Medical Machines

January 28, 2009 by Rebecca Deal  
Filed under Massage & Wellness, Physical Therapy

Modern physical therapy often involves the use of modalities. Modalities are anti-inflammatory machines designed to reduce swelling around an injured body part.   During the acute phase of an injury (generally lasts 1-6 days), inflammatory byproducts enter the traumatized area to remove debris and limit bleeding.   The inflammatory phase is characterized by heat, swelling, pain, redness, and loss of function.  The more quickly this phase is resolved, the lower the probability of joint destruction, excessive pain, swelling, weakness, immobilization, and loss of function.  Using anti-inflammatory modalities can accelerate patient progress toward more active participation in rehabilitation and expedite therapy goals for an early return to function.

Electrical Stimulation

Electrical stimulation has a wide variety of clinical applications in physical therapy.  Electrical stimulation is based on the principles of charged particles flowing to reduce inflammation and control pain.  Clinical units generally use two different types of currents to electrically stimulate muscles.  An interferential current is a waveform produced by the interference of two different medium frequency alternating currents from separate channels.  An interferential current is set up with four electrodes in an “X” pattern over a large body part.  A premodulated current uses one channel to deliver a continuous waveform with a medium frequency and a fluctuating current amplitude.  Premodulated electrical stimulation is delivered with two electrodes evenly spaced over a small, inflamed area.  Electrical stimulation treatments are often combined with temperature modalities (hot packs, cold packs) at the end of a physical therapy session for fifteen minutes to control swelling after activity.

Transcutaneous Electrical Neuromuscular Stimulation (TENS) is a popular electrical stimulation modality for controlling pain.  According to the gate control theory of pain, activation of A-beta nerve fibers can inhibit the transmission of the pain signal from the spinal cord to the brain.  Electrical stimulation, when set with appropriate parameters, can selectively activate the A-beta nerve fibers and block the brain from receiving the pain signal from the body.  TENS units deliver a low voltage current and the patient feels a strong, but comfortable tingling sensation.  Patient-friendly TENS units are available for home use at affordable prices.  A physical therapist can give you product recommendations and detailed instructions on how to set the TENS unit for maximum pain relief.  Contact the therapy team at North Tahoe Physical Therapy for pricing and information.

Ultrasound

Ultrasound is a medical machine that uses sound waves to penetrate into tissue for both thermal and non-thermal healing effects.  Ultrasound functions under the principles of piezoelectricity: the ability to change shape in response to an electrical current.  An electrical current is applied to the crystal in the ultrasound “wand” called a transducer.  The piezoelectric crystal responds to the current by expanding and contracting, creating an ultrasound wave.  This wave is able to penetrate through skin using a conducting gel to tissue depths of 1-3mm to bring blood to the injured site and stimulate healing.  Macrophages are cells that work to localize the inflammatory process and recruit repair cells.  The ultrasound machine increases macrophage activity to consolidate inflammation and accelerate the cellular repair response.

Ultrasound treatment can be performed using either a continuous or pulsed setting for duration of eight minutes. Continuous wave ultrasound is used to produce heat and warm the tissues.  Pulsed wave ultrasound recruits macrophages is recommended for anti-inflammatory effects.  During the ultrasound treatment, the patient may feel a minimal sensation from the ultrasound wave.  The patient may perceive warmth from the ultrasound conductive gel.  Ultrasound can be done for a single session or repeated in consecutive treatments to produce the desired anti-inflammatory effects.

Iontophoresis

Iontophoresis is transdermal anti-inflammatory drug delivery using a low voltage direct current to move charged ions across the skin barrier. Ions are transported through skin pores to deliver Dexamethasone (a corticosteroid recommended for the treatment of inflammatory conditions) in the manufacturer recommended 40mA.minutes dosage.  This machine is set up with the medicated, active electrode over the inflamed tissue and a ground electrode at a distant site.  The patient perceives a light tingle under the medicated patch for the duration of the treatment.   Iontophoresis can be done one time, for several sessions consecutively, or in combination with other modalities to produce an overall anti-inflammatory effect.

Modern physical therapy now has several anti-inflammatory modalities from which to choose during the acute phase of healing.  Other medical professionals (MDs, chiropractors, and acupuncturists) may introduce you to similar tools in treatment designed to control inflammation.  Now that you understand the concept of inflammation and how each modality works to reduce swelling and decrease symptoms you can help your medical team make an educated decision about what combination of medical machines will work best for your body under each condition.