INTRODCUTION Since 1950 when the profession of Athletic Training began, acute traumatic injuries were treated with rest, ice, compression and elevation (RICE). 4 This method is still used today because it is clinically proven to be effective to treat edema and manage pain. Preventing and treating edema can be difficult and time consuming, especially for Athletic Trainers trying to rehabilitate athletes back into the game. “Edema is the result of an imbalance in the filtration system between the capillary and interstitial, which causes venous obstruction, increased capillary permeability, and increased plasma volume secondary to sodium and water retention.” 13 Edema is commonly encountered in clinical setting of Athletic Trainers. “It usually results from an imbalance of forces controlling fluid exchange.”8 Edema is characterized as a buildup of excessive fluids in a interstitial space in the body due to an underling injury to muscle tissue. 8 Edema mostly affects lower extremities like the foot and ankle. Blood circulation of the involved limb is obstructed and can possibly be very painful. It also affects the healing process, causing it to delay and can develop ischemia. Edema can also increase the chance of a skin infection, which can be dangerous if left untreated. Protocols with Electrical Stimulation on Edema Over the years, clinicians frequently use electrical stimulation to prevent and reduce postacute edema. Today’s research supports the use of electrotherapy for curbing and reducing edema. Electrical stimulation may increase venous return and deplete lymphatic fluids when exercise cannot be performed. Using electric stimulation creates a muscle contraction that may reduce edema. 7,14 Studies have been done on several animals to find out the effectiveness on quite a few varieties of electrical stimulation (ES), but high-voltage pulsed current is used mostly for controlling acute posttraumatic edema.10 High-voltage pulsed current (HVPC) was designed to manage edema with sensory level stimulation. “It provides a monophasic current with a twin peak waveform, a relatively short pulse duration with a long interpulse interval and an amplitude range above 150 mVolts”.7 The most effective method for edema control is to initiate treatment within six hours after injury. Using high sensory-level electrical stimulation to treat edema can increase lymphatic flow, but does not decrease limb volume. 10 Another method to mange swelling is using a motor-level stimulation for edema reduction. This protocol generates repetitive muscle contractions to assist in lymphatic and venous return by forcing fluids out from the involved limb. With a low pulsed frequency and a comfortable muscle contraction can increase the muscle milking effect to relieve edema. One research study experimented on the effect of neuromuscular stimulation (NMES) on ankle swelling. NMES is used frequently to decrease swelling in the early period of the inflammatory phase of the healing process.9 Neuromuscular electrical stimulation is mostly designed for muscle re- education to prevent atrophy. The electrodes are placed on healthy muscles and the intensity creates muscle contractions similar voluntary muscle contractions. Effects of High-Voltage Electric Stimulation on Edema Prevention Over the years experimental studies revealed that cathodal high-voltage pulsed current (CHVPC) at 120 pulses per second and 90% of motor threshold is successful in curbing acute edema development in laboratory animals. 9 One experiment’s objective treatment effects with ibuprofen and (CHVPC) on acute edema formation with treatment of ibuprofen and CHVPC after direct trauma. The subjects used for this study were 21 Zucker Lean rats. It is believed that rats in general probably serve as useful models for humans with regard to aspects of the inflammatory response.3 Recent studies confirm positive treatment effects with Zucker Lean rats than any other rat specie. 3 Measurements were taken before and after blunt trauma. Measurements of limb volumes of each participant were also taken every thirty minutes over the four hours of treatment. The procedure to form edema consisted of a steel rod being dropped on each of the subject’s foot. The precipitants were then divided into three groups. Group one consisted of taking a nonsteroidal anti-inflammatory drug; group two received electrotherapy and group three received a combination of both. Animals who received ibuprofen was injected 100mg of IBU per 5mL to the stomach. Animals in group two received three received continuous hours of CHVPC at 120 pulses per second and 90% of motor threshold in water for four hours. 4 The results of the experiment confirmed that the treated limbs were smaller than those of untreated limbs for all treatments after 30 minutes. The results remained the same throughout the four hour experiment. The measurements also concluded that swelling was reduced to 50% compared to the untreated limbs, but no treatment was more effective than the other. It is interesting how each of the three groups that were treated differently for curbing edema resulted in the same measurements. Researchers did measurements every thirty minutes for the four hour treatment. If measurements were taken twenty four hours after the experiment, the findings from the day after treatment might have shown different results from each of the three groups. This hypothesis can determine what treatment was more effective. Another research study was to determine to find the best approach to control edema with high-voltage electrical stimulation with cool water immersion, in both alone and in combination of treatment. This experiment used thirty-four anesthetized Zucher Lean rats as subjects. Each of the subject’s limbs was measured for volume before and after direct trauma to create edema. Measurements were also recorded after each of the four treatments and rest periods. Each participant were randomly received treatment of cold water immersion, cathodal high-voltage pulsed current or combination of both techniques. Both feet of the thirty four subjects were traumatized by dropping a steel rod that weighed 85.5 g with a height of 30cm. The subjects were then assigned to one of the three groups. The thirty minute rest periods started as soon as each of the rat’s limbs were traumatized and edema was formed. The cool-water immersion, cathodal high-voltage electric stimulation, and simultaneous application of these treatments were effective in curbing edema after blunt injury. The combination of CWI and CHVPC was not more effective than either CWI or CHPC alone. 2 The combination of the cool water immersion and high-voltage electrical stimulation wasn’t more effective due to the result of gravity. Immersing an acute traumatic ankle in water is a fight against gravity. High-voltage pulsed electrical stimulation would have the best results if it was performed with some elevation. Elevating the injured site above the heart alone will reduce the formation of edema. Effect of Neuromuslcular Electrical Stimulation on Edema A variety of treatment protocols are used to control swelling in the postacute phase of an injury. It is thought that neuromuscular electrical stimulation (NMES) that stimulates muscle contractions can compress venous and lymphatic vessels. This mechanical effect may assist in the resolution of posttraumatic and chronic edema. 