Cryotherapy & Thermotherapy

Chapter 4Therapeutic Modalities

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

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

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 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

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

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

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).

Sensations with Cold Application

• Cold• Burning• Aching• Analgesia (absence of pain)– of n. conduction velocity & threshold are

required to fire the nerve(s).

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

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

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

• 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 (=).

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

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

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

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

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

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

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

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

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

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

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

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.

Cryotherapy (Ice)

Application– Ice massage• 7-10 minutes• Excellent for muscle spasm

and deep soreness

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

Ice Massage

Ice Pack

Chemical Cold Pack

Reusable Gel Pack

Cryo-cuff

Ice Bucket

Cold Whirlpool

Fluori-methane