Measuring Cerebrovascular Reactivity: Sixteen Avoidable Pitfalls

Sobczyk, Olivia; Fierstra, Jorn; Venkatraghavan, Lakshmikumar; Poublanc, Julien; Duffin, James; Fisher, Joseph A.; Mikulis, David

doi:10.3389/fphys.2021.665049

Cited by 11 publications

(13 citation statements)

References 60 publications

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“…and the magnitude of the response with the ramp, are important for assessing the efficacy of collateral blood flow in patients at risk. 1 , 26 , 27 …”

Section: Discussionmentioning

confidence: 99%

“…25 Both analyses are important for assessing the efficacy of collateral blood flow in patients at risk. 1,26,27 At our institution, a standardized hypercapnic protocol establishes a baseline BOLD signal distribution at the individual's resting PETO 2 and PETCO 2 and then applies standardized isoxic, pattern of hypercapnic changes. These protocols are usually well tolerated.…”

Section: Introductionmentioning

confidence: 99%

“… 25 Both analyses are important for assessing the efficacy of collateral blood flow in patients at risk. 1 , 26 , 27 …”

Section: Introductionmentioning

confidence: 99%

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Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity

Sayin,

Duffin,

Poublanc

et al. 2023

J Cereb Blood Flow Metab

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Evaluation of cerebrovascular reactivity (CVR) to hypo- and hypercapnia is a valuable test for the assessment of vasodilatory reserve. While hypercapnia-induced CVR testing is usually performed at normoxia, mild hyperoxia may increase tolerability of hypercapnia by reducing the ventilatory distress. However, the effects of mild hyperoxia on CVR was unknown. We therefore recruited 21 patients with a range of steno-occlusive diseases and 12 healthy participants who underwent a standardized 13-minute step plus ramp CVR test with a carbon dioxide gas challenge at the subject’s resting end-tidal partial pressure of oxygen or at mild hyperoxia (PetO2 = 150 mmHg) depending on to which group they were assigned. In 11 patients, the second CVR test was at normoxia to examine test-retest differences. CVR was defined as % Δ Signal/ΔPetCO2. We found that there was no significant difference between CVR test results conducted at normoxia and at mild hyperoxia for participants in Groups 1 and 2 for the step and ramp portion. We also found no difference between test and retest CVR at normoxia for patients with cerebrovascular pathology (Group 3) for step and ramp portion. We concluded normoxic CVR is repeatable, and that mild hyperoxia does not affect CVR.

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“…and the magnitude of the response with the ramp, are important for assessing the efficacy of collateral blood flow in patients at risk. 1 , 26 , 27 …”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity

Sayin,

Duffin,

Poublanc

et al. 2023

J Cereb Blood Flow Metab

Self Cite

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“…Thus, CVR reflects changes of blood flow in response to the stimulus via vasodilation. One can then use CVR to see how much blood flow changes in different vessels and collateral pathways ( Sam et al, 2014 ; Sobczyk et al, 2021a ).…”

Section: Neurovascular Changes In Strokementioning

confidence: 99%

Understanding recovery of language after stroke: insights from neurovascular MRI studies

Ivanova

Pappas

2023

Front. Lang. Sci.

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Stroke causes a disruption in blood flow to the brain that can lead to profound language impairments. Understanding the mechanisms of language recovery after stroke is crucial for the prognosis and effective rehabilitation of people with aphasia. While the role of injured brain structures and disruptions in functional connectivity have been extensively explored, the relationship between neurovascular measures and language recovery in both early and later stages has not received sufficient attention in the field. Fully functioning healthy brain tissue requires oxygen and nutrients to be delivered promptly via its blood supply. Persistent decreases in blood flow after a stroke to the remaining non-lesioned tissue have been shown to contribute to poor language recovery. The goal of the current paper is to critically examine stroke studies looking at the relationship between different neurovascular measures and language deficits and mechanisms of language recovery via changes in neurovascular metrics. Measures of perfusion or cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) provide complementary approaches to understanding neurovascular mechanisms post stroke by capturing both cerebral metabolic demands and mechanical vascular properties. While CBF measures indicate the amount of blood delivered to a certain region and serve as a proxy for metabolic demands of that area, CVR indices reflect the ability of the vasculature to recruit blood flow in response to a shortage of oxygen, such as when one is holding their breath. Increases in CBF during recovery beyond the site of the lesion have been shown to promote language gains. Similarly, CVR changes, when collateral vessels are recruited to help reorganize the flow of blood in hypoperfused regions, have been related to functional recovery post stroke. In the current review, we highlight the main findings in the literature investigating neurovascular changes in stroke recovery with a particular emphasis on how language abilities can be affected by changes in CBF and CVR. We conclude by summarizing existing methodological challenges and knowledge gaps that need to be addressed in future work in this area, outlining a promising avenue of research.

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“…With this respect, stressor of +10 mmHg with respect to resting PETCO2 from baseline is considered the best stimulus in order to improve CVR comparability between subjects as a consequence of normalization of vascular tone to each subject's own resting PCO2. [66] Differently from previous studies, an additiona l O2 protocol was executed consisting of a 80 seconds hypoxic pseudo square wave plateau at 70 mmHg, while mainta ini ng iso-capnic conditions, followed by 100s returning to the O2 baseline (ie., normoxia), with a last step of a pseudo square wave of a iso-capnic hyperoxia plateau at 300 mmHg for 80 seconds. As hyperoxic and hypoxic challenges do not have a significant vasoactive effect, in this instance a uniform baseline was chosen.…”

Section: Standardized Iso-oxic Hypercapnic Stimulus and Iso-capnic Hy...mentioning

confidence: 99%

Feasibility of glioblastoma tissue response mapping with physiologic BOLD imaging using precise oxygen and carbon dioxide challenge

Stumpo

Sebök

Niftrik

et al. 2021

Magn Reson Mater Phy

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Objectives: Innovative physiologic MRI development focuses on depiction of heterogenous vascular and metabolic features in glioblastoma. For this feasibility study, we employed blood oxygenation leveldependent (BOLD) MRI with standardized and precise carbon dioxide (CO2) and oxygen (O2) modulation to investigate specific tumor tissue response patterns in patients with newly diagnosed glioblastoma. Materials and methods: Seven newly diagnosed untreated patients with suspected glioblastoma were prospectively included to undergo a BOLD study with combined CO2 and O2 standardized protocol. %BOLD signal change/mmHg during hypercapnic, hypoxic, and hyperoxic stimulus was calculated in the whole brain, tumor lesion and segmented volumes of interest (VOI) [contrast-enhancing (CE) -tumor, necrosis and edema] to analyze their tissue response patterns. Results: Quantification of BOLD signal change after gas challenges can be used to identify specific responses to standardized stimuli in glioblastoma patients. Integration of this approach with automatic VOI segmentation grants improved characterization of tumor subzones and edema. Magnitude of BOLD signal change during the 3 stimuli can be visualized at voxel precision through color-coded maps overlayed onto whole brain and identified VOIs. Conclusions: Our preliminary investigation shows good feasibility of BOLD with standardized and precise CO2 and O2 modulation as an emerging physiologic imaging technique to detail specific glioblastoma characteristics. The unique tissue response patterns generated can be further investigated to better detail glioblastoma lesions and gauge treatment response.

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Measuring Cerebrovascular Reactivity: Sixteen Avoidable Pitfalls

Cited by 11 publications

References 60 publications

Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity

Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity

Understanding recovery of language after stroke: insights from neurovascular MRI studies

Feasibility of glioblastoma tissue response mapping with physiologic BOLD imaging using precise oxygen and carbon dioxide challenge

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