Hydrotherapy, Thermotherapy, & Cryotherapy

• Hydrotherapy comes from Greek words meaning "water" and "healing"
• Hydrotherapy uses water in any form (liquid, ice, steam) and temperature (hot, cold) to treat physical or psychological issues
• Water is a heat transfer medium in hydrotherapy
• Thermotherapy involves using heat to treat diseases
• Examples of thermotherapy can include hot packs and paraffin baths (moist heat), along with fluidotherapy and air-activated heat wraps (dry heat)
• Cryotherapy uses cold to treat diseases
• Examples of cryotherapy are ice packs and vapocoolant sprays
• Aquatic therapy treats diseases with water
• Aquatic therapy includes aquatic therapy pools, whirlpools, and Hubbard tanks, which can be cold or warm

Thermal Agents

• Heat is a form of energy, caused by moving atoms and molecules
• Temperature measures an object's ability to spontaneously release energy and indicates the level of molecular motion with heat

Classifications of Therapeutic Heating Agents

• Superficial heating agents primarily increase the temperature of the skin and subcutaneous tissue
• The effect on deeper structures is less pronounced (0.5-2 cm depth)
• Superficial thermal modalities can heat tissues deeper than 2 cm, but not enough for therapeutic effects
• Examples include hot packs, paraffin wax, warm whirlpool, fluidotherapy, air-activated heat wraps, and infrared radiation
• Deep heating agents cause a tissue temperature rise (TTR) in deeper tissues
• They include large muscles and periarticular structures (2–5 cm depth)
• Examples are therapeutic ultrasound and diathermy

Physical Mechanisms/Modes of Heat Exchange

• Heat always goes from objects of higher temperature to objects of lower temperature
• Conduction is heat transfer through direct contact with materials of different temperatures
• If using a hot pack, the body absorbs heat
• If using cold packs, the skin loses heat
• Convection is thermal energy transference to a body via moving air, matter, or liquid
• A warm or cold whirlpool results in a temperature change due to the water's movement around the body part
• Fluidotherapy circulates warm air through fine-grained cellulose particles around body parts
• Conversion is when energy changes from one form to another, such as transforming non-thermal (mechanical or electrical) energy into thermal energy
• Examples include therapeutic ultrasound that converts sound waves (mechanical energy) to heat (thermal energy) as absorbed by tissue and diathermy
• Radiation is heat energy transfer through rays, waves, or particles, moving through air from a warmer source to a cooler source
• An infrared heat lamp provides therapy
• Evaporation is the transformation from liquid to gas for resultant cooling
• An example is sweating
• Ethyl chloride is a vapocoolant spray for cooling of the skin via evaporation

Physical Principles of Heat Exchange

• Specific heat is the capability of a substance to store heat
• It represents the heat amount (in calories) needed to raise one gram of a substance by 1°C
• Water's specific heat is 1.0, the standard unit for other substances
• Air's specific heat capacity is 0.001
• Water holds heat approximately 1000 times better than an equal volume of air
• The rate of heat transfer by conduction is (Thermal conductivity × Temperature difference × Area of contact) / Tissue thickness

Thermal Conductivity

• Thermal conductivity means means a substance can transfer heat to other substances
• Materials with high thermal conductivity transfer heat more quickly, such as metals
• Water's thermal conductivity is moderate
• Air has low thermal conductivity
• Heating and cooling agents usually blend moderate thermal conductivity for safety and effectiveness
• The high heat, high specific heat, and moderate thermal conductivity of water allows efficient heat transfer
• Six-eight layers of toweling is placed between the patient and the hot pack is because direct pack-to-skin contact is too hot and able to easily burn
• Thicker towels and covers are better insulators
• Tissues with high water content, like muscles/blood, conduct heat better than adipose
• Subcutaneous fat insulates due to its low thermal conductivity
• Ice conducts heat better than water

Other notes

• Metal has high thermal conductivity. Remove jewelry to avoid overheating/burns.
• Joint replacements should be considered prior to thermotherapy.
• The relationship between temperature gradient and heat transfer - the greater the temperature difference between a heating or cooling agent and the body part, the faster the heat transfer.
• Select conductive agents that change temperature fast for quick and safe temperature control.
• Area of contact affects total heat transfer the larger the contact area between a thermal agent and the patient, the heat transfer will be greater. For a hot pack applied to the entire back versus a smaller application to the calf, the whole body or using something like a a Hubbard tank causes more heat transferral
• The rate of heat rise changes due to tissue thickness. A patient's skin temperature increases the most when using a thermal agent; deeper tissues are less affected.

Thermotherapy

• The hypothalamus maintains the body’s temperature between 36°C and 38°C (96.5°F to 99.5°F).

