Core temperature dynamics and survival outcomes in rats exposed to Diazepam and ethanol: Differentiating hypothermia types for forensic application

Primary hypothermia arises from prolonged exposure to low environmental temperatures without underlying pathology, whereas secondary hypothermia is triggered by impaired thermoregulation due to factors such as disease, trauma, or substance use. This study aimed to investigate core temperature changes in rats exposed to specific water temperatures over time, with a focus on differentiating primary and secondary hypothermia induced by alcohol and benzodiazepines.Survival analysis was performed using Kaplan–Meier survival curves to compare the time to event (in minutes) among three experimental groups: Control, ethanol, and Diazepam. Core temperatures were recorded at five key points: baseline (normal temperature), post-ketamine anesthesia, during immersion, at hypothermia onset, and at the time of death. Survival times were also recorded and statistically analyzed. Median survival times were highest in the control group (35 minutes), followed by Diazepam (29 minutes) and ethanol (28 minutes). Pairwise comparisons using the log-rank test, adjusted for multiple comparisons via the Benjamini-Hochberg method, revealed a statistically significant difference between the control and diazepam groups (p = 0.018), with the control group demonstrating longer survival time. A significant interaction between Diazepam and time was observed (β = -0.23, 95% CI: -0.35 to -0.12, p < 0.001), indicating that the rate of temperature decline over time was significantly greater in the Diazepam group compared to the control group. Our results indicate that Diazepam accelerates the decrease in body temperature over time, which may contribute to its observed effect on survival, and that Diazepam administration is associated with a significant reduction in survival time compared with untreated controls. Ethanol did not significantly alter the measured thermoregulatory or survival outcomes in this pilot study. Any potential forensic relevance of ethanol-induced hypothermia remains speculative and requires further investigation in larger, adequately powered studies. Our results could have potential forensic implications in differentiating between primary and drug-induced as secondary hypothermia in medico-legal investigations.