Impaired cerebral autoregulation detected in early prevasospasm period is associated with unfavorable outcome after spontaneous subarachnoid hemorrhage: an observational prospective pilot study

Abstract

Background: Subarachnoid hemorrhage (SAH) patients with cerebral autoregulation (CA) impairment at an early post-SAH period are at high risk of unfavorable outcomes due to delayed cerebral ischemia (DCI) or other complications. Limited evidence exists for an association between early-stage CA impairments and SAH patient outcomes. The objective of this prospective study was to explore associations between CA impairments detected in early post-SAH snapshot examinations and patient outcomes.

Methods: The pilot observational study included 29 SAH patients whose CA status was estimated 2-3 days after spontaneous aneurysm rupture and a control group of 15 healthy volunteers for comparison. Inflatable leg recovery boots (reboots.com, Germany) were used for the safe controlled generation of arterial blood pressure (ABP) changes necessary for reliable CA examination. At least 5 inflation‒deflation cycles of leg recovery boots with a 2-3 min period were used during examinations. CA status was assessed according to the delay time (∆T_CBFV) measured between ABP(t) and cerebral blood flow velocity (CBFV(t)) signals during artificially induced ABP changes at boot deflation cycle. CBFV was measured in middle cerebral artery by using transcranial Doppler device.

Results: Statistically significant differences in ∆T_CBFV were found between SAH patients with unfavorable outcomes (∆T_CBFV = 1.37 ± 1.23 s) and those with favorable outcomes (∆T_CBFV = 2.86 ± 0.99 s) (p < 0.001). Early assessment of baroreflex sensitivity (BRS) during the deflation cycle showed statistically significant differences between the DCI and non-DCI patient groups (p = 0.039).

Conclusions: A relatively small delay of ∆T_CBFV <1.6 s between CBFV(t) and ABP(t) waves could be an early warning sign associated with unfavorable outcomes in SAH patients. The BRS during boot deflation can be used as a biomarker for the prediction of DCI.

Trial registration: ClinicalTrials.gov Identifier: NCT06028906. Registered 31 August 2023 - Retrospectively registered, https://www.

Clinicaltrials: gov/study/NCT06028906 .

Keywords: Baroreflex; Cerebral blood flow autoregulation; Delayed cerebral ischemia; Snapshot examination; Subarachnoid hemorrhage; Transcranial Doppler.

Fig. 1

Generation of artificial ABP changes for assessment of CA in healthy volunteer by using air compression boots

Fig. 2

Example of ABP changes generated during deflation moments and registered responses in cerebral blood flow velocity (CBFV) and heart rate (HR). Dashed lines show the peak of ABP drop (nadir) moments during deflation cycle, which were used to synchronize responses from each boot deflation cycle in order to calculate average response of CBFV

Fig. 3

Examples of averaged transient responses of human cerebral blood flow autoregulation function in healthy volunteers (a) and SAH patients with favorable outcomes (b), severe disability with DCI (c) and fatal outcomes without DCI (d). The time moments at t = 0 show the peak of ABP drop (nadir) moments during the boot deflation cycle. The patients with later development of DCI are characterized by synchronous ABP and HR variation during the boot deflation phase (c)

Fig. 4

Distribution of delay time between ABP(t) and CBFV(t) during deflation cycle (∆TCBFV) identified for SAH patients with fatal outcome (GOS 1), survivors (GOS > = 2) and healthy control group (a), and for SAH patients with unfavorable (GOS < = 3) and favorable (GOS > 3) outcomes and the healthy control group (b). Dashed lines show the threshold values that statistically significant separate fatal and survivors (a) and unfavorable and favorable patients groups (b)

Fig. 5

Distribution of BRS-related factor (∆T_IBI/∆ABP_recovery) calculated at the recovery phase after the ABP drop among SAH patients with DCI and non-DCI and the healthy control group. Dashed line shows the threshold value that statistically significant separate fatal and DCI and non-DCI patients groups