A thermoregulation model for hypothermic treatment of neonates

Abstract

This paper presents a thermoregulation finite element model (FEM) to simulate hypothermia procedures for the treatment of encephalopathy hypoxic-ischemia (EHI) in neonates, a dangerous ischemic condition that can cause neurological damages and even death. Therapeutic hypothermia is the only recommended technique to reduce sequels caused by EHI in neonates; intervention with moderate cooling for neural rescue in newborns with hypoxic-ischemic brain injury clinics that cannot currently afford the available expensive equipment and techniques. In this work, we developed a FEM package using isoparametric linear three-dimensional elements which is applied to the solution of the continuum bioheat Pennes equation. Blood temperature changes were considered using a blood pool approach. The results of the FEM model were compared to those obtained through the implementation of a user-defined function (UDF) in the commercial finite volume software FLUENT and validated with experimental tests. Numerical analyses were performed using a three-dimensional mesh based on a complex geometry obtained from MRI scan medical images.

Numerical modelling of skin tumour tissue with temperature-dependent properties for dynamic thermography

“…The parameters are usually evaluated or estimated because of the lack of measurement data or because the values have large deviation [10,45,46]. It is known that central and local thermoregulation of the human body influence the metabolic heat generation and blood perfusion rate of the skin, muscle and other tissues, which play an important role in keeping the body core temperature as constant as possible [35,38,39]. In other words, thermoregulation tries to keep the human body warm in cold conditions and vice-versa.…”

“…Therefore, arterial blood flow reaches capillary bed with body core temperature. The change of T a is only reasonable when the thermoregulation of the whole body is modelled [35,36,[38][39][40]. In dynamic thermography the application of local cold stress does not affect the body core temperature or the central nervous system, as well as the fact that the patient is acclimatised during the examination and is in a resting position.…”

“…Thermoregulation of the blood perfusion rate in skin and other tissues has usually been modelled similarly to the metabolic heat generation, because the blood perfusion rate is in correlation with the metabolic rate by oxygen and nutrition demand. Fiala et al [35,47] used the proportional model of the metabolic rate change, while Laszczyk and Nowak [40] and Silva et al [38] used the same model as for the metabolic rate:…”

“…The denominator for the proposed model has been chosen as 10 [35,38,47,53], while the blood perfusion rate or metabolic heat generation rate change can be controlled by the value of the Q 10 coefficient.…”

“…However, none of them took into account local thermoregulation of the skin tissue [35][36][37], which mostly affects the blood perfusion rate. Fiala et al [35] and others [36,[38][39][40] modelled the local tissue temperature response using an exponential temperature distribution when simulating thermoregulation of the whole body. Therefore, to successfully model the bioheat transfer during the cooling-rewarming process of dynamic thermography, the local thermoregulation response of the tissue needs to be included in the model.…”