currents intersect and the amplitude adds up. At other times, the currents do not intersect and the amplitude is the difference of the two frequencies. IFC is used for pain management, edema, and muscle spasm reduction. IFC settings may differ from machine to machine. Beat frequency (the interference frequency) ranges from 1-200 Hz. The Carrier frequency ranges from 1000-5000 Hz where some machines are set to 4000 Hz. The linear sweep function should be set to continuously modulating from maximum to minimum frequency. The peak to peak parameter should be set to alternately modulating between maximum and minimum frequency. IFC uses four electrodes set up so that the two wave currents intersect on one another perpendicularly. Because it is unclear where exactly to predict the currents will intersect, some machines offer a vector scan. A vector scan is a modulation of amplitude that changes the position of the interference pattern. The vector scan is used to cover a larger treatment area. Intensity is increased to patients’ tolerance. Patients should feel a comfortable tingling sensation. Electrical stimulation is generally contraindicated in pregnancy. Another contraindication includes the presence of active tuberculosis.

In essence, physical agent modalities are excellent options for rehabilitation technology to be utilized by therapy practitioners. Occupational therapists specifically use these modalities to establish, restore, or modify function in a client to improve occupational performance and increase overall quality of life and wellbeing. Physical agent modalities such as cold, superficial heat, ultrasound, and neuromuscular electrical stimulation can be used as preparation for, or in conjunction with purposeful activity and muscle re-education.