The effect of quantity of ice and size of contact area on ice pack/skin interface temperature.

OBJECTIVE To determine the effect of quantity of ice and contact area on ice pack/skin interface temperature during a 20-minute cooling period. DESIGN Repeated measures. SETTING Laboratory setting in an educational institution. PARTICIPANTS Twenty healthy males aged between 18 and 22 years. INTERVENTIONS An ice pack was applied to the right thigh with compression using an elastic bandage. The effects of three packs measuring 18 cm x 23 cm containing 0.3, 0.6 and 0.8 kg of ice, and one pack measuring 20 cm x 25 m containing 0.6 kg of ice were compared. MAIN OUTCOME MEASURE The reduction in temperature at the ice pack/skin interface during 20-minute ice applications was monitored at 1-minute intervals. RESULTS The application of 0.8-kg and 0.6-kg ice packs led to a significantly greater decrease in the interface temperature compared with the 0.3-kg ice pack [0.8 kg vs. 0.3 kg: -2.35 degrees C, 95% confidence interval (CI) of the difference -3.36 to -1.34 degrees C; 0.6 kg vs. 0.3 kg: -2.95 degrees C, 95% CI -4.07 to -1.83 degrees C]. No significant difference in temperature was found between the 0.6-kg and 0.8-kg ice packs (0.8 kg vs. 0.6 kg: 0.6 degrees C, 95% CI -0.12 to 1.32 degrees C, P>0.05). The size of the contact area did not alter the degree of cooling significantly (difference between smaller and larger pack: 0.05 degrees C, 95% CI -0.93 to 1.03 degrees C, P>0.05). The lowest temperature during ice application was reached after 8-9 minutes of cooling. CONCLUSION Application of an ice pack containing at least 0.6 kg of ice leads to a greater magnitude of cooling compared with application of a 0.3-kg ice pack, regardless of the size of the contact area. Thus, clinicians should consider using ice packs weighing at least 0.6 kg for cold treatment.