A prospective observational study to evaluate the magnitude of temperature changes in children undergoing elective MRI under general anesthesia

Abstract

Context: Induction of general anesthesia and mandatory low-ambient temperature in the magnetic resonance imaging (MRI) suite renders the pediatric patient prone to fall in core temperature. Previously done studies have shown mixed results with core temperature showing both rise and fall.

Aims: The aim of this study is to evaluate which effect, hypothermia or hyperthermia, predominates in children anesthetized for MRI. Is the change in temperature the same across age groups and for different MRI scanners?.

Settings and design: Prospective, observational study in a tertiary care teaching hospital.

Subjects and methods: Two hundred and fifty children of age between 1 month and 16 years scheduled for MRI under propofol-based total intravenous anesthesia (TIVA) were recruited. A baseline core temperature (pre-scan) was recorded with the pediatric nasopharyngeal temperature probe after induction of anesthesia and also after the scan in the recovery room.

Results: The study shows that there is a significant fall in temperature of 1.022°C (CI = 0.964, 1.081) following MRI (P < 0.001) but the difference across different age groups and type of MRI scanner used are not significant. There is a significant correlation between duration in the MRI room and a decrease in temperature (P value = 0.003). Using simple linear regression analysis, it is found that if there is a 1-min increase in the duration of MRI, there is a decrease of 0.006°C in temperature.

Conclusion: Vigilant temperature preservation strategies have to be maintained during the time the anesthetized child is present in the MRI suite. MRI compatible active warming devices are warranted especially in high turnover centers.

Keywords: General anesthesia; hypothermia; magnetic resonance imaging; pediatrics; propofol TIVA.

Figure 1

Flowchart depicting the flow of study participants

Figure 2

Distribution of post-MRI temperatures. Nasopharyngeal temperatures of 250 children who underwent magnetic resonance imaging (MRI) under general anesthesia with propofol total intravenous anesthesia (TIVA) were measured immediately before and after the scan. The post-MRI temperatures show normal distribution with mean ± SD of 35.5 ± 0.5°C

Figure 3

Distribution of decrease in temperature. Nasopharyngeal temperatures of 250 children who underwent MRI under general anesthesia with Propofol TIVA were measured immediately before and after the scan. There was a decrease in temperatures in 97.6% of children while comparing the pre and post-scan temperatures. The distribution of decrease in temperatures follows a normal distribution with a mean ± SD of 1.04 ± 0.45°C

Figure 4

Relationship between temperature change and duration of MRI scan. Using simple linear regression analysis, 1-min increase in the duration of MRI is associated with a decrease of 0.006°C in temperature