Purpose: The temperature of a warm fluid infused into a patient is lowered because the line that allows the fluid to be infused into the patient is exposed to room air. This study evaluated the effects of aluminum foil used as an insulator surrounding the fluid infusion lines when using warm crystalloid fluids to treat traumatic shock patients. Methods: The study measured the differences in fluid temperature between infusion lines with and without the aluminum-foil insulation. We used 1L of normal saline at $40^{circ}C$ as the infusion fluid, and the fluid infusion line was 200 cm long. The differences in temperature were measured for various fluid flow rates from 12,000 mL/min to 100 mL/min. We performed three experiments at each flow rate. Results: The results showed the differences in temperature between the groups with and without the aluminum insulation were significant for flow rates above 100 mL/min. Conclusion: Hypothermia in trauma patients results in many adverse complications such as peripheral vascular constriction, tissue hypoxia, metabolic acidosis, heart dysfunction and so on. Thus, the use of warm fluids and blood components is essential to reduce the probability of hypothermia. This study showed the aluminum foil wrapped around the infusion line had an insulator effect. As a result, such a wrapping can be used to avoid the adverse effects of hypothermia.