Cerebral Autoregulation: The Concept the Legend the Promise

Lazaridis, C.

doi:10.1007/s12028-020-01186-w

Cited by 4 publications

(6 citation statements)

References 14 publications

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“…Overall, cerebrovascular reactivity and the factors affecting it are regrettably still poorly known [ 24 ]. Previously, modification and optimization of CVR in brain injury and ICH by altering blood pressure and ventilation have been described in the literature [ 25 , 26 ].…”

Section: Discussionmentioning

confidence: 99%

“…The numerical results for CVR may not be applicable to patients monitored with other NIRS equipment as proprietary algorithms and optode designs to avoid extracranial contamination of the signal [ 44 ] generate different results [ 40 ]. The retrospective, observational design of this study means that no causal inferences may be made, and the results should be viewed to demonstrate associations and generate hypotheses for future investigation with TOx a potential clinical heuristic [ 24 ]. Comparisons of CVR in the COMACARE study with a cohort of healthy volunteers, while intended in the published protocol [ 19 ], were abandoned because of significant and unreconcilable incongruities in monitoring time and resolution, NIRS equipment and the degree and origin of MAP variations.…”

Section: Discussionmentioning

confidence: 99%

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Association of deranged cerebrovascular reactivity with brain injury following cardiac arrest: a post-hoc analysis of the COMACARE trial

et al. 2021

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Background Impaired cerebrovascular reactivity (CVR) is one feature of post cardiac arrest encephalopathy. We studied the incidence and features of CVR by near infrared spectroscopy (NIRS) and associations with outcome and biomarkers of brain injury. Methods A post-hoc analysis of 120 comatose OHCA patients continuously monitored with NIRS and randomised to low- or high-normal oxygen, carbon dioxide and mean arterial blood pressure (MAP) targets for 48 h. The tissue oximetry index (TOx) generated by the moving correlation coefficient between cerebral tissue oxygenation measured by NIRS and MAP was used as a dynamic index of CVR with TOx > 0 indicating impaired reactivity and TOx > 0.3 used to delineate the lower and upper MAP bounds for disrupted CVR. TOx was analysed in the 0–12, 12–24, 24–48 h time-periods and integrated over 0–48 h. The primary outcome was the association between TOx and six-month functional outcome dichotomised by the cerebral performance category (CPC1-2 good vs. 3–5 poor). Secondary outcomes included associations with MAP bounds for CVR and biomarkers of brain injury. Results In 108 patients with sufficient data to calculate TOx, 76 patients (70%) had impaired CVR and among these, chronic hypertension was more common (58% vs. 31%, p = 0.002). Integrated TOx for 0–48 h was higher in patients with poor outcome than in patients with good outcome (0.89 95% CI [− 1.17 to 2.94] vs. − 2.71 95% CI [− 4.16 to − 1.26], p = 0.05). Patients with poor outcomes had a decreased upper MAP bound of CVR over time (p = 0.001), including the high-normal oxygen (p = 0.002), carbon dioxide (p = 0.012) and MAP (p = 0.001) groups. The MAP range of maintained CVR was narrower in all time intervals and intervention groups (p < 0.05). NfL concentrations were higher in patients with impaired CVR compared to those with intact CVR (43 IQR [15–650] vs 20 IQR [13–199] pg/ml, p = 0.042). Conclusion Impaired CVR over 48 h was more common in patients with chronic hypertension and associated with poor outcome. Decreased upper MAP bound and a narrower MAP range for maintained CVR were associated with poor outcome and more severe brain injury assessed with NfL. Trial registration ClinicalTrials.gov, NCT02698917.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Association of deranged cerebrovascular reactivity with brain injury following cardiac arrest: a post-hoc analysis of the COMACARE trial

et al. 2021

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“…A MAP below the LLA (e.g., 50 mm Hg) increases the risk of cerebral ischemia; comparatively, a MAP above the ULA (e.g., 150 mm Hg) increases the risk of cerebral hyperemia [18][19][20]. However, contemporary data challenges the traditional dogmatic view of CA and suggests that the CA plateau, should it truly exist, is far narrower than traditionally reported and is individual specific [21,22]. Furthermore, changes in CBF remain highly susceptible to various physiological and clinical alterations, such as physical manipulations (i.e., head-up tilt) and vasoactive drugs [21].…”

