Study Of Effectiveness And Safety Of High Frequency Nerve Electrical Conduction Block

High frequency nerve electrical stimulation,also known as kilohertz alternative current(KHAC)nerve block,can cause reversible inhibition of nerve conduction function,and has good clinical application prospects,including labor pain,anesthesia,relieving spasm,helping patients with urinary tract dysfunction on urinating,etc.However,in the process of research,we found that the inhibition of high-frequency AC on nerve conduction function is not completely reversible,that is,blocking the nerve is often accompanied by injury.In order to improve the blocking effect of electrical stimulation and reduce the collateral nerve injury,it is necessary to discuss the safety and practicability of high-frequency electrical stimulation.In this paper,the bullfrog sciatic nerve was used as the experimental object.By analyzing the compound action potential(CAP)of the nerve after high-frequency asymmetric waveform pulse stimulation and interval blocking stimulation,the amplitude of cap was used as the basis to evaluate the nerve conduction function.According to multiple groups of comparative experiments,the safe high-frequency electrical stimulation parameters were selected.And a kind of interval stimulation scheme with certain application is proposed.By changing the frequency and symmetry of high frequency asymmetric waveform(the ratio of cathode pulse width to anode pulse width,r),several groups of nerve electrical stimulation experiments were carried out.The design of the waveform used in the experiment is based on the principle that the total net charge of the electrode on the nerve output is zero.The blocking and injury of the nerve are analyzed by comparing the three frequencies of the high-frequency blocking signal(f1 = 1k Hz,f2 = 2KHz,f3 = 5KHz)and the three pulse width ratios(r1 = 1,r2 = 2,r3 = 3).The results showed that when the amplitude of high frequency stimulation was the same,the higher the frequency of blocking signal,the smaller the blocking and damage of nerve;The higher the R value is,the better the blocking effect is.In terms of different R value,although the nerve damage increases with the increase of R value at the end of stimulation,the damage can be recovered by time,that is,the additional damage caused by asymmetric waveform high-frequency nerve electrical stimulation is reversible.In order to screen out a better stimulation scheme,nine groups of high-frequency symmetrical /asymmetrical waveform were used for the three values of the above two parameters,and the cross experiments were carried out on the sciatic nerve of bullfrog,and the results of blocking rate(BR)and injury rate(IR)of nine groups of nerves were obtained.Through t-test analysis,in nine groups of stimulation parameters,three kinds of nerve blocking signals with low comprehensive damage were selected,which were f = 2k Hz,r = 2 and f = 2k Hz,r = 3 f =5k Hz,r = 2 high-frequency asymmetric electrical signals and f = 5KHz,r = 1 symmetric high-frequency signals.The concept of nerve interval stimulation was also proposed in this paper.High frequency interval waveform with different blocking cycles and different stimulation duration in blocking cycles were used to block the nerve.The experiments found that when the high frequency blocking interval was less than 3 ms,the nerve could produce conduction blocking phenomenon without applying high frequency electrical signal.And the initial injury rate of nerve will increase with the increasing of stimulation time in the blocking cycle,and recover after 60 s.The results show that the blocking effect of high frequency asymmetric waveform is better than that of traditional high frequency symmetric waveform.Inserting a rest interval in the middle of the high-frequency waveform can reduce nerve injury under the condition of ensuring occlusion.Both of them provide a relatively safe stimulation scheme for the clinical application of high frequency electrical stimulation.