Assessment of intra-interobserver reliability of the sonographic optic nerve sheath diameter measurement

Diagnosis and measuring the level of increase in intracranial pressure (ICP) is critical, especially for the management of trauma patients in the emergency department and intensive care unit. However, measurements are operator-dependent as in all of the sonographic diagnoses. The aim of this study is to assess the operator variations in the measurement of optic nerve sheath diameter (ONSD). There were four emergency medicine specialists involved in the study. Each had at least 1 year of experience of ultrasound scans and performed at least 25 prior ocular scans examining the ONSD. Two measurements were made 1 week apart from both axial and longitudinal planes. Sixty healthy adults were involved in the study and every investigator obtained four measurements from each. Intra-interobserver reliabilities were tested. The investigators performed 60 ocular ultrasounds on individual healthy adults and obtained two measurements in axial and longitudinal planes 1 week apart. Therefore, 960 measurements were analyzed. The levels of compatibilities for most of the measurements were found at acceptable levels statistically. However, it is not possible to say that there was a perfect compatibility among the sonographers according to the previously conducted reliability studies of ultrasound measurements. According to our results, it is hard to say that sonographic measurement of the ONSD is a highly reliable method both in longitudinal and transverse planes.