Therapeutic Modalities: Thermotherapy, Cryotherapy, and Ultrasound

A complete set of vocabulary flashcards covering thermotherapy, cryotherapy, thermal modalities, and therapeutic ultrasound based on kinesiology lecture notes.

Conduction

Heat loss or gain through direct contact between materials with different temperatures (e.g., Hot Packs and Cold Packs).

Either heat loss (touching cold) or heat gain (touching hot).

Convection

The transference of heat to a body by the movement of air, matter, or liquid around or past the body (e.g., sauna, hot tub, pool).

Radiation

The transference of heat (usually through air) from a warmer source to a cooler source (e.g., infrared heat lamp).

Conversion

The temperature change that results when energy is transformed from one form to another, such as mechanical or electrical energy (e.g., therapeutic ultrasound).

Evaporation

The transformation from a liquid state to a gas state, where heat is given off as liquids transform (e.g., sweating).

Mild Heat

Thermal application where tissue temperatures are raised to less than $104^\text{o}\text{F}$.

Vigorous Heat

Thermal application where tissue temperatures are raised above $104^\text{o}\text{F}$ (usually up to a maximum of $114^\text{o}\text{F}$).

Hyperemia

Skin redness indicating a desirable increase in blood flow.

Mottling

White and red blotches on the skin caused by rebound vasoconstriction, serving as a warning sign of potential tissue burning.

Hot Packs

Superficial moist heat modality filled with silica gel/sand-like material maintained in a bath ranging from $130^\text{o}\text{F}\text{ to }180^\text{o}\text{F}$, applied for $15\text{--}20\text{ min}$.

For increased soft tissue healing.

Paraffin Bath

Moist heat modality combining paraffin wax and mineral oil at $126^\text{o}\text{F}\text{ to }130^\text{o}\text{F}$, commonly used for hands and feet with arthritic conditions.

Fluidotherapy

Dry convection modality circulating warm air through natural cellulose particles in a cabinet, allowing movement during treatment without heat loss over time.

Oxygen-Hemoglobin Dissociation Curve (Thermotherapy)

The physiological response to tissue heating that shifts the curve down and to the right, promoting oxygenation of tissues.

Cryotherapy Temperature Gradient

Thermal gradient where temperatures of $50^\text{o}\text{F}$ and below can lead to tissue damage, reaching exposure depths of $1\text{--}4\text{ cm}$.

Oxygen-Hemoglobin Dissociation Curve (Cryotherapy)

The physiological response to tissue cooling that shifts the curve up and to the left, inhibiting tissue oxygenation.

Ice Packs

Crushed or cubed ice in a bag applied directly to skin for $10\text{--}15\text{ min}$, inducing cold, burning, aching, and analgesia in about $2\text{--}3\text{ min}$.

Cold Packs

Reusable plastic shell containing semi-gel material that stays cold for approximately $10\text{ min}$ and conforms fairly well to the body.

Ice Massage

Direct ice application using paper or Styrofoam cups covering an area of about $10\text{--}15\text{ cm}^2$ in about $5\text{--}10\text{ min}$.

Cold Baths (Immersion)

Cryotherapy immersion using partially melted ice in water at $55^\text{o}\text{F}\text{ to }65^\text{o}\text{F}$ for a duration of $10\text{--}15\text{ min}$.

Vapocoolant Spray

Fluoromethane or ethyl chloride spray that produces cooling via evaporation to treat trigger points and severe muscle spasm regions.

Contrast Baths

Treatment alternating warm baths ($100^\text{o}\text{F}\text{ to }110^\text{o}\text{F}$ for $5\text{--}6\text{ min}$) and cold baths ($55^\text{o}\text{F}\text{ to }65^\text{o}\text{F}$ for $2\text{--}4\text{ min}$) over $20\text{--}30\text{ min}$ to alternate vasodilation and vasoconstriction.

Therapeutic Ultrasound

Introduction of mechanical acoustical energy into the body within an intensity range of $0.1\text{ W/cm}^2\text{ to }3.0\text{ W/cm}^2$ to bring about thermal and/or non-thermal effects.

Reverse Piezoelectric Effect

The mechanism where an electrical current compresses a crystal in the sound head, causing it to vibrate and transmit mechanical pressure sound waves into tissue.

