Brain temperature is maintained by CBF, which serves as a body-coupled heat exchanger system penetrating all brain structures. Data presented herein quantitatively validate the manner in which CBF protects against extracranial cooling via the temperature shielding
Brain temperature is maintained by CBF, which serves as a body-coupled heat exchanger system penetrating all brain structures. Data presented herein quantitatively validate the manner in which CBF protects against extracranial cooling via the temperature shielding effect. It is often assumed that cerebral metabolism is responsible for maintaining brain temperature. However, according to Eq. 2 cerebral metabolism can only change brain temperature, compared with the temperature of incoming arterial blood, by the quantity Tm. Accordingly, for hematocrit level of 40% and arterial blood oxygen saturation of 100%, the maximum effect of metabolism on brain temperature cannot exceed 0.9°C even if all delivered oxygen is consumed [oxygen extraction fraction (OEF) = 1]. In practice, OEF rarely exceeds 40%, which results in a 0.3–0.4°C increase in brain temperature compared with that of incoming blood (32). Experimental measurements of arter