Cerebral Arterial Compliance in Traumatic Brain Injury

Dobrzeniecki, Michael; Trofimov, Alex; Bragin, Denis E

doi:10.1007/978-3-319-65798-1_5

Cited by 8 publications

(4 citation statements)

References 10 publications

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“…Our hypothesis concerning the association between s and delayed ischemic deficit is that s reduction may be driven by decreased compliance in this specific context due to both stiffening of more proximal parts of the cerebral vasculature hindering their further increase in volume in response to ABP on one hand, and dilation of more distal parts of arterial segments impeding more vasodilation of these segments on the other hand. 32,44 In our study, both CBFV and s had moderate accuracy as DCI predictors. The model that integrated both s and CBFV parameters demonstrated the highest performance.…”

Section: Discussionmentioning

confidence: 48%

Predictive value of cerebrovascular time constant for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Uryga,

Kasprowicz,

Budohoski

et al. 2024

J Cereb Blood Flow Metab

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Time constant of the cerebral arterial bed (τ) is a transcranial Doppler (TCD) based metric that is expected to quantify the transit time of red blood cells from the insonation point to the arteriole-capillary boundary during a cardiac cycle. This study aims to assess the potential of τ as an early predictor of delayed cerebral ischemia (DCI). Consecutive patients (56 ± 15 years) treated for aneurysmal subarachnoid haemorrhage were included in the study. τ was assessed through a modelling approach that involved simultaneous recordings of arterial blood pressure and cerebral blood flow velocity (CBFV) from TCD's first recordings. 71 patients were included. 17 patients experienced DCI. τ was significantly shorter in patients who later developed DCI: 187 ± 64 ms vs. 249 ± 184 ms; p = 0.040 with moderate effect size (rG = 0.24). Logistic regression showed that there was a significant association between increased CBFV, shortened τ, and the development of DCI (χ2 = 11.54; p = 0.003) with AUC for the model 0.75. Patients who had both shortened τ and increased CBFV were 20 times more likely to develop DCI (OR = 20.4 (2.2–187.7)). Our results suggest that early alterations in τ are associated with DCI after aSAH. The highest performance of the model including both CBFV and τ may suggest the importance of both macrovascular and microvascular changes assessment.

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Section: Discussionmentioning

confidence: 48%

Predictive value of cerebrovascular time constant for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Uryga,

Kasprowicz,

Budohoski

et al. 2024

J Cereb Blood Flow Metab

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“…A larger prospective study would be needed to further establish its potential usefulness in clinical practice. Finally, the model used in this trial has been validated with other monitoring or imaging techniques, emphasizing its validation with perfusion CT in trauma patients [10].…”

Section: Discussionmentioning

confidence: 99%

“…This effect could influence tau in the opposite direction, shortening it. In normo-ventilated TBI patients, a decrease in arterial cerebral compliance has also been observed [10].…”

Section: Introductionmentioning

confidence: 98%

Hypocapnia after traumatic brain injury: how does it affect the time constant of the cerebral circulation?

Puppo

Kasprowicz

Steiner

et al. 2019

J Clin Monit Comput

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The time constant of the cerebral arterial bed ("tau") estimates how fast the blood entering the brain fills the arterial vascular sector. Analogous to an electrical resistor-capacitor circuit, it is expressed as the product of arterial compliance (Ca) and cerebrovascular resistance (CVR). Hypocapnia increases the time constant in healthy volunteers and decreases arterial compliance in head trauma. How the combination of hyocapnia and trauma affects this parameter has yet to be studied. We hypothesized that in TBI patients the intense vasoconstrictive action of hypocapnia would dominate over the decrease in compliance seen after hyperventilation. The predominant vasoconstrictive response would maintain an incoming blood volume in the arterial circulation, thereby lengthening tau. We retrospectively analyzed recordings of intracranial pressure (ICP), arterial blood pressure (ABP), and blood flow velocity (FV) obtained from a cohort of 27 severe TBI patients [(39/30 years (median/IQR), 5 women; admission GCS 6/5 (median/IQR)] studied during a standard clinical CO 2 reactivity test. The reactivity test was performed by means of a 50-min increase in ventilation (20% increase in respiratory minute volume). CVR and Ca were estimated from these recordings, and their product calculated to find the time constant. CVR significantly increased [median CVR pre-hypocapnia/during hypocapnia: 1.05/1.35 mmHg/(cm 3 /s)]. Ca decreased (median Ca pre-hypocapnia/during hypocapnia: 0.130/0.124 arbitrary units) to statistical significance (p = 0.005). The product of these two parameters resulted in a significant prolongation of the time constant (median tau pre-hypocapnia/during hypocapnia: 0.136 s/0.152 s, p ˂ .001). Overall, the increase in CVR dominated over the decrease in compliance, hence tau was longer. We demonstrate a significant increase in the time constant of the cerebral circulation during hypocapnia after severe TBI, and attribute this to an increase in cerebrovascular resistance which outweighs the decrease in cerebral arterial bed compliance.

