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Exposure Values For Medical Devices
Published in Marvin C. Ziskin, Peter A. Lewin, Ultrasonic Exposimetry, 2020
Pulse repetition frequencies and pulse lengths have been included in several surveys.3,12,16 For imaging, pulse durations in the range 0.12 to 1.2 μs have been reported, with M-mode pulse repetition frequencies between 0.5 and 4.0 kHz. For pulsed Doppler applications a much wider range of pulsing regimes is used with pulse lengths in the range 0.74 to 15 μs and repetition frequencies up to about 50 kHz. Very long pulses may be used for some fetal heart monitors, in which pulse durations up to 90 μs may be used. A broad comparison between the pulsing regimes used in various diagnostic and therapeutic systems is given in Table 4.
Energy Medicine: Focus on Nonthermal Electromagnetic Therapies
Published in Len Wisneski, The Scientific Basis of Integrative Health, 2017
Len Wisneski, Bernard O. Williams
The EnerMed is currently approved for sale in Canada. It is not, at this time, approved for sale in the United States. Double-blind, placebo-controlled studies required to obtain FDA approval are proceeding (Lappin, 1998, 1999; Lappin and Lawrie, 2003; Lappin et al., 2003). Research with placebo devices and blinding is possible because the pulsing field cannot be felt. A multisite, double-blind, placebo-controlled, crossover trial of 117 patients with clinically confirmed multiple sclerosis showed improvements in fatigue and significantly greater overall quality of life outcomes with the active device (Lappin et al., 2003). There were no significant improvements for bladder control or a disability composite of measures taken from the MSPS (MS Performance Scale) and benefits for spasticity had mixed results. Each subject received 4 weeks of the active and placebo treatment separated by a 2-week washout period. The clinical effects were small, but consistent with previous studies showing symptom relief from PEMF stimulation (Lappin et al., 2003). Previous studies, using more weeks of treatment, showed greater benefit for the physical symptoms (Richards, 1997).
Skin Electroporation for Transdermal and Topical Drug Delivery
Published in Richard H. Guy, Jonathan Hadgraft, Transdermal Drug Delivery, 2002
Véronique Préat, Rita Vanbever
Sensation due to current applied to skin is often caused by direct electrical excitation of nerves (Reilly, 1992). Effects range from sensation of localized heat or cold, through tingling and itching, slight pricking, muscle contraction, to outright pain (Ledger, 1992; Prausnitz, 1996a). In general, increased current/charge, pulse rate, and pulse length all increase the levels of sensation. Because these effects will be strongly affected by the electrical field properties and distribution within the skin, careful design of electrodes and pulsing protocols will be essential for the reduction of unwanted side effects.
Systematic Review and Meta-Analysis: Efficacy of Vancomycin Taper and Pulse Regimens in Clostridioides difficile Infection
Published in Expert Review of Anti-infective Therapy, 2022
Kanika Sehgal, Inuk Zandvakili, Raseen Tariq, Darrell S. Pardi, Sahil Khanna
Treatment guidelines recommend extended vancomycin courses such as a standard course followed by a taper, pulse, or a taper-and-pulse to reduce the incidence of CDI recurrence based on small individual studies [11,12]. The rationale of extended durations of vancomycin is to suppress Clostridioides difficile vegetative forms followed by an extended regimen either as a taper or pulse or taper-and-pulse to potentially allow reestablishment of nonpathogenic flora. Several regimens have been described in clinical practice with variability in tapering and pulsing. These extended regimens start with a standard course of vancomycin for 10–14 days. A vancomycin taper regimen generally includes a taper to a lower dose decreasing the dose by 25–50% every 1–2 weeks with no skipped days for 4 to 10 weeks. Pulse regimens include the administration of vancomycin with skipped days for 3 to 4 weeks. Taper-and-pulse regimen generally entails a taper for 2 weeks, followed by a pulse for 2 to 8 weeks. It is unknown if the efficacy amongst regimens (taper-and-pulse or taper alone or pulse alone) is different from each other.
Predicting electrotransfer in ultra-high frequency sub-microsecond square wave electric fields
Published in Electromagnetic Biology and Medicine, 2020
Arūnas Murauskas, Gediminas Staigvila, Irutė Girkontaitė, Auksė Zinkevičienė, Paulius Ruzgys, Saulius Šatkauskas, Jurij Novickij, Vitalij Novickij
Higher conductivity buffer (BUF2 = 0.16 S/m) showed a better efficiency of permeabilization, which is in agreement with the simulation model, while the highest conductivity buffer (PBS = 1.6 S/m) showed the highest permeabilization rate for both the 1 Hz and 1 kHz protocols. The response of the cells to the ultra-high frequency pulsing of is upmost interest. As it can be seen in Figure 5 the ultra-high frequency pulsing resulted in a dramatic increase in permeabilization efficiency for both low conductivity buffers. The number of permeabilized cells doubled solely due to the alteration of the pulsing frequency without any changes in the total energy of the burst. It implies that maintaining the TMP above the threshold during the whole burst using MHz pulsing can effectively improve permeabilization of the cells. The predicted (Figure 4b) loss of the TMP accumulation phenomena was also occurrent experimentally. The permeabilization efficiency that was triggered in PBS buffer during 1 MHz pulsing was comparable to 1 Hz and 1 kHz procedures (P > .05). Therefore, it was experimentally confirmed that the new modality of unipolar ultra-high frequency electroporation is a polarization-based phenomenon.
Percutaneous radiofrequency ablation of HCC: reduced ablation duration and increased ablation size using single, internally cooled electrodes with an optimized pulsing algorithm
Published in International Journal of Hyperthermia, 2020
Luigi Solbiati, Tiziana Ierace, Nicolò Gennaro, Riccardo Muglia, Eric R. Cosman, S. Nahum Goldberg
Recently, more thorough and systematic optimization of RF pulsing algorithms has been reported in ex vivo tissues [17]. This optimization allows for the administration of a greater amount of current and provides dynamic energy deposition through an optimized pulsing algorithm using internally cooled electrode exposures of up to 5 cm. In the current study, our preliminary experience of percutaneous ablation in a small group of hepatocellular carcinomas (HCCs) using this method is reported. The aim of this single-center retrospective study of prospectively collected data is to assess whether this optimized RF energy delivery overcomes some of the classical limitations of RF ablation, specifically by achieving ablation in shorter times than the previously recommended (i.e., conventional) 12 min ablation duration or by creating larger ablative zones by increased energy application via longer 4 cm electrode tip exposures [8].