Impairment of Dynamic Pressure Autoregulation Precedes Clinical Deterioration after Aneurysmal Subarachnoid Hemorrhage

Fontana, Johann; Wenz, Holger; Schmieder, Kirsten; Barth, Martin

doi:10.1111/jon.12295

Cited by 11 publications

(14 citation statements)

References 29 publications

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“…Direct cerebral blood flow measurements require lengthy time scales and consequently, provide only a snapshot of autoregulation in steady state settings (114). Fantini et al provide a comprehensive review of the techniques utilized to quantitatively measure cerebral blood flow, which notably includes 133 Xe clearance, positron emission tomography, thermal diffusion, magnetic resonance imaging arterial spin labeling, and perfusion computed tomography (114). Utilizing these approaches for autoregulation studies generally requires pharmacological interventions to persistently alter blood pressure, although positional changes can also be used.…”

Section: Static Autoregulation Measurementmentioning

confidence: 99%

Cerebral Autoregulation in Subarachnoid Hemorrhage

2021

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Subarachnoid hemorrhage (SAH) is a devastating stroke subtype with a high rate of mortality and morbidity. The poor clinical outcome can be attributed to the biphasic course of the disease: even if the patient survives the initial bleeding emergency, delayed cerebral ischemia (DCI) frequently follows within 2 weeks time and levies additional serious brain injury. Current therapeutic interventions do not specifically target the microvascular dysfunction underlying the ischemic event and as a consequence, provide only modest improvement in clinical outcome. SAH perturbs an extensive number of microvascular processes, including the “automated” control of cerebral perfusion, termed “cerebral autoregulation.” Recent evidence suggests that disrupted cerebral autoregulation is an important aspect of SAH-induced brain injury. This review presents the key clinical aspects of cerebral autoregulation and its disruption in SAH: it provides a mechanistic overview of cerebral autoregulation, describes current clinical methods for measuring autoregulation in SAH patients and reviews current and emerging therapeutic options for SAH patients. Recent advancements should fuel optimism that microvascular dysfunction and cerebral autoregulation can be rectified in SAH patients.

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Section: Static Autoregulation Measurementmentioning

confidence: 99%

Cerebral Autoregulation in Subarachnoid Hemorrhage

2021

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“…In aneurysmal subarachnoid hemorrhage (SAH), CPA may be disturbed to different extents [ 15 ]. Disturbed CPA in SAH is associated with delayed cerebral ischemia (DCI), vasospasm and unfavorable outcome [ 5 , 7 , 16 ]. CPA can be assessed with a number of methodologies, one of which is the pressure reactivity index (PRx) [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Increased risk of critical CBF levels in SAH patients with actual CPP below calculated optimal CPP

et al. 2017

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BackgroundCerebral pressure autoregulation can be quantified with the pressure reactivity index (PRx), based on the correlation between blood pressure and intracranial pressure. Using PRx optimal cerebral perfusion pressure (CPPopt) can be calculated, i.e., the level of CPP where autoregulation functions best. The relation between cerebral blood flow (CBF) and CPPopt has not been examined. The objective was to assess to which extent CPPopt can be calculated in SAH patients and to investigate CPPopt in relation to CBF.MethodsRetrospective study of prospectively collected data. CBF was measured bedside with Xenon-enhanced CT (Xe-CT). The difference between actual CPP and CPPopt was calculated (CPP∆). Correlations between CPP∆ and CBF parameters were calculated with Spearman’s rank order correlation coefficient (rho). Separate calculations were done using all patients (day 0–14 after onset) as well as in two subgroups (day 0–3 and day 4–14).ResultsEighty-two patients with 145 Xe-CT scans were studied. Automated calculation of CPPopt was possible in adjunct to 60% of the Xe-CT scans. Actual CPP < CPPopt was associated with higher numbers of low-flow regions (CBF <10 ml/100 g/min) in both the early phase (day 0–3, n = 39, Spearman’s rho = −0.38, p = 0.02) and late acute phase of the disease (day 4–14, n = 35, Spearman’s rho = −0.39, p = 0.02). CPP level per se was not associated with CBF.ConclusionsCalculation of CPPopt is possible in a majority of patients with severe SAH. Actual CPP below CPPopt is associated with low CBF.

