Optic Nerve Sheath Diameter in retrobulbar ultrasound as a surrogate measure for intracranial pressure before and after non-invasive strategies.

Abstract

Background : Raised intracranial pressure is a complication that leads to adverse outcomes. In the critically ill, invasive measurement by an intraventricular catheter is the gold standard; its use in non-specialized centers is limited, besides neuroimaging by computed tomography or magnetic resonance imaging scans entail transfer of a critically ill patient out of the ICU. Dilatation of the optic nerve sheath has been shown to be a much earlier manifestation of ICP rise. The optic nerve sheath diameter (ONSD) is fairly easy to visualize by ultrasonography by insonation across the orbitMethods: 90 patients, divided into three groups. Group M received mannitol 20% 0.5gr kg -1 , Group H received NaCl 7.5% 1.5 ml kg -1 and Group P patients were positioned on reverse Trendelenburg position 30 degrees. ONSD was measured 3 mm behind the optic disc. The measurements T1 before and T2 after the strategies according to group 30min, T3 at 60min, and T4 at 90minResults: Similar trend between invasive monitoring and ONSD measurement was observed. Invasive measurement the intracranial pressure was 40.2 at T1, there was a sustained and significant decrease in the three groups at 30, 60 and 90 minutes. ONSD measured at baseline, average was 7.0mm in group M, 7.1 in group H and 6.7 in group P, and subsequently it was significantly reduced at 30, 60 (p=0.002) and 90 minutes (p=0.003).Conclusion: ONSD in retrobulbar ultrasound is a reliable method to detect intracranial pressure variations before and after non-invasive strategies to reduce it acutely Keywords: intracranial hypertension, intracranial pressure, optic nerve sheath diameter, osmotherapy, Reverse Trendelenburg position. Trial registration: Clinical Trials; NCT03634176 ; registered August 16, 2018; https://clinicaltrials.gov/ct2/show/NCT03634176 .