Efficacy of a Theoretical-practical Course for the Ultrasound Measurement of the Optic Nerve Diameter in Different Healthcare Operators

The study evaluates the effectiveness of a theoretical-practical training course for the ultrasound measurement of the optic nerve sheath diameter (ONSD), a non-invasive method used to estimate intracranial pressure (ICP). The optic nerve sheath is continuous with the subarachnoid space, which contains cerebrospinal fluid (CSF). An increase in ICP leads to an increase in CSF within the sheath, enlarging its diameter. ONSD measurement is typically performed by placing an ultrasound probe on the closed eyelid, allowing visualization of the optic nerve behind the eyeball.

While the correlation between ONSD enlargement and elevated ICP is well-documented, there is variability in diagnostic cut-off values due to differences in measurement techniques, equipment, and operator experience. Previous studies have shown that even novice operators can achieve clinically acceptable accuracy after brief training.

This study aims to assess whether medical students, nursing students, anesthesiology and intensive care residents, and intensive care nurses can learn to perform reliable ONSD measurements after a short training session.

Methodology:

The study will involve 40 participants unfamiliar with ONSD measurement: 10 medical students, 10 nursing students, 10 anesthesiology and intensive care residents, and 10 experienced intensive care nurses. The training will consist of a four-hour session, including a 30-minute lecture on ocular anatomy and ultrasound techniques, a real-time demonstration, and supervised hands-on practice with at least 20 measurements.

Participants must pass a multiple-choice test with at least 70% correct answers to proceed to practical verification, where they will measure ONSD in five healthy volunteers. These measurements will be compared with those taken by an expert tutor.

Measurement Technique:

The ultrasound technique follows expert consensus guidelines, using a linear probe with a minimum frequency of 7.5 MHz. Volunteers will be positioned semi-seated at a 45° head elevation with closed eyelids. The ONSD measurement will be taken 3 mm behind the retina on the right eye. Care will be taken to avoid pressure on the eyeball, and safety parameters will be monitored to ensure compliance with FDA guidelines.

The study aims to demonstrate that various healthcare professionals can achieve accurate and reliable ONSD measurements with proper training, enhancing the utility of this technique in diverse clinical settings.