Heating Pad

Heating Pad

A heating pad is a device utilized for warming specific areas of the body to alleviate pain. The localized application of heat prompts the blood vessels in the targeted area to expand, enhancing blood flow to the affected tissue. Various types of heating pads are available, including electrical, chemical, and hot water bottles.

Electrical heating pads typically function using household current and require safeguards against overheating. Moist heating pads, used directly on the skin, can reach temperatures ranging from 170 to 180 degrees Fahrenheit (76 to 82 degrees Celsius) and are designed for deep tissue therapy. However, they can pose a risk if left unattended.

Moist heating pads are primarily utilized by physical therapists but are also available for home use. Adding a moist cloth with a stupe cover can further increase moisture during treatment.

Chemical heating pads, such as sodium acetate heat pads, employ a one-time exothermic chemical reaction, such as catalyzed rusting of iron or dissolving calcium chloride. These pads contain separate compartments for the reagents. When the user squeezes the pad, the compartments break, allowing the reagents to mix and generate heat.

Reusable heat pads commonly contain a supersaturated solution of sodium acetate in water. Flexing a small, flat disc of notched ferrous metal within the liquid triggers crystallization, releasing stored energy. To reuse the pad, it is placed in boiling water for 10–15 minutes to dissolve the sodium acetate trihydrate and recreate a supersaturated solution. Once cooled to room temperature, the pad can be triggered again.