Low intracranial pressure variability is associated with delayed cerebral ischemia and unfavorable outcome in aneurysmal subarachnoid hemorrhage

Teodor Svedung Wettervik,Anders Hånell,Per Enblad,Elisabeth Ronne-Engström,Timothy Howells,Anders Lewén

doi:10.1007/s10877-021-00688-y

Teodor Svedung Wettervik, Anders Hånell + Show 4 more

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https://doi.org/10.1007/s10877-021-00688-y

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Abstract

PurposeHigh intracranial pressure variability (ICPV) is associated with favorable outcome in traumatic brain injury, by mechanisms likely involving better cerebral blood flow regulation. However, less is known about ICPV in aneurysmal subarachnoid hemorrhage (aSAH). In this study, we investigated the explanatory variables for ICPV in aSAH and its association with delayed cerebral ischemia (DCI) and clinical outcome.MethodsIn this retrospective study, 242 aSAH patients, treated at the neurointensive care, Uppsala, Sweden, 2008–2018, with ICP monitoring the first ten days post-ictus were included. ICPV was evaluated on three time scales: (1) ICPV-1 m—ICP slow wave amplitude of wavelengths between 55 and 15 s, (2) ICPV-30 m—the deviation from the mean ICP averaged over 30 min, and (3) ICPV-4 h—the deviation from the mean ICP averaged over 4 h. The ICPV measures were analyzed in the early phase (day 1–3), in the early vasospasm phase (day 4–6.5), and the late vasospasm phase (day 6.5–10).ResultsHigh ICPV was associated with younger age, reduced intracranial pressure/volume reserve (high RAP), and high blood pressure variability in multiple linear regression analyses for all ICPV measures. DCI was associated with reduced ICPV in both vasospasm phases. High ICPV-1 m in the post-ictal early phase and the early vasospasm phase predicted favorable outcome in multiple logistic regressions, whereas ICPV-30 m and ICPV-4 h in the late vasospasm phase had a similar association.ConclusionsHigher ICPV may reflect more optimal cerebral vessel activity, as reduced values are associated with an increased risk of DCI and unfavorable outcome after aSAH.

Highlights

Aneurysmal subarachnoid hemorrhage is a severe disease that is associated with high mortality and neurological sequele [1]
We chose to focus on the late vasospasm phase for these analyses, since we found in the analysis of outcome that all three intracranial pressure (ICP) variability (ICPV) measures were associated with outcome in that phase and because this phase represents a period with high incidence of delayed cerebral ischemia (DCI), which makes it most interesting from a clinical point of view
We only considered treatment of triple-H or thiopental, respectively, as “yes” if the patient received it within the late vasospasm phase, since e.g. thiopental would not be expected to have any effect on ICPV if it had ready been eliminated to a concentration below that value

Summary

Introduction

Aneurysmal subarachnoid hemorrhage (aSAH) is a severe disease that is associated with high mortality and neurological sequele [1]. We found in TBI that higher ICP variability (ICPV) was associated with unfavorable variables such as higher ICP and a reduced intracranial compliance, it independently predicted favorable clinical outcome [11]. One possible explanation could be that higher ICPV reflects a healthier and more adaptive cerebrovascular system that better regulates cerebral blood flow (CBF) according to metabolic demand, resulting in reduced secondary. A low ICPV could be associated with reduced variation of cerebral blood volume (CBV) due to increased cerebrovascular tone from vasospasm. In one study on 90 aSAH patients, Kirkness et al evaluated mean values of ICPV and found that higher short-term ICPV predicted favorable outcome, but ICPV was not associated with cerebral vasospasm (according to transcranial Doppler) [17].

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