Section: Physiologymentioning

confidence: 99%

“…Furthermore, changes in CBF remain highly susceptible to various physiological and clinical alterations, such as physical manipulations (i.e., head-up tilt) and vasoactive drugs [21]. The protective response of the cerebral vasculature is now thought to be dependent on not only the speed at which MAP changes but also the directionality of the change [21,22]. Alterations in the limits and mechanisms of CA in neonates and infants remain incompletely understood.…”

Section: Physiologymentioning

confidence: 99%

Cerebral Autoregulation: A Target for Improving Neurological Outcomes in Extracorporeal Life Support

Chalifoux,

Ko,

Slovis

et al. 2024

Neurocrit Care

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Despite improvements in survival after illnesses requiring extracorporeal life support, cerebral injury continues to hinder successful outcomes. Cerebral autoregulation (CA) is an innate protective mechanism that maintains constant cerebral blood flow in the face of varying systemic blood pressure. However, it is impaired in certain disease states and, potentially, following initiation of extracorporeal circulatory support. In this review, we first discuss patient-related factors pertaining to venovenous and venoarterial extracorporeal membrane oxygenation (ECMO) and their potential role in CA impairment. Next, we examine factors intrinsic to ECMO that may affect CA, such as cannulation, changes in pulsatility, the inflammatory and adaptive immune response, intracranial hemorrhage, and ischemic stroke, in addition to ECMO management factors, such as oxygenation, ventilation, flow rates, and blood pressure management. We highlight potential mechanisms that lead to disruption of CA in both pediatric and adult populations, the challenges of measuring CA in these patients, and potential associations with neurological outcome. Altogether, we discuss individualized CA monitoring as a potential target for improving neurological outcomes in extracorporeal life support.

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“…Nevertheless, no single method has been universally accepted as a gold standard. This may be a consequence of the limited reproducibility of the analytical methods (Sanders et al 2018, Lazaridis 2021. In a series of multicenter studies, coordinated by the CARNet, the reproducibility of the main parameters available to quantify CA was assessed (Meel-van den Abeelen et al 2014, Sanders et al 2018, Sanders et al 2019.…”

Section: Introductionmentioning

confidence: 99%

CAAos platform: an integrated platform for analysis of cerebral hemodynamics data

Salinet¹,

Moura²,

Romaneli³

et al. 2021

Physiol. Meas.

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Objective. The purpose of this article is to introduce readers to the concept and structure of the CAAos (Cerebral Autoregulation Assessment Open Source) platform, and provide evidence of its functionality. Approach. The CAAos platform is a new open-source software research tool, developed in Python 3 language, that combines existing and novel methods for interactive visual inspection, batch processing and analysis of multichannel records. The platform is scalable, allowing for the customization and inclusion of new tools. Main results. Currently, the CAAos platform is composed of two main modules, preprocessing (containing artefact removal, filtering and signal beat to beat extraction tools) and cerebral autoregulation (CA) analysis modules. Two methods for assessing CA have been implemented into the CAAos platform: transfer function analysis (TFA) and the autoregulation index (ARI). In order to provide validation of the TFA and ARI estimates derived from the CAAos platform, the results were compared with those derived from two other algorithms. Validation was performed using data from 28 participants, corresponding to 13 acute ischemic stroke patients and 13 age- and sex-matched control subjects. Agreement between estimates was assessed by intraclass correlation coefficient and Bland–Altman analysis. No significant statistical difference between the algorithms was found. Moreover, there was an excellent correspondence between the curves of all parameters analysed, with the intraclass correlation coefficient ranging from 0.98 (95%CI 0.976–0.999) to 1.00 (95%CI 1 -1). The mean differences revealed a very small magnitude bias indicating an excellent agreement between the estimates. Significance. As open-source software, the source code for the software is freely available for noncommercial use, reducing barriers to performing CA analysis, allowing inspection of the inner-workings of the algorithms, and facilitating networked activities with common standards. The CAAos platform is a tailored software solution for the scientific community in the cerebral hemodynamic field and contributes to the increasing use and reproducibility of CA assessment.

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Cerebral Autoregulation: The Concept the Legend the Promise

Cited by 4 publications

References 14 publications

Association of deranged cerebrovascular reactivity with brain injury following cardiac arrest: a post-hoc analysis of the COMACARE trial

Association of deranged cerebrovascular reactivity with brain injury following cardiac arrest: a post-hoc analysis of the COMACARE trial

Cerebral Autoregulation: A Target for Improving Neurological Outcomes in Extracorporeal Life Support

CAAos platform: an integrated platform for analysis of cerebral hemodynamics data

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