Cryotherapy .
Cryotherapy is also known as Hypothermy .The therapeutic use of local cold application for the treatment of various diseases and disorders is known as cryotherapy. In the past, it was often termed as hypothermy. Personally, I prefer to call it as hypothermy. Heat abstraction or cooling by cryotherapeutic agents mostly occurs by conduction except in case of vapocoolant spray.
The magnitude of cooling depends on: area of body surface exposed to cold, A time of exposure, temperature difference between body tissues and cooling agent, thermal conductivity of the tissues and type of cooling agent. The physics of cooling is based on ‘Newton’s law of cooling’. Cryotherapy is commonly used in the treatment of acute trauma and subacute injury. The temperature of the body tissue is reduced and the heat is transferred from the body tissue to the cold medium.
The magnitude of cooling depends upon the area of the body tissue exposed, temperature of the cooling agent and the duration of exposure. The depth of penetration is also related to intensity and duration of cold application and the circulatory response to the body segment exposed.
Methods of Application of Cryotherapy .
Vapocoolant sprays, ice cube massage, cold packs, ice packs, ice towels, cold immersion, compressive cryotherapy and chemical cold packs can be used to apply cryotherapy.
1. Vapocoolant Sprays .
Vapocoolant sprays or cryogenic sprays are commonly used in the management of sports injuries. The most common type of vapocoolant spray used in physiotherapy is fluoromethane. In past, ethyl chloride vapocoolant sprays were used. But ethyl chloride is flammable, explosive and should not be inhaled. Hence, nowadays, ethyl chloride sprays are rarely used.
The spray removes heat from the skin underlying tissue and can be felt like a cool jet stream of fluid on the skin. Spray can be applied along with stretch. The advantage of the spray is, it can be used at home and it takes very little time to apply the spray.
Technique of application .
First demonstrate it to the patient by applying it on yourself. Then you can apply it on the patient by tilting the spray bottle upside down and aligning it at 30°C to the body part, hold it at 45 cm away from the body part and then apply the spray in a parallel sweep fashion, with a speed of 10 cm per second. You can apply the spray so as to cover the area twice or thrice. This will cause adequate cooling of the body part. If more spray is indicated, then the body part must be re-warmed to avoid injury to the skin.
2. Ice Massage .
Ice massage is usually done over a small area. Ice massage is used for pain relief in local area and facilitation of muscle contraction. Muscle contraction can be facilitated by rapid and brief application over the skin dermatome. Massage with ice is simple and inexpensive.
Ice cubes are easily available and hence, it is one of the easily accessible modality to the therapist as well as patient. It is usually applied over bursa, tendon, muscle belly, trigger point (before deep massage) and small areas of muscle spasm. Ice massage can be taught to patients so that it can be used at home.
Technique of application .
Water can be frozen in paper cups to make handling of the ice by the physiotherapist easier. The cup is peeled back as the ice melts. As an alternative, water may be frozen in a wax or styrofoam cup with a wooden tongue stick (ice lollipops) in the middle so that the person applying ice will not get cold. Ice cubes from household fridge also can be used for ice massage.
During application, a towel can be used to wipe water seepage from the treated area because excess water will be cold and will make the patient uncomfortable. Ice is rubbed over the skin by using small overlapping circles. An area of 10 to 15 cm can be treated in 5 to 10 minutes. If a larger area is involved then, any other method of applying cryotherapy should be considered.
The treatment takes usually 5 to 10 minutes for the area to have reduced sensation. Patient will usually experience four distinct sensations, including intense cold, numbness, burning, aching and then analgesia. When the patient touches the area and finds inability to feel the touch sensation, the treatment is completed. Ice massage produces analgesia and continues to do so for three to five minutes after treatment. To take maximum advantage of analgesic effect, manual therapy should be done immediately after the ice massage.
3. Cold Packs .
Cold packs are canvas bags containing silicate gel. Cold packs are available in various sizes and shapes to contour the area to be treated. These packs can be stored in a special refrigerator unit or in a household freezer. Storage temperature should be −5°C for at least two hours before use. These packs are reusable, do not reduce the skin temperature as quickly as ice bags, the patients who do not like the cold therapy can tolerate them, cold packs can easily mold to the body part and they do not open easily as ice packs.
Technique of application .
