Electricity and Magnetism
Sarah Armstrong, Barry Clifton, Lionel Davis in Primary FRCA in a Box, 2019
Diathermy is the device used to pass electrical current through tissue to generate heat in order to coagulate blood vessels or cut and destroy tissueThe heat produced is proportional to the power developed, typically 50–400 WUnipolar diathermy uses the forceps as one electrode, with a large surface area plate attached to the patient – usually on the leg. Current density is high at the forceps, which causes the coagulation or cutting, but is low at the plate, so little heating occurs thereBipolar diathermy uses current passing between two blades of the forceps; no plate is required. The power used is smaller, so it may be used for eye surgery, digits and neurosurgery to localize the current and prevent collateral tissue damage. However the range of available electrodes is less and so it may not be suitable for some usesCutting diathermy uses an alternating sine-wave current at 0.5 mHzCoagulation diathermy uses a pulsed sine-wave current at 1–1.5 mHzEffects of diathermy depend on frequency
Energy Medicine: Focus on Nonthermal Electromagnetic Therapies
Len Wisneski in The Scientific Basis of Integrative Health, 2017
Current flow in diathermy involves complex processes, so patient observations of perceived heating and the rates of applied power are used to guide these therapies. AC current in tissue causes charged particles to oscillate. As the oscillations decay, kinetic energy is distributed among surrounding molecules, increasing their motion—which is heat. The rise in tissue temperature depends on the specific absorption rate of the AC current energy. More heat will be produced in tissue that conducts more easily, making the specific absorption rate greater. Diathermy is effective for heating deep muscle tissue because current flows more easily in muscle than in fat. The fundamental frequency is often delivered in pulses, which are more effective for producing charged particle oscillation. The power applied during therapy is thus a combination of pulse amplitude, duration, and frequency. Typical peak pulse amplitudes range from 100 to 1000 watts, in pulse durations of 25–400 ms and with the average power in the current delivered to the patient being a few watts (McMeeken and Stillman, 2002).
Basic surgical skills and anastomoses
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
There are two basic types of diathermy system in use, monopolar diathermy and bipolar diathermy (Figure7.24). In monopolar diathermy, which is the most commonly used form, an alternating current is produced by a suitable generator and passed to the patient via an active electrode which has a very small surface area. The current then passes through the tissues and returns via a very large surface plate (the passive electrode) back to the earth pole of the generator. As the surface area of contact of the active electrode is small in comparison to the passive electrode, the concentrated powerful current produces heat at the operative site. However, the large surface area electrode of the patient plate spreads the returning current over a wide surface area, so it is less concentrated and produces little heat. In bipolar diathermy, the two active electrodes are usually represented by the limbs of a pair of diathermy forceps. Both forceps ends are therefore active and current flows between them, and only the tissue held between the limbs of the forceps heats up. This form of diathermy is used when it is essential that the surrounding tissues should be free from either the risk of being burned or having current passed through them.
Effects of deep heating modalities on the morphological and elastic properties of the non-insertional region of achilles tendon: a pilot study
Published in International Journal of Hyperthermia, 2022
Daniele Munari, Anna Serina, Arianna Leonardelli, Davide Lanza, Alberto Caramori, Andrea Guerrini, Modenese Angela, Mirko Filippetti, Nicola Smania, Alessandro Picelli
The first factor is that the thermal property of diathermy induces a superficial and deep hyperthermia. As temperature increases, the tissue viscosity is modified by the improvement of the collagen extensibility and the reduction connective, subsequently, the extensibility of soft tissues is increased [2,32]. Basically, diathermy therapy promotes the natural physiological processes of tissue metabolism by transferring energy without introducing radiant energy from the exterior rather by using the physical principle of the condenser. This enables the production of an endothermic effect that depends on the applied power and the impedance offered by the tissues upon passage of the current [33,34]. Indeed the effect of the capacitive system is due to the increase in cell membrane potential, due to the kinetic effect of the ions in both intracellular and intermediate fluid and due to the subsequent increase in internal temperature [35].
Microwave diathermy induces mitogen-activated protein kinases and tumor necrosis factor-α in cultured human monocytes
Published in Electromagnetic Biology and Medicine, 2019
George Lagoumintzis, Andreas Andrikopoulos, Adam Adamopoulos, Ioannis Seimenis, Constantinos Koutsojannis
The thermal effects of diathermy on biological tissue resemble the more general effects of heating, with experimental evidence indicating that therapeutic responses will occur as a result of elevating tissue temperatures in the range of 40–45°C (Draper et al., 1999). Hyperthermia in the range of 40–45°C has numerous effects on living cells in a time- and dose-dependent manner (Roti Roti, 2008). The temperatures used in whole body treatments vary from 38–42°C and in the local-tissue therapies from 40–45°C. It has been reported that a 60–80 W mean output MW irradiation in muscle at 2.45 GHz, to the maximum tolerable temperature, for 1–30 min, can result in a considerable blood flow rise post treatment (Lehman et al., 1962; Moseley, 1988; Sekins et al., 1980). Indeed, subsequent studies concluded that maximum blood flow in heated muscle results once a temperature of 42°C is achieved (Conradi and Pages, 1989; Goats, 1990).
Device profile of the Proclaim XR neurostimulation system for the treatment of chronic pain: an overview of its safety and efficacy
Published in Expert Review of Medical Devices, 2020
Jonathan M. Hagedorn, Alyson M. Engle, Priyanka Ghosh, Timothy R. Deer
Per manufacturer instructions, diathermy therapy is prohibited, whether the system is on or off. Severe injury or death can occur if diathermy is used due to the transfer of energy through the system. For electrocautery use during surgery, monopolar devices are prohibited, and if using bipolar electrocautery, the device must be placed in surgery mode prior to the procedure and confirmation of function should take place after surgery. There is always a possibility of interaction between the neurostimulation system and implanted cardiac systems and implanted cardiac defibrillators. Therefore, it is recommended to maximize the distance between the two systems, confirm that each system is working without affecting the other and that either device is never programmed into a unipolar mode. For external cardiac defibrillators, safety has not yet been established. High-output ultrasonics, lithotripsy devices, and ultrasonic scanning devices may not be used directly over the IPG. For radiation therapy, conclusive studies have not been done, but the IPG area must be shielded with lead for any treatments. Studies in pediatric, pregnant, and nursing populations have not been done; therefore, there are currently no safety data on these patient populations [21].
Related Knowledge Centers
- Cauterization
- Edema
- Electrotherapy
- Muscle
- Pelvic Inflammatory Disease
- Ultrasound
- Hyperthermia
- Neoplasm
- Electrical Injury
- Radiation Therapy