INTERRUPTED DIRECT CURRENT

The most common alteration to direct current is interruption, when the current flows start and stop at regular intervals. Impulses that are sawtooth, trapezoidal, triangular, or abrupt in their rise and decrease in intensity are examples of these two types of impulses. Graphics are used to illustrate these impulses. Because a contraction of denervated muscle can frequently be induced with a strength of current that is insufficient to excite the motor neurons because accommodation occurs, impulses with a slow rise in current are frequently referred to be "selective." The impulses' frequency and duration can be changed; 100 ms is the typical duration, however increasing it to 300 or 600 ms is frequently advantageous. About 30 times per minute is needed for an impulse with a duration of 100 ms; however, if the duration is extended, the frequency must be lowered. The time interval between the impulses is typically noticeably longer and should never be less than the impulses themselves.

Advancements in Safe Electrotherapy Techniques

Certain devices permit a low-level reversible current to flow between the impulses, resulting in what are known as depolarized impulses. Chemical reactions occur at the electrodes when a direct current (d.c.) flows through an electrolyte. Chemical burn risks have been decreased as constant DC is no longer frequently utilized. Pulsed DC poses less of a risk, and the use of depolarized impulses further lowers it. The chemical formation is reduced by the reverse wave of current between the impulses; if the amount of electricity passed in the reversed current equals that in the forward one, any chemicals created are neutralized and the risk of burns is eliminated. As a result, the patient has less skin irritation during treatment, which increases patient comfort. Modern equipment typically uses circuits that use transistors and timing devices to produce interrupted DC. Changes in the circuit components through which current flows can modify the length of the generated electrical pulse, and a selector switch offers a selection of many fixed-interval pulses and frequencies. Potentiometers are used to apply current to patients in order to increase its intensity from zero.

Physiological effects of interrupted direct current.

A denervated muscular contraction can be started as long as the current intensity and impulse length are sufficient. Compared to when the motor neuron is activated, the contractions are sluggish and the relaxation occurs more slowly. Since motor nerves have the property of accommodation, which denervated muscle tissue lacks, a current rising gradually can nevertheless cause a contraction just as effectively as one rising quickly. Furthermore, a contraction of denervated muscle can frequently be induced by a slowly increasing current, even though the current is insufficient to specifically stimulate the motor neuron. The smallest impulse that is typically deemed enough for treating denervated muscle is 100 ms, yet it is frequently required to extend this impulse in order to completely stop innervated muscle contractions. Both of these elements ought to be considered

Effects of Interrupted DC Stimulation

Sensory nerves are stimulated when the body receives interrupted DC power. The effect is rather noticeable, resulting in a burning or stabbing sensation because the impulses have a pretty long duration. The superficial blood vessels enlarge reflexively, causing cutaneous erythema as a result. The muscles that are supplied contract when motor nerve stimulation is coupled with an interruption in direct current. Because the stimuli are repeated often, each one causes a rapid twitch of the muscles, which is immediately followed by relaxation. Therefore, the muscles don't benefit all that much.

Use cases for interrupted DC power.

Interrupted DC is mostly useful because it can cause denervated muscular contractions. A muscle's structure and characteristics typically alter when it loses its nerve supply. Muscle fibers show noticeable atrophy, and if the degeneration lasts for a long time, they often become fibrosed and lose their extensibility, elasticity, contractability, and irritability. Although no one has yet demonstrated in a controlled experiment that this is the case, electrical stimulation of the muscle fibers may slow down these changes. It is also unlikely that the mass or characteristics of lost muscle can be recovered using these methods. According to other authors, electrical stimulation is not necessary since irreversible alterations in muscle fibers only occur after a significant period of denervation; once re-innervation occurs, exercise can help restore lost muscle size.

Optimizing Muscle Contractions in Therapy

In the event that electrical stimulation is employed, it must be powerful enough to cause a sufficient number of muscle contractions. For every therapy, three hundred contractions of each muscle are ideal. This isn't often feasible because the injured muscle aches too much or because treating multiple damaged muscles would need too long of a recovery period. The minimal number of contractions required for treatment to be successful is typically thought to be ninety; however, if weariness sets in before this number is achieved, treatment time should be shortened.

