Machata A-M, Willschke H, Kabon B, Prayer D, Marhofer P
Department of Anaesthesia, General Intensive Care and Pain Therapy, Medical University of Vienna, General Hospital, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
Br J Anaesth. 2009 Mar;102(3):385-9. doi: 10.1093/bja/aen388. Epub 2009 Jan 26.
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.
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.
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 degrees C (0.1-0.3), and the median (IQR) rectal temperature increase was 0.2 degrees C (0-0.3) (P<0.001). After 3 T scans, the median (IQR) tympanic temperature increase was 0.5 degrees C (0.4-0.7), and the median (IQR) rectal temperature increase was 0.5 degrees C (0.3-0.6) (P<0.001).
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.
接受镇静下磁共振成像（MRI）检查的儿童有体温过低或过高的风险。之前尚未报道过不同磁场强度的脑部MRI对镇静状态下婴幼儿体核温度的影响。
两组各38名婴幼儿（年龄1个月至6岁5个月）因与脑部疾病相关的不同适应症，分别在1.5特斯拉（T）和3T的MRI设备上接受脑部MRI检查。所有患者均接受了包括咪达唑仑、纳布啡和丙泊酚的深度镇静。在右鼓膜和直肠部位测量扫描前和扫描后的体温。检查过程中未使用主动加温设备。
扫描前后右鼓膜和直肠部位的体核温度测量结果相似。1.5T扫描后，扫描前至扫描后鼓膜温度的中位数（四分位间距）升高0.2℃（0.1 - 0.3），直肠温度升高的中位数（四分位间距）为0.2℃（0 - 0.3）（P<0.001）。3T扫描后，鼓膜温度升高的中位数（四分位间距）为0.5℃（0.4 - 0.7），直肠温度升高的中位数（四分位间距）为0.5℃（0.3 - 0.6）（P<0.001）。
在1.5T和3T检查期间体核温度显著升高；在3T MRI检查期间升高更为明显。尽管在镇静状态下尽量减少被动热损失且未使用加温设备，但患者仍出现了体温升高。
