Effect of brain magnetic resonance imaging on body core temperature in sedated infants and children

Abstract

Background: Children undergoing magnetic resonance imaging (MRI) under sedation are at risk of hypo- or hyperthermia. The effect of brain MRI at differing magnetic field strengths on body core temperature in sedated infants and young children has not been reported previously. Methods: Two groups of 38 infants and children (aged 1 month to 6 yr 5 months) underwent brain MRI for different indications related to cerebral diseases, at 1.5 Tesla (T) and 3 T MRI units, respectively. All patients received deep sedation comprising midazolam, nalbuphine, and propofol. Pre-scan and post-scan temperatures were measured at the right tympanic and at rectal sites. No active warming devices were used during the procedures. Results: Body core temperature measurements were similar between right tympanic and rectal site before and after the scans. After 1.5 T scans, the median (IQR) increase from pre-scan to post-scan tympanic temperature was 0.2°C (0.1-0.3), and the median (IQR) rectal temperature increase was 0.2°C (0-0.3) (P<0.001). After 3 T scans, the median (IQR) tympanic temperature increase was 0.5°C (0.4-0.7), and the median (IQR) rectal temperature increase was 0.5°C (0.3-0.6) (P<0.001). Conclusions: Body core temperature increased significantly during 1.5 and 3 T examinations; this increase was more profound during 3 T MRI. Patient heating occurred despite minimal efforts to reduce passive heat loss under sedation and without the use of warming devices. © The Board of Management and Trustees of the British Journal of Anaesthesia 2009. All rights reserved.