How does blood regulate cerebral temperatures during hypothermia?

Abstract

Macro-modeling of cerebral blood flow can help determine the impact of thermal intervention during instances of head trauma to mitigate tissue damage. This work presents a bioheat model using a 3D fluid-porous domain coupled with intersecting 1D arterial and venous vessel trees. This combined vascular porous (VaPor) model resolves both cerebral blood flow and energy equations, including heat generated by metabolism, using vasculature extracted from MRI data and is extended using a tree generation algorithm. Counter-current flows are expected to increase thermal transfer within the brain and are enforced using either the vascular structure or flow reversal, represented by a flow reversal constant, CR. These methods exhibit larger average brain cooling (from 0.56 °C ± <0.01 °C to 0.58 °C ± <0.01 °C) compared with previous models (0.39 °C) when scalp temperature is reduced. An greater reduction in core brain temperature is observed (from 0.29 °C ± <0.01 °C to 0.45 °C ± <0.01 °C) compared to previous models (0.11 °C) due to the inclusion of counter-current cooling effects. The VaPor model also predicts that a hypothermic average temperature (<36 °C) can be reached in core regions of neonatal models using scalp cooling alone.

Diurnal brain temperature rhythms and mortality after brain injury: a prospective and retrospective cohort study

“…14,16,19 Indeed, higher temperatures in white matter-rich areas concur with predictions based on modelling perfusion, blood volume fraction, and heat generation in different brain tissues. 13,58-60…”

A porous circulation model of the human brain for in silico clinical trials in ischaemic stroke

“…When considering organ-scale perfusion models, it is becoming common practice to use onedimensional network models (for instance, [33,34,35,36,37]) for large arteries and multicompartment porous continuum models for the microcirculation [20,21,22,23,24]. The microcirculation model proposed here builds on the same principles.…”

“…The present study sets out to investigate the capabilities of porous continuum models in terms of estimating the perfusion changes in various brain territories as a result of a large intracranial vessel occlusion. To this end, we aim to improve the recently introduced organscale cerebral microcirculation models [20,21]. As shown in Figures 1(a) and (b), the descending arterioles (and ascending venules) originating from the pial vessels are oriented perpendicularly to the cortical surface.…”

“…As shown in Figures 1(a) and (b), the descending arterioles (and ascending venules) originating from the pial vessels are oriented perpendicularly to the cortical surface. The continuum representation of such networks requires anisotropic permeability fields [22,23,24] which have been disregarded in previous studies for simplicity [20,27,21]. It has been demonstrated that capturing such spatial variation in the properties of the continuum models plays an important role in the description of organ-scale physiological processes [28,29].…”

“…Scaling such models to the entire brain is computationally resource intensive, because it requires capturing the flow in the corresponding large networks of arterioles and venules. Nevertheless, with simplifications regarding the vessel networks, this approach has been successfully employed to investigate the temperature regulation of the human brain [22]. To overcome difficulties originating from the large networks, a two-compartment porous continuum model has been implemented for the human brain [23] where the arteriole and venule compartments include the majority of the small vessels.…”