Vol. 6 •Issue 2 • Page 86
Diathermy for Wound Care
Diathermy is the application of shortwave (10 to 100 MHz frequency) or microwave (300 MHz to 300 GHz frequency) electromagnetic energy to tissues. For most clinical applications, shortwave diathermy (SWD) is more popular than microwave diathermy (MWD) because it delivers energy much more evenly.
SWD can be delivered in a continuous or pulsed mode. When delivered with a high-enough average intensity, it can heat tissue.1,2 When delivered at a low-average intensity, it causes no measurable temperature change in the body.
How it Works
Although heating tissues with diathermy produces physiological effects (vasodilation, increased nerve conduction rate and accelerated enzymatic activity), this is not the mechanism by which it helps promote wound healing. Instead, pulsed short-wave diathermy (PSWD) promotes tissue healing through nonthermal mechanisms.
When applied at nonthermal levels, PSWD produces its clinical effects because the incident electromagnetic fields (and the resulting electric currents) modify ion binding and stimulate cellular production of ATP and proteins.3 By altering ion binding, PSWD also can trigger a cascade of biological processes, including growth factor activation in fibroblasts and nerve cells, macrophage activation and changes in myosin phosphorylation.4-6
PSWD also alters calcium ion binding. In doing so, it can help regulate the cell cycle, accelerate cell growth and division when it’s too slow, and inhibit it when it’s too fast.7,8 A recent in-vitro study also demonstrated increased fibroblast and chondrocyte proliferation in response to PSWD.9
Moreover, PSWD may promote wound healing by increasing local microvascular perfusion and, thus, tissue oxygenation, nutrient availability and phagocytosis. The reduction in pain and edema that can occur with PSWD also may contribute to its efficacy in chronic wound treatment.10
Although diathermy, and particularly PSWD, is generally a safe treatment, it’s contraindicated for some patients and in certain circumstances. All forms of diathermy are contraindicated in patients with implanted or transcutaneous stimulators; the electromagnetic energy of diathermy may interfere with the functioning of the device. Cases of coma and death have been reported when diathermy was applied to patients with implanted deep brain stimulators. Thermal-level diathermy shouldn’t be used in patients with metal implants or malignancy, in patients who are pregnant, over the eyes, testes or growing epiphyses.
Michelle H. Cameron is the owner of Health Potentials, a health education and consulting company.