Initial or Primary Responses

• Heat and cold receptors are strongly stimulated initially with an abrupt change in temperature.
• This stimulation gradually decreases if the receptors adjust to temperature change.

Secondary Responses

• The opposite effect begins when the maximum therapeutic effect from heat/cold is achieved.
• Maximum vasodilation from heat application is achieved in 20 to 30 minutes; continuation beyond 30 to 45 minutes can cause congestion and constricted vessels.
• Similarly, cold application might cause vasoconstriction, but continued application past 30 mins, up to one hour may induce vasodilation for 10-15 minutes.

Physiological and Therapeutic Effects

• Mild heating occurs if tissue temps are under than 40°c; vigorous heating happens if tissue temp is 40°- 45°C.
• At temperatures over 45°C, enzymes and proteins denature, causing tissue damage, thermal pain, and burns.
• The ideal temperature for heating is a therapeutic elevation without adverse effects, (40°C to 45°C).

Local Physiological Effects

• Heat dilates blood vessels, increasing blood flow by 1½ to 2 times the normal resting rate, distributing heat and protecting the heated skin.
• Skin surface heating causes erythema (hyperemia and redness) Increasing blood flow
• boosts nutrients and oxygen to the heated zone
• Increases antibodies present in the heated area

Vasodilation

1. Heat stimulates cutaneous thermoreceptors, causing reflex vasodilation in blood vessels
2. Inflammation mediators such as histamine and bradykinin increase local release
3. Increased metabolism releases carbon dioxide and lactic acid, increasing acidity and causing dilatation

• Superficial heating causes pronounced vasodilation in local blood vessels and less in deeper vessels within muscles
• Blood flow in distal extremities (not directly heated) increases when one area (e.g., lower back) is heated; safe for patients with peripheral vascular disease (PVD)
• Heat circulation is removed by the area of a local tissue temperature rise (TTR) to cool and stop damage.
• Heat is transferred via the blood to areas that dissipate it called heat sinks
• The lungs and skin act as major heat sinks. The lungs dissipate heat via respiration, the skin via perspiration and radiation.
• The application is only safe if heat sinks dissipate as quickly as you apply, for areas with improper flow, this is dangerous and can cause tissue destruction.
• A greater portion of the body under the the water of a whirlpool bath means less of the temperature should be applied

Heat Increases Metabolic Rate

• Metabolism is the conversion of carbohydrates, fats, and proteins to heat.
• Heat speeds up chemical reactions, including enzymatic reactions
• Heat increases enzymatic activity within tissues at 39°C to 43°C, increasing reaction rates by 13% for every 1°C which doubles reaction rate at every increase of 10°C of temp.
• Increase in the metabolic rate
• Enhances oxygen absorption in tissues
• Increases waste excretion from cells
• Hastens cellular interactions like phagocytosis and growth
• Accelerates wound and periwound perfusion by expanding bloodflow
• Improves oxygen within wounds, to assist bacteria removal

Increasing Fluid Dynamics

• Heat raises capillary permeability to reabsorb edema. It enhances venous and lymphatic drainage, which aids in removing waste and reabsorbing enduring edema.
• Heat leads tissue to expand and improve range in motion
• Increasing the temperature (40 - 45°C) increases the extensibility of collagen and soft tissue.
• Heat softens viscosity, increases visco-elastic qualities to tissue, ligaments/tendons, making them more flexible as connective properties help stiffness. Applying heat before/during stretch affects elastin.
• Heat helps lessen muscles when it decreases muscle spasm
• Increased heat reduce spasm to type II (muscle spindle afferents) and gamma (type Ib from Golgi afferents), these things stop Alfa motor neuron firing, and minimize muscle spasm.
• A reduction in spasm or guarding and/or leads to pain reduction (pain-spasm-pain).

Muscle strength during heat

• Within the first 30 mins of applying heat: muscle endurance and strength will be decreased
• After a 30 min period, but still less than 2 hours, then strength will recover and increase over time

Pain Control with Heat

• Heat raises threshold for pain sensitivity (for pain onset)
• Every 1°C temp increase, can raise conductivity by 2 meters per second
• Direct thermal stimuli can counter irritation caused by painful stimuli by activating cutaneous thermoreceptors (A-beta) which impede pain signals at the spinal cord
• Indirect: waste drops, edema goes away, less muscle spasm, and tissue regeneration
• May lead to sedative-like result with improved sleep due to reduced pain

Systemic and Generalized Effects of Heat

• Sweating increases
• Pulse rate increases
• Breathing increases
• Kidney function increases
• Decreasing blood pressure due to water, nitrogen and sodium

