Maintenance of Normothermic conditions during Dexmedetomidine administration 

Lavon et al. (2017) studied the effect of the drug Dexmedetomidine on metastasis in rodent models of breast, lung, and colon cancers. However, this drug is reported to cause potential hypothermia in rodent models. The animal can face cold stress for up to 8 hours after Dexmedetomidine administration. The researchers used heating pads (temperature adjusted at 40oC) for about 8 hours to resolve this problem. The hypothermic effects of the drug were easily overcome by the heating pad that induced normothermic conditions in the subject. They injected the subjects with the drug of choice, studied its effects, and concluded that dexmedetomidine increases metastasis and tumor cell retention in mammary and colon adenocarcinoma.

Prevention of Hypothermia in Stereotaxic Surgeries

Poole et al. (2019) anesthetized the animals for stereotaxic surgery to implant guide cannulas in rodent brains for administering drugs to the targeted regions and used a heating pad for thermoregulation. They took 28 to 30 days old postnatal male Sprague-Dawley rats weighing up to 120g housed in normal cages and shifted them into an induction chamber filled with 0.5% isoflurane. The isoflurane percentage was increased by 0.5% every 20 seconds until it reached 3.5%. The animals were allowed to inhale 3.5% isoflurane for approximately 3 minutes to get anesthetized. The animal was fixed into the stereotaxic frame. To prevent hypothermia, they placed the animal on a heating pad. A towel was placed as a barrier to avoid the animal’s direct contact with the heating pad. The lack of sensation was confirmed by ‘the pinch withdrawal reflex. They decreased the isoflurane concentration to 3% and then used a lubricated rectal thermometer for a temperature check. Researchers also ensured that the heating pad did not let the temperature drop below 37oC and increase above 37.5oC. They shaved the skin of the animal; the skull was incised and open for full exposure. And then removed pericranial tissues via cotton swabs, and the cannula was mounted on the bregma. In a nutshell, the researchers successfully implanted the cannulas with an overall mortality rate of 0%.  

Heating Pad’s Efficiency Assessment

Zhang et al. (2017) assessed the efficiency of the heating pad after Isoflurane administration in Sprague-Dawley rats. They aimed to ascertain an effective ‘warming period’ for maintaining normothermia during recovery. The researchers took eight male and nine female rats free from any bacterial or viral infection, habituated in polycarbonate cages in the form of pairs in a controlled housing environment (22% humidity, 23oC temperature, and 12:12h light and dark reactions). The animals were provided with food and water ad libitum. They pre-warmed the heating pad for 30 minutes and assessed its performance by measuring the temperature at different points on its surface. The rats were also acclimated to the recovery cages before testing, where they were handled for 15 minutes by the experimenter and presented with a reward. The animals were exposed to 5% isoflurane for 40 minutes until the loss of reflex and then shifted into the recovery cages. They were placed into two treatment groups: a) 30 minutes warming post-recovery and b) 60 minutes warming post-recovery. Experimenters measured the rectal and cage floor temperatures every 10 minutes, and the time spent in the recovery cage was 2 hours for each group.  This duration for the first group was divided into “30 min in the recovery cage and 90 min in the home cage”. For the second group, this time was divided into “60 min in the recovery cage and 60 min in the home cage”. They concluded that 60 minutes is an effective warming period for preventing rodents from hypothermia while recovering from general anesthesia.