Construction and evaluation of a manikin for perioperative heat exchange

Abstract

Background: During surgery hypothermia can be avoided only if the heat exchange between the body surface and the environment can be controlled. To allow a systematic analysis of this heat exchange, we constructed and evaluated a copper manikin of the human body.

Methods: The manikin consists of six tubes (head, trunk, two arms and two legs) painted matt-black to simulate the emissivity of the human skin. Hot-water mattresses are bonded to the inner surface of the copper tubes to set the surface temperature. Calibrated heat flux transducers were placed on the following points to determine the heat exchange coefficient for radiation and convection (hRC) of the manikin: Forehead, chest, abdomen, upper arm, forearm, dorsal hand, anterior thigh, anterior leg and foot. Room temperature was set to 22 degrees C. Surface temperature of the manikin was set between 22 degrees C and 38 degrees C. The hRC was determined by linear regression analysis as the slope of the temperature gradient between the manikin and the room versus the measured heat flux. Subsequently we studied five minimally clothed volunteers in a climate chamber. Initial chamber temperature was set to 29 degrees C and was lowered slowly to 12 degrees C. The hRC was determined as described above for each volunteer.

Results: The hRC of the manikin was 11.0 W m(-2) degrees C(-1) and hRC of the volunteers was 10.8 W m(-2) degrees C(-1).

Conclusion: The excellent correlation of hRC between the volunteers and the manikin will allow the manikin to be used for standardised studies of perioperative heat exchange.