Introduction to shortwave therapy
Pulsed Short Wave Therapy (PSWT) is a widely used modality in physical therapy, also commonly referred to as Pulsed Electromagnetic Energy (PEME), a term that is sometimes imprecise. The older term also used Pulsed Shortwave Diathermy is also not really relevant with today’s technologies.
PSWT uses the same operating frequency as SWD at 27.12MHz. The emitter of the pulsed shortwave therapy machine is controlled such that the ‘on’ time is significantly shorter than the ‘off’ time, so that the average power delivered to the patient is relatively low despite the peak power. (i.e. during on) of the machine can be quite high (usually around 150 – 400 Watts with modern machines).
The control panel on the machine will allow the doctor to change the average power and the pulse parameters of the energy adjustment. Usually, the average power is probably the most important parameter.
The basic transmitter on today’s shortwave therapy machines is often referred to as a ‘monode’ or ‘drum’ (various names). All physical therapy studies were evaluated using the monode type. There have been no formal studies on the measurable clinical benefit of applying PSWT using sheet-based (electrostatic) devices.
The pulsed electromagnetic field emitted by the machine travels through tissues, and is absorbed in low impedance tissues, such as muscles, nerves, tissues with high vascularity, tissues in which edema, effusion or hematoma.
Shortwave generator in therapy
As for the effects of shortwave therapy it can heat the tissue while the pulse is on, but this heat dissipates during the prolonged ‘off’ phase & hence it can treat without causing increase in tissue temperature (tissue temperature does not change before and after treatment).
The settings applied on the machine determine the average power level applied to the treatment. The non-thermal effects of this therapeutic modality are generally thought to be positively significant. They appear and accumulate during treatment and have a significant effect after a period of time can be from 6-8 hours.
An active research program has been conducted in the last few years regarding the thermal nature of PSWT. In fact, there is some opinion that shortwave pulse therapy is a non-thermal modality. Research has demonstrated that continuous therapeutic shortwave can generate heat, and that tissue heating can occur in different treatment settings such as in continuous mode.
This is important because if shortwave therapy is to be used in situations where heat generation would be inappropriate or contraindicated, the physiotherapist needs to adjust the power/energy level accordingly. to avoid temperature rise in tissue.
If the therapy is oriented towards ‘no heat’ during the treatment, the average power setting must remain below a level capable of producing significant heating effects (refer to the level of power less than 5 watts). If the thermal effect is the goal of the treatment then providing a power level in excess of 5 watts is perfectly appropriate, but this should be done by the therapist and is contraindicated for those without specialized in physical therapy.
Effects of short wave therapy
They can be basically divided into two types as electric & magnetic fields. There seems to be almost no literature or research regarding the effects of electric field pulses. Almost all studies have focused on the therapeutic effects of magnetic fields. This is not to say that the electric field pulse has no effect, but research evidence for this effect is lacking. Therefore, the information in this article focuses mainly on the effect of magnetic field pulses (i.e. through drums or unipolar emitters).
The main effects of pulsed magnetic fields are at the membrane level and are related to the transport of ions across the membrane. Several published studies have strongly supported ‘non-thermic’ effects at the cell membrane level (Luben 1997, Cleary 1997).
Normal cell membranes exhibit potential differences due to the relative concentration differences of different ions on either side of the membrane (mentioned in Charman 1990). Of these ions, sodium (Na+), potassium (K+), calcium (Ca++), chloride (Cl-), & bicarbonate (HCO3-) are probably the most important.
Cells in the inflammatory process demonstrate decreased membrane potential and, consequently, impaired cellular function. The altered potential affects ion transport across the membrane and as a result ionic imbalance alters the cellular osmotic pressure.
Applying PSWT to affected cells in this way is claimed to restore membrane potentials to their ‘normal’ values and also restore normal membrane transport & ionic balance. .
There appears to be a strong similarity in the mechanism of action of ultrasound, laser and pulsed shortwave – all three seem to have major effects at the membrane level, with the result being ‘enhanced regulation. Modification of cell behavior is key to therapeutics.
The clinical effects of PSWT are mainly related to inflammatory phases and in skeletal muscle/soft tissue.
Goldin et al. (1981) list the following as the main effects of short pulse pulses:
- Increases the number of white cells, histocytes and fibroblasts in the wound.
- Improve edema dispersion rate.
- Encourage absorption of the hematoma.
- Reduces (dissolves) the inflammatory process.
- Promotes faster fibrin orientation and collagen deposition.
- Encourage collagen layering at an early stage.
- Stimulation of bone formation.
Source: Editor thietbiketnoi.com