thermal agents cold and heat

Question 1

Modes of Heat Transfer

Answer 1

• conduction
• convection
• conversion
• radiation
• evaporation

Question 2

Conduction

Answer 2

• energy exchange through direct contact

Question 3

Rate of heat transfer=

Answer 3

area of contact x thermal conductivity x temperature difference= tissue thickness

Question 4

convection

Answer 4

heat transfer by direct contact of circulating medium and another material of different temperature

• thermal agent is in motion
• more efficient than conduction.
• EX: whirlpool heats skin faster than if just immersed in a bowl of water of same temp

Question 5

examples of convection

Answer 5

• fluidotherapy

- whirlpool

Question 6

conversion

Answer 6

• heat transfer by conversion of non-thermal energy, such as mechanical , electrical or chemical energy, into heat. does not require direct contact of the agent and the patient

ex: US and diathermy
- heat transfer depends on the power of the energy source

Question 7

examples of conversion

Answer 7

• US

- diathermy

Question 8

radiation

Answer 8

• direct transfer of energy e/o need for contact or intervening medium. higher heat directed at lower heat area
• infared lamp, laser, UV light

Question 9

evaporation

Answer 9

• energy absorption because of conversion of material from liquid to vapor
• vapocoolant spray
• spray and stretch technique
• sweating

Question 10

cooling is used to:

Answer 10

• control inflammation, pain and edema
• reduce spasticity
• control symptoms of multiple sclerosis
• facilitate movement

Question 11

cryotherapy Is most effective when

Answer 11

• in the acute stage of healing

- can be continued into the reconditioning stage

Question 12

cryotherapy effects the body by influencing the following processes:

Answer 12

• hemodynamic
• neuromuscular
• metabolic processes

Question 13

cryotherapy hemodynamic effects

-initial decrease in blood flow

Answer 13

• vasoconstriction
• <15-20 minutes duration
• • repeating ice applicstion after an initial 20 minute application for two repetitions of 10 minutes off the 10 minutes on lowers blood flow more than a single 20 minute application

Question 14

Hunting response

Answer 14

• when cold is applied longer or when tissue temperature is below 10 deg C cold induced vasodilation occurs
• indistal extremities exposed to cold more than 15 minutes there is a resultant in “hunting response”
• maintained vasodilation is seen in forearms at 1 deg C for 15 mintues

Question 15

cryotherapy neuromuscular effects

Answer 15

• decreaseing nerve conduction velocity
• elevating the pain threshold
• altering muscle strength
• decreasing spasticity
• facilitating muscle contrcation

Question 16

5 minutes cooling

Answer 16

• decreases nerve conduction velocity

- fully reverses within 15 minutes in normals

Question 17

greater than 20 minutes of cooling

Answer 17

• reversal takes >30 minutes

- cold reduces conduction of both sensory and motor fibers. especially A-delta pain fibers

Question 18

cryotherapy to decrease spasticity

Answer 18

• apply cold for up to 30 minutes on a hypertonic region
• effects can last 1-1.5 hours
• BRIEF ~5 minutes can cause decr in DTR
• 10-30 minutes decrease clonus

Question 19

cryotherapy inflammation control

Answer 19

• less than 15 minutes for distal extremities
• up to 30 minutes for larger regions
• used in acute inflammatory phase

Question 20

cryotherapy for pain control

Answer 20

• 10-15 minutes of cold, gives pain control for 1+ hours

- pain control due to: a-delta fiber blocking, gate control theory, reduced muscle spasm

Question 21

cryokinetics

Answer 21

combines cold an exercise to treat pathology
- apply cold to the point of numbness to decr pain then allow exercise to regain ROM

• 20 minutes of cold then 3-5 minutes of exercise

Question 22

cryostretch

Answer 22

• application of a cooling agent before stretching

- purpose: reduce muscle spasm allowing greater ROM increase

Question 23

reasons for considering heat

Answer 23

• promotion of relaxation
• increased extensibility of collagen tissue and decr joint stiffness
• pain relief
• reduction of muscle spasm
• increase blood flow
• resolution of inflammatory infiltrates
• prepare stiff joints/tight muslces for exercise

Question 24

heat effects tissue via:

Answer 24

• hemodynamic
• neuromuscular effects
• metabolic effects
• altered tissue extensibility

Question 25

changes in muscle strength

Answer 25

• strength and endurance decreases during the initial 30 minutes after application of deep or superficial heating agents
• beyond 30 minutes and for up to 2 hours there is a gradual return in strength to rpior level, then an increase to above pretreatment strength levels

Question 26

best practice for maximum increase of length is:

Answer 26

• tissue temp maintained at 41-45 deg C for 5-10 minutes

Question 27

burns cell death temp

Answer 27

• cell dath above 45 deg C