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“…Unfortunately, comparison with previous studies investigating CBF control in SAH is difficult. The majority of studies utilised linear correlation at frequencies < 0.05 Hz as a metric of CBF control [6][7][8][9]14 , and did not report results on the coupling between ABP at CBF around 0.1 Hz. In the single study that performed a frequency domain analysis 11 , the reported frequency band (0.03 Hz -0.15 Hz) encompasses much of the very low frequency domain (0.02-0.07 Hz).…”

Section: Low Frequency Pulsatile Flowmentioning

confidence: 99%

“…These findings are in line with other dCA studies in SAH which, although predominantly performed using time domain linear correlation, show a stronger linear relationship between ABP-CBFV at frequencies below 0.05 Hz. [6][7][8][9]14 Using linear correlation, Budohoski et al demonstrated that disturbed autoregulation in the 5 days after SAH was associated with DCI at 21 days. 6 We failed to demonstrate a difference in baseline phase synchronisation below 0.07 Hz between patients that developed DCI and those that did not.…”

Section: Dynamic Cerebral Autoregulationmentioning

confidence: 99%

“…The term refers to a multifactorial global cerebral injury that develops in the first 72 hours following SAH. 5 A growing body of clinical studies suggest that disruption to cerebral blood flow (CBF) control may play a critical role in the pathophysiology of EBI, and that its severity directly correlates with the development of DCI [6][7][8][9][10][11][12][13][14] . As a consequence, the role of the nitric oxide (NO) signalling pathway EBI has garnered considerable interest.…”

Section: Introductionmentioning

confidence: 99%

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Phase dynamics of cerebral blood flow in subarachnoid haemorrhage in response to sodium nitrite infusion

Ezra

Garry

Mitsis

et al. 2020

Preprint

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word count: 197 (200) Number of figures and tables: 7 (7) 5 AbstractAneurysmal subarachnoid haemorrhage (SAH) is a devastating subset of stroke. One of the major determinates of morbidity is the development of delayed cerebral ischemia (DCI).Disruption of the nitric oxide (NO) pathway and consequently the control of cerebral blood flow (CBF), known as cerebral autoregulation, is believed to play a role in its pathophysiology.Through the pharmacological manipulation of in vivo NO levels using an exogenous NO donor we sought to explore this relationship.Phase synchronisation index (PSI), an expression of the interdependence between CBF and arterial blood pressure (ABP) and thus cerebral autoregulation, was calculated before and during sodium nitrite administration in 10 high-grade SAH patients acutely post-rupture. In patients that did not develop DCI, there was a significant increase in PSI around 0.1 Hz during the administration of sodium nitrite (33%; p-value 0.006). In patients that developed DCI, PSI did not change significantly.Synchronisation between ABP and CBF at 0.1 Hz has been proposed as a mechanism by which organ perfusion is maintained, during periods of physiological stress. These findings suggest that functional NO depletion plays a role in impaired cerebral autoregulation during EBI, but the development of DCI may have a distinct pathophysiological aetiology.

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Impairment of Dynamic Pressure Autoregulation Precedes Clinical Deterioration after Aneurysmal Subarachnoid Hemorrhage

Abstract: The results demonstrate the capability of the ARI to serve as a reliable early warning system after SAH. Further trials with larger study populations are needed to validate these promising preliminary data.

Cited by 11 publications

References 29 publications

Cerebral Autoregulation in Subarachnoid Hemorrhage

Cerebral Autoregulation in Subarachnoid Hemorrhage

Increased risk of critical CBF levels in SAH patients with actual CPP below calculated optimal CPP

Phase dynamics of cerebral blood flow in subarachnoid haemorrhage in response to sodium nitrite infusion

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