Optimizing Electrical Stimulation for Rehabilitation

If the patient is unable to feel the regenerating muscle during the early stages of re-innervation, electrical stimulation may be helpful as a re-education tool. Next, the ideal contraction should be achieved by using a pulse duration that is both comfortable for the patient and effective. Though the patient has demonstrated voluntary movement, this could very well be a long-duration current. It's crucial to remember that just because the muscle is healing, a faradic current that is, a short-duration current must be applied. In actuality, a longer current let's say 30 ms might be more efficient and comfortable.

Choice of impulse type

Rectangular impulses can be utilized to produce a decent muscular contraction, although "selective" impulses frequently work better. The time it takes for the current strength to reach its maximum distinguishes the different types of impulses. As long as the impulses have the same duration, the rise is abrupt for rectangular impulses, quite sluggish for trapezoidal, even slower for triangular, and even slower for sawtooth impulses. The benefits of a gradual increase in current intensity include the elimination of unwanted contractions of normally innervated muscles in the area, as denervated muscle often responds to lower current levels than those needed to stimulate motor nerves. Denervated muscle can also be contracted with less sensory stimulation than when rectangular impulses are used. When there is no longer any response to a rectangular impulse, a muscular contraction may be elicited with a slow-rising current in long-term denervation.

length of the impulse

To ensure that all of the denervated muscle fibers are stimulated, an impulse of at least 100 ms is required; if shorter impulses are employed, some of the muscle fibers may not contract. It is typically required to extend the impulse length to 300 or 600 ms in order to abolish contractions of regularly innervated muscles or to stimulate a muscle that has been denervated for some time.

Methods for treating DC interruptions.

Techniques of use

The goal of modified direct current stimulation is to directly stimulate the muscle fibers; therefore, the treatment plan must be set up so that the current flows through each muscle fiber. There are several ways to accomplish this. Each muscle group's origin can have one pad put over it. Muscle that is individually stimulated by the active electrode. The active electrode is a tiny pad or disc that is gently rubbed down the muscle to be stimulated or held over the bottom end of its fleshy belly (labile technique). By moving the electrode across the muscle, you can make sure that the current flows through as many fibers as possible. Additionally, there is less skin discomfort than when the active electrode is kept stationary the entire time. The benefits of both of these approaches are that individual muscles are relaxed while other muscles in the group are stimulated, and the current may be adjusted to achieve each muscle's ideal contraction. They have the drawback that it is impractical to generate a lot of contractions of each muscle if there are numerous muscles that need to be stimulated.

Optimizing Muscle Stimulation Techniques

An approach would be to apply two disc electrodes, one over each end of the muscle that has to be activated. The extensor pollicis longus, which is a muscle that is difficult to isolate, can be stimulated with this method, however it can be challenging for the operator to hold both electrodes at the same time and adjust the current intensity. The two pads can be fixed (stabile technique) with one over the muscle group to be stimulated origin and the other over its lower end. This approach has the benefit of allowing for the elicitation of a high number of contractions, so long as every muscle contracts similarly. Nonetheless, extreme caution must be used to ensure that every muscle contracts adequately. Additionally, there may be a propensity for current to leak onto nearby innervated muscles; however, this can typically be avoided by applying selective impulses long enough to prevent their contraction.

Preparation of equipment

The equipment is ready for the previously mentioned treatments, and the apparatus has been tested. Verify that there are a minimum of eight layers of lint covering the pads and disc electrodes. This is due to the possibility of chemical burns from long-duration pulses if the treatment is administered at the same location for extended periods of time, especially if the chosen current is not depolarized, or lacks the reverse wave of current between the impulses. The patient's tissues should never come into contact with any metal.

