Frequency-dependent properties of cerebral blood transport—An experimental study in anaesthetized rabbits

Czosnyka, Marek; Richards, Hugh K.; Pickard, John D.; Harris, Neil G.; Iyer, Vijay

doi:10.1016/0301-5629(94)90008-6

Cited by 34 publications

(29 citation statements)

References 14 publications

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“…By definition, CrCP denotes a threshold of ABP, below which the brain microvascular blood pressure is inadequate to prevent the collapse and cessation of blood flow. 35 Given the association of CrCP with the vasomotor tone of small blood vessels (i.e., wall tension), this concept may be able to provide information regarding the state of cerebral hemodynamics in several neurological conditions 35,[37][38][39][40] and for this method was applied as a variable for nCPP estimation. …”

Section: Noninvasive Intracranial Pressure Methodsmentioning

confidence: 99%

Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods

Cardim

Robba

Donnelly

et al. 2016

Journal of Neurotrauma

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Elevation of intracranial pressure (ICP) may occur in many diseases, and therefore the ability to measure it noninvasively would be useful. Flow velocity signals from transcranial Doppler (TCD) have been used to estimate ICP; however, the relative accuracy of these methods is unclear. This study aimed to compare four previously described TCD-based methods with directly measured ICP in a prospective cohort of traumatic brain-injured patients. Noninvasive ICP (nICP) was obtained using the following methods: 1) a mathematical ''black-box'' model based on interaction between TCD and arterial blood pressure (nICP_BB); 2) based on diastolic flow velocity (nICP_FVd); 3) based on critical closing pressure (nICP_CrCP); and 4) based on TCD-derived pulsatility index (nICP_PI). In time domain, for recordings including spontaneous changes in ICP greater than 7 mm Hg, nICP_PI showed the best correlation with measured ICP (R = 0.61). Considering every TCD recording as an independent event, nICP_BB generally showed to be the best estimator of measured ICP (R = 0.39; p < 0.05; 95% confidence interval [CI] = 9.94 mm Hg; area under the curve [AUC] = 0.66; p < 0.05). For nICP_FVd, although it presented similar correlation coefficient to nICP_BB and marginally better AUC (0.70; p < 0.05), it demonstrated a greater 95% CI for prediction of ICP (14.62 mm Hg). nICP_CrCP presented a moderate correlation coefficient (R = 0.35; p < 0.05) and similar 95% CI to nICP_BB (9.19 mm Hg), but failed to distinguish between normal and raised ICP (AUC = 0.64; p > 0.05). nICP_PI was not related to measured ICP using any of the above statistical indicators. We also introduced a new estimator (nICP_Av) based on the average of three methods (nICP_BB, nICP_FVd, and nICP_CrCP), which overall presented improved statistical indicators (R = 0.47; p < 0.05; 95% CI = 9.17 mm Hg; AUC = 0.73; p < 0.05). nICP_PI appeared to reflect changes in ICP in time most accurately. nICP_BB was the best estimator for ICP ''as a number.'' nICP_Av demonstrated to improve the accuracy of measured ICP estimation.

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Section: Noninvasive Intracranial Pressure Methodsmentioning

confidence: 99%

Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods

Cardim

Robba

Donnelly

et al. 2016

Journal of Neurotrauma

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“…This is confirmed by analysis of the changes of the TCD waveform. An immediate decrease in systolic FV coupled with a more variable response of diastolic FV, in which a significant decrease develops with time, strongly suggests that the primary response of basilar artery to L-NAME is an increase of its basal tone and hence a decrease in compliance and increase in resistance [3,4]. The participation of NO in the maintenance of the basal tone of basilar artery supports data obtained in other species using different techniques [7,14,18].…”

Section: Fast Response In the Basilar Artery Blood Flow Velocitymentioning

confidence: 65%

Changes in transcranial Doppler flow velocity waveform following inhibition of nitric oxide synthesis

Richards

Kozniewska²,

Czosnyka

et al. 1997

Acta neurochir

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“…The invasive parts requiring ICP measurements are CPP (calculated as ABP − ICP) and cerebrovascular resistance (CVRi), approximated as: 40 CVRi ¼ CPP FVUS a mm HgUs cm 3 The parameter S a in the denominator represents the unknown cross-sectional area of the insonated vessel. Ca can be estimated as: 32,33 Ca ¼ CaBV1USa A1…”

Section: Appendix Calculation Of Noninvasive Crcpmentioning

confidence: 99%

“…26 Approximating CrCP noninvasively, we used the CrCP formula, substituting CPP with ABP, with CVRi being now approximated noninvasively as: 40 …”

Section: 33mentioning

confidence: 99%

Cerebral Vasospasm Affects Arterial Critical Closing Pressure

Varsos

Budohoski

Czosnyka

et al. 2014

J Cereb Blood Flow Metab

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The effect of cerebral vasospasm (CVS) after aneurysmal subarachnoid hemorrhage (SAH) on critical closing pressure (CrCP) has not been fully delineated. Using cerebral impedance methodology, we sought to assess the behavior of CrCP during CVS. As CrCP expresses the sum of intracranial pressure (ICP) and vascular wall tension, we also explored its role in reflecting changes in vascular tone occurring in small vessels distal to spasm. This retrospective analysis was performed using recordings from 52 patients, diagnosed with CVS through transcranial Doppler measurements. Critical closing pressure was calculated noninvasively using arterial blood pressure and blood flow velocity. Outcome was assessed at both discharge and 3 months after ictus with the Glasgow Outcome Scale. The onset of CVS caused significant decreases in CrCP (P = 0.025), without any observed significant changes in ICP (P = 0.134). Vasospasm induced asymmetry, with CrCP ipsilateral to CVS becoming significantly lower than contralateral (P = 0.025). Unfavorable outcomes were associated with a significantly lower CrCP after the onset of CVS (discharge: P = 0.014; 3 months after SAH: P = 0.020). Critical closing pressure is reduced in the presence of CVS in both temporal and spatial assessments. As ICP remained unchanged during CVS, reduced CrCP most probably reflects a lower wall tension in dilated small vessels distal to spasm.

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Frequency-dependent properties of cerebral blood transport—An experimental study in anaesthetized rabbits

Cited by 34 publications

References 14 publications

Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods

Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods

Changes in transcranial Doppler flow velocity waveform following inhibition of nitric oxide synthesis

Cerebral Vasospasm Affects Arterial Critical Closing Pressure

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