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PHTH 550- Orthopaedic Management Final > Lecture 15: Thermal Modalities and Therapeutic US > Flashcards

Lecture 15: Thermal Modalities and Therapeutic US Flashcards

1
Q

What are the physiological effects of cryotherapy (therapeutic cold)?

A
  1. Limit Blood Flow: Vasoconstriction of the cutaneous blood vessels and reduction in BF-> reduces bruising, bleeding and edema. Decrease in histamine and bradykinin-> reduces inflammatory process including fluid filtration from blood vessels.
    * Vaslolidation: after a period of time at 10degrees or less, vasodilation may occur, but blood flow still remains below normal levels.
  2. Limit secondary hypoxic tissue injury: cooling reduces local metabolism and cellular energy demand which prevents cell death by allowing cells to remain viable in a hypoxic environment.
  3. Slower nerve conduction velocity: Cold increases the threshold for nerve depolarization, so slows nerve conduction velocity->analgesic effect. Good for muscle relaxation->tone and spasticity.
  4. Reduce muscle force production: b/c of reduced bf and changes in biomechanical properties of the muscle. >10min cooling needed for major muscle groups.
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2
Q

What are the consequences of applying cold for too long?

A
  1. Edema formation: damage of superficial vessels due to cold-induced ischemia causing leakage of fluid from vessels during reperfusion.
  2. Frostbite: tissue freezing/death (limited or impaired circulation RF).
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3
Q

What are the three methods of thermal exchange?

A
  1. Conduction: physical contact with heat or cold sources. Also evaporation cooling.
  2. Convection: heat exchange with moving fluid (prevents equilibration of T).
  3. Radiation: Thermal energy is emitted as EMR. Warm object heats cool environment.
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4
Q

What are some other factors that influence cooling effect of a cold modality?

A
  1. Temperature difference
  2. Time of exposure
  3. Thermal conductivity of area being cooled
    CPA: Remove jewelry but it is safe to apply cold over intact skin over implants.
  4. Total body surface area cooled
  5. Size of cooling agent/ability of the cooling agent to maintain its temperature.
  6. Activity Level
  7. Type of cooling agent
    * it talks longer for a cooled area to return to normal temperature then a warmed area.
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5
Q

Why does skin turn red once cold is removed or after 10-15 min of cold application?

A
  1. Vasodilation 2. Oxygen does not dissociate as freely from Hb at lowered temperatures (more oxygenated in venous system).
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6
Q

What are the main uses of cryotherapy?

A
  1. Acute MSK
    - vasoconstriction to reduce bleeding
    - decrease metabolism and vasoactive agents (inflammation, edema, hypoxic damage)
    - Increase pain threshold
  2. Reduce muscle spasm
    - Reduce pain
    - Neuronal effects
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7
Q

What are the guidelines for cryotherapy?

A
  1. Test for hypersensitivity to cold.
  2. Crushed ice for at least 10 min. Different durations for other modalities.
    - Many types of modalities
  3. Activity during application is counterproductive.
  4. Be careful after treatment b/c analgesic may provide false sense of security and sensation may be impaired.
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8
Q

What needs to be charted for cryotherapy?

A

Type of cold, duration, site of application, patient response, adverse reaction, concurrent compression or elevation, position of pt.

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9
Q

What are contraindications to the use of cryotherapy?

A
  • Cold urticaria
  • Raynaud’s disease
  • Cryoglobulinemia
  • Hemoglobulinemia
  • Impaired circulation
  • Chronic wounds
  • Regenerating nerves
  • Tissue affected by TB
  • Hemorrhaging tissue
  • Active DVT or thrombophlebitis
  • Anterior neck and carotid sinus .

-Home cold-therapy programs for persons with cognitive or communication problems that affect their ability to follow directions.

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10
Q

For what conditions must precautions be taken when using cryotherapy?

When is it safe to use cryotherapy?