Contraindications for heat

• Heat agents are ill-advised in acute injury or signs of inflammation due to inflammatory responses
• Don't use with trombophlebitis due heat dislodges thrombi that can cause morbidity
• Using heat over hemorrhages which increase bleeding
• Avoid using with tumor since heat increases reproduction rate
• Avoid heat over infections it will spread
• Do not heat the abdomen/back of the pregnant especially during trimester 1 because it affect the fetus
• New healed tissues is sensitive, heat worsen vasodilation, avoid healing

Metal area near heated area

• Risk of burn due to the inability to circulate heat
• Risk of overheating
• Can increase menstrual flow

Adverse Effects of Thermotherapy

• To avoid burns, do not use heating agents for extended periods. Those with circulation is poor, reduce heating period
• Blood or pressure gets reduced, a patient feel weakness during that time raise head
• After Vasodilatation, bleeding or recent vascular lesions may occur if heat persists

Preping Test

• Temperature over 15 or 45 is not useful, but you can recognize sensation of pain with it

Hydrocollator facts

• A hot pack is composed of moist & super heated
• It distributes warmth to skin in a way that surface to surface is ideal to spread and absorb.
• Packs have to be water sealed which is 60-70 c.
• Some of the more common brands are hydro and silica gels Procedure before placing
• Make sure you are comfortable!

Do not place over exposed skin to prevent hot and burn issues

• You can prevent that if you cool it for a long time.
• To heat packs it take 30 minutes, or in extreme cold conditions, 2-3 hours

To prevent heat issues, add extra layers like commercial hot packs covers on a regular towels

Benefits of pack cooling system

• It helps to insulate the heater
• Prevents major burns

There are hot packs with various sizes

• DO NO reack into the heating surface to avoid major injuries!
• Remove extra liquid dripping!

Eight level of covering. For some key factors avoid overheating issues

• The heat is easy to hold with no dripping water.

Towlel application

• Cool it or let the water drop to 115 F
• The patients must explain any sudden heat.

Dosage is about a few minutes until a hot sensation occurs

Heat at homes exist too Moist heat are used too!

Advantages

• Moisturize heating ability!
• Shape is flexible
• Can perform local ability

Disadvantages

• Weight may be discomforting
• Packs maybe to long
• Difficult to shape

Air Wraps

• It helps deliver heat at a continuous temperature

• They form iron, water, carbon, sodium at high oxidation

• And It retain is great for moist at 100%

• Effective for joints flexibility, span, and comfort

• No getting wet

• Low heat of contact

Paraffin baths

• Help keep moisture
• It's easy is effective for small joints in limbs
• 55 or 45 c is temperature
• The conduction of it is effective to spread and use
• They come in multiple and smaller styles

Preparing it

• Remove jewelry/clothing, or any foreign objects since it be too hot

• Inspect the skin first!!

• Maintain the temp!!

• Apply some oil

Dip wrapping It goes like 7 to 12 times!

The procedure is 10 and 30!

There's a more popular popular route!

Brushing!

• Make sure the elbow are being properly moved
• 41 c is right to prevent heat!

Benefits of Wax

• Great for circulation
• Help prevent heat, since it slowly heats
• Helps add oil to sking

Cons:

• messy
• no room to spread

For fluidothers

For the extremities!

• Place the leg right to a stream ,
• Thermostat can stay from 38 to 47c
• Great for heat. ROM increase, reducing and healing injuries!

With viscosity helps you avoid injury You move with heat with no hard splints

Good to implement with bandagges

Exercise when affected For wrist ,foot, and hands

It may run for 20 mins

Benefits are as follows!

• Easy and administer
• Comfortable

Avoid dip with hot heat! Heat that is controlled

• It soothes Has limitations with a closed container

Cymatherapy

There an method of cold for diseases. For ice or cold packs to be applied Cryo for surgical cases, may get cooled The softest part gets freeze, and get a temp shock

• 28c

Cooling and reduce temp

• Remove heat
• Its within the therapeutic stage
• It effects can really do well with a deep surface

The exposure depends on gradient duration.

Cardio Response

Reduced blood is 15 to 20 The nerve block is the greatest to stop the heat Peroneal at lateral knee is common to be blocked

Cold sensation reduce pain

It works with thermosensors receptors and NCD to effect

Cryo

• Cooling can hurt and effect performance
• It reduces swelling in joints so good at heal Contraindications is hypersensitive- cold Skin problems include allergic reactions too

Over sensitive to cold

You lose the ability to regenerate! With sensation loss Avoid the test is skin shows

Precautions

• Performed heat can block nerve Eastic might block that Those whom are sensitive, risk is present Younger people are susceptible!

The effects

Improper freezing and long damage may occur