The effect of heating duration on the efficiency of hot pack

Abstract

To achieve therapeutic efficiency of hot pack, 30 min immersion is suggested. In practice, there may be a limit for the immersion time. Therefore, the objective of this study was to determine the shortest heating duration to achieve suitable therapeutic temperature which is indicated by the pack temperature, skin temperature, and skin blood flow. A total of 25 male subjects were recruited for this study. Hot pack (size 25x30 cm.) was boiled in 75 ±2 °C hydrocollator heating unit for 30, 25, 20, 15, 10, and 5 minutes, respectively. The pack temperature was immediately measured using infrared thermometer and wrapped in 8 layers of toweling to prevent skin burning before applying it to the volunteer’s calf for 30 minutes. Skin temperature and skin blood flow were measured using digital thermometer and Laser Doppler blood flow monitor, respectively, every 5 minutes during local heating with the hot pack. This study found that all parameters were associated with heating duration, longer period resulting in higher temperature and efficiency. The pack temperature, skin temperature, and skin blood flow of hot pack heated for 5 and 10 minutes were statistical significantly lower than 30 minutes (p<0.05), whereas, hot pack heated for 15, 20 and 25 minutes were not different from 30 minutes (p>0.05). The results suggested that 15-minute pack immersion was the shortest heating duration that provide therapeutic effect as good as 30-minute pack immersion.