Lecture 2: Thermal Agents Flashcards

1
Q

What are thermal agents

A

transfer energy to increase/decrease tissue temp

2
Q

examples of thermotherapy

A

icepack
hot pack
US
whirlpool
diathermy

3
Q

modes of heat transfer

A

conduction
convection
conversion

evaporation

4
Q

what is conduction

A

energy exchange by direct contact of stationary materials at different temp

heat goes from material at a higher temp to material at a lower temp

5
Q

factors that affect heat transfer

A

tissue thickness (inverse relationship)
area of contact
thermal conductivity
temp difference

6
Q

rules for conduction

A

greater temp difference = faster rate of heat transfer

make sure conductive agents are not significantly different from pts skin temp to avoid burns

use materials that can create a safe medium for heat transfer

7
Q

ex of materials that have high/low thermal conductivity

A

high = metal

low = towels

8
Q

how many layers of towels are recommended for heat transfer

A

6-8 towels

9
Q

what is convection

A

direct contact vetween circulating medium and other material of a diff. temp

faster transfer with faster movement

ex = whirplool and fluid therapy and hyperice X

10
Q

what is conversion

A

converting a non thermal form of energy to heat

i.e. mechanical, chemical, or electrical

doesnt require direct contact

DOES require intervening material to help transmit the certain type of energy (i.e. US gel)

rate of transfer depends on power source

11
Q

examples of conversions

A

US (mechanical energy) = absorbs sound waves

diathermy (electromagnetic) = rotation of polar molecules; friction between molecules increases temp

12
Q

what do we need to know about specific heat

A

greater = more energy required for increase of temp to occur

i.e. water has a higher specific hear than air

tissues with high specific heat may require more time with thermal agents (fat has lower specific heat than muscle)

13
Q

main effects of cryotherapy

A

hemodynamic (vasoconstrict)

neuromuscular (reduce pain)

metabolic (lower inflammation)

14
Q

how long does it take for vasoconstriction to occur

A

10-15 min to reduce blood flow

most pronounced in area of direct skin contact

15
Q

what is the cold induced vasodilation phenomenon

A

following initial decrease of blood flow there is a later increase on blood flow which cycles up and down

occurs when cold is applied for more than 15 min or when tissue becomes less than 50 deg

16
Q

how does pain reduction occur with cryotherapy

A

decrease nerve conduction velocity of sensory and motor nerves (myelinated nociceptive- A delta)

increased pain threshold by stimulation of cold receptors (blocks peripheral pain stimuli)

17
Q

describe how muscles are affected by cryotherapy

A

decreased spasticity (effects last 1-1.5 hours due to decrease in gamma motorneruon activity)

increase muscle strength by facilitating muscle contraction (isometric increases in less than 5 min, 30 min of cryo causes an initial decrease in isometric strength then increase in strength an hour later that is sustained for 3 hours)

18
Q

what are the metabolic reactions to cryotherapy

A

cold decreases the rate of all metabolic rxns

decrease in rate of inflammation by decreasing the activity of cartilage degrading enzymes and level of histamines

decrease in inflammatory process die to joint disease such as OA or RA

19
Q

what does cryotherapy do during the acute phase of healing

A

control bleeding, edema, and pain due to inflammation

20
Q

how does cryo directly decerase the heat and edema associated with inflammation

A

by decreasing blood flow

21
Q

other inflammatory benefits of cryotherapy

A

acute flare ups for chronic inflammatory diseases

reduced severity of DOMS

22
Q

how does cryotherpay help edema

A

reduced release of histamines (which increase vascular permeability)

increases blood viscosity and devreases blood flow

fluid doesnt build up

23
Q

what is cryokinetics

A

apply ice after injury ASAP

allows pain free ex during numbness for 3-5 min

repeat 5x

used in athletics to minimize loss of play time

24
Q

what is cryostretch

A

capocoolant spray used as coolign agents

followed up with stretch to decrease muscle spasm and increase ROM

25
Q

what can thermotherapy do

A

control pain
increase soft tissue extensibility and circulation
accelerate healing

hemodynamic, neuromuscular, metabolic effects asa well as altered tissue extensibility

26
Q

of the uses of physical agents, which are specific to heat

A

accelerate healing
pain management
collagen extensibility

27
Q

physiological considerations of thermotherapy

A

the deeper the tissue, the less heat energy

to heat deep muscles, use exercise or deep heating modalities such as US or diathermy

28
Q

hemodynamic effects of thermotherapy (heat)

A

increase blood flow

increase permeability (can increase edema)

29
Q

what are the neuromuscular effects of thermotherapy

A

increase n conduction

changes frequency of nerve firing rate (decreased firing of muscle spindle) = relax muscle, decrease spasm, decrease resistance to passive stretch

30
Q

muscular effects of thermotherapy

A

muscle endurance and strength decreases during forst 30 min

muscle strength gradually recovers for the next 2 hours above pre treatment levels

31
Q

metabolic effects of thermotherapy

A

increase rate of cellular biochemical rxns (increased metabolic activity)

increased o2 uptake (accelerate healing bc more o2 available for tissue repair)

BUT also increased metabolic rate of destructive processes (avoid areas of inflammation or pts with acute/chronic inflammatory diseases like OA or RA)

32
Q

what happens when collagen tissue is stretched without prior heating

A

elastic deformation

33
Q

what happens when tissue is heated before stretched

A

increase in stretch
greater increase in length with stretch occurs
less force required to achieve increased length
decrease risk of tissue tear

34
Q

what are superificial heating agents good for when stretching

A

cutaneous scar tissue or superficial tendonds

35
Q

what are deep heating agents good for when stretching

A

large deep muscles or deep tendons

36
Q

how does heat control pain

A

cutaneous thermoreceptors “gate” pain

nociceptor signals blocked by thermoreceptors

body feels temp instead of pain

** not to use in inflammatory stage

37
Q

how does heat increase joint ROM

A

increased soft tissue extensibility

max increase in length with low risk to injury 5-10 min of low load prolonged stretch while heating

38
Q

how does heat decrease joint stiffness

A

due to increased extensibility and vsicoelasticity of joint capsule and surrounding ligaments

via warm water, paraffin bath, or infared lamp

39
Q

how does heat accelerate healing

A

increased circulation and enzymatic activity

accelerates blood delivery to tissues
brings oxygen/nutrients
increases amount of o2 via dissociation from hemoglobin

best during proliferative or remodeling stage

40
Q

how does heat cause superficial muscle relaxation

A

change frequency of n firing

decreased firing of alpha motor neurons

decrease spasm

good for LBP/spasm

41
Q

contraindications for heat

A

acute inflammatory/MSK conditions
impaired sensations
malignant tumors
impaired cognition
thrombophlebitis (DVT)
acute trauma
recent/potential hemorrhage

42
Q

precautions for heat

A

pregnancy (avoid abdomen/low back)
poor circulation
edema
cardiac insufficiency
areas with metal (staples/jewelry)
over open wound
areas where topical counterirritants have been applied
demyelinated nerves

43
Q

A

burns (superficial agents safer; make sure don’t fall asleep)

fainting (vasodilation = decreased blood flow to brain; orthostatic effects post treatment)

bleeding (may aggravate in areas of acute trauma/hemophilia)

always give pt way to stop treatment

44
Q

PT considerations for heat

A