After removal of a cold pack from refrigerator, it is applied on top of the body part to be treated. Keep checking at frequent intervals. For hygienic reasons, a layer of towel can be placed between the pack and the skin surface. Patient should not lie on the top of the cold pack.
Many physiotherapists apply a wet towel first to the skin and then apply the cold pack and cover it with another towel or a sheet to insulate the area. If the towel is wet with the room temperature or lukewarm water, the initial contact will be more comfortable for the patient. A strap can secure the cold pack so that the area is well supported.
Cold packs are usually applied for 20 minutes. After the removal of cold pack from the treatment area, they should be refrozen for at least two hours before the next use of them. For the longer use, the pack should be replaced with another cold pack.
4. Ice Packs .
Here, a plastic bag is filled with crushed ice. It can be placed directly on the body part or with wet towel in between patient’s skin and ice bag. Ice pack or bag treatment time ranges from 10 to 20 minutes. They are particularly of help in the treatment of patients who had undergone surgery. Ice packs in these patients can reduce the swelling and decrease pain.
5. Ice Towels .
Superficial cooling may be achieved by the use of ice towels. Here, terry towel is placed in a bucket containing flaked ice and water then wrung out and applied to the part. It may be used for 5 to 10 minutes for analgesia to occur. Larger area may be covered but the towel needs to be replaced frequently as it warms up rapidly. Treatment with ice towels can be given for up to 20 minutes. Many physiotherapists use this method for cryokinetics or cryo-stretching techniques.
6. Cold Immersion .
Here, extremity is immersed for three to five seconds in slush bath and then it is removed from bath. Ice immersion can be effectively used for the treatment of extremities.
7. Compressive Cryotherapy .
Here, the compressive pumps provide external pressure and cold water to an extremity through the sleeve. It is used to reduce swelling in an area and to prevent loss of function. These machines apply intermittent pressure to the body part, so as to increase the interstitial pressure and pump the fluid back into the venous system. Pressure values used to treat upper extremity are 40 to 60 mm Hg and for lower extremity approximately 60 to 80 mm Hg (10 mm less than diastolic blood pressure of the patient).
Usually the on and off time ratio is 3:1. Treatment time varies and usually lasts for 10 to 15 minutes. With some larger units, two limbs may be treated simultaneously. These machines are used at sports medicine centers for the treatment of sprains, strains, and contusions for reducing edema in acute injuries. Patients with circulatory problems, possibly will have extreme difficulty in tolerating this treatment.
8. Chemical Cold Packs .
These are prepacked chemical packs that become cool when chemicals inside it are squeezed. For example, a pack with two components, one filled with water and other with ammonium nitrate which when squeezed, mixes with other contents to produce cooling.
These packs are expensive can be used only once and they can be preferred when ice is not available. These packs may cause a chemical skin burn, if they open accidentally. Chemical cold packs tend to cause poor cooling. These packs are too small and they are mostly used for immediate management of musculoskeletal injuries.
Indications to Cryotherapy .
- Treatment of acute musculoskeletal injuries (0 to 72 hours) .
- To reduce the acute pain .
- To reduce muscle spasticity .
- For relief of muscle spasm .
- To initiate muscle contraction .
- Arthritis (acute onset and acute exacerbation on chronic background) .
- Quadriceps lag .
- Edema/swelling .
- Ankle sprain .
- Tennis elbow .
- Bell’s palsy .
- Postsurgical pain .
- Bed sores .
Contraindications t0 Cryotherapy .
Cryotherapy is contraindicated in
- Raynaud’s disease, Raynaud’s phenomenon .
- Buerger’s disease .
- Cryoglobulinemia, paroxysmal cold hemoglobinuria .
- Open wound (after 48 hours) .
- Regenerating peripheral nerves .
- Vasospastic disease .
- Impaired sensation .
- Cold urticaria .
- Arteriosclerosis.
Precaution of Cryotherapy .
Precautions should be taken while treating a patient with hypertension and local cryotherapy application into an area where nerves are superficial such as, medial epicondyle, axilla and head of fibula. Precautions should also be taken while treating a patient with cardiovascular disease. While treating a patient with hypertension, monitor the blood pressure throughout the treatment.
Physiological Effects of Cryotherapy .
Physiological effects of cryotherapy are reduced body temperature, reduction in blood supply, reduction in metabolism and behavioral changes.
1. Body Temperature .
Cold causes fall in local body temperature. However, severe local cooling may result in hypothermia. Hypothermia is a condition where the core temperature is below 35°C. It may be a life-threatening situation.
2. Circulatory Effect .
Cold application causes reflex vasoconstriction of cutaneous vessels. Application of cold causes increase in sympathetic nerves activity, smooth muscle contraction and may increase the viscosity of blood. All these changes result in reduced blood flow in the area that is directly cooled. However, when the temperature is reduced below 10°C then, cold-induced reflex vasodilation may occur. Reflex vasodilation tends to occur in a cyclic manner and is believed to result from an axon reflex.
Reflex vasodilation following cold application was first recognized and reported by Lewis, in 1930. The repeated cyclic vasodilation and vasoconstriction is known as Huntington’s reaction. Cooling more than 10°C causes pain. Pain impulse or afferent impulse is carried antidromically towards skin arterioles. It leads to liberation of H substance and thereby vasodilation. Once again, continued cooling causes vasoconstriction and these events are repeated.
3. Metabolism .
Cooling of tissue decreases the metabolic activity and hence, the energy and oxygen requirements of cells get reduced. This effect is one of the most important effects of cryotherapy especially from the acute injury point of view.
4. Behavioral Changes .
Person receiving cold application for prolonged time may adopt a contracted posture. Arms and legs may be drawn up to the body by which the surface area exposed to cooling can be minimized. It is said that contracted posture can reduce the heat loss by up to 60 percent.
Therapeutic Effects of Cryotherapy .
1. Pain Relief .
Cold is one of the highly effective physiotherapeutic modality in relieving pain. It is commonly used for the relief of acute pain. It can also be used for the relief of acute exacerbation of pain with a chronic background. Pain relief may occur due to counter-irritation, reduced nerve conduction, decreased inflammatory process and relief of muscle spasm.
2. Muscle Spasm .
Cryotherapy is effective in relieving the muscle spasm. Relief of spasm may occur due to decreased muscle spindle activity and secondary to the relief of pain.
3. Inflammation .
It may bring about early resolution of inflammation by reducing vascular or cellular component of inflammation as a result of vasoconstriction.
4. Swelling .
Cold application can reduce the swelling following an acute injury. It may be due to vasoconstriction of arterioles and reduction in extravasations of fluid into interstitial space.
5. Connective Tissue Extensibility .
Cryotherapy increases tissue viscosity and consequently decreases the extensibility of the connective tissue. Patient may report an increase in stiffness after cold application and hence thermotherapy is a better choice in the treatment of tightness, contracture and stiffness.
6. Trauma .
Cryotherapy is one of the very effective modalities in the treatment of acute injuries. Cryotherapy reduces pain, bleeding and swelling. In addition to this, cryotherapy increases the survival rate of the tissues. Death of cells following injury may occur due to hypoxia and increased enzyme activity. Hypoxia may occur due to physical tears of blood vessels, edema and vascular congestion. Since the cryotherapy application reduces metabolism and enzyme activity, the survival rate of the damaged tissues increases.
7. Muscle Tone .
Cryotherapy can reduce the muscle tone. Hence, it is used in the treatment of spasticity. Reduction in spasticity may occur due to decreased activity of efferent gamma fibers.
8. Muscle Strength and Endurance .
Muscle strength may increase with short-term application of cryotherapy. But on long-term application, muscle strength gets reduced. However, one hour after the cessation of cooling, muscle strength may increase. Motor endurance decreases after cooling below 27°C.
9. Agility .
Agility or motor skill gets reduced by cold application. Thus, even though cold reduces spasticity but to teach a motor task after cold application is somewhat difficult.
10. Peripheral nerves .
Cold can reduce the velocity of sensory conductivity, motor nerve conductivity and synaptic activity, if the temperature of the nerve decreases. Cooling below 12°C may cause paralysis of local sensory and motor nerves.
Lewis-Hunting reaction .
The initial response of the body tissue to cold is that to preserve the heat. This is accomplished by an initial phase of local vasoconstriction. When homeostasis is reached and the body part has become cooled, there follows phase of vasodilatation. Then there follows alternate periods of vasoconstriction and vasodilatation. This appears as hunting toward the mean point and is known as Lewis-Hunting reaction
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