Cryotherapy & Thermotherapy

1. Cryotherapy & Thermotherapy Chapter 4 Therapeutic Modalities

2. Physiology Basics • Vasodilation • Increased size of vascular structures • Means more oxygen to the tissue • Vasoconstriction • Decreased size of vascular structures • Useful for preserving compromised/injured cells/tissue

3. Physiology Basics • Analgesia • Diminished/reduced sensation • Metabolic rate • Activity level of cells • Reducing MR can preserve cells damaged by injury • Inflammation • Series of events that hinder optimal function

4. Modalities • Alter cell metabolism • Each 1.8°F (1°C) change in tissue temp. results in a 13%  or  in the tissue’s metabolic rate. • Energy absorbed by one tissue later can’t be transmitted to deeper layers. • Law of Grotthus-Draper • The more energy absorbed by superficial tissues  the amount absorbed by deeper tissue.

5. 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

6. Mechanisms of Energy • 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

7. Cryotherapy – Cold Therapy • Cold modalities range in temp. between 32°F-65°F • Heat is removed from the body & absorbed by the cold modality • Tissue temperature is LOWERED • To obtain therapeutic benefits, the skin temp. must be lowered to approx. 57°F. • Cold therapy applied is thought to activate a mechanism used to conserve heat in the body’s core • This mechanism triggers a series of metabolic & vascular events that produce the beneficial effects of cryotherapy. • Can be used during all stages of healing

8. Cryotherapy • Normal skin temp. is approx. 91°F • The deeper the tissue in the body, the higher the temp. • Skin is cooler than adipose which is cooler than muscular tissue. • Thermoreceptors in skin are responsive to heat or cold (more to cold than heat).

9. Sensations with Cold Application • Cold • Burning • Aching • Analgesia (absence of pain) •  of n. conduction velocity &  threshold are required to fire the nerve(s).

10. Cryotherapy Indications • Acute injury or inflammation • Pain • Muscle spasm, acute or chronic • Restoration of ROM • Small, superficial, 1st degree burns • Post-surgical pain & edema • Neuralgia • Post-exercise

11. Cryotherapy Contraindications • Situations where the body is unable to cope with temp. change because of allergy, hypersensitivity, or circulatory insufficiency • Cardiac or respiratory involvement • Uncovered open wounds • Circulatory insufficiency • Cold allergy • Anesthetic skin • Advanced diabetes • Raynaud’s phenomenon or other Peripheral Vascular Disease • Lupus

12. Local Effects of Cryotherapy •  cell metabolism rate – PRIMARY BENEFIT •  need for oxygen • Lowers tissue temperature • Vasoconstriction •  production of cellular wastes • Prevents or limits swelling •  in pain by  pain threshold •  in acute & chronic muscle spasm • Limits area of original injury

13. Deeper tissues cool more slowly & to a lesser extent than skin • Muscle tissue requires longer to cool than bony areas • Deeper tissue temps. have been proven to drop for several minutes following the removal of an ice pack • Research has shown that deeper tissues remaining at rest will be cooled for 2 hr or more after a 20- to 30- min. ice pack application • The cold modality will continue to remove body heat until temps. are (=).

14. Precautions • Take into consideration the amount of pain that occurs during exercise after cold has been applied • Be careful when applying an elastic wrap over a cold pack over superficial nerves (Nerve Palsy) • Uticaria – hives

15. Cellular Response •  cellular metabolic rate • During a 20-min. treatment, cell metabolism  19% • With  b. flow, there is less metabolic activity & O2 demand on the cells •  need for O2 • Reduces number of cells killed by lack of O2 • Reduces secondary hypoxic injury damage • Reduces amount of chemical mediators released in area • Slows nerve conduction

16. Vascular Responses • Vasoconstriction occurs due to stimulation of n. receptors • Viscosity of blood & tissue fluids  • Resistance to b. flow  • Soft tissue  of 26% & skeletal b. flow  of 19% with 20-min. ice pack in injured ankles • Amount of b. flow is still under debate • Most studies indicate that b. flow  • Because of effects associated with rubbing the skin, IM may  b. flow, at least to the skin