A

Precautions:

  • Areas of impaired sensation
  • Infected tissue
  • Near or over eyes
  • Damaged or at-risk skin
  • Cold therapy that causes peripheral vasoconstriction should be used carefully in people w/ hypertension or cardiac failure.

Safe:

  • Active epiphysis
  • Intact skin over implants (metal, plastic, ceramic)
  • Electronic devices
  • Know or suspected malignancy
  • Low back and abdomen of pregnant women
  • Radiated tissue
  • Reproductive organs
  • Skin disease
  • Chest, heart, head
  • Tissues inflamed as a result of a recent injury or exacerbation of chronic inflammatory conditions.
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11
Q

What are the main uses of therapeutic cold versus therapeutic heat?

A

Cold: reduce pain and limit the formation of edema
Heat: Reduce pain and reduce tissue stiffness/alter tissue viscoelasticity (improve ROM/Flexibility)

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12
Q

What temperature must a tissue reach to achieve therapeutic effects?

A

Between 40-45 degrees C.

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13
Q

What are the physiological effects of therapeutic heat?

A
  1. Alters viscoelastic properties of connective tissues: increased load-relaxation (maintain increased length under less load) and creep (continued deformation under constant load). Heat predisposes tissue to viscoelastic deformations which are permanent changes in the tissues that are not reversed when tissue is unloaded.
  2. Increase cellular activity and metabolic rate: release of o2 by Hb and uptake of O2 by tissues-> may promote tissue proliferation and remodelling.
  3. Vascular effects: Vasodilation occurs as a means to lose heat. Activated via multiple mechanism: axon reflex, chemical mediators and spinal cord reflex. In Skeletal muscle heating produces vasodilation via different mechanism then exercise. So together heat and exercise have a cumulative effect on BF/vasodilation.
  4. Neuromuscular Effects:
    A) increase pain threshold: Different mechanisms then cryotherapy (i.e. nerve conduction velocity increases)
    Thermal gate theory: firing of cutaneous thermal receptors may block primary nociceptive afferents.
    B) Reduction in muscle spasm/muscle-guarding spasms: Associated with change in muscle spindle firing rate.
    C) Decrease in muscle strength and endurance (especially for 30min after application and then it may increase after this up to 2.5 hrs).
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14
Q

What are mechanism of superficial heat application?

A

Superficial Heat:

  • Heat applied to skin causes greatest degree of temperature elevation within 05.-2cm of skin surface. Adequate blood supply, temp will increase in 6-8minutes.
  • Muscle may increase at depth 1-2 cm, takes longer duration of exposure.
  • At 3 cm only possible to increase temp by < 1 degree.

Superficial Heating Modalities that will Produce an Increase in Temperature 1-3cm below the skin:

  • Hot packs
  • Paraffin wax bath
  • Fluidotherapy
  • Warm whirlpool
  • Microwavable gel packs
  • Air-activated heat wraps
  • Electric heating pads.
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15
Q

How can tissue temperature be increased at a deeper level?

A

Continuous ultrasound
Continuous shortwave diathermy
May increase temperature 1-5 cm of the skin surface.

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16
Q
  1. The physiological effects of heat are dependent on what factors?
  2. What degree of heat should pt sense with all forms of heating modalities?
A
  1. Thermal conductivity of tissue
    Body volume exposed
    Time of exposure
  2. Mild to moderate sensation of heat during application
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17
Q

What needs to be charted for heat therapy?

A
  • Type of heating (approach to wax baths)
  • Duration
  • Site of heat application
  • Pt response
  • Adverse response
  • Use of concurrent elevation or compression
  • Pt position
18
Q

What are the contraindications to superficial heat?

