Diathermy Research Angela Perkins, Corinne Nyman, Laurel Petersen, Nate Smith
Purpose of this Study • Is to ascertain the pulse repetition rate (PRR) required to generate a perceptible thermal effect using a specific combination as follows • Treatment Group • Constant Pulse Frequency 400 Hz • Peak intensity 200 W • Placebo • Peak intensity 0 W
Comparison Study • Murray and Kitchen found that PSWD will produce ‘definite’ thermal effect with a pulse power of 190W , pulse duration of 400µsec, mean power of 21.19 (±8.27) W while steadily increasing the PRR every two minutes to a mean value of 278.8 (±108.8)Hz.
Method • Study Design: A randomized, controlled, double-blind experimental study design was used to investigate the effects of PRR on thermal perception for PSWD. • Subjects: Sixteen volunteers (8male; 8 female) from the student population at Weber State University were recruited for the study. The subjects ranged in age from 21-36, were currently on no medication, free of any recent injuries or illness, and were general healthy. Subjects were free of any diathermy contraindications, and had no history of adverse reactions to diathermy.
Method • Apparatus: PWSD will be administered using a Mettler Auto*Therm 390 (Mettler Electronics Corporation, Anaheim, CA) using a single arm induction drum. The pulse duration was 400 Hz and peak intensity 200 W in the treatment group and 0W in the control group. The PRR was increased every two minutes from 65,100, 200, 300 to 400 (5 increments of two minute applications) for the treatment group. • The specifications of this apparatus were as follows: • Frequency 27.12 MHz • Pulse duration 0-400μs • Pulse frequency 65, 100, 200, 300, 400Hz • Pulse power 0-200W • Mean power 0-32 • Treatment time 2x5, 10 min
Apparatus continue: • An infraredthermometer was used to measure skin surface temperature. Manufactures’ specifications defined the reliability of ±3°C. • Skin-fold calipers were used to measure body fat percentage, and measurements were taken by the same examiner every time to allow for consistency. • A digital thermometer was used to measure room temperature at the beginning and conclusion of each session. • A single operator controlled the PSWD machine, and was the only examiner to know which group the subject was in. • Another single examiner attained all the history and measured the participants’ body fat percentage with the skin calipers. • Another single examiner interacted wit the subjects, questioned them and obtained skin temperature readings.
Procedure Subjects were directed to abstain from physical exercise for at least four hours before PSWD application. Upon arrival subjects completed a medical questionnaire, had their height, weight, adipose thicknesses of their right thigh measured and marked. Subjects were standing when the examiner measured three inches from their patella for the first reference point, which marked where the edge of the PSWD drum was placed and then measured again six inches from the patella for the second reference point, which marked where the adipose thickness of the thigh was measured and where skin surface temperature was taken during the treatment, approximately center of the drum. Skin-fold calipers were used to measure the adipose thickness. An adipose thickness of greater than 20mm resulted in exclusion from the study.12 Excessive adipose tissue appears to affect the rate of thermal conduction; slowing the increase of the intramuscular temperature. Additionally subjects had their thermal sensation tested with different temperatures of water and placed on the subjects’ second reference point. The subjects were then responsible for identifying whether the test tube contained cold, warm or room temperature water.
Procedure • Subjects were then asked to sit in the treatment room for 10 minutes, allowing them to acclimatize to the temperature of the room. • Subjects were propped up in a half lying position with a cushion behind them, allowing their muscles to relax.
Procedure • The edge of induction drum was placed on the first reference point. A terry cloth towel was placed between the subject’s skin and drum. The PSWD was applied in 2 minute bursts for each PRR assessed. Skin surface temperature was measured and then the subjects were asked the following questions • “Did you think you could feel a change in temperature after the last application?” (This is a possible thermal sensation) • “Did you definitely feel a change in temperature after the last application?”(A definite thermal sensation). • The sequence of applications was stopped when subjects reply that they could defiantly feel a thermal effect at the point of application.
Procedure • Dosage • Treatment Group • For the treatment group, peak intensity was kept at a constant 200 W and the pulse duration was set at 400чs. The PRR was increased every two minutes and ranged from 65Hz to 400Hz in 5 increments of two-minute applications. Placebo Group • In the control group the peak intensity (0), pulse frequency (400 Hz) and PRR (65) were kept at their lowest settings throughout the entire experiment to ensure an a-thermal effect only.
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