Cold Therapy in Rehabilitation

Cryotherapy

• Cryotherapy is the local or systemic application of cold for diagnostic or therapeutic purposes.

Methods of Cooling

• Convective cooling: Use of an electric fan.
• Evaporative cooling: Use of volatile fluids like ethyl chloride and chlorofluoromethane.
• Conductive cooling: Ice packs, frozen gel packs, iced towels, and ice cubes.

Conductive Cooling

• Conductive cooling is the most common method, where heat is conducted away from the tissues.
• The magnitude of temperature change depends on:
  • Temperature difference between the object and the tissue.
  • Time of exposure.
  • Thermal conductivity of the area being cooled.
  • Type of cooling agent.
  • Vascular supply.

Temperature Gradient

• The greater the temperature gradient, the greater the tissue temperature reduction.
• The deeper the tissue, the longer the time required to reduce its temperature.
• Muscle at a depth of 4 cm can be lowered by 3.5 degrees Celsius with 30 minutes of ice pack application.

Thermal Conductivity

• Tissues with high water content (e.g., muscle) have better thermal conductivity than fat.
• The amount of fat influences how much and how fast muscle cools. Muscle at a 2 cm depth can show a 2-degree Celsius temperature reduction after 10 minutes if covered by 1 cm of fat. If the fat layer is thicker, 30 minutes may be needed.

Type of Cooling Agent

• Ice packs produce greater temperature reduction compared to cold water baths and gel packs.
• Vapocoolant spray reduces skin temperature quickly without substantial change in deeper tissue temperature.

Physiological Effects

• Vascular effects: Immediate vasoconstriction of cutaneous blood vessels (reduced blood flow). This is due to a reflex action and cold's effect on smooth muscles.
  • Vasoconstriction lasts for 10-30 minutes.
  • Increased blood viscosity.
  • Liberation of histamine-like substances, leading to vasodilation (hunting response) when cold application is intense (e.g., 10 degrees Celsius), following initial vasoconstriction. Vasodilation lasts for 4-6 minutes. This is to remove the H substance. Cycles of vasoconstriction and vasodilation occur at 15-30-minute intervals.
• Overall Net Effect: Reduced temperature and circulation.

Physiological Effects Continued

• Metabolic effects: Metabolic rate decreases with cooling, reducing oxygen and nutrient demand and metabolic waste production. This can contribute to slower healing.
• Inflammatory processes: These may be modified, influenced by the intensity and duration of cold application.

Neural Effects

• Reduction of peripheral nerve conduction velocity (sensory and motor)—can lead to conduction failure.
• Magnitude of change depends on the duration and degree of temperature change.
• "A" fibers are blocked at 12 degrees Celsius before "C" fibers. Gamma fibers are blocked before alpha fibers. To block C fibers, the temperature should be near 0 degrees Celsius. Blocking of synaptic transmission also occurs at 15 degrees Celsius.
• At temperatures near freezing, all sensory neuron activity ceases.

Sensations From Cold Application

• Sensations felt during cold application include: cold, painfully cold, less cold, burning, numbness, and then anesthesia.

Longer Cold Application

• Longer applications (e.g., 20 minutes) can decrease motor nerve conduction velocity and affect muscle performance.

Effect on Swelling

• Cold reduces the filtration rate of fluid into the interstitial space due to vasoconstriction.

Neuromuscular Effects

• Direct cooling reduces muscle spindle afferent discharge and gamma motor neuron activity (through cutaneous stimulation). This reduces spasticity.

Long-Duration Cold Application

• Long-duration cold application (15-30 minutes) decreases muscle temperature and strength, reduces muscle blood flow, and increases viscous properties at 10 degrees Celsius.

Short-Duration Cold Application

• Short-duration cold application (1-2 minutes) has a facilitatory effect on alpha motor neurons.

Tissue Damage

• Tissue damage can occur depending on the duration and intensity of cold application.
  • First degree: Red, inflamed, mild edema.
  • Second degree: Marked edema, blisters.
  • Third degree: Necrosis, blue skin color.
  • Fourth degree: Gangrene and neurological complications.

Summary of Physiological Effects

• Decrease in circulation/vasoconstriction.
• Decrease in exudate formation.
• Decrease in hemorrhage following trauma.
• Decrease in spasm and spasticity.
• Decrease in pain.
• Decreased metabolism.
• Decreased extensibility of tissue.
• Increased blood viscosity.

