Non-invasive Intracranial Pressure Assessment in Brain Injured Patients Using Ultrasound-Based Methods.

Background: Non-invasive measurement of intracranial pressure (ICP) can be invaluable in the management of critically ill patients. Invasive measurement of ICP remains the "gold standard" and should be performed when clinical indications are met, but it is invasive and brings some risks. In this project, we aim to validate the non-invasive ICP (nICP) assessment models based on arterious and venous transcranial Doppler ultrasonography (TCD) and optic nerve sheath diameter (ONSD).
Methods: We included brain injured patients requiring invasive ICP monitoring (intraparenchymal or intraventricular). We assessed the concordance between ICP measured non-invasively with arterious [flow velocity diastolic formula (ICP _FVd ) and pulsatility index (PI)], venous TCD (vPI) and ICP derived from ONSD (nICP _ONSD ) compared to invasive ICP measurement.
Results: Linear regression showed a positive relationship between nICP and ICP for all the methods, except PIv. ICP _ONSD showed the strongest correlation with invasive ICP (r = 0.61) compared to the other methods (ICP _FVd , r = 0.26, p value = 0.0015; PI, r = 0.19, p value = 0.02, vPI, r = 0.056, p value = 0.510). The ability to predict intracranial hypertension was highest for ICP _ONSD (AUC = 0.91; 95% CI, 0.85-0.97 at ICP > 20 mmHg), with a sensitivity and specificity of 85%, followed by ICP _FVd (AUC = 0.67; 95% CI, 0.54-0.79).
Conclusions: Our results demonstrate that among the non-invasive methods studied, ONSD showed the best accuracy in the detection of ICP.