A
  • Large areas that would raise core temp in pregnant women
  • Regions of known suspected malignancy
  • Infected tissue or ppl w/ Tb
  • Active DVT
  • Areas of impaired sensation
  • Active bleeding tissue
  • Recently radiated tissue
  • Larger areas that would increase core temp in ppl w. cardiac disease or cardiac failure
  • Person w/ cognition or communication impairments sufficient to prevent them from giving accurate and timely feedback
  • Areas with impaired circulation
  • Tissue inflamed as a result of recent injury or exacerbation of chronic inflammatory condition
  • Areas w/ heat-sensitive skin disease
  • Skin breakdown or damage producing uneven heat conduction
  • Severe edema
  • Reproductive organs (testes)
19
Q
  1. What precautions need to be taken with superficial heat?

2. When is it safe to use superficial heat?

A
  1. Near or over eyes
    Anterior neck and carotid sinus
    Pregnant women
    People w/ cardiac failure
2. Intact skin over implants 
Over electronic devices
Near Chronic Wounds 
Superficial or regenerating nerves
Heat, heart or chest 
Active epiphysis 
Persons w/ hypertension
20
Q

What are the contraindications for continuous or pulsed ultrasound?

A

Neither Continuous or Pulsed for:

  • Low back or abdomen of pregnant women
  • Region malignancy
  • Electronic devices
  • Active bleeding or hemorrhagic disorders
  • DVT
  • Radiated tissues
  • Myositis ossificans
  • Eyes
  • Anterior neck or carotid sinus
  • Reproductive organs
  • Tissues w/Tb

Continuous US causing tissue heating should not be used for:

  • Ppl w/ cognition or communication impairments which prevent them from giving accurate and timely feedback
  • Infected tissues under tension (abscess)
  • Tissue inflamed as a result of recent injury or exacerbation of chronic inflammatory condition
  • Impaired circulation
  • Impaired sensation (cannot give feedback)
  • Heat-sensitive skin diseases
  • Skin overlying implants containing cement or plastic.
21
Q
  1. What conditions/locations must be treated w/ caution when using US.?
  2. What condition/scenarios are not contraindicated for US?
A 
1. 
Continous or pulsed:
-Spinal cord or superficial peripheral nerves
-regenerating nerves
-active epiphysis
-at risk or fragile skin

Pulsed:

  • Intact skin over implants (cement or plastic)
  • Impaired sensation
  • Pt w/ cognitive or communication impairments
  • Impaired circulation
  • Heat-sensitive skin diseases
  • Infected tissue with open drainage
  • Regenerating nerves
  • Tissue inflamed as a result of recent injury or exacerbation of chronic inflammation
  1. Pulsed or continuous:
    - intact skin over metal implants
    - head
    - chest wall, provide rib cage intact
    - persons w/ heart failure or hypertension

Pulsed: areas near or over chronic wounds.

22
Q

What are the main uses for cryotherapy?

A
  1. Acute MSK injury
    - arteriolar vasoconstriction to reduce bleeding (after 10 min can get vasodilation but BF will not return to regular level)
    - Decrease in metabolism and vasoactive agents (histamine and kinins)
    • Reduces inflammation
    • Reduces outward fluide filtration (edema)
    • Reduces cellular energy demands/secondary hypoxic tissue injury (have to reduce by 5-10 degrees to have an effect)
      - Pain threshold elevated
  2. Reduce muscular spasms
    - Reduce pain
    - Decrease in gamma-motoneuron activity through stimulation of cutaneous afferents
    - Decrease in afferent spindle discharge by direct cooling
23
Q

What are factors to keep in mind when applying cold therapy? (5 things)

A
  1. Temperature of cold modality:
    - Ice can be safely applied directly to skin
    - Cold gel packs should have a damp towel btwn skin and pack (prevent ice burns)
  2. Time of exposure
    - ACSPM recommends >10min w/ crushed ice
    - Some guidelines up to 30 min (try to get a deeper effect, but studies have not shown to be effective and increased risk of injury)
  3. Thermal conductivity of area being cooled
    - CPA position stand says safe to use ice over metal implants, but remove jewelry)
    - Fat, muscle, and bone good insulators and may prevent deep cooling (some areas just can’t be cooled)

How deep cooling effect penetrate? What are you trying to target? Cannot cool deep structures with ice (does not penetrate more then a few centimetres) like muscle temp.

