Shrestha Gentle Sunder, Upadhyay Binayak, Shahi Aanchal, Jaya Ram K C, Joshi Pankaj, Poudyal Bishesh Sharma
Department of Anaesthesiology, Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal.
Department of Critical Care, Alka Hospital Private Limited, Jawalakhel, Lalitpur, Nepal.
Indian J Crit Care Med. 2018 Sep;22(9):646-649. doi: 10.4103/ijccm.IJCCM_104_18.
Transbulbar sonography for measuring optic nerve sheath diameter (ONSD) is noninvasive bedside technique for detection of raised intracranial pressure. This study aims to evaluate the number of sonographic evaluations required for a novice operator to learn proper measurement of ONSD after a formal training and supervised scanning session.
Three novice operators and one expert operator measured ONSD of 27 healthy volunteers using linear array transducer HFL38x (frequency range of 6-13 MHz) (MicroMaxx®; SonoSite, USA). In each eye, ONSD was measured three times by each observer and mean value was determined. Correlation coefficient was calculated between the novice and the experienced operator and in between the novice operators. Number of scans, after which the significant correlation developed between novice and the experienced operator and between the novice operators, was analyzed.
Cronbach's alpha was tested to evaluate the reliability of the values obtained from intra- and interobservations. For all 27 cases, the value of Cronbach's alpha was high: 0.80-0.99 for the right eye and 0.69-0.97 for the left eye. The mean interobserver variations were plotted on a graph which fluctuated largely in the first 17 cases but oscillated around 0.5-0.30 in the last 10 cases.
Learning curve for novice operators to measure ONSD is steep and they can be taught to measure ONSD in healthy volunteers by sonography in supervised clinical session with an acceptable clinical precision and accuracy comparable to an experienced operator.
经眼球超声检查测量视神经鞘直径（ONSD）是一种用于检测颅内压升高的无创床边技术。本研究旨在评估新手操作员在经过正式培训和监督扫描后，学习正确测量ONSD所需的超声评估次数。
三名新手操作员和一名专家操作员使用线性阵列换能器HFL38x（频率范围为6-13MHz）（MicroMaxx®；美国SonoSite公司）测量27名健康志愿者的ONSD。每位观察者在每只眼中测量ONSD三次，并确定平均值。计算新手与经验丰富的操作员之间以及新手操作员之间的相关系数。分析新手与经验丰富的操作员之间以及新手操作员之间出现显著相关性之前的扫描次数。
对Cronbach's alpha进行检验，以评估从内部和观察者间观察获得的值的可靠性。对于所有27例病例，Cronbach's alpha值都很高：右眼为0.80-0.99，左眼为0.69-0.97。将观察者间的平均差异绘制在图表上，在前17例中波动很大，但在后10例中在0.5-0.30左右波动。
新手操作员测量ONSD的学习曲线很陡，在有监督的临床检查中，可以教会他们通过超声检查测量健康志愿者的ONSD，其临床精度和准确性与经验丰富的操作员相当，是可以接受的。
