Transcript superfecial heating modalities

Superficial Heating Modalities
Lecture 7
Dr. Afaf Ahmed Shaheen
Outlines
 Factors affecting magnitude of physiologic
effects
 Physiological effects
 Indications
 Contraindications
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5 Mechanisms of Energy (Heat) Transfer
in the Body: Added or Removed
 Conduction – transfer of heat through the direct
contact between a hotter and a cooler area (2 objects
touching each other)
– Ice Massage, Hydrocollator Pack, Ice Pack
 Convection – transfer of heat by the movement a
medium (air, liquid) between regions of unequal
temperature
– Whirlpool
 Conversion – energy is changed from one form to
another; does not relate to superficial heat or cold
– Electrical energy into heat, Acoustical energy into heat
– Ultrasound, Diathermy
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 Radiation – emitted from surfaces with
temperatures above absolute 0° (all atomic &
molecular motion ceases)
– Transfer of energy without the use of a medium
– Body, Sun, Infrared lamp, LASER, Ultraviolet
light
 Evaporation – change from liquid state to
gaseous state requiring thermal energy be
removed from the body
– Vapocoolant Spray
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Superficial Heating Modalities
 Therapeutic application of heat is known as
thermo-therapy
 Used to heat joints with little soft-tissue
covering
 Heating deeper structures through reflex
mechanisms.
 Therapeutic heat………40ºC to 45ºC
 More than45ºC………….tissue damage.
 Less than 40ºC………….mild heating.
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Biophysical Effects
(physiologic effects)
 Factors affecting magnitude of
physiologic effects:
Extent of temperature rise
• Temp. must be elevated 40-45oC
Rate at which energy is being added to
tissue
• Very slow: heat balanced by cooler
blood
• Very fast: stimulates pain receptors
Volume of tissue exposed
• Larger tissue area affected: systemic
reaction
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1)Hemodynamic effect (effect on vascular
bed)
Dilatation of the blood vessels (vasodilatation) leads
to hyperemia and sweating.
 a)Direct reflex
activation of
smooth muscles
of blood vessels
by cutaneous
thermoreceptors.
b) indirect activation
of spinal cord
reflexes by
cutaneous
thermoreceptors or
by increasing the
local release of
chemical mediators
of inflammation
(histamin+prostaglandin).
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Effects on Blood Flow
 Vasodilatation: blood flow
– Response to temp. change not always the
same:
• Skin blood flow: maintenance of constant
body core temp. under sympathatic
adrenergic nerves
– Has arteriovenous (AV) anastomoses,
important for heat loss (bypass
capillary bed), triggered by heated blood
through anterior hypothalamus
• Skeletal-muscle blood flow: metabolic
regulation with greatest response to level
of exercise
– Minimal or no change in blood flow
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With maximal vasodilatation
there are
 Rise in pulse rates.
 Drop in blood pressure
 Profuse sweating with chloride
loss
 Increase fluid transfer across the
capillary wall with increased
removal of tissue metabolites
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Neuromuscular effects
1On muscles:
a) Relaxation:
· This occurs when the warm blood
reaches deeper and deeper into
the muscles causing the vessels
to expand.
·
Relaxation
relieve of
pain by easing any pinching of
nerves or blood vessels and by
helping the muscles to remove
lactic acids and other metabolic
wastes.
·
Relaxation
in ROM
allowing for gentle exercises and
stretching.
b)
·
Increase blood flow
Heat
increase blood
flow in the muscles
this
is beneficial in muscle spasm or
sustained contractions where
ischemia may contribute to the
pain.
 2) On nerve
 Analgesia on the
peripheral and central
nervous system.
 Sedative action: as the
body tries to register a
temperature change, the
central nervous system
becomes depressed,
contributing to muscle
relaxation and temporarily
relieve of pain.
 The thermal stimulus that
affects the pain sensation
is explained by the gait
control theory of pain.
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Neuromuscular Effects
 Heat used to reduce spasm:
– Elevation of pain threshold
– sensory nerve-conduction velocity
– Change in muscle spindle firing rate
(gamma afferent fibers)
– Muscle strength and endurance?
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Change in muscle strength
1) Decrease in the initial 30 minutes after the
application of superficial and deep agents
due to
•
•
•
change in the firing rates of type II muscle
spindle efferent,
gamma efferent
and type Ib fibers from golgi tendon organs.
2) Beyond 30 minutes after the application of
heat and for the next 2 hours, muscle
strength gradually recovers and then
increase to above pretreatment levels.
