Can accurate ultrasonographic measurement of the optic nerve sheath diameter (a non-invasive measure of intracranial pressure) be taught to novice operators in a single training session?

Abstract

Novices can be quickly and easily taught to ultrasonographically measure optic nerve sheath diameter as a noninvasive surrogate for intracranial pressure. One intensive care unit senior medical officer, one junior intensive care unit registrar, one junior neurosurgery trainee and two registered nurses, all ultrasound novices, were given a four-hour workshop on how to measure the optic nerve sheath diameter with ultrasound. One week later they had the accuracy of their technique assessed by recording their measurements for both eyes of 12 healthy volunteers. Each eye was measured three times and the average and 'best' measurements were determined. The median, 5th and 95th centiles and standard deviation for intra-observer variation were calculated. Median, 5th and 95th centiles for inter-observer variation were obtained by comparing each of the novice operator's measurements with those of an experienced sonographer. Median intra-observer difference was ≤0.27 mm, standard deviation ≤0.46 mm and 95th centiles ≤1.19 mm for the five novice operators. Comparing the average of three measurements for each eye, median inter-observer difference for all operators was ≤0.42 mm and 95th centile values ≤1.15 mm. Using the single 'best' measurement for each eye, median inter-observer difference was ≤0.3 mm and 95th centiles ≤1.43 mm. Ultrasonographic optic nerve sheath diameter measurement can be taught to novice operators in a four-hour workshop with variation comparable to published results collated from 'experts'.