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“…7,12 As a consequence of lower CAC, cerebral blood vessels are exposed to higher degrees of arterial pulsation, leading to small vessel damage (ie, white matter hyperintensities) and resulting cognitive impairment. 13 Individuals with cTBI may have impaired CAC due to vascular structural damage from the original injury 14,15 and/or lifestyle changes after TBI (ie, reduced physical activity). 16,17 However, CAC has not been studied in subjects with cTBI.…”

mentioning

confidence: 99%

Carotid Arterial Compliance and Aerobic Exercise Training in Chronic Traumatic Brain Injury: A Pilot Study

Tomoto

Tarumi

et al. 2021

Journal of Head Trauma Rehabilitation

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Objective: Decreased carotid arterial compliance (CAC) is associated with cerebral microvascular damage, cerebral blood flow (CBF) dysregulation, and increased risk for stroke and dementia, which are reported to be prevalent after traumatic brain injury (TBI). However, the effect of TBI on CAC has not been reported. The purposes of this pilot study were to (1) compare CAC between participants with chronic traumatic brain injury (cTBI) and age-matched healthy control (HC) subjects and (2) to examine whether CAC changed after 3 months of exercise training in those with cTBI. Setting: Community based. Participants: Nineteen participants with cTBI (6-72 months postinjury) and 19 HC matched for age and sex were tested at baseline. The same cTBI cohort was enrolled in a proof-ofconcept randomized controlled exercise training program to investigate the effects of 3 months of aerobic exercise training (AET) or nonaerobic stretching and toning (SAT) on cerebrovascular parameters. Design: Cross-sectional study and randomized controlled trial. Main Measures: CAC was measured by tonometry and ultrasonography at the common carotid artery; CBF was measured by ultrasonography at the bilateral internal carotid and vertebral arteries, and pulsatile CBF was measured by transcranial Doppler ultrasonography at the middle cerebral arteries. Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by total CBF. Results: Relative to HC, the participants with cTBI had lower CAC (0.10 ± 0.03 vs 0.12 ± 0.03 mm 2 /mm Hg, P = .046) and higher CVR (0.17 ± 0.03 vs 0.15 ± 0.03 mm Hg/mL/min, P = .028). CAC tended to increase after AET compared with SAT (P = .080). Increases in CAC were associated with decreased pulsatile CBF (r = −0.689, P = .003). Conclusion: These findings suggest that the individuals with cTBI have decreased CAC, which may potentially be improved by AET.

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Cerebral Arterial Compliance in Traumatic Brain Injury

Abstract: The cAC in TBI gets significantly lower compared with the conditional norm (p < 0.001). After removal of the intracranial hematomas, compliance in the perifocal zone remains much lower (р = 0.017) compared with compliance of the other brain hemisphere.

Cited by 8 publications

References 10 publications

Predictive value of cerebrovascular time constant for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Predictive value of cerebrovascular time constant for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Hypocapnia after traumatic brain injury: how does it affect the time constant of the cerebral circulation?

Carotid Arterial Compliance and Aerobic Exercise Training in Chronic Traumatic Brain Injury: A Pilot Study

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