What is superficial heat ?

Superficial heat is the heat that apply the heat directly on the skin superficialy.Superficial heating modalities usually do not heat deep tissues, including muscles, because the subcutaneous layer of fat beneath the skin surface acts as a thermal insulator and inhibits heat transfer. Additionally, increased cutaneous blood flow from superficial heating causes a cooling reaction as it removes the heat that is applied externally.

In general, the transfer of heat (whether the purpose is heating or cooling) often is classified into 3 general types of heat transfer:

1. conduction
2. convection
3. conversion

1. Characterized of heat transfer:

• Conductive heating - This is defined as heat transfer from one point to another without noticeable movement in the conducting medium. Typically, direct contact takes place between the heat source and the target tissues. Superficial heat is usually conductive heat. Like- hot water baths, hot packs, electric heating pads, warm compresses.

• Convective heating - This form of heating is produced by the movement of the transferring heating medium, usually air or a fluid. Methods for providing convective superficial heat. Like- Fluidotherapy, whirlpool, moist air baths, and hot air baths.

• Conversion heating - This involves the conversion of one energy form (eg, light, sound) into another (heat). Superficial heat is produced by heat lamps or radiant light bakers, with heat being transferred when the conveying medium (light energy) is converted to heat energy at the skin surface.

Superficial heat modalities categorized by primary heat transfer mode are summarized as follows:

• Conduction - Hot pack, paraffin bath
• Convection - Fluidotherapy, hydrotherapy, moist air
• Conversion - Radiant heat

The factors determine the extent of the physiologic response to heat, including the following:

• level of the tissue temperature (usually 40-45 º C)
• Duration of the tissue temperature increase
• Rate of increase in the tissue temperature
• Size of the area being treated