Low and medium Frequency Electrotherapy - Implox

8 WOUND HEALING
8.1 Introduction
When tissue is damaged, a sequence of complex physiological processes come into action, which should promote
normal wound healing.
In some pathological conditions (e.g. varices, conditions affecting the peripheral arterial circulation, decubitus ulcers)
the physiological wound healing process can be disrupted, resulting in ischaemic ulceration of the skin, followed by
necrosis. This in turn can lead to gangrene, necessitating amputation.
Various techniques can be used to promote wound healing. From the literature, it is not yet clear which of these is the
most effective. Furthermore, the underlying mechanisms of the effects of electrotherapy in accelerated wound healing
are also not yet entirely understood. There is also some discussion of the effects of various current types. In the
U.S.A., considerable use is made of ‘microcurrent’. Although there is (as yet) no unequivocal scientific proof, this
current type is said to produce good results. In addition, good results are apparently obtained with intermittent direct
current, in the form of ‘high voltage stimulation’.
All the claims that have been and are being made on this subject indicate that wound healing by electrostimulation
has a great future, but that there is still a lack of unequivocal explanations.
With respect to direct current and TENS current types, a number of publications have appeared that are worth
mentioning. Various workers describe a favourable effect of electrostimulation on wound healing (4, 10, 12, 20, 30, 31) . On
the basis of these publications, some guidelines regarding the application of direct current and TENS current types
are given in paragraph 8.3 below.
Fig. 33.
The nociceptor and its (micro-) environment, Zimmermann (34) .
8.2 The mechanisms of wound healing
During a physiological wound healing process, various substances are released. As it is beyond the scope of this
book to give a complete description of all the complex mechanisms involved in wound healing, we shall confine
ourselves to giving a brief explanation of the working of one of these substances: ‘Substance P’ (SP). This is a
neurotransmitter that plays an important role in the wound healing process.
Substance P has two principal effects (33) .
When tissue is damaged, SP stimulates the mast cells to produce histamine, causing vasodilation. The resulting
hyperaemia causes an inflammatory reaction, and is the first stage in wound healing.
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