In rat or man, increased temperature causes an exponential increase in blood perfusion. Increased perfusion in humans has been associated with an increase in core body temperature as well as in local skin temperature . Patel et al. studied the effect of temperature and pressure on perfusion in fuzzy rats and found that there was a significant increase in perfusion with increased temperature at surface pressures below 50 mmHg. This result was attributed to a local autoregulatory mechanism . In addition, increased temperature caused skin to become stiffer in response to increased surface pressure with resultant decreases in deformation and creep. Thus, by warming the fluid (air or other viscous material) in support surfaces by several degrees (1-5 C), the induced increase in skin stiffness may be beneficial in preventing tissue breakdown. However, these beneficial temperature effects must be balanced against the increasing metabolic requirements of the tissue.