Critical Closing Pressure Determined with a Model of Cerebrovascular Impedance

Varsos, Georgios V.; Richards, Hugh K.; Kasprowicz, Magdalena; Budohoski, Karol P.; Brady, Ken; Reinhard, Matthias; Avolio, Alberto; Smielewski, Peter; Pickard, John D.; Czosnyka, Marek

doi:10.1038/jcbfm.2012.161

Cited by 72 publications

(73 citation statements)

References 30 publications

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“…The full derivation has been previously published. 40 Values of CrCP are rendered from 20-second epochs and updated in nonoverlapping 20-second intervals over each recording session.…”

Section: Critical Closing Pressurementioning

confidence: 99%

The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants

Rhee

Fraser²,

Kibler

et al. 2016

Acta Neurochirurgica Supplement

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Objective-To quantify cerebrovascular autoregulation as a function of gestational age (GA) and across the phases of the cardiac cycle.Study design-The present study is a hypothesis-generating re-analysis of previously published data. Premature infants (n=179), with a GA range of 23 to 33 weeks were monitored with umbilical artery catheters and transcranial Doppler insonation of the middle cerebral artery for 1-hour sessions over the first week of life. Autoregulation was quantified by three methods, as a moving correlation coefficient between: 1) systolic arterial blood pressure (ABP) and systolic cerebral blood flow (CBF) velocity (Sx); 2) mean ABP and mean CBF velocity (Mx); and 3) diastolic ABP and diastolic CBF velocity (Dx). Comparisons of individual and cohort cerebrovascular pressure autoregulation were made across GA for each aspect of the cardiac cycle.Results-Systolic, mean and diastolic ABP increased with GA (r=0.3, 0.4, and 0.4; p<0.0001). Systolic CBF velocity was pressure-passive in infants with the lowest GA, and Sx decreased with advancing GA (r=−0.3; p<0.001), indicating increased capacity for cerebral autoregulation during systole during development. By contrast, Dx was elevated, indicating dysautoregulation, in all subjects and showed minimal change with advancing GA (r=−0.06; p=0.05). Multivariate analysis confirmed that both GA (p<0.001) and "effective cerebral perfusion pressure" (ABP minus critical closing pressure; p<0.01) were associated with Sx. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptConclusion-Premature infants have low and usually pressure-passive diastolic CBF velocity. By contrast, the regulation of systolic CBF velocity by pressure autoregulation developed in this cohort between 23 and 33 weeks GA. Elevated effective cerebral perfusion pressure derived from the critical closing pressure was associated with dysautoregulation.

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“…The full derivation has been previously published. 40 Values of CrCP are rendered from 20-second epochs and updated in nonoverlapping 20-second intervals over each recording session.…”

Section: Critical Closing Pressurementioning

confidence: 99%

The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants

Rhee

Fraser²,

Kibler

et al. 2016

Acta Neurochirurgica Supplement

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“…Critical closing pressure (expressed in mm Hg) was estimated through a noninvasive version of the impedance CrCP methodology, 40 based on ABP and TCD FV (see Appendix):…”

Section: Calculation Of Noninvasive Crcp and Cppmentioning

confidence: 99%

“…28 As CrCP is associated with the vasomotor tone of small blood vessels, knowledge of its behavior has been recognized as able to provide valuable information regarding the state of cerebral hemodynamics in different pathologies. 11,25,28,32,40 We have recently introduced a new method for estimating CrCP that is an apparent improvement on traditional methodology, 25,40 in which the new, impedance model-based method does not render negative values. 32,40 However, this method is invasive, as ICP measurements are required, possibly limiting its clinical applications in situations in which measuring ICP is not an option.…”

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confidence: 99%

“…11,25,28,32,40 We have recently introduced a new method for estimating CrCP that is an apparent improvement on traditional methodology, 25,40 in which the new, impedance model-based method does not render negative values. 32,40 However, this method is invasive, as ICP measurements are required, possibly limiting its clinical applications in situations in which measuring ICP is not an option. For this reason, an equivalent noninvasive version of this model has been introduced, which only requires measurements of ABP and FV.…”

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A noninvasive estimation of cerebral perfusion pressure using critical closing pressure

