Week 2- Thermotherapy Flashcards
4 mechanisms of heat transfer
conduction
convection
conversion
radiation
Conduction
- heat transfered by direct contact between subject and the source
- STATIC APPLICATION (sticks on, stays put)
hot packs, paraffin bath, hot bath… nothing moving.. still static application
Convection
- Heat transferred when particles (air or water) move across the body creating a temperature change
- DYNAMIC APPLICATION
Warm whirlpool, fluidotherapy
Conversion
Heat transferred by a device that CONVERTS energy from one form to another (heat to soundwaves)
ultrasound, diathermy
Radiation
Heat transferred through a CONDUCTING MEDIUM (typically air)
infrared lamps, laser (not used anymore)
Specific Heat- amount of energy needed to raise the temperature of a material
Water: 4.19 J
Air: 1.01 J
Paraffin: 1.2 J
Thermal conductivity
Rate at which material transfers heat
Water at 20 cel= 0.0014 HIGH CONDUCTOR
Fat= 0.0005 MORE OF INSULATOR
Rate of Heat Transfer in body
Rate of heat transfer= area of contact x thermal conductivity x temperature difference/ tissue thickness
4 Effects of Thermotherapy
- Hemodynamic Effect
- Metabolic Effects
- Neuromuscular Effects
- Tissue extensibility Effects
Hemodynamic Effect
- Local vasodilation (opens up) at site of heat application
- direct reflex activation of smooth muscle of local blood vessels by cutaneous thermoreceptors (acetylcholine on cholinergic receptors)
- Local release of Chemical mediators of inflammation (histamine and prostaglandins)
- Vasodilation allows INCREASE BLOOD FLOW
- Increased blood flow brings more O2 and nutrients to the site.
Metabolic Effect
- increase in local tissue temperature increases the metabolic rate
- metabolism increases 13% for every 10 degree C (18 F) increase
- hemoglobin releases twice as much oxygen at 41 degrees C (104 degrees) compared to 36 degree C (97 degrees)
OXYGEN drives metabolism
Neuromuscular effect
- Heat DECREASES the intensity of pain VIA THE GATE CONTROL THEORY
- activation of large, fast tactile fibers which block smaller slower pain transmitting fibers (A Deltas and C Fibers)
-Heat DECREASES muscle guarding and spasms
-inhibitory response to muscle neurons
Alpha motor neurons slow down
(i.e when hurt, rub/blow heat performs in similar way through gate control theory)
Tissue Extensibility
- Heat increases tissue extensibility
- achieved when tissue temperature is maintained at 104-113 degrees F for 5-10 mins.
- Thermotherapy vs exercise to warm up tissues
Internal heating is best
pt. on cycle for 5-10 mins if possible but not always possible for pt.
Paraffin Bath
Paraffin wax mixed with mineral oil
- six parts paraffin to one part mineral oil
- melting point of 129 degrees
- addition of mineral oil decreases the melting point to 113-122 degress
- higher temp than water
- typically longer lasting pain relief
DIP immersion with wrapping
Dip 10-12 immersions, wrap plastic bag and towel, 20-30 mins.
Brushing with wrapping
7-10 superimposed coasting are brushed on. place in plastic and wrap with towel. 20-30 mins
Continuous immersion
7 dips, continuous for 30 mins, coating is removed
Continuous immersion with retention
7 dip, continuous for 30 mins, 30 min retention out of the bath, wrapping option.
Diathermy
- Application of electromagnetic waves in the radio frequency range of the electromagnetic spectrum (SWD)
- diathermy can penetrate tissue deeper than hot packs
- most typical frequency used for SWD and PEMF is 27.12 MHz
