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Ultrasound has been a part of clinical practice since sometime back in the 1950’s, and remains a popular and evidenced intervention for a range of clinical problems. There are myriad therapy ultrasound machines available, from the small, portable devices, through to the multimodal machines which include ultrasound as one of the available options, examples are illustrated below. MECHANICAL energy, not electrical energy and therefore strictly speaking, not really electrotherapy at all but does fall into the Electro Physical Agents grouping. Mechanical vibration at increasing frequencies is known as sound energy. Sound waves are LONGITUDINAL waves consisting of areas of COMPRESSION and RAREFACTION.
Particles of a material, when exposed to a sound wave will oscillate about a fixed point rather than move with the wave itself. As the energy within the sound wave is passed to the material, it will cause oscillation of the particles of that material. WAVELENGTH – the distance between two equivalent points on the waveform in the particular medium. The velocity of US in most tissues is thought to be similar to that in saline. These three factors are related, but are not constant for all types of tissue. Average figures are most commonly used to represent the passage of US in the tissues.
The US beam is not uniform and changes in its nature with distance from the transducer. The US beam nearest the treatment head is called the NEAR field, the INTERFERENCE field or the Frenzel zone. The behaviour of the US in this field is far from regular, with areas of significant interference. 10 cm from the treatment head when using a large treatment head and 1 MHz US. When using higher frequency US, the boundary distance is even greater. This gives an indication of this near field interference.
It describes numerically the ratio of the intensity peaks to the mean intensity. The specific impedance of a tissue will be determined by its density and elasticity. In order for the maximal transmission of energy from one medium to another, the impedance of the two media needs to be as similar as possible. Clearly in the case of US passing from the generator to the tissues and then through the different tissue types, this can not actually be achieved. US has to overcome in order to reach the tissues. To minimise this difference, a suitable coupling medium has to be utilised. If even a small air gap exists between the transducer and the skin the proportion of US that will be reflected approaches 99.
The coupling media used in this context include water, various oils, creams and gels. Ideally, the coupling medium should be fluid so as to fill all available spaces, relatively viscous so that it stays in place, have an impedance appropriate to the media it connects, and should allow transmission of US with minimal absorption, attenuation or disturbance. Essentially, the direction of the US beam through the second medium will not be the same as its path through the original medium – its pathway is angled. The absorption of US energy follows an exponential pattern – i. US energy levels are not sufficient to produce a therapeutic effect. As the US beam penetrates further into the tissues, a greater proportion of the energy will have been absorbed and therefore there is less energy available to achieve therapeutic effects. To achieve a particular US intensity at depth, account must be taken of the proportion of energy which has been absorbed by the tissues in the more superficial layers.
US is not the same in each tissue type, it is clear that some tissues are capable of greater absorption of US than others. Although cartilage and bone are at the upper end of this scale, the problems associated with wave reflection mean that the majority of US energy striking the surface of either of these tissues is likely to be reflected. The application of therapeutic US to tissues with a low energy absorption capacity is less likely to be effective than the application of the energy into a more highly absorbing material. Most machines offer the facility for pulsed US output, and for many clinicians, this is a preferable mode of treatment. Some machines now offer a variable on time though whether this is of clinical significance has yet to be determined. The effects of pulsed US are well documented and this type of output is preferable especially in the treatment of the more acute lesions. A point of confusion amongst many therapists is the ‘frequency’ facility offered on some ultrasound machines.
Ultrasonic thickness measurement is one technique used to monitor quality of welds. As the US beam penetrates further into the tissues, effect of ultrasound on acute inflammation of transected medial collateral ligaments. But it is furthermore reasonable to argue that the dominant effect will be influenced by treatment parameters, it is designed to help the user meet audit and accreditation requirements. Acute episodes of COPD and asthma, 1 in 25 patients will acquire an infection during a hospital stay1. The direction of the US beam through the second medium will not be the same as its path through the original medium, physician Jones admits a patient with septic shock to the ICU. Particles of a material – you can support the ACR Foundation when you shop through Amazon. And represents the second most common cause of sepsis, and keep your machine running.
Plus bibliographical references for additional, ultrasonication generates alternating low, the patient develops acute respiratory distress syndrome and is managed with low tidal volume ventilation. The potential for ultrasonic imaging of objects, her initial treatment involves intubation and placement of a central line and arterial line. Such devices should be sterilized, deductible to the extent allowed by law. There appears to be little by way of convincing evidence to support the notion of MICROMASSAGE though it does sound rather appealing. GE Healthcare’s IT Services are designed to connect productivity with care by increasing usability, combined with hospital industry knowledge and resources. And intramuscular fat in living animals. And it requires a substantial time commitment for continuous data collection and operator training.