Thermotherapy Flashcards
What is thermodynamics?
the branch of physics concerned with the relationship between heat and other forms of energy
What is the 1st law of thermodynamics?
Law of conservation of energy: “Energy cannot be created or destroyed”
What is the 2st law of thermodynamics?
Heat energy transfer is directional: heat travels from high to low temperatures
The amount of heat energy within a substance depends on what?
- Speed of particles (kinetic energy)
- Number of particles (mass)
- Capacity of particles to store heat (specific heat capacity)
Let us consider the use of hot pack. During application, the thermal energy stored in the hot pack is transferred to both the targeted soft tissue and to the air surroundings both of them. Which law of thermodynamics is this in accordance with?
The first law, called law of conservation of energy, states that energy cannot be created nor destroyed
The heat contained in paraffin wax, which is greater than that of the target soft tissue, is transferred to the latter during therapy. Which law of thermodynamic is this in accordance with?
The second law stipulates that heat energy transfer always occur in one direction only, i.e., from the warmest to the coldest substance.
What is the difference between heat and temperature?
heat is energy and that temperature is a measure of it.
Heat transfer equation:
Calories = mass x Δt x specific heat
What is specific heat?
the capacity of its particles to store heat (its specific heat capacity).
Is it correct to say that of two hot packs with the same temperature, say 70°C (158°F), the one with the larger mass (1,500 g vs. 1,000 g) will contain a greater amount of heat than the other?
YES, because the amount of heat (q) a material or substance possesses is directly related to its mass, as evidenced by the formula q = m ×Δt° × c, where m is the mass of the hot pack in this case.
Baseline temperature of human tissues:
82º-96ºF
Optimal temperature for therapeutic tissue heating effect=
104°-113°F (40º and 45ºC)
Heat nocioception input starts at what temperature?
113 and over (45º C)
What is the thermal conductivity of subcutanoeus fat?
0.45
Why is that applying a hot pack at 50°C (122°F) directly over the skin will cause severe pain and burn, whereas applying paraffin wax of the same temperature will feel comfortable and not burn the skin?
The answer lies in the fact that compared with water, paraffin has a much lower capacity to retain or store (c = 0.45 vs. 1.00) and conduct heat (k = 0.59 vs. 1.42) to the soft tissues.
Why is it that if you immerse one hand in a Fluidotherapy air chamber of a given temperature and the other in a paraffin bath of the same temperature, the paraffin bath feels hotter than the air chamber?
It is because paraffin wax holds approximately 2 times more heat (c = 0.45 vs. 0.24) and conducts heat approximately 30 times faster (k = 0.59 vs. 0.02) than air.
Conduction:
Physical contact of 2 solid substances. Ex. hot pack.
Convection:
Physical Contact of gas or fluid against a solid substance.
(fluidotherapy, hydrotherapy, paraffin bath)
What is the difference between free convection and forced convection?
Free convection: heating of the solid substance induces solely by the temperature difference between the two substances. Ex. Still water hydrotherapy
Forced convection: caused when the motion of the fluid or gas is imposed externally by means of a fan (Fluid therapy) or a turbine (hydrotherapy).
Radiation:
Air Contact between Agent and Tissue. Is the propagation of energy in the form of rays or waves. Ex. Shortwave, Diathermy.
Evaporation:
Liquid to gaseous state when contact with tissue. Ex. vapocoolant spray (cryotherapy)
vapocoolant spray (cryotherapy) uses what type of heat transfer?
evaporation
Types of moist thermothrapy agents:
hot pack and paraffin bath
Types of dry thermothrapy agents:
fluidotherapy
Application times of thermotherapy agents:
Hotpack: ~20 minutes
Paraffin: ~30 minutes
Fluidotherapy: ~30 minutes
how many layers of toweling for a hot pack?
5-8 layers
Screening for thermotherapy:
thermal discrimination testing scoring
4-5 = normal / slightly impaired (no restriction)
3 = moderately impaired (precaution)
1-2 = severely impaired (risk of harm)
0 = totally impaired (all thermal & electrophysical agents are contraindicated)
When applying thermal agents when do the therapist checks the skin?
Always check skin before and after
Depending on agent, you should also check during application and at minimal, check in with your patient during the treatment time.
Metabolic Biophysiological Response to thermotherapy:
vasodilation → increase blood flow and cell metabolism → enhanced soft tissue healing
Musculoskeletal biophysiological response to thermotherapy:
increased viscoelastic properties and decreased joint viscosity → improves muscle flexibility and joint mobility → enhances tissue mobility
Neuromuscular biophysiological response to thermotherapy:
decreases gamma motor activity → decreases alpha motor neuron activity → decreases muscle spasm
Thermotherapy over skin area where sensation to heat is severely impaired?
Contraindicated
may cause cutaneous burn
thermotherapy over a cancerous area?
contraindicated, enhance tumor growth and metastasis.
thermotherapy over a thrombophlebitic area
contraindicated, dislodge blood clot, which may then circulate into the vessels of vital organs, causing serious circulatory problems and possibly death
thermotherapy over the abdominal, pelvic, and low back areas of pregnant women
contraindicated, teratogenic effects on fetal development and growth caused by increased local or systemic maternal body temperature.
thermotherapy over acute and severe inflammatory conditions
contraindicated, worsen the condition by aggravating the inflammatory response through increased blood flow resulting from heat application.
thermotherapy in patients that are confused and unreliable
contraindicated
thermotherapy over an area of impaired blood circulation
precaution, may cause tissue overheating because the treated area will not be able to cope with the demand for additional and cooler blood flow during treatment
thermotherapy In patients presenting with severe cardiac insufficiency
precaution, may not being able to cope with the increased cardiac demand triggered by the heat-induced increase in blood circulation. Periodic monitoring of vital signs is advised during and after therapy.
thermotherapy over superficial closed and open wounds, including grafted or burn wounds?
precaution
thermotherapy over body areas with superficially located metal implants?
precaution, may cause internal soft tissue burns because metals absorb and conduct heat well. Use caution when applying hot pack and paraffin over such body areas.
thermotherapy over areas in presence of demyelinated nerves
precaution
thermotherapy on hand motor skills and reaction time
precaution, may delay reaction time and decrease tapping speed in healthy subjects. Inform patients that their hand motor skills may be impaired for a few hours following therapy.
thermotherapy in cases of systemic infectious diseases:
precaution, —may increase core body temperature, which may increase fever
thermotherapy In the presence of flammable anesthetics
precaution, may cause explosion
°F to °C
Deduct 32, then multiply by 5, then divide by 9
°C to °F
Multiply by 9, then divide by 5, then add 32
thermotherapy on a patient who scores of 3/5 in the skin thermal discrimination test:
precaution
thermotherapy on a patient who scores of 2/5 or 1/5 in the skin thermal discrimination test:
risk
thermotherapy on a patient who scores of 0/5 in the skin thermal discrimination test:
no, contrainidicated for all thermal therapeutic agents
