Lo C, Ormond G, McDougall R, Sheppard S J, Davidson A J
Department of Anaesthesia and Pain Management, Royal Children's Hospital, Melbourne, Victoria, Australia, and Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.
Anaesth Intensive Care. 2014 May;42(3):333-9. doi: 10.1177/0310057X1404200310.
Children undergoing magnetic resonance imaging (MRI) often require general anaesthesia (GA). Children under GA are at risk of decreases in body temperature. This risk may be greater during MRI due to MRI scanners requiring cool ambient temperatures. Conversely, radiofrequency radiation emitted by MRI scanners is absorbed by the patient as heat energy, creating a risk of an increase in body temperature. The aim of this study was to determine the proportion of anaesthetised children undergoing an MRI scan who develop hyperthermia or hypothermia, and the risk factors associated with temperature changes in these children. Pre-scan and post-scan tympanic temperatures were obtained from 193 children (aged three months to six years) undergoing an MRI procedure under GA. No active warming or cooling devices were used during the MRI scans. The median duration for anaesthesia was 42 minutes (35 to 57 minutes). Fifty-two percent of children were hypothermic after their scan, while no subjects were hyperthermic after their scan. The mean (± standard deviation) pre-scan temperature was 36.2°C±0.5°C, and the mean (± standard deviation) post-scan temperature was 35.9°C±0.6°C (an overall mean temperature decrease of 0.28°C was observed [95% confidence interval, -0.36°C to -0.19°C], P <0.001). In conclusion, core body temperature was found to decrease slightly during an MRI scan under GA. These results suggest that more focus is needed regarding the cooling effects of GA agents during MRI, as opposed to the heating effects of the MRI scanner.
接受磁共振成像（MRI）检查的儿童通常需要全身麻醉（GA）。处于全身麻醉状态的儿童有体温下降的风险。由于MRI扫描仪需要较低的环境温度，在MRI检查期间这种风险可能更大。相反，MRI扫描仪发出的射频辐射会作为热能被患者吸收，从而产生体温升高的风险。本研究的目的是确定接受MRI扫描的麻醉儿童中发生体温过高或过低的比例，以及与这些儿童体温变化相关的风险因素。从193名年龄在3个月至6岁之间、在全身麻醉下接受MRI检查的儿童身上获取扫描前和扫描后的鼓膜温度。在MRI扫描期间未使用主动加热或冷却装置。麻醉的中位持续时间为42分钟（35至57分钟）。52%的儿童在扫描后体温过低，而扫描后没有儿童体温过高。扫描前的平均（±标准差）温度为36.2°C±0.5°C，扫描后的平均（±标准差）温度为35.9°C±0.6°C（观察到总体平均温度下降0.28°C[95%置信区间，-0.36°C至-0.19°C]，P<0.001）。总之，发现在全身麻醉下进行MRI扫描期间，核心体温会略有下降。这些结果表明，与MRI扫描仪的加热效应相比，在MRI期间需要更多地关注全身麻醉药物的冷却效应。
