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

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.

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).

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.

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.