Diathermy

 

First observed in the 1800's by D'Arsonval, it wasn't unti 1907 that Nagelschmidt coined the term diatherm - meaning "through heat." The 1920's saw the birth of the long wave diathermy machine which used a frequency of 500 kHz - 10MHz and needed a wed pad in place for transmission. Short wave diathermy (SWD) was introduced in the 1930's. The first models used continuous input. the second models were pulsed and have continued to evolve to modern short wave diathermy which allows for switching from continuous to pulsed short wave diathermy.

 

Continuous SWD and pulsed SWD may each ave thermal and athermal effects that increase cell metabolism and function, leading to the enhancement of soft tissue healing. Diathermy is known to have an effect for heating tissues and increasing blood flow. 

 

Biophysical Characteristics

• Frequency

  • 13.56 Mhz (22m)

  • 27.12 Mhz (11m) - most common

  • 40.68 Mhz (7m)

• Radiation

  • ​Ionizing = x-ray

  • Non-ionizing = SWD, ultrasound and laser

• Electromagnetic wave

  • ​Travel at the speed of light 300mm/sec

• Electromagnetic Resonance

  • ​Key biophysical phenomenon

  • Tuning - when patient tissue oscillates at the same frequency as the device (27.12 Mhz)

  • Full energy transfer

  • Typically done automatically, but patient must minimize motion

 

Diathermy is applied to the body using one of two types of applicators: