Using Superficial Heat and Cold Applications for Treatment

Superficial cold therapy can reduce swelling and pain. Superficial heat therapy can reduce pain, and increase muscle relaxation.

Superficial heat and cold therapy are adjunctive therapy used for pain control and sports injury treatment. These therapies exert their effects at a depth of 1-2 cm. In general, these therapies limit tissue damage, control symptoms, and restore the function of the injured part.

Superficial heat therapy exhibits the following effects in the body:

• Dilation of the blood vessels
• Increase in cell metabolism
• Muscle relaxation
• Pain reduction due to relaxed muscle
• Sedative effect
• Reduction in the viscosity of the synovial fluid (fluid surrounding the joints) to reduce joint stiffness
• Acceleration in inflammation

Superficial cold therapy exhibits the following opposite effects as those exhibited by heat therapy:

• Constriction of blood vessels
• Numbing effect
• The decrease in blood flow
• The slowdown in the cell metabolism
• Reduction of oxygen in the injured part
• Reduced swelling
• Reduced muscle efficiency
• Pain reduction

The transfer of heat is generally classified into three types:

• Conductive heating: The transfer of heat takes place as direct contact with the conducting medium. Examples of conductive heating are hot water baths, hot packs, electric heating pads, and warm compresses.
  • Hot packs contain silica gel in a cotton bag. These packs are placed in a hot water tank, which is controlled at a temperature of 71.1-79.4°C. The silica gel soaks a large quantity of water and has high heat capacity.
• Convective heating: The transfer of heat takes place with the help of the movement of heat (energy) through the conducting medium such as air or fluid. Examples of convective heating are fluid therapy, moist air baths, hydrotherapy, and hot-air baths.
  • Fluidotherapy uses a bed of round, uniform, finely divided solids, such as glass beads, into which the temperature-controlled warm air is blown to generate a warm, semiliquid mixture. The patient’s hand, foot, or leg is immersed in the mixture for superficial heating.
• Conversion heating: In this, one energy form (light, sound) is converted into another (heat).  An example of conversion heating is radiant heat. Radiant heat involves the penetration of high-energy photons into the tissues, where the energy is converted into heat.

Patients with the following conditions are indicated for the application of hot packs (conductive heating):

• Painful muscle spasm
• Abdominal muscle cramping
• Menstrual cramps
• Superficial thrombophlebitis (an inflammatory process that causes a blood clot to form)

Patients with the following conditions are indicated for using convective heating:

• Arthritic conditions of small joints
• Infected draining wound
• Back muscle spasms
• Inflammation or pain in the joints

Cold therapy or cryotherapy has the primary effect of cooling the tissues. Local application of cold therapy is indicated in patients

• To reduce swelling/edema.
• To treat burns.
• To reduce pain.
• To decrease the acute inflammatory reaction.
• To reduce muscle contraction.
• To treat muscle weakness.
• To treat restricted knee bending due to lower leg fractures.

Conductive heating in the form of paraffin baths should be avoided when treating open wounds.

Convective heating should be avoided in the following situations:

• Fluidotherapy is not recommended for treating open wounds in patients.
• Hydrotherapy should be avoided in patients immediately following surgery.
• Hubbard tank (a tank used for full-body immersion) should not be used in patients who have undergone tracheostomy or any patient with a “stoma”.
• Convective heating should be avoided in patients who are pregnant.

Radiant heat is avoided in patients with the following conditions:

• Sensitivity to the sunlight
• Bleeding disorder
• Decreased sensation
• Acute inflammation

Cryotherapy is avoided in patients with the following conditions:

• Increased blood pressure
• Raynaud’s disease (smaller arteries supplying blood to the skin constrict excessively in response to cold)
• Rheumatoid arthritis (inflammation of the joints)
• Constriction of the artery
• Cold urticaria (allergy to cold)
• Inadequate blood supply to the leg or hand
• Peptic ulcer disease