Single pulse pressure wave analysis by fast Fourier transformation

Area of Science:

• Neurosurgery
• Biomedical Engineering
• Neurology

Background:

• Normal pressure hydrocephalus (NPH) is a condition characterized by enlarged ventricles and abnormal cerebrospinal fluid (CSF) dynamics.
• Intracranial pressure (ICP) monitoring is crucial for managing neurological conditions, but traditional methods can be invasive.
• Pulse pressure wave (PPW) analysis offers a potential non-invasive method to assess intracranial compliance.

Purpose of the Study:

• To investigate the relationship between pulse pressure wave (PPW) components and intracranial pressure (ICP) parameters in patients with normal pressure hydrocephalus (NPH).
• To explore the potential of Fourier transform (FFT) analysis of PPW to predict changes in cerebral compliance.
• To evaluate the feasibility of using pressure volume index (PVI) in this patient cohort.

Main Methods:

• Analysis of pressure recordings from 16 NPH patients undergoing controlled intracranial hypertension.
• Utilized a computer system for automatic computation of mean intracranial pressure (MICP), pulse amplitude (PA), rise time coefficients (RT), and fast Fourier transformation (FFT) of PPW.
• Correlated FFT harmonies with MICP, PA, and RT.

Main Results:

• A significant correlation was found between the first FFT harmony and both MICP and PA.
• The fifth FFT harmony showed a good correlation with RT.
• Increasing RT correlated with a higher presence of high-frequency components in the PPW, suggesting a link to altered cerebral compliance.
• No correlation was observed between any FFT harmonies and the pressure volume index (PVI).

Conclusions:

• High-frequency components derived from FFT analysis of PPW may serve as predictors of changing cerebral compliance.
• RT is a dynamic parameter reflecting changes in brain compliance.
• The pressure volume index (PVI) proved difficult to perform and evaluate in this study, limiting its utility.