9 Provoking muscle contractions by using neuromuscular electrical stimulation may increase venous return and lymphatic flow, which may reduce edema. Ivy Man studied neuromuscular electrical stimulation on edema. The purpose of his experiment was to evaluate neuromuscular electrical stimulation effectiveness of decreased swelling in the acute phase of an ankle sprain. Thirty-four subjects within 18 to 60 years of age were used as subjects for Man’s study. All participants were recovering from an ankle sprain. Measurements were taken from each subject. Body mass, height, and ankle girth were measured. Ankle girth was measured with the figure eight tape technique. The participants were then submersed their leg into a jug of water. The displaced water was collected and weighed. The same jug was used in each trial to collect the displaced water and was used before and after each trial. 9 The purpose of placing the injured leg into a jug of water signifies amount of swelling in each of the subject’s ankle. The subjects were then placed into three groups and scheduled for three sessions at 30 minute treatments. The participants were not informed on what type of treatment they were going to be assigned. The three groups were set up with four electrodes applied over the tibialis anterior muscle and the gastroenemius. Group one received NMES and group two received submotor electrical stimulation. Group three was given sham treatment. For the subjects in the NMES group, the intensity of ES was set to the subjects' maximum level of tolerance and was adjusted if necessary throughout the 30-minute test period. 7 The submotor electrical stimulation groups had a total of 360 cycles, with each cycle lasting 5 seconds. “Each cycle consisted of 400 pulses having different combinations of pulse-to-pulse intervals and duration values.” 7 The participants in the sham electrical stimulation group were informed that they shouldn’t feel anything during the 30 minutes of treatment The data was collected and calculated from all the subjects. The results showed no significant difference among the three different treatments. This experiment implies that the NMES has no beneficial results compared to the other two groups. Stimulation on Edema Reduction Edema that continues for several weeks can be frustrating to reduce especially if it involves with the upper extremity. 6 Many studies have been done to find the best protocol to reduce edema. Mohr is one of the early researchers who experimented on the effect on edema reduction on rats with high voltage electrical stimulation. 11 Mohr discovered that muscular movement can increase venous drainage, lymphatic flow, and increase blood flow. 11 “Newton compared changes in edema and range of motion in patients with posttraumatic hand edema when HVPC was combined with placement of the affected hand in cool water.” 6 The result of Newton’s study shown that range of motion progressed but edema did not diminish after treatment with high-voltage pulsed current. One particular study focuses on the results of Mohr’s experiment, and compares the effectiveness of intermittent pneumatic compression (IPC), High voltage pulsed current and placebo HVPC with chronic hand edema. The participants in this study include thirty patients with chronic posttraumatic hand edema. The subjects were randomly assigned to one of the three groups where they received one day of treatment for a thirty minute period. “During HVPC treatment, one active electrode was placed over the median nerve in the antecubital fossa, with another over the ulnar nerve at the medial epicondyle.”6 According to Bolter, he revealed an increase in lymphatic flow using a 10 pps frequency to induce continuous muscle contractions. This experiment used a set frequency of 8 pps. It is significant to elicit minimal contractions of the hand muscles to prevent fatigue. 6 The hand volume measurements before and after treatment found no significant difference between HVPC and the placebo HVPC treatment. However, the results of intermittent pneumatic compression indicated a significant edema reduction in some participants after one 30 minute treatment. The researchers for this experiment believe protocols needed to be rearranged with the high-voltage pulsed current treatment. They believe a longer treatment time and a different electrode placement may have shown greater results with edema reduction with HVPC treatment. The researchers stated that the next step is to further evaluate the effectiveness of IPC and HVPC for reduction of posttraumatic hand edema. Most Effective Treatment The measurements with the use of NSAIDs and HVPC concluded that edema was reduced by almost half compared to the untreated limbs, but no treatment was more effective than the other. This confirms ibuprofen and high-voltage electrical stimulation is effective for curbing edema but the combination of the two doesn’t show a greater effect. The data collected from the subject experimented on NMES verified no beneficial results with controlling swelling in the ankle. The study that measured hand volume between HVPC and the placebo treatment concluded no significant difference. However, a significant amount of edema was reduced when compared with the results with the IPC treatment. This shows the most effective treatment when out of all of the following experiments. CONCLUSION Edema formation can cause pain and reduce range of motion. It obstructs the healing process and is frustrating and difficult to manage. Clinical research studies focused on finding on a protocol that benefits best with curbing and reducing edema. Clinical experiments have been performed to curb and reduce edema. Research tried using certain protocols to treat edema in the postacute phase of an injury with electrotherapy. Electric stimulation is proven to be successful in curbing acute edema formation in animals. 2 Other research studies experimented and shown cryotherapy high-voltage electrical stimulation and NSAIDs reduce permeability of lymphatic flow. From the preceding research studies discussed, electrical stimulation had little or no effect when it comes reducing edema. However, the most effective protocol for curbing edema was the intermittent pneumatic compression and high-voltage pulse current. The true purpose of all the clinical experiments was to find a technique that would be most effective to curb edema after acute trauma. By creating a better healing environment from controlling edema, athletes can recover more quickly from a minor acute injury. Today, the best method for dealing with edema is RICE, which is being used for over fifty years. However, it is understandable that further research is needed involving electric stimulation treatment on edema.
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