NON-INVASIVE METHOD OF MONITORING INTRACRANIAL PRESSURE FOR THE EVALUATION OF HEPATIC ENCEPHALOPATHY.

Background: Liver diseases often occur with hepatic encephalopathy (HE), whose pathophysiology may involve increased intracranial pressure (ICP). Tools for monitoring ICP and its pulse morphology can be useful for assessing HE. The use of a non-invasive and sensitive procedure would be extremely useful in managing these cases.

Objective: To evaluate the feasibility and performance of a new, non-invasive method of monitoring ICP, as an alternative to invasive methods, and to correlate the clinical diagnosis of HE with the morphological findings of ICP.

Methods: This is a cross-sectional analytical study, conducted in a tertiary hospital and pioneer in the application of Brain4Care® BWS equipment. The ICP pulse morphology is parallel to the arterial one, where there are three frequent peaks: percussion peak (P1), due to plasma extravasated by the choroid plexus; tidal wave (P2), due to the degree of intracranial compliance to the reflection of P1, and dicrotic notch (P3), due to the closure of the aortic valve. Normality indicates P1>P2>P3. These peaks determine intracranial compliance through their relationship with cerebral blood volume, where P2/P1 ratio >1 suggests a pathological morphology, with a sustained increase in ICP and decreased compliance. Another way to evaluate this would be by a change in the time-to-peak (TTP). These data were compared between patients with and without clinical signs indicative of HE. The study was approved by the Institution's Research Ethics Committee (number 5.493.775).

Results: A total of 40 liver disease patients were evaluated, of which, at the time of collection, 20 did not have a clinical picture of HE (59.5±9.3 years; 70.0% male) and 20 had a clinical picture of HE (59.6±11.9 years; 65.0% male). The groups are demographically, clinically and laboratory similar; and statistically significant differences were identified in the morphological patterns of ICP between the groups evaluated, as well as trends in the parameters. The difference in the P2/P1 ratio was not significant (Mann Whitney: two-tailed P=0.2978); however, TTP proved to be a parameter with a statistically significant difference between the groups (Mann Whitney: two-tailed P=0.0282; median difference = 0.04). Analysis using the C statistic, using the ROC curve, suggested P2/P1=1.31 (AUROC: 0.5975) and TTP=0.22 (AUROC: 0.7013) as optimal cutoff points, where the presence of HE in liver disease patients would be associated with obtaining parameters below these thresholds.

Conclusion: The brain4care® BWS system proved to be feasible for use in liver disease patients with or without clinical signs of hepatic encephalopathy and was able to differentiate them. Pathophysiological explanations, however, still require better causality explanation and understanding of the intracerebral hydrodynamic picture in hepatic encephalopathy. Given the low sample power found, new studies need better clinical heterogeneity and longer-term follow-up for definitive conclusions.