Indications

• Reduction of acute pain, slow nerve conduction velocity, and counterirritant.
• Control of bleeding and swelling associated with acute trauma (sprains, strains). Vasoconstriction and increased blood viscosity.
• Treatment of acute burns (reduce pain and blistering).
• Reduction of spasm (decrease nerve conduction velocity in muscle spindle afferents).

Indications Continued

• Reduction of spasticity. Decreased nerve conduction velocity; decrease firing of muscle spindle afferents. Cold may reduce spasticity for up to 90 minutes (examples: stroke, SCI, UMNL).
• Facilitation of motor responses in patients with neurological or orthopedic problems.
• Decrease inflammation and pain associated with joint mobs and friction massage.

Contraindications/Precautions

• History of frostbite.
• Impaired circulation.
• Impaired sensation.
• Very old or very young patients.
• Sensitivity or allergy to cold.
• Before exercises or stretching.
• Raynaud's disease.
• Allergic reactions to cold (cold urticaria).
• Open wounds.
• Over regenerating peripheral nerves.

Dangers

• Cold intolerance (severe pain, redness, cyanosis, mottling).
• Burns.
• Hypertensive response.
• Frostbite (erythema, blistering, gangrene).
• Cold urticaria (allergic skin reaction).

Applications/Techniques

• Ice Towels: Comfortably position the patient, explain the procedure, and check for contraindications. Examine signs/symptoms, skin for cuts/bruises, thermal/pain sensation. Protect clothing, and test patient's reaction to ice; apply oil to skin. Warn about different sensations, excessive burning.
• Place ice flakes/cold water in a container, fold a towel lengthwise/place it in the container, remove, wring, and place it on patient. Change towels every minute, keep at same temperature (10-14 degrees Celsius), total treatment time is 10-15 minutes, assess area and patient's response.
• Ice Packs: Same preparation as ice towels. Place ice chips in moistened terry towel or sealed plastic bag. Mold pack to the area to ensure even contact. Treat for 5-15 minutes or 20-40 minutes for deeper muscle issues. For swelling, bandage the pack, with compression and elevation (RICE).
• Cryogel Packs: Stored at temperatures of −5 degrees Celsius. Refrigerate for 2 hours prior to use. Wrap in towel, place on patient's skin and secure with strap Treat for 10-15 minutes.
• Chemical Cold Packs: Seal is broken, activating chemicals for single use only.

Continued

• Ice Immersion: Same preparation as ice packs. Place part of the body in a container filled with water, placing ice chips within. For pain and swelling, immerse part and withdraw when discomfort is felt. Repeat up to 10 times; For spasticity, immerse and leave as long as possible. Shivering and hypothermia can increase spasticity. Apply heat elsewhere to counteract. Total body immersion for 5-7 minutes.
• Ice Massage: Done for small localized areas of pain/swelling. Use an ice cube or ice lolly, massaging the area slowly and with constant pressure. Avoid dripping water. Patient may experience burning, aching, and then numbness. Treat for 5-10 minutes.

Ice Massage Modalities

• Includes various tools for ice massage to support the localization of treatment.

Ice for Stimulation/Facilitation

• Run ice quickly over muscle belly (3–5 swipes).
• Immediately ask the patient to contract the muscle.
• There should be no dripping.
• Effect can be immediate or delayed (27–42 minutes).
• Used for neurological disorders (e.g., stroke, peripheral nerve injuries).
  • Examples: swallowing, speech (supra sternal notch); knee extensors (vastus medialis and lateralis); dorsiflexion (tibialis anterior); deep breathing (T7–T12).

Vapocoolant Sprays

• Position the patient to expose the area and protect eyes.
• Hold the spray bottle upside down. 18 inches away from the body part.
• Spray the entire length of the muscle at a rate of 4 inches per second while maintaining the stretched position.. Repeat,. Spraying should not exceed 6 seconds, to prevent frostbite.
• Ethyl chloride spray bottles may explode.

Cryocuff

• Applies cold and compression.
• Uses a cuff, cooler, and tube to apply to shoulder, knee, foot, ankle, thigh, and calf.
• 1 inch of elevation is equal to 1.8 mmHg of pressure.

Choice of Agent

• Depends on:
  • Desired effects (facilitation, edema control).
  • Accessibility of the body part.
  • Size of the area to be cooled.
• Example: Foot—immersion; Knee—packs, cryocuff; Ankle—pack, immersion, cryocuff.