  1. Total body surface area cooled
    - Cooling larger areas is more effective (to effect blood flow)
  2. Ability of cooling agent to maintain its temperature
  3. Test skin sensitivity prior to application. Monitor skin and pt reaction during application.
    - Compression in addition to ice is used to reduce swelling, but must be careful not to constrict tissue.
24
Q

What are the main uses of heat therapy?

A
  1. Alter the viscoelastic properties of connective tissue
    - Temp >40 degrees
    - Predispose tissue to viscoplastic deformation: changes in the tissue that remain when you remove heat. Use prior to exercises to increase ROM. When heated tissue does not have the same ability to resist stretch and strain (be careful not to cause damage)
  2. Reduce pain (increase pain threshold)
    - Multiple mechanisms
    - Heat is effective in reducing back pain.
  3. Reduction in muscle spasm/ muscle-guarding spasms
    - Increase temp> 42 degree (may require more then superficial heat)
    - Reduction of tonic extrafusal fiber activity (decrease in firing rate type 2 afferents, increase in type 1b fibers from GTO and decrease in alpha motor neuron).

Heat can penetrate deeper then cold, but is still limited by tissue in the surrounding area.

Heat isn’t necessarily beneficial when there is swelling (edema).

25
Q

What modalities do you use for muscle spasms?

A

Chronic condition w/ muscle spasm: Heat

Acute condition w/ muscle spasm: Cold

26
Q

How should heat be applied?

  1. Hot Packs
  2. Paraffin Wax
A
  1. Store in hydrocollator heat at 70-75 degrees, so wrap in towels (2-3 layers thick) or more if pt lying on top of hp, remove clothing/jewelry. Apply for 20-30 min. Check for adverse effects after 5 min.
    * Check T sensitivity first in area.
2. Use for areas that are more contoured (hands, feet). 
Wax bath: 45-50 degrees. 
Approach: Remove jewelry, wash and dry area. 
-Dip hand or foot in bath (6-10 times) 
-Wrap in bag or towel 
-Elevate extremity
-Caution pt doesn't move extremity 
-Leave 10-15 min 
-Remove wax and inspect

Checking for circulation issues is important with therapeutic heat.

27
Q

What is Ultrasound?

A

High-frequency waves of mechanical (acoustic) energy directed through a given medium.

Wave of areas of compression and rarefaction. High frequency wave pattern causes molecules of medium to vibrate.

Dense media transmit US energy more efficiently then less dense media.

28
Q

What are the characteristics of US wave pattern?

A

Frequency: Number of times particle goes through a complete cycle in 1 sec.
( 1 or 3 MHz for Therapeutic US)

Wavelength: Distance between 2 equivalent points on the wave. (1.5 or 0.5 mm)

Velocity: rate at which wave travels through medium.

29
Q

Therapeutic Ultrasound Dose:

  1. What is the primary determinant of treatment depth?
  2. What is a half value depth?
  3. What are the typical depths reached by US?
A
  1. Frequency of the US. Lower frequency penetrates deeper then higher frequency (Higher F also produces faster thermal effect).
    Standard frequency: 1 or 3 MHz.
  2. Depth at which 1/2 of the energy is delivered. Different for different tissues.
  3. 1 MHz-> 4 to 6 cm
    3 MHz-> 2 cm
30
Q

Therapeutic US Dose: Intensity

  1. What is intensity?
  2. How is it calculated?
  3. What is the Beam Non-Uniformity Ration?
A
  1. The amount of energy delivered per unit time (W) and it is reported per unit area (W/cm2)
  2. Spatial Average Intensity=power(W)/Effective Radiating Area (cross-sectional area of the US beam delivered by the sound head).

There is also:
Spatial Average-Temporal Average= SAIXDuty Cycle
3. BNR: representation of inconsistency in energy delivery by the sound head. Lower BNR=more consistent energy delivery.

