ABSTRACT
This paper discusses the relationship between stimulating pulse width and the threshold of electrically evoked compound action potential (ECAP). Firstly, the rheobase and chronaxy from strength-duration curve of nerve fiber was computed using the shepherd's experiment results. Secondly, based on the relationship between ECAP and the action potential of nerve fiber, a mathematical expression to describe the relationship between stimulating pulse width and ECAP threshold was proposed. Thirdly, the parameters were obtained and the feasibility was proved to the expression with the results of experiment using guinea pigs. Research result showed that with ECAP compared to the action potential of nerve fiber, their threshold function relationship with stimulating pulse width was similar, and rheobase from the former was an order smaller in the magnitude than the latter, but the chronaxy was close to each other. These findings may provide meaningful guidance to clinical ECAP measurement and studying speech processing strategies of cochlear implant.
Subject(s)
Animals , Action Potentials , Auditory Threshold , Cochlear Implantation , Cochlear Implants , Electricity , Evoked Potentials , Guinea Pigs , Neural ConductionABSTRACT
Objective To assess the efficacy of stone fragmentation and clearance of this new intracorporeal ultrasound lithotripter (CQS-01) compared with currently available ultrasound units (EMS-Ⅲ/Ⅳ).Methods Twenty phantom stones composed of dental gypsum were randomly divided into four groups,and CQS-01 ultrasound lithotripter (70％ power and 70％ duty factor),EMS-Ⅲ ultrasound lithotripter (70％ power and 70％ duty factor),EMS-Ⅳ ultrasound lithotripter (type A,70％ power and 70％ duty factor) and EMS-Ⅳ ultrasound lithotripter (type B,70％ power and 100％ duty factor) were used to fragment and removepbantom stones.The mean stone breakdown time and fragment removal time and stone fragmental sizes for the standard ultrasound devices were compared to determine the completeness and efficiency of stone fragmentation and removal.Results The average time for stone breakdown was 7.4 ± 1.9 s,9.4 ± 1.6 s,82.2 ± 12.6 s and 51.4 ± 18.7 s,respectively.There was no significant difference between CQS-01 and EMS-Ⅲ (P ＞ 0.05),but there was significant difference between CQS-01 and EMS-Ⅳ (A or B) (P ＜ 0.001).The average time for stone clearance using the ultrasound devices was 387.8 ± 68.0 s,41 1.6 ± 57.6 s,568.0 ± 119.1 s and 383.6 ± 75.6 s,respectively.In addition,the average size of the largest fragments removed was the same among the groups (＜ 3 mm).Conclusion The ultrasound capabilities in a newly developed lithotriter (CQS-01) exhibited the same ability to fragment and clear phantom stones compared with standard ultrasound devices.
ABSTRACT
This article introduces the mechanisms and clinical implications of high-intensity focused ultrasound (HIFU) for the treatment of malignant tumor, and discusses the efficacy,limitations, and prospects of this technology. Dispite the recent advances, the clinical application of HIFU is still limited. Multiple trials are currently underway worldwide to determine its efficacy.
ABSTRACT
Objective To explore the clinical effect of high intensity focused ultrasound(HIFU)combined with transcatheter arterial chemoembolization(TACE)in the treatment of primary liver cancer.Methods A total of 106 patients with primary liver cancer were divided into two groups:50 cases were treated with TACE,and the other 56 were treated with combination of HIFU and TACE.The changes of AFP levels and the size of tumors after three months treatment were analyzed and compared with each other.The survival rates for one,two and three years were calculated with Kaplan-Meier method and compared between the two groups.Results In the two groups,AFP decreased significantly after treatment,but the combined group was superior to the other in AFP decrease.In the combined group,the 1-,2-and 3-year survival rates were higher than those in the TACE group with 82.3%,60.8%and 39.2% vs 68.0%,42.6%and 21.0%respectively(P＜0.01).No serious complications were seen,such as burn of skin,bleeding,gastrointestinal perforation. Conclusion The use of HIFU combined with TACE in the treatment of patients with primary liver cancers is feasible and safe.The combined group is superior to simple TACE for the management of primary liver cancers,and the former is more effective in decreasing AFP level and improving survival rates.