Compression Phase

The positive-pressure phase of an ultrasound wave where molecules in the path of the wave are squeezed together.

Rarefaction Phase

The negative-pressure phase of an ultrasound wave where molecules spread out more than before pressure was applied.

Ultrasound Generators and Transducers

The pressure wave is generated by causing a crystal in the sound head to vibrate.

Made of natural quartz or a synthetic material that responds to an alternating electrical current by contracting during one phase of current and expanding during the opposite.

Transducer: applicator that houses crystal (sound head). Sizes - 1, 2, 5, and 10 cm squared. 5 and 10 are the most common.

Absorption and Penetration

Fluid elements, such as blood and water, have the lowest impedance values and the lowest acoustic absorption coefficients. This means that these elements are poor absorbers of ultrasound. Bone, the densest of tissues, has the highest impedance value and the highest acoustic absorption coefficient. Thus, bone is a good absorber of ultrasound.

Frequency

Determines the number of sound wave cycles generated each second.

Also referred to as the “oscillation rate.”

Possible operating ranges: 0.75 million cycles/second (MHz) to 5.0 MHz.

Normal operating ranges: 1.0 MHz to 3.0 MHz.

Determines the depth of ultrasound penetration.

1.0 MHz goes deeper than 3.0 MHz. When energy is absorbed, it doesn’t penetrate.

Intensity

Term used to define the magnitude of the force in a sound wave.

Nothing to do with penetration depth.

Acoustical intensity = watts/cm squared.

Spatial Distribution of Energy

Ultrasound transducers produce pressure waves in tissues that form a near-cylindrical beam, with a cross-sectional area roughly equal to the crystal's diameter.

Beam Non-uniformity Ratio: the ratio of the maximum spatial intensity in the beam to the average spatial intensity.

Waveforms

Continuous: duty factor = 100% and a warming sensation (thermal).

Pulsed: duty factor = duration of pulse (ON)/ pulsed period (Off + On).

Common duty factors: 10% (1:9), 20% (1:4), 50% (1:1).

Subsensory = nonthermal

Thermal Effects

The goal is to increase tissue temp and collagen extensibility, thus yielding decreased joint stiffness, alteration in blood flow, changes in nerve conduction velocity, diminished pain perception, decreased muscle spasm, changes in contractile activity of skeletal muscle, assist in healing response and increased enzymatic activity, increased metabolic rate, and decreased swelling.

Ultrasound Depth

Ultrasound is considered a deep heater because it delivers at least 50% of its thermal energy beyond 1 cm into underlying tissue. Approximately 3 to 5 cm of penetration. Tissue temps can reach 104 F to 113 F.

Mechanical Effects

1. Micro-massage: the compression phase of a US wave deforms tissue molecules.

2. Stable Cavitations: expansion and compression of small gas bubbles in blood and tissue fluids.

3. Acoustical Streaming: mechanical movement of fluids along boundaries of cell membranes and increased cell wall permeability.

Coupling Agents

Ultrasound gel, water (best), lotion (not lanolin-based and must be water based), and hydrocortisone cream.

Phonophoresis

US drives medication into the underlying skin. It heats superficial tissue and causes vasodilation of dermal capillaries. The increased permeability of cell membranes enhances diffusion of medication into the cell.

Moving vs Stationary Techniques

1. Circular motion should be used (1-4 cm/sec), full contact at all times.

2. Only treat an area 2-3 times, the size of a sound head (ERA).

3. Patient shouldn’t feel much, just mild warmth.

Treatment Parameters

Healing tissue: low-intensity pulsed US stimulates cellular activities that then trigger a chain of events leading to enhanced tissue repair.

Frequency: 3.0 MHz normally, 1.0 MHz if target tissue is >4.5 cm

Duty Factor: Pulsed - 50% or below (20% for this ex)

Intensity: 0.1 to 0.2 w/cm2

Treatment time: 30 to 60 sec/ERA

Indications

Soft Tissue Injuries: tendonitis, bursitis, adhesive scars, myositis, organized hematomas, effusions/edema.

Precautions

Metal implants, cancer, unhealed fractures, epiphyseal plates in kids, DVTs, reproductive organs, areas of impaired sensation, eyes, heart, spinal cord, ears, infection.