Invasive and Noninvasive Intracranial Pressure Pulse Waveform in Neurocritical Care Patients with Different Cranium Integrity

Background Pulse shape index (PSI) is a novel artificial intelligence–supported parameter that evaluates the pressure–volume compensatory reserve of the craniospinal system through intracranial pressure (ICP) pulse waveform classification. This study assessed the agreement between PSI derived from invasive ICP monitoring (PSI ICP ) and noninvasive brain4care (B4C) sensor signal (PSI B4C ) and investigated the influence of cranial integrity, age, and internal jugular vein (IJV) compression on PSI values. Methods Simultaneous ICP and B4C monitoring was performed in 47 adult patients ( age: 43 (30) years) before and during IJV compression. Patients were grouped by cranial integrity: intact skull bone ( n = 17), large skull fractures or craniotomies ( n = 17), and craniectomies ( n = 13). Pulse waveforms were automatically classified into four classes (from 1 = normal to 4 = pathological) by a neural network, and PSI was calculated as the weighted average of class numbers. Values are presented as median (interquartile range). Results Bland–Altman analysis demonstrated good agreement between PSI ICP and PSI B4C , with approximately 6% outliers. PSI was significantly higher in patients who underwent craniectomy compared with those with intact skulls (PSI ICP : 3.5 (0.8) vs. 2.0 (1.2) arbitrary units, p < 0.002; PSI B4C : 3.0 (0.4) vs. 2.0 (0.6) arbitrary units, p < 0.005) or those with craniotomies or large fractures (PSI ICP : 3.5 (0.8) vs. 2.0 (2.1) arbitrary units, p < 0.05; PSI B4C : 3.0 (0.4) vs. 2.0 (2.2) arbitrary units, p < 0.05). IJV compression did not affect PSI. Both PSI ICP (r s = 0.35, p < 0.02) and PSI B4C (r s = 0.37, p = 0.01) correlated with age. Conclusions This study supports the B4C signal’s capability to noninvasively reflect ICP waveform morphology via PSI, offering a promising monitoring alternative. PSI appears to be influenced by age and craniectomy but not by a slight, sudden ICP change induced by IJV compression.