Table of Contents
Advertisement
Shortwave therapy equipment normally uses the band centred on
27.12 MHz. This corresponds to a wavelength, in a vacuum, of
approximately 11 metres.
Shortwave therapy is normally applied at a level which produces
detectable heating and the benefits are those associated with the
heating effect - encouragement of healing, pain relief, reduction of
muscle spasm, increase in mobility etc.
The difference between shortwave therapy and other methods of
heating is that it provides "deep heat". Other heating techniques such
as infrared therapy, hot-packs etc., provide the heat externally
whereas shortwave therapy generates heat within the tissue.
As with any electrotherapy, there are several potential dangers
associated with shortwave therapy. Since relatively high powers are
used, there is the possibility of producing burns if the patient is
unaware of the heat due to reduced thermal sensation, or if the
patient does not know what to expect during treatment. Metal in
treatment area will provide low impedance paths to the induced radio
frequency current, producing local heating and the possibility of
burning. In particular, treatment should never be given in the area of
metal implants, metal jewellery, buckles etc must be removed and
treatment must never be given with the patient on metal framed
couches or chairs. Patients with implanted electronic devices such
as cardiac pacemakers must not be treated. Other equipment,
including patient connected devices, may be adversely affected
when in close proximity to shortwave therapy equipment.
Pulsed Shortwave Therapy
Conventional shortwave therapy equipment described above,
produces a continuous wave output at 27.12 MHz. Pulsed shortwave
therapy equipment delivers the energy in pulses or bursts of
shortwave energy. The pulses are typically 20 to 400 microseconds
in duration (pulse width) and are repeated with a frequency of 5 to
800 Hz (pulse frequency). As with other modalities such as
ultrasound, it is found that delivering the energy in pulses is often
therapeutically more beneficial that providing the same amount of
energy in continuous wave form. Pulsed shortwave therapy appears
to be effective for many conditions especially in the early stages of
recovery.
OM265EN issue 16
7
Advertisement
Table of Contents
