Evaluation of Rectal and Skin Temperature Variations of Anesthetised Dogs Undergoing Magnetic Resonance Imaging Diagnosis

Abstract

General anesthesia produces different degrees of central nervous depression and changes in the peripheral circulation, therefore affecting the patient’s thermoregulatory mechanism. Moreover, the lack of proper, specially designed equipment for magnetic resonance imaging (MRI) environment monitoring can represent a challenge for the anesthetist. We examined the temperature variations correlated with different anesthetic protocols in dogs that underwent general anesthesia in order to evaluate changes in rectal and distal extremities temperature, before and after anesthesia. This study was conducted at the Faculty of Veterinary Medicine in Bucharest, on 21 dogs that were divided in 3 groups depending on the anesthetic protocol used. First group (B) received butorphanol (0.2 mg/kg, intravenously IV), second group (BK) had butorphanol (0.2 mg/kg) and a low dose of ketamine (2 mg/kg) IV, and group 3 (BM) was premedicated with butorphanol (0.2 mg/kg) and midazolam (0.2 mg/kg) IV. All patients were induced with propofol i.v. (3.24±0.68), intubated and maintained with isoflurane and oxygen. We determined rectal temperature before and right after the end of anesthesia with a digital thermometer and distal extremities temperature with the use of a thermal imaging camera attached to a smartphone. There was no significant difference between the rectal temperature before and after anesthesia within the 3 groups. Patients in group BK had a significant change in skin temperature at the end of anesthesia in all limbs (from 310C to 29.8 0C, p=0.008 and from 31 0C to 29.70C, p=0.009), respectively). Temperature variations were presented before and at the end of anesthesia, for all the groups especially at skin level. This study revealed that mobile thermal imaging represents a non-invasive technique that is helpful in assessing real time temperature changes in patients undergoing general anesthesia.