Randomized Controlled Clinical Study On Efficacy And Safety Of Low Frequency Ultrasound In Promoting Permeation Of The Anesthetic Drugs Across The Skin

Objective: To detennine efficacy and safety of low frequencyultrasound with eutectic ndxttire of local anesthetics rsMLA) on skinin reducing time of onset of anaesthesia and decreasing the painintensity.Methods: Concurrent randondzed controlled with self two arinsmatched trial was designed. In each subject EMLA andEMLA+Ultrasound procedure were randorIily aPplied to either one ofthe tWo arms. tow frequency ultrasound was conducted for l0ndnutes with frequency of 20 kHz and outPut of 0.5 Wlcm2. Oncontrol ann, placebo with same instrUment was put on the EMLA.Before and after 30 ndnutes, the thresho1d of pain on the sldn andpain intensity were measured, the later measurement was conducted36in a time interval of 5 minute and lasted for 1.5 hours. Time of onset of anaesthesia and pain intensity of skin were compared between two groups using paired t test, immediately after the experiments, the involved skin was examined microscopically to observe if therewere some pathological changes.Results: 24 volunter in our university participated in the study. The average time of onset of the local anaesthesia in experimental group is 34.58 + 3.87 min, the control group 43.75+4.72 min. The onset time difference of the two groups is statistically significant with P<0.01. The pain intensity in ultrasound group is 33.66?.16g, which is significantly longer than the figure of 29.71?.73g in control group with P<0.01. The microscopical observation showed no pathological changes in the experimental area of the skin. Conclusion: The low frequency ultrasound can promote the EMLA permeation across the human being' s skin, and reaching more depth in the skin. So that time onset of anaesthesia was shortened and intensity of anaesthesia was increased...