22
Rev.2.13.A
ULTRASOUND ACTION MECHANISM
Mechanical effects:
the mechanical action is due to the particles movement of the
tissues crossed by the ultrasonic wave.
Although the movement of the single particles is small, the pressure variations that it
produces are so considerable to generate important mechanical effects on tissues.
The mechanical modifications induced by the device determine:
a) acceleration of the processes of diffusion through cellular membranes.
b) Scission of complex molecules (proteins, polysaccharides., etc.).
c) tissue micromassage
Thermal effects;
the passage of ultrasound through "the soft" tissues creates an elevation
of the temperature for:
- absorption due to viscosity,
- absorption due to thermal conductivity and chemical absorption.
The ultrasound produces heat through the vibrations, the collision and the friction of the
cellular
and
intercellular
structures that compose the tissues, crossed by the sound waves. The thermal elevation
generates, as secondary effects, an increase of the cellular metabolism and
vasodilatation.
Chemical effects:
the chemical action with the modification of the local ph, the
permeability of cellular membranes and with molecular changes is caused by the
remarkable accelerating forces to which tissue particles are subjected to the passage of
the ultrasonic wave.
The therapy with ultrasound can be used following two different methods: direct contact,
with mobile head and immersion.
Direct contact method
The direct contact modality consists in the application of the emission head to a skin
direct contact with the interposition of a substance (usually a special conductive gel)
which favors the transmission between the skin and the head, the sliding of the head and
the elimination of possible air placed between the skin and the diffuser, because it could
hinder, for its reflecting capacity, the transmission of the ultrasonic waves.
Immersion method
It is useful when the areas to be treated are too small or irregular or when the area is so
hurting to impede the direct contact.
The area to be treated should be immersed in a container with water together with the
diffuser. The diffuser must be placed at a maximum distance of 2-3 cm from the body
surface in order to avoid an excessive dispersion of the ultrasonic beam that could
decrease the therapeutic effect.
The water temperature has to be about 37°, the lower the water temperature is the more
is the cutaneous heat loss and the less is the therapeutic effect.