31
Q

What are the guidelines for therapeutic US treatment intensity?

A

Non-Thermal Effects:
Acute: 0.1-0.3 W/cm2
Sub-acute: 0.2-0.5
Chronic: 0.3-1.0

Thermal Effect: Higher intensity (possibly 1.5)

32
Q

What are the modes of therapeutic US application?

A
  1. Continuous
    - Generally used for thermal effects.
  2. Pulse: alternating on and off cycles.
33
Q

Define:

  1. Pulse duration
  2. Pulse ratio
  3. Pulse Period
  4. Pulse Frequency
  5. Duty Cycle
  6. Coefficient of Operation
A
  1. PD: On time during a cycle (usually 2ms)
  2. PR: ratio of on:off time.
  3. PP: Total on and off time.
  4. PF: Inverse of the pulse period.
  5. Percentage of the cycle during which energy is delivered.

DC=(pulse duration/pulse period).

  1. Inverse of the duty cycle and represents the proportion by which you need to increase the treatment time to deliver the same total energy.

Add numbers in the pulse ration (i.e.: 1:4= 5)

34
Q

What are the guidelines for treatment mode?

A

Larger pulse ratios early healing phases and lower ratios later phases of healing.

Acute: 1:4 or 1:3
Sub-acute: 1:2 or 1:1
Chronic: 1:1 or continuous

35
Q

What are the rules for treatment area?

A

Total area over which you wish to deliver US.

  • Treatment are should be no grater than 4X ERA
  • Treatment area will always be larger than ERA (b/c continuously moving the sound head).
36
Q

What are the two ways to calculate treatment time? What are their different uses?

A
  1. Treatment time=60sX treatment area x coefficient of operation/ERA

Based on 60 sec of treatment being delivered over the entire treatment area.

  1. -Shoulder pain and injury .
    -Treatment areas was no larger than 2XERA.(treatment area not consider only shoulder studied, so time would need to be adjusted for larger areas)
    -Chronic conditions.
    Studies that showed US effectiveness when delivering > 2250 J per session.

Min Treatment Time-2250J/average intensityX duty cycleX ERA

37
Q

What are the therapeutic effects of US-Thermal?

A
  • Acoustic (kinetic) energy is delivered to tissue and as energy is transmitted some dissipates as heat.
  • Continous high energy US is used to achieve thermal effect.
  • Higher frequency US provides rapid thermal effect
  • Denser tissue will absorb more energy, heated preferentially. Least to most absorption: blood, fat, nerve, muscle, skin, tendon, cartilage and bone.
  • Same precautions apply as other thermal modalities. Pt should feel a warming effect.
38
Q

What are the therapeutic effects of US-Non-thermal?

A

Cells respond to mechanical stimuli by altering metabolic state. US may up regulate cellular activity helping in tissue repair. 2 Mechanisms:

  1. Acoustic streaming: eddying of fluids near a vibrating structure may affect diffusion and membrane permeability up regulating certain metabolic processes.
  2. Cavitation: Formation of gas filled voids within tissue and body, helps to enhance acoustic streaming.

Inflammatory phase: US not anti-inflammatory but promotes resolution inflammatory events.
Proliferative: maximizes efficiency
Remodelling: may influence collagen

39
Q

What needs to be charted for US?

A
  • Machine
  • Machine settings (frequency, intensity, time, pulse parameters)
  • Treatment area
  • Duration
  • Effects (was pain reduced, did pt feel thermal effect)
  • Therapeutic Dose
40
Q

What is the suggested frequency for US treatment?

A
  • Daily for 10 days for chronic scar
  • 3-4 times per week for sub-acute/chronic condition
  • 2 times per week for acute condition
41
Q

How do you calculate the therapeutic dose?

A

Therapeutic Dose (J/cm2)=Total energy per treatment/treatment area

or
TD=Average intensity Xduty cycle XERA Xtreatment time/Treatment area

PHTH 550- Orthopaedic Management Final (13 decks)

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