Dosing Heat: Expected Core Temperature Change with Warmed or Cooled Intravenous Fluids.

Area of Science:

• Thermodynamics and Biomedical Engineering
• Clinical Temperature Management
• Mathematical Modeling in Medicine

Background:

• Patient core temperature management is critical in various medical conditions.
• Advanced temperature control methods are not always accessible.
• Intravenous (IV) fluids are widely available and can be used for temperature modification.

Purpose of the Study:

• To approximate body temperature changes resulting from IV crystalloid boluses.
• To develop a mathematical model for predicting temperature shifts based on fluid volume and temperature.
• To provide clinicians with a tool for estimating the impact of IV fluids on patient temperature.

Main Methods:

• Developed a mathematical model based on thermodynamic principles.
• Assumed rapid fluid infusion and a specific heat capacity for the human body (3.47 J/kg·°C).
• Calculated temperature changes for various patient temperatures (18°C-45°C) and crystalloid temperatures (4°C, 20°C, 42°C).

Main Results:

• A 30 mL/kg dose of 20°C crystalloid can decrease hyperthermic patient temperature by 0.6°C-0.9°C.
• A 30 mL/kg dose of 4°C crystalloid can decrease hyperthermic patient temperature by 1.2°C-1.4°C.
• A 30 mL/kg dose of 42°C crystalloid can increase hypothermic patient temperature by 0.2°C-0.8°C.

Conclusions:

• IV crystalloid boluses can induce predictable core temperature changes (0.2°C-1.4°C per 30 mL/kg).
• This model offers a method for clinicians to estimate temperature effects of IV fluid therapy.
• Careful consideration of fluid volume, electrolytes, and patient conditions (e.g., heart, liver, kidney failure) is essential.