Table 1.

Methods of warming systems, description and mechanism of heat transfer(4, 6).

Warming device	Description	Mechanism of Heat transfer
Warming blanket	Air delivered to variety of blankets at three settings: high (43 °C), medium (38 °C), low (32 °C).	Convection
Circulating Water garment	circulates water from the control unit to polymer hyper/hypothermia blankets. Manual settings: 4–42 °C; automatic: 30–39 °C	Conduction
Heated air mattress	Ineffective, because limited body surface area comes into contact with the mattress.	Conduction
Hot packs	Temperature at approximately 54.5 °C. Mean increase in temperature of 1.4 °C.	Conduction
Humidified gases	Delivery of warm, humidified gas, which can increase the core temperature by 0.5–0.65 °C/h.	Evaporation
Fluid warmer	Warmed fluids were found to increase the temperature by about 1.3 °C.	Conduction
Forced Air Warming Systems	Forcing warmed air through the warming device to the container, which is in direct contact with the patient's skin (usually a two-layer blanket).	Convection