Varsos

Kolias

Smielewski

et al. 2015

JNS

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T he circulation of cerebral blood flow (CBF) is driven by cerebral perfusion pressure (CPP), which is defined as the vascular pressure gradient across the cerebral bed and can be calculated as the difference between arterial blood pressure (ABP) and pressure in cortical or bridging veins. 15,24 Due to difficulties in measuring the pressure of bridging veins, invasive intracranial pressure (ICP) measurements are used instead as an approximation, defining CPP as ABP − ICP. 1,26,34,39 Cerebral perfusion pressure in clinical practice is considered an esabbreviatioNs ABP = arterial blood pressure; AUC = area under the curve; CBF = cerebral blood flow; CPP = cerebral perfusion pressure; CrCP = critical closing pressure; CVR = cerebrovascular resistance; eCPP = noninvasive estimator of CPP; FV = flow velocity; GCS = Glasgow Coma Scale; GOS = Glasgow Outcome Scale; ICP = intracranial pressure; IQR = interquartile range; MCA = middle cerebral artery; nICP = noninvasive estimator of ICP; ROC = receiver operating characteristic; TAU = time constant of the cerebrovascular arterial bed; TBI = traumatic brain injury; TCD = transcranial Doppler. obJect Cerebral blood flow is associated with cerebral perfusion pressure (CPP), which is clinically monitored through arterial blood pressure (ABP) and invasive measurements of intracranial pressure (ICP). Based on critical closing pressure (CrCP), the authors introduce a novel method for a noninvasive estimator of CPP (eCPP). methods Data from 280 head-injured patients with ABP, ICP, and transcranial Doppler ultrasonography measurements were retrospectively examined. CrCP was calculated with a noninvasive version of the cerebrovascular impedance method. The eCPP was refined with a predictive regression model of CrCP-based estimation of ICP from known ICP using data from 232 patients, and validated with data from the remaining 48 patients. results Cohort analysis showed eCPP to be correlated with measured CPP (R = 0.851, p < 0.001), with a mean ± SD difference of 4.02 ± 6.01 mm Hg, and 83.3% of the cases with an estimation error below 10 mm Hg. eCPP accurately predicted low CPP (< 70 mm Hg) with an area under the curve of 0.913 (95% CI 0.883-0.944). When each recording session of a patient was assessed individually, eCPP could predict CPP with a 95% CI of the SD for estimating CPP between multiple recording sessions of 1.89-5.01 mm Hg. coNclusioNs Overall, CrCP-based eCPP was strongly correlated with invasive CPP, with sensitivity and specificity for detection of low CPP that show promise for clinical use.

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“…CrCP is posited to be the sum of vascular wall tension and intracranial pressure (2). CrCP can be conceptualized as a factor for the normalization of ABP to an "effective cerebral perfusion pressure" or "closing margin" (3,4). The "effective cerebral perfusion" or "closing margin" (ABP-CrCP) can be determined for any phase of the cardiac cycle by subtracting the CrCP from systolic, mean, or diastolic ABP.…”

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Ontogeny of cerebrovascular critical closing pressure

Rhee

Fraser²,

Kibler

et al. 2015

Pediatr Res

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Background: Premature infants are at risk of vascular neurologic insults. Hypotension and hypertension are considered injurious, but neither condition is defined with consensus. Cerebrovascular critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases. CrCP may serve to define subject-specific low or high ABP. Our objective was to determine the ontogeny of CrCP. Methods: Premature infants (n = 179) with gestational age (GA) from 23-31 wk had recordings of ABP and middle cerebral artery flow velocity twice daily for 3 d and then daily for the duration of the first week of life. All infants received mechanical ventilation. CrCP was calculated using an impedance-model derivation with Doppler-based estimations of cerebrovascular resistance and compliance. The association between GA and CrCP was determined in a multivariate analysis. results: The median (interquartile range) CrCP for the cohort was 22 mm Hg (19-25 mm Hg). CrCP increased significantly with GA (r = 0.6; slope = 1.4 mm Hg/wk gestation), an association that persisted with multivariate analysis (P < 0.0001). conclusion: CrCP increased significantly from 23 to 31 wk gestation. The low CrCP observed in very premature infants may explain their ability to tolerate low ABP without global cerebral infarct or hemorrhage. c erebrovascular critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which blood flow to the brain ceases due to vascular collapse. Also referred to as collapsing pressure, CrCP can be easily and noninvasively monitored at the bedside using Doppler ultrasound and ABP measurements (1). CrCP is posited to be the sum of vascular wall tension and intracranial pressure (2). CrCP can be conceptualized as a factor for the normalization of ABP to an "effective cerebral perfusion pressure" or "closing margin" (3,4). The "effective cerebral perfusion" or "closing margin" (ABP-CrCP) can be determined for any phase of the cardiac cycle by subtracting the CrCP from systolic, mean, or diastolic ABP.Limited data sets report CrCPs in term and preterm newborns ranging from 24 to 33 mm Hg, which is similar to reported values in mature subjects (5,6). Low ABP in premature infants results in a closing margin that is strikingly low (Figure 1). Premature infants are commonly treated for low values of blood pressure based on mean ABP thresholds related to their gestational age (GA) (7-9), and these thresholds are within the range of published CrCP values (5,6). Moreover, during postnatal transition, a period of time often characterized by shock, premature infants can have CBF limited to the systolic phase of the cardiac cycle (10).Disparity in the definition of hypotension and treatment thresholds for low ABP are likely attributable to a lack of outcome data in premature infants demonstrating a benefit for treating low ABP (11). We propose that an important confounding factor may be the low closing margin relative to the range of CrCP in this population. For example, a difference of 10 mm Hg Cr...

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Critical Closing Pressure Determined with a Model of Cerebrovascular Impedance

Cited by 72 publications

References 30 publications

The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants

The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants

A noninvasive estimation of cerebral perfusion pressure using critical closing pressure

Ontogeny of cerebrovascular critical closing pressure

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