Therapeutic hypothermia: quantification of the transition of core body temperature using the flexible mixture bent-cable model for longitudinal data

TL;DR

This paper introduces a Bayesian bent-cable regression model to analyze core body temperature transitions during hypothermia therapy, capturing both gradual and abrupt changes to identify critical time points for physiological breakdown.

Contribution

The study develops a novel Bayesian framework for bent-cable regression that models both gradual and abrupt temperature transitions in longitudinal hypothermia data.

Findings

39% of rats show gradual temperature transition

Critical time point is similar across transition types

Temperature increases then decreases significantly during hypothermia

Abstract

By reducing core body temperature, T_c, induced hypothermia is a therapeutic tool to prevent brain damage resulting from physical trauma. However, all physiological systems begin to slow down due to hypothermia that in turn can result in increased risk of mortality. Therefore, quantification of the transition of T_c to early hypothermia is of great clinical interest. Conceptually, T_c may exhibit an either gradual or abrupt transition. Bent-cable regression is an appealing statistical tool to model such data due to the model's flexibility and greatly interpretable regression coefficients. It handles more flexibly models that traditionally have been handled by low-order polynomial models (for gradual transition) or piecewise linear changepoint models (for abrupt change). We consider a rat model for humans to quantify the temporal trend of T_c to primarily address the question: What is the critical time point associated with a breakdown in the compensatory mechanisms following the start of hypothermia therapy? To this end, we develop a Bayesian modelling framework for bent-cable regression of longitudinal data to simultaneously account for gradual and abrupt transitions. Our analysis reveals that: (a) about 39% of rats exhibit a gradual transition in T_c; (b) the critical time point is approximately the same regardless of transition type; (c) both transition types show a significant increase of T_c followed by a significant decrease.