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.