Thermal Modalities: Cryotherapy Flashcards
what are the 5 heat transfer mechanisms
which of the 5 heat transfer mechanisms is not natural
conduction, convection, radiation, evaporation, conversion
conversion
define conduction and give an example
conduction travels from ___ temperature to ___ temperature until temperature is ___
conduction to objects makes up ___% of normal transference
heat transfer by direct collision between molecules of different temperatures
hot/cold packs, paraffin bath, ice massage
high, low, equal
3%
define thermal conductivity
which materials transfer heat more rapidly
a good heat conductor also conducts ___ well
the rate at which a material transfers heat by conduction
materials with high thermal conductivity (metal > water > air)
electricity
what is the equation for rate of heat transfer
which factors in this equation can you change
area of contact x thermal conductivity x temperature difference / tissue thickness
area of contact (larger hot pack = more transfer)
thermal conductivity (wet a towel)
temperature difference (make hotter/colder)
T or F: skin, adipose tissue, skeletal muscle, blood and bone all have different levels of thermal conductivity
T
what acts as an insulation to underlying tissues
what contains high water contents and readily absorb and conduct thermal energy resulting in temperature change
skin and adipose tissue (limits degree of temperature change in deeper tissues)
muscle and blood
define convection and give an example
convection to air currents accounts for __% of normal transference
what kind of contact occurs in convection
heat transfer by the movement of air or water around or past the body (whirlpool)
15%
contact between a circulating medium and another material of different temperature (not constant)
define radiation and give an example
the rate of heat transfer in radiation depends on what
radiation accounts for __% of normal transference
transfer of heat through air from a warmer source to a cooler source (the sun, infrared lamps, laser, UV light)
the intensity, the relative sizes of the radiation source, the area being treated, the distance and angle of radiation to the tissue
60%
define evaporation
evaporation is under the control of what
evaporation accounts for __% of normal heat transference
transformation from a liquid state to a gas state, and heat is given off when liquids transform into gases
autonomic NS
22%
define conversion
give an example
what does rate of transfer depend on
heat transfer by conversion of a non-thermal form of energy (electrical, mechanical, chemical) into thermal energy
ultrasound
power, size of treated area, size of applicator, tissue type, efficiency
what are the haemodynamic responses to cryotherapy
decrease in BF, increase in blood viscosity
decrease in production and release of vasodilators (histamines, prostaglandins)
reflex action of sympathetic adrenergic neurons is vasoconstriction locally and distant
cutaneous thermal receptors stimulate vessel wall smooth muscle contraction
why does pain decrease when you apply cryotherapy
what is the hunting response
why does this response occur
because there is a decrease in the release of prostaglandins
cyclical vasoconstriction and vasodilation mostly in the distal extremities (cold induced vasodilation)
if you keep shutting down BF via constriction it would have a detrimental effect on tissues (is a protective response)
how long does the hunting response last for and what is it followed by
why is the skin red after application of ice
4-6 mins followed by vasoconstriction lasting 15-30 mins
because of the concentration of oxyheamoglobin at the site because the blood becomes more viscous (NOT due to vasoconstriction)
what are the metabolic responses to cryotherapy
when should you avoid heat and why
decreased metabolic rate
decreased metabolic reaction rate including those involved in inflammation and healing
control acute inflammation
avoid if healing is delayed because it could further impair recovery (due to ability to slow down metabolic rate)
what are the neuromuscular responses to cryotherapy
decreased nerve conduction velocity, increased pain threshold, facilitation of muscle contraction (alpha motor neuron activity)
the decrease in nerve conduction velocity following cryotherapy has the greatest effect on which fibres
how does cryotherapy increase the pain threshold
small or non myelinated fibres (a delta/pain fibres)
by decreasing muscle spasm, sensory nerve conduction, edema, BF, spasticity, spindle and organ activity
for the first 24-48 hours after injury what is the modality of choice
name the 3 reasons why this is the modality of choice within this timeframe
ice/cold
fluid filtration (edema) into the interstitial fluid can be reduced via vasoconstriction
pain can be reduced by effecting nerve conduction
reduction in cellular metabolic rate leads to decreased secondary hypoxic tissue injury
what are the 4 indications for why we should choose cryotherapy
why do individuals with MS prefer cryotherapy
inflammatory control, pain control, spasticity, facilitation of neuromuscular activity
because heat promotes further inflammation which is the underlying cause of MS (inflammation of myelin causes breakdown in CNS)
when can you use heat instead of ice within the first 24-48 hours
when should you not use heat instead of ice
why would we want to use heat instead of ice in the first 24-48 hours
when there are low level sprains or muscle contusions
on individuals who have other serious pathologies (post surgical, conditions where cryotherapy provides inflammatory management like MS)
because dilation causes healing properties to flow into the injured area, assisting with healing of injured tissue
explain the differences between contraindication, precaution and risk
contraindication = do not do
precaution = use with caution
risk = any treatment has inherent risk
what are the contraindications for cryotherapy
vasospastic pathologies, cold hypersensitivity or intolerance, over regenerating nerves
what are vasospastic pathologies
what are the signs of vasospastic pathologies
vasoconstrict too much compromising blood supply and causing spasm
sudden pallor (white) or cyanosis (blue) and becoming red after removing the cold
what may cause vasospastic pathologies
what is cold hypersensitivity
raynauds syndrome, thoracic outlet syndrome, carpal tunnel, recent trauma
vascular reaction to cold (red or pale, elevated and itchy)
what are the signs of significant intolerance to cryotherapy
cold hypersensitivity and intolerance can be caused by what
severe pain, numbness, colour changes
rheumatic disease, trauma, familial links (genetic)
what are over regenerating nerves
why is it a bad idea to place cold on regenerating nerves
which nerves should you not place cold on
nerves that were traumatized and are trying to heal
because nerves are so sensitive it would effect BF and metabolism which would impair the healing process
common peroneal and ulnar nerves
what is cryoglobulinemia
what is haemoglobulinemia
aggregation of serum protein with cooling causing ischemia and gangrene (no BF whatsoever)
release of haemoglobin into the urine making urine purple
what are the precautions for cryotherapy
over a superficial main branch of a nerve
over an open wound (reduces insulation)
hypertension (may increase BP further)
poor sensation
altered mental state or poor communication skills
very young or very old (thin tissues)
what are the 4 safety considerations for cryotherapy
frostbite
superficial nerve injury (peroneal, subclavian)
sensation (skin test)
exercise (collagen stiffness increases and reduced proprioception causes risk of further injury)
what are the factors affecting response to cryotherapy
if the patient doesn’t improve in 2-3 treatments what should you do
patient (subcutaneous fat, local circulation, skin)
type of cryotherapy, moisture, % total body SA
temperature differential, application time course
re-evaluate and alter the treatment
how do the sensations change the longer you leave cold on on area
how long should you wait before applying cold again
go from cold to burning/aching to numb
1-2 hours so body can return to homeostasis
name the types of cryotherapy from depth of penetration (deep to superficial)
what is the conventional duration for cryotherapy treatment
ice bath, ice bag, cold pack, ice massage, vapo spray
15-20 mins
what is the intermittent protocol for cryotherapy
duration of cryotherapy should be adjusted based on what
10 mins on, 10 mins off, 10 mins on
the individual’s needs and situation (all timeframes are beneficial for reducing swelling and pain)
how does cryotherapy increase inflammatory mediators
because metabolic activity decreases so the inflammatory mediators are not flushed out due to vasoconstriction
