Rodents are highly susceptible to peri-anesthetic hypothermia because of their small body size, large surface area to volume/mass ratio, and anesthetic-induced thermoregulatory depression. Early heat loss during induction is rapid and can be difficult to reverse, emphasizing the need for simple, reliable warming solutions during anesthetic induction. We designed and validated a low-cost, Arduino-controlled heated induction chamber for mice and evaluated its safety and efficacy in preventing early hypothermia. The device uses proportional integral derivative control to regulate a heated chamber floor. Bench testing quantified warm-up time, steady-state stability, and the temperature offset between the embedded thermistor and surface temperature. In a randomized, paired, repeated-measures design, 10 adult C57BL/6 mice underwent 2 experimental conditions, unheated induction compared with heated induction, followed by a standardized 10-minute anesthetic maintenance phase on a prewarmed, heated surgical monitoring platform. Core body temperature was measured with intraperitoneal radio frequency identification transponders, while rectal temperature and physiologic parameters (peripheral oxygen saturation, heart rate, respiratory rate) were recorded during maintenance. Recovery time was measured from isoflurane discontinuation until the first voluntary movement. The heated chamber reached thermal stability within 10 minutes; at steady state, a constant average surface temperature near 37.5 °C was reliably obtained. During induction, unheated controls showed a rapid decline in core temperature, while during the heated-chamber induction, they maintained normothermia. The control group did not regain baseline temperature until several minutes into the maintenance phase and stabilized at values ∼1 °C lower than those of the heated group. Both groups remained physiologically stable during anesthetic maintenance and recovered within comparable times. This cost-effective, Arduino-based chamber prevented early hypothermia without compromising physiologic stability and represents a practical refinement to improve rodent anesthetic procedures, animal welfare, and experimental reproducibility.
Corea et al. (Thu,) studied this question.