Diathermy

Question 1

What type of modality is Diathermy?

Answer 1

Heat

Question 2

What are the two types of generators of Diathermy?

Answer 2

Shortwave (most common) and microwave

Question 3

What is diathermy?

Answer 3

• High frequency electromagnetic energy
– Generate heat in body tissues (deep heating)
– Non-thermal effects (questionable)

Question 4

T/F: Electromagnetic energy travels at the speed of sound?

Answer 4

FALSE; it travels at the speed of LIGHT! (300,000,000 m/s)

Question 5

What is the most common frequency of shortwave diathermy?

Answer 5

27.12 MHZ, 11 meter λ

Question 6

Does microwave or shortwave diathermy penetrate deeper?

Answer 6

Shortwave

Question 7

Is shortwave or microwave diathermy safer?

Answer 7

Shortwave

Question 8

What type of electrode is used to produce an electrical field?

Answer 8

Capacitor electrode

Question 9

What type of electrode is used to produce a magnetic field?

Answer 9

Induction electrode

Question 10

Why should the capacitive technique be used on Thin patients?

Answer 10

It may heat subcutaneous fat more than muscle. Use for patients/areas with low subQ fat
– Knee, foot, hand, shoulder

Question 11

When should you use the inductive technique?

Answer 11

Greatest absorption in high electrolyte,
high dipole tissue
– Deeper
– Muscle, tendon, joint
• Use for patients with more subQ fat /
obese patients

Question 12

What law is Dose vs response?

Answer 12

Arndt-Schultz Law

Question 13

What law is Absorption vs therapeutic effect?

Answer 13

Grotthuss-Draper Law

Question 14

Inverse square

Answer 14

– Dose vs divergence
– E.g. Change from 10 cm
to 20 cm = 2x distance
– Inverse of 2 = ½
– Square of ½ is ¼
– Therefore ¼ as much
heat with 2x the
perpendicular distance

Question 15

Cosine Law

Answer 15

Lambert’s
Cosine law
– Angle of
application
– Reduced
energy if angle
is increased.

Question 16

Physiologic responses to diathermy:

Answer 16

• Continuous Short Wave Diathermy
– CSWD
– Less common
• Pulsed Short Wave Diathermy
– PSWD
– More common
– Heat vs no heat
• Heat
– Pain relief, wound management, joint
contracture

Question 17

What are the indications to use diathermy?

Answer 17

• Research
– Osteoarthritis
– Neck/back pain
– Ankle pain
– Dermal wounds
• Other musculoskeletal injuries /
musculoskeletal pain

Question 18

What are the contraindications of diathermy?

Answer 18

• Loss of sensation
• Electronic implants (even if device is gone but leads remain)
• Surgically implanted metal (clips, rods, pins, etc)
• Metal in contact with the skin (jewelry, tmt table, etc)
• Over cancerous areas
• Pregnant patients – abdomen, pelvis, and low back
• Hemorrhagic areas
• Ischemic areas
• Testes
• Eyes
• Open growth plates in children

Question 19

What are the risks associated with Diathermy?

Answer 19

• Pregnant operator should not be exposed
daily
– Remain 3 feet from functioning SWD device
• Copper IUDs
• Other patients near the device
– 10 foot distance
• Other EPA devices – 10 foot distance
• Mentally confused patients

Question 20

How do you apply diathermy?

Answer 20

• Test cold/warm sensation first
• Remove jewelry
• 2-3 cm layer of towels for spacing
• Advise patient to remain still