Danilo Cardim, PhD
Post-doctoral PhD Research Fellow
UT SouthWestern, United States
Disclosure information not submitted.
Nina Zobenica-Moore, MD
Neurosurgeon
Cleveland Clinic, United States
Disclosure information not submitted.
Joao Gomes, MD, FCCM
Physician Head, Neurointensive Care Unit
Cleveland Clinic Foundation
Cleveland, Ohio, United States
Disclosure information not submitted.
Title: Assessment of Cerebral Autoregulation Using Invasive and Non-Invasive Methods for ICP Monitoring
Introduction:
The pulse amplitude index (PAx - a descriptor of cerebrovascular reactivity) correlates the changes of pulse amplitude (AMP) of intracranial pressure (ICP) with changes in mean arterial pressure (MAP). While PAx can aid in prognostication after acute brain injuries as a tool for the assessment of cerebral autoregulation, invasive ICP is required for its calculation. Our aim was to evaluate the relationship between nPAx derived from a novel non-invasive device for ICP monitoring (nICP), with PAx derived from gold standard invasive methods.
Methods:
We retrospectively analyzed ICP (external ventricular drain) and nICP (mechanical extensometer - Brain4Care Corp.) waveform morphology data collected in adult brain-injured patients with invasive arterial blood pressure monitoring admitted to the Neurointensive Care Unit between 04/2021 and 07/2021. PAx/nPAx were calculated as the moving correlation coefficient of 10-s averages of AMP or nAMP and MAP. AMP/nAMP was determined by calculating the fundamental Fourier amplitude of the ICP/nICP signals over a 10-second window, updated every 10s. The time series from all signals were first treated to remove movement artifacts. We then evaluated the relationship between invasive PAx and non-invasive nPAx using Pearson’s correlation coefficient analysis. Data were analyzed using ICM+ and RStudio software platforms. Results are presented as mean±SD.
Results:
Ten patients were identified. Age was 47.5 ± 20.5 years with intracranial hemorrhage as the most common etiology (90%). All patients underwent mechanical ventilation and 60% were sedated with mean GCS 9.5 ± 3.1. PAx was 0.076±0.397 and nPAx was 0.062±0.348. The correlation between PAx and nPAx was strong, R=0.8 (95% CI 0.775 – 0.813, p< 0.0001).
Conclusion:
Non-invasive PAx can be detected reliably using a novel nICP monitoring device as an index of cerebrovascular reactivity/autoregulation. Further study of the applications of this clinical tool is warranted with the goal of intervening early to improve neurologic outcomes following acute brain injuries.