BEDSIDE ULTRASONOGRAPHIC OPTIC NERVE SHEATH DIAMETER TO ASSESS INCREASED INTRA-CRANIAL PRESSURE: AN OBSERVATIONAL STUDY

Point of care optic nerve sheath ultrasound (ONSUS) is a bedside practice that can be used to evaluate for increased intracranial pressure. Systematic review and meta-analysis have shown that ONSD of more than 5.00 to 5.70 mm has a concurrent ICP value above 20 mm Hg.

The use of point-of-care ultrasound (POCUS) has expanded considerably over the past two decades allowing for enhanced and swift evaluations, rapid triage, improved diagnostic capabilities in austere situations, and real-time assessment of focused clinical questions in critically ill patients in the intensive care unit (ICU). Emergency medicine physicians have led the way in establishing and educating bedside use of ultrasound. In 2001, the American College of Emergency Physicians (ACEP) published the first Emergency Ultrasound Guidelines to clarify the primary indications, the scope of practice, training, and continuing education regarding the use of emergency ultrasound.

The main complication associated with cerebral acute brain injury (ABI) is elevated intracranial pressure (ICP), as it is associated with high morbidity and mortality. Intracranial hypertension is defined as a sustained ICP greater than 20 mm Hg.  In these patients, multimodal neurological monitoring has positioned itself as a fundamental tool, both in emergency departments and in intensive care units (ICU), with a tendency, in recent years, to be minimally invasive. So much so that, in the care of these patients, the detection of increased ICP remains crucial, since it is associated with a worse prognosis. Thus, its early and timely diagnosis together with the implementation of adequate therapeutic measures are essential to ensure better patient outcomes. Ultrasound evaluation of the optic nerve sheath diameter (ONSD) has emerged in recent years as a useful non-invasive tool for estimating ICP or detecting intracranial hypertension. It is a safe technique that can be conducted at the bedside, in real time, and is reproducible, relatively low cost, and does not carry the risks of radiation.

OBJECTIVES:

1)     To correlate increase in optic nerve sheath diameter to raised intra-cranial pressure.

2)     To assess ONSD as predictor of unfavaourable outcome