Preparation of the patient

To prepare the skin for additional electrical treatments, cleanse it and cover any abrasions. To reduce skin resistance and warm the muscles, it is frequently beneficial to bathe the affected area in warm water prior to treatment. However, if there is significant loss of sensation, caution must be given to ensure the water is not overly heated. The easiest way to get contractions is to support the affected area so that the muscles that need to be contracted are shortened. As an alternative, the muscles may be partially extended while the current is applied; however, this should only be done if the contractions are powerful enough to shorten the muscle and consequently generate joint movement. If this is accomplished, the beneficial effects should be amplified by the load opposing the muscular activity. Typically, movement can only be produced in the smallest joints, like the wrist.

Utilizing interrupted DC power.

Although it's not always the case, connecting the active electrode to the anode facilitates muscle contractions the greatest. It is important to evaluate each patient to find out which gives a greater response—the anode or the cathode—and which pole works best for the active electrode. Following the application of the electrodes, the current intensity is increased until a strong muscle contraction is achieved. While it is ideal to have several contractions, any evidence of exhaustion, such as a weakening of the contraction, should prompt a reduction in the treatment's duration. Usually, contractions are made in bunches, with intervals of rest allowed.

IONTOPHORESIS

This is the word used to describe the process of driving therapeutically beneficial ions into the patient's tissues through their skin. The fundamental idea is to apply an ion to an electrode that has the same charge as the ion—for example, applying a negative ion to the cathode. The "active electrode" would then be this electrode. The ion is then electrically driven into the patient using a continuous (direct) current. Even though continuous (direct) current is rarely utilized these days, it is a good option for treating hyperhidrosis, or excessive perspiration, which is a very prevalent ailment that responds well to this kind of care.

Equipment and Preparation for Electrotherapy

Treatment for the hands and feet may be necessary, but it is not recommended to try to treat both conditions on the same day. Instead, a few days should pass between treatments.
The necessary equipment is:
(a) a low-voltage, low-amperage source of continuous (direct) current;

(b) an anode-containing shallow plastic tray;

(c) a cathode-containing foot or arm bath;

(d) two sizable electrodes and leads;

(e) two sizable lint pads to cover the electrodes;

(f) an anticholinergic compound solution; and

(g) distilled water.

Before using the machine, it should be tested. Leads are connected to terminals and held in a bowl of tap water with their free ends held apart and not touching. To make sure that the current is regulated evenly, the control should be increased and the milliampere meter's needle observed. The physiotherapist may then check the current for faradic-type current on oneself.

Approach to Care

Hands

The patient sits next to the shallow plastic dish that is set on an arm bath table. After positioning the active electrode (anode) within the plastic tray, one of the lint pads is placed over it. To ensure optimal contact between the electrode and the tissues, as well as to effectively absorb any chemicals that may accumulate during the therapy, the pads should have a minimum of eight layers.  Additionally, there is enough distilled water on the tray to completely submerge the hand in a 0.05 percent solution of the anticholinergic drug glycopyrronium bromide. The electrode is attached to the treatment unit's positive terminal, and the hand is positioned within the tray. In the foot bath, one of the patient's feet is submerged in a few centimeters of warm water on top of a lint pad that covers the electrode that is attached to the negative terminal. Now that the current is turned on, it is gradually increased to the desired level for the required length of time.

Feet

The configurations for treating the feet should be switched around, with the arm bath with the cathode for the arm to complete the circuit and the shallow tray with the anode on the floor. Quantity Skin tolerance is taken into account and the patient's size determines the first course of treatment. Twelve milliamps for twelve minutes is the norm for an adult; for a youngster, this quantity is halved. Every patient is different when it comes to the necessity of repeating the treatment; some feel better for months following a single session, while others need to return in less than four to six weeks.

Take Care

1. Abrasion of the skin
2. Take off the patient's jewelry.
3. Advise the patient to stay still while receiving therapy.
4. Verify the pads' appropriate thickness.

Adverse consequences

Due to the atropine-like effects of anticholinergic drugs, patients may experience:

1. Dryness in the throat and mouth.
2. Limited perspiration throughout the body. It is advisable to urge the patient not to partake in any strenuous activities that necessitate sweating for the purpose of maintaining body temperature for the remainder of that day.

Contraindications

1. Pregnancy
2. Conditions where there is congestion of the lungs and respiratory system.