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Effects on Connective Tissue
 Temperature elevation + Stretch:
change viscoelastic properties of
connective tissues
 Heating decreases joint stiffness
and increase tissue extensibility.
 Length change with damage:
stretch + heat
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On the whole body and metabolism
 Rise body temperature.
 Increased pulm onary ventilation.
 Increased metabolism: 10 ºC
increase in the temperature will
twice or triple the metabolic rate
leading to an increase of oxygen
uptake, an increase of nutrients
and promotion of healing.
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Effects on Metabolism
 Metabolic rate  2-3 times for each
10 oC
–  energy expenditure
–  oxygen uptake
–  nutrients: healing
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Reflex effect of prolonged heat
1. Prolonged heat to one extremity causes
vasodilatation of the contra-lateral
extremity.
2. Prolonged heat to the abdominal wall
causes a decreased in the intestinal
blood flow, diminish in the intestinal
motility and decrease in the secretion of
acid in the stomach.
3. Prolonged heat to the pelvis relaxes the
musculature of the pelvic organs,
dilates the blood vessels and increases
menstrual flow.
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Reflex effect of prolonged heat
4. Prolonged moist heat to the chest
promotes ease of respiration and
expiration.
5. Prolonged heat to the trunk, such as a
hot trunk pack, relaxes the ureters or
bile ducts and relieves renal or
gallbladder colic.
6. Prolonged moist heat to the area over
the kidneys in the back and over the
lower abdomen in front increases the
production of urine.
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Thermotherapy Effects
 Local Effects
–  metabolic rate
– Vasodilation
–  capillary permeability
–  nerve conduction
velocity
–  pain
–  muscle spasm
– Edema formation
 Systemic Effects
–  body temperature
–  pulse rate
–  respiratory rate
–  blood pressure
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Question:
Compare between the effects of cold and heat
in terms of their biophysical effects.
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Indications
 Reduction of pain
– Before exercises
 Alleviation of muscle spasm
 Increase range of motion
 Improve tissue healing (increase blood flow
& nutrients)
 Temperature: 40-45oC
 Duration: 20-30
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Contraindications
 Sensitivity to temperature and pain
 Circulatory impairment (arterial disease)
 Likelihood of bleeding or hemorrhage (e.g.
hemophilia, postacute trauma, long term
steroid therapy)
 Acute injury or inflamation
 Impaired sensation
 Malignancy - thrombophebitis
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Precautions
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Pregnancy
Impairment circulation
Poor thermal regulation
Cardiac insufficiency
Metal in the area
Over an open wound
Over areas where topical counterirritants have
recently been applied
 Edema
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Conductive heat agents
 Hot packs
– Superficial moist heat
– Canvas cases filled with hydrophilic silicate
– Stored in thermostatically controlled cabinet
in water at temperature ~ 71.1 oC
– Wrapped in toweling before application (6-8
layers)
– Should feel mild to moderate sensation of
heat
– Between treatments pack returned to unit
and completely immerse in hot water (30
min)
– Come in sizes and shapes
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Conductive heat agents
 Paraffin wax
– Melting point 45.5oC stay liquid at
temperature more than 47.8oC when
mixed with mineral oil in a 6:1 or 7:1
ratio of paraffin to oil
– 2 techniques: dip & wrap OR dip &
reimmerse
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Case Study
A 25-year old female is seen in physiotherapy
8 weeks following reduction and casting of
a right Colle’s fracture. The cast was
removed yesterday. There is mild swelling
on the dorsum of the hand. Range of motion
of the wrist is limited in all planes.
Metacarpophalangeal flexion is reduced in
all digits. Pain is present on active and
passive motion but not at rest
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Convective Heating: Fluidotherapy
 Convection: heat transfer
in which the heated
molecules move from one
place to another
 Fluidotherapy:
– dry heat agent transfer
energy by forced
convection
– Warm air circulated
through a container
holding fine cellulose
particles
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Radiant heating: Infrared lamps
 Radiation:
Increase in infrared
energy causing
the molecular
motion in the
cooler object to
increase, thus
increasing heat.
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Regulation of body temperature
1) The rate of heat production usually
balances the rate of heat loss.
2) The thermostatic control of temperature
occurs in neural centers in the spinal
cord and in the hypothalamic region.
3) Reflex and semi-reflex thermoregulatory
centers include autonomic, somatic,
endocrine and behavioral patterns.
4) Reflex responses activated by the cold
are controlled from the posterior
hypothalamus, while those activated
by warmth are controlled from
anterior hypothalamus
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