View
223
Download
4
Category
Tags:
Preview:
Citation preview
Topics
• Physical basis of heat and cold• Measurement of temperature:
Thermometry• Mapping of body’s surface
temperature: Thermography• Heat Therapy and uses of cold in
medicine
States of Matter
Solids
Liquids
Gases
http://www.emsb.qc.ca/laurenhill/science/kinetic.html
Vibrations
Kinetic Energy of molecules associated with temperature
Measurement of Temperature
• Indirectly by measuring the change in a physical quantity that changes with temperature
• Different temperature scales
Construction of Thermometer
• Principle: Differential Expansion of materials
• 1cm3 of mercury increases in volume when temperature changes from 0C to 100 C
• Smaller the diameter of capillary greater the sensitivity: 0.1mm
• Visibility is increased by
Cross section of Thermometer
Capillary
Lens Front
White Backing
Variation in body temperature
• External factors• Internal –Metabolic– Circulatory (Major)
• Far Infrared (IR)• Stefan-Boltzmann law–W = e T4
• = 5.7 x 10-12 W/cm2 K4
Diathermy
• diathermy [di´ah-ther″me] means "electrically induced heat" the use of high-frequency electromagnetic currents
• Greek words dia and therma, and literally means “heating through.
• short-wave radio frequency (range 1–100 MHz)
• Microwave energy (range 434–915 MHz)
Description
• High-frequency electrical currents–Radio waves
• Pass through the tissues• Cause molecular vibration• Results in deep heating• Capable of heating large volumes of
tissues• Causes both thermal and non-thermal
effects
Uses
Thermal Effects• Deep heat• Increased blood
flow• Increased cell
metabolism• Increased tissue
extensibility• Muscular relaxation• Possible changes in
enzyme reactions
Non-thermal Effects
• Edema reduction• Lymphedema
reduction• Superficial wound
healing• Treatment of
venous stasis ulcers
Induction Field Diathermy
• Places the patient in the electromagnetic field
• Selectively heats muscle• Also referred to as:–Condenser field diathermy–Magnetic field diathermy
Induction Field Diathermy (Cont.)
• A coil is housed within a drum
• Current flowing within the coil produces a rotating magnetic field
• Magnetic field produces eddy currents in the tissues
• Eddy currents cause friction that produce heat
• Although rare, cables are sometimes used in place of drums
Capacitive Field Diathermy
• Uses the patient’s tissues as a part of the circuit
• The tissues’ electrical resistance produces heat
• Selectively heats skin–Muscle is heated via conduction from
the adipose
• Also referred to as “condenser field diathermy”
Capacitive Field Diathermy (Cont.)
• Heat is produced by the dipole effect
• Charge particles within membrane align with the field
• The movement produces heat
---
-
-+
++
+ +
+
Modes of Application
Continuous• Increases tissue temperature• Increased risk of burnsPulsed• May or may not increase
temperature• Pulses allow for increased
treatment intensity and duration• Not the same as “non-thermal”
Ultrasound & SWD Comparison
Diathermy Ultrasound Shortwave
Energy typeAcousticalElectromagneticTissue heated Collage-rich C: Skin,
adipose tissueI: Muscle, vessels
Tissue volume Small (20 cm2) Large (200 cm2)
Temp increase 1 MHz: > 6.3°F C: > 7°F3 MHz: > 14.9°F I: > 18°F
Heat retention 3 min > 9 minC = Capacitive methodI = Induction method
Biophysical Effects
Inflammation• Assists in removal of cellular
debris and toxins• Non-thermal:–Alters diffusion rate across the cell
membrane
• Thermal– Increases intramuscular metabolism
Biophysical Effects
Blood and Fluid Dynamics• Vasodilation increases:–Blood flow–Capillary filtration–Capillary pressure–Oxygen perfusion
• Effects occur deeper than other forms of heat
Biophysical Effects
Tissue Elasticity• SWD can vigorously heat deep tissues • Alters collagen properties, allowing it
to elongate• Requires stretching during and/or
immediately following the treatment• Multiple treatments are required
Recommended