Cerebral Vascular Changes During Acute Intracranial Pressure Drop

Abstract

Objective: This study applied a new external ventricular catheter, which allows intracranial pressure (ICP) monitoring and cerebral spinal fluid (CSF) drainage simultaneously, to study cerebral vascular responses during acute CSF drainage.Methods: Six patients with 34 external ventricular drain (EVD) opening sessions were retrospectively analyzed. A published algorithm was used to extract morphological features of ICP recordings, and a template-matching algorithm was applied to calculate the likelihood of cerebral vasodilation index (VDI) and cerebral vasoconstriction index (VCI) based on the changes of ICP waveforms during CSF drainage. Power change (∆P) of ICP B-waves after EVD opening was also calculated. Cerebral autoregulation (CA) was assessed through phase difference between arterial blood pressure (ABP) and ICP using a previously published wavelet-based algorithm. Results:The result showed that acute CSF drainage reduced mean ICP (P = 0.016) increased VCI (P = 0.02) and reduced ICP B-wave power (P = 0.016) significantly. VCI reacted to ICP changes negatively when ICP was between 10 and 25 mmHg, and VCI remained unchanged when ICP was outside the 10-25 mmHg range. VCI negatively (r = − 0.44) and VDI positively (r = 0.82) correlated with ∆P of ICP B-waves, indicating that stronger vasoconstriction resulted in bigger power drop in ICP B-waves. Better CA prior to EVD opening triggered bigger drop in the power of ICP B-waves (r = − 0.612). Conclusions:This study demonstrates that acute CSF drainage reduces mean ICP, and results in vasoconstriction which can be detected through an index, VCI. Cerebral vessels actively respond to ICP changes or cerebral perfusion pressure (CPP) changes in a certain range; beyond which, the vessels are insensitive to the changes in ICP and CPP.

Autonomic control of cerebral blood flow: fundamental comparisons between peripheral and cerebrovascular circulations in humans

“…1992; Liu et al . 2019). The role of ICP in mediating sympathetic discharge is supported in subarachnoid haemorrhage patients with early brain injury leading to increases in ICP, and deceased CBF (Zhang et al .…”

Morphological changes of intracranial pressure quantifies vasodilatory effect of verapamil to treat cerebral vasospasm

“…Using MOCAIP technology, Asgari et al found reliable changes in ICP MOCAIP morphology in response to CO 2 inhalation, and with the morphologic template matching method were able to develop a standardized metric for assessment of VCI and VDI 11 16. These indices have been validated across several different patient cohorts and have shed insights into autoregulation and dynamic cerebral vascular changes which occur after cerebrospinal fluid drainage 11 13. Our study is the first to employ a similar template matching method for assessment of cerebral blood vessel dilation and constriction in response to EVT in patients with aneurysmal SAH and vasospasm.…”

“…In this study, we applied a validated algorithm, morphological clustering and analysis of ICP (MOCAIP) algorithm, to extract the morphological features of an ICP pulse, including pulse amplitude, time intervals among subpeaks (P1, P2, P3), curvature, slope, and decay time constants (shown in online supplementary doc 1). 10 12 13 16 17 In general, consecutive raw ICP pulses are segmented and then clustered into distinct groups based on their morphological distance; by doing this, the noise and artifacts can be excluded; then the largest cluster is identified and the averaged pulse of this largest cluster calculated and termed the dominant ICP pulse 18. A reference library of validated ICP pulses is used to recognize legitimate dominant pulses,12 and then the MOCAIP algorithm is used to perform a comprehensive search for all landmark points on an ICP pulse and use them as candidates for designating the three subpeaks.…”

“…In this way, we were able to smooth out the variations in VDI/VCI that are probably due to respiration. For more details of VCI/VDI calculation, please refer to our previous publications 10 12 13…”

“…Our premise is that distal cerebral arterial changes induce a consistent pattern of morphological changes in the intracranial pressure (ICP) pulse. To accomplish this we used a previously published algorithm that was based on a template of observed ICP pulse morphological changes associated with cerebral arterial vasodilation and vasoconstriction 10–13. Based on this algorithm, two parameters were developed to assess the likelihood of cerebral vasodilation and vasoconstriction from ICP signals recorded at the bedside and during EVT,10 12 respectively.…”