17. Tissue Temperature Changes • 57°F skin temp. – optimal decrease in local blood flow • 58°F skin temp. – analgesia occurs • Temp. within the joint decreases proportionally to temp. of skin overlying a joint decreases • Temp. changes most rapidly in skin & synovium

18. Muscle Spasm • Cold therapy affects pain threshold •  nerve conduction velocity by slowing communication at the synapse •  pain by reducing the threshold of afferent n. endings. •  sensitivity of m. spindles • May inhibit the stretch reflex mechanism reducing m. spasm & breaking pain-spasm cycle

19. Inflammation • Changes in cellular function & blood dynamics serve to control effects of acute inflammation. • Cold suppresses the inflammatory response by: •  the release of inflammatory mediators (histamine, prostaglandin) •  prostaglandin synthesis •  capillary permeability •  leukocyte/endothelial interaction •  creatine-kinase activity

20. Pain Control • Cold therapy acts as a counterirritant • Cold application affects pain perception & transmission by: • Interrupting pain transmission (stimulates large-diameter A-beta n. fibers) • Decreasing n. conduction velocity • Reducing m. spasm • Reducing or limiting edema

21. Systemic Effects of Cold Exposure • If circulating blood temp.  0.2°F, then the hypothalamus (body’s thermoregulatory center) kicks in • General vasoconstriction in response to cooling of the posterior hypothalamus • Decreased respiratory & heart rates • Heart rate  (wants to localize the cold area) • Shivering & increased muscle tone • If heart rate  too much where the core temp. reaches hypothermia

22. Application of Cryotherapy • Ice Massage:Should not be applied during acute inflammatory stage as it’s not compatible with compression • 5-15 mins. – reduces pain, desensitizes trigger points • Vigorous Ice Massage • Ice Pack: type of ice – cubed, flaked • Commercial Cold Packs: chemical, reusable (Gel) • Be aware of frostbite; use insulating layer in between • Cryo-cuff/Polar Care:provide approx. 40 mm Hg • Cold Water Immersion: • Ice bucket: 40 °-50°F • Whirlpool: 50 °-60°F • Vapocoolant Spray:superficial, rapid cooling through evaporation; virtually no temperature change below epidermis; will numb area briefly (trigger points) • Intermittent Compression:Segmental compression with cold

23. Cryotherapy • Duration usually15-30 mins. Don’t apply for more than 60 minutes! • Depends on skinfold thickness • Ice with compression – affects deeper tissues • Compression encourages  lymphatic drainage • Circumferential: compression around entire area (ace wrap) • Collateral: compression on both sides (aircast, gelcast) • Focal: direct pressure to soft tissue surrounded by bony structure (horseshoe) • Cooling of tissue: rapid at first, then slows, then levels off • Skin reactions: • Hyperemia, pallor

24. Cryokinetics for Sub-Acute Injury Stage • Alternating cold therapy with exercise • Use good judgment! Do not cause further harm! • Place cryotherapy to body part for approx. 20 min. (analgesia feeling) • Remove cryotherapy & begin active exercise • Place cryotherapy back on body part once feeling/pain returns • Repeat

25. Hunting Response • 1930’s ; Lewis performed skin studies with temperature change during cold treatments. • When the fingers were immersed in cold water, alternating periods of cooling & warming were seen in the skin. • Thoughts were that intermittent cold-induced vasodilation (CIVD) lasting 4-6 min. after approximately 30 min. of cryotherapy application (p. 109) • Stated that it prevented local tissue injury • Today’s researchers state that CIVD does not occur during standard cryotherapy sessions.

26. Cryotherapy (Ice) Application • Ice massage • 7-10 minutes • Excellent for muscle spasm and deep soreness

27. Cryotherapy (Ice) Application • Ice bags, ice towels, or cold packs • 15-20 minutes (no longer than 30) • If using packs, be sure to avoid direct contact to protect skin! • Cold whirlpool / ice immersion • 5-15 minutes, 55-65 degrees • Duration and temperature depends on surface area immersed

28. Ice Massage

29. Ice Pack

30. Chemical Cold Pack

31. Reusable Gel Pack

32. Cryo-cuff

33. Ice Bucket

34. Cold Whirlpool

35. Fluori-methane