Cold/Heat therapies Flashcards
what are the physiological effects of cold therapy?
Magnitude of tissue cooling in the target tissue (not just the overlying skin),
Reduced metabolic function
Reduced motor and sensory nerve conduction velocities.
what is the ideal tissue temperature to achieve the optimal physiological effect of cold therapy
15 to 25°C (59-75 °F)
where is the internal thermometer located?
prep-tic region of the anterior hypothalamus
Reflex activation of temperature receptors or stimulation of heat
loss mechanisms triggered in part by the circulation of blood through the preoptic region of the anterior hypothalamus
what is the theory of heat abstraction?
All cooling occurs via heat leaving one material and going into another.
Cold is never added to something to reduce its temperature.
what is the physical principals of cryotherapy?
Conduction
what is conduction?
the transfer of heat by direct
interaction of molecules (e.g., cold pack)
what are the factors that should be considered with cryotherapy?
temperature gradient between
warm and cool surfaces, type of tissue,
length of exposure, tissue depth
what are the local effects of cryotherapy?
↓ blood flow due to vasoconstriction
↓ nerve conduction velocity (NCV)
↓ tissue temperature
what is convection?
heat abstraction by direct contact between the skin and moving fluid particles (e.g., cold whirlpool)
What is the best way to use convectional?
Practical only for distal extremities and in a dependent position
How can you use cold therapy in post traumatic edema and inflammation?
For the first 24-48 hrs after injury, cold is usually modality of choice
Fluid filtration into interstitial tissue may be reduced with cold because of vasoconstriction
Inflammation and pain may be reduced
Local metabolism is decreased, leading to reduction in cellular energy demands, decrease in secondary hypoxic tissue injury
How does evaporation work in the case of cold therapy?
Vapocoolant sprays (e.g., Spray and Stretch, Instant Ice)
Trigger points, stretching
Effects: ↓ skin temperature, ↓ motor neuron activity
Negligible effects on deeper tissues
what are the hemodynamic bio physiological principles in cold therapy?
Reflex vasoconstriction
↓ blood flow
↑ viscosity. viscosity contributes to resistance to blood flow. If viscosity increases, resistance to blood flow increases.
When tissue temperature is below 10°C (50°F), cyclical
vasodilation, vasoconstriction
(Vasodilation photos on slide 9)
What is the hemodynamic effects?
When cold is applied –
vasoconstriction of cutaneous blood vessels
Reduction in blood flow
Blood flow to the skin is under neural control
Vasoconstriction of cutaneous vessels occurs as part of the heat-retention mechanisms of the body.
When skin temp is lowered, cold thermal sensors in the skin are stimulated, causing vasoconstriction.
This reflex vasoconstriction can also result in a generalized cutaneous vasoconstriction that may also occur in the contralateral extremity
How does cold therapy specifically work to cool the tissue post traumatic edema and inflammation (24-48 hours after injury)?
May ↓ fluid filtration into interstitial fluid
May ↓ inflammation and pain,
May ↓ local metabolism
May ↓ intramuscular pressure
may reduce the risk for compartment syndrome.
Moderate cooling best (several hours or less)
prolonged intense cold may INCREASE edema formation
Combine with compression and elevation
Describe the effects of cold stimulus on local blood flow?
slide 12
what are the peripheral nerve effects of tissue cooling?
↓ Nerve Conduction Velocity (↑ pain threshold)
what are the muscle performance effects of tissue cooling?
Short duration: no effect/slight ↑
Long duration: significant ↓ in muscle performance
↓ strength, proprioception, agility
what are the neuromuscular effects of tissue cooling?
↓ spasticity
Management of some neurological conditions
what is nerve conduction velocity and what needs to be considered when using the ice? (specific to this effect)
Sensory nerves cannot be cooled selectively
Reduced motor/muscle ability should be considered if your patient will be engaging in activity after the application of cold
Describe the effects of cold therapy on muscle performance?
Thermal agents can affect the ability of a muscle
to generate tension.
Longer exposure to cold (10 min vs 3 min)
resulted in decreased muscle performance.
Cold could be applied before exercise to reduce
pain- but how does the muscle then perform?
Because cold can alter muscle force generation,
strength assessments should be performed either
before or several hours after cold modality is
used.
describe the neuromuscular effects of cold therapy?
Patients with spasticity: cold can temporarily decrease the amplitude of DTR and frequency of clonus
Facilitates alpha motor neuron activity and decreases gamma motor neuron firing
Spasticity reduction with cold may occur through at least two mechanisms:
1. A reflex decrease in gamma-motor neuron activity through stimulation of cutaneous afferents
2. A decrease in afferent spindle discharge by direct cooling of the muscle
