The effects of physiological thermoregulation on the efficacy of surface cooling for therapeutic hypothermia

Abstract

Therapeutic hypothermia is rapidly becoming an integral part of post-resuscitative care for post-cardiac arrest and neurotrauma patients. Despite the significant impact of thermoregulation on core temperature drop during rapid cooling, current mathematical models for thermoregulation have not been validated for hypothermic conditions. A geometrically accurate 3D model of an upper leg was developed by segmenting anatomical images from the visible human dataset into fat, muscle, bone, and blood vessels. Thermoregulation models from literature were implemented in the model. The numerical model results were compared with surface cooling experiments. There was a good agreement of simulation results with experimental data at 18 °C water immersion using existing models. However, at lower temperatures, the model parameter values needed to be significantly altered to account for cold-induced vasodilation in the superficial blood vessels and variation in muscle perfusion to match experimental observations. Additionally, results indicate that thermal mass has a dominant effect on cooling rate; therefore, uniform cooling over a large surface area will be more effective than targeted cooling of areas with superficial blood vessels. This study is the first to analyze the effects of thermoregulation in hypothermic conditions and identify unique thermoregulatory effects that differentiate hypothermic and normal conditions.

Thermoregulation: A journey from physiology to computational models and the intensive care unit

“…A computational thermal model has been used to evaluate patient‐warming situation during or following a medical operation with warming blankets with the aim to optimize the strategy (Vallez et al, 2016). Along similar lines, numerical models were utilized to reinforce experimental findings and provide additional knowledge to partial (M. Kalra, Bahrami, & Sparrey, 2015) or whole‐body surface cooling with mattresses (Silva, Wrobel, & Ribeiro, 2018), specialized temperature management systems (Vanlandingham, Kurz, & Wang, 2015), cooling with gel‐coated circulating water mattress (Bräuer et al, 2004), and air‐cooling (Romadhon, Rinata, Suprijanto, Bindar, & Soelami, 2017; Wakamatsu & Utsuki, 2009). Moreover, cooling with peripheral infusion of a coolant is a widely used and relatively safe systemic method in clinical practice and has already been studied by means of mathematical models (Esposito, Ebner, Ziemann, & Poli, 2014).…”