The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants

Rhee, Christopher J.; Fraser, Charles D.; Kibler, Kathleen K.; Easley, R. Blaine; Andropoulos, Dean B.; Czosnyka, Marek; Varsos, Georgios V.; Smielewski, Peter; Rusin, Craig G.; Brady, Kenneth Martin; Kaiser, Jeffrey R.

doi:10.1007/978-3-319-22533-3_31

Cited by 28 publications

(26 citation statements)

References 36 publications

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“…In premature newborns (22-33 weeks), the degree of cerebral autoregulation impairment (using the Sx method) is inversely correlated with gestational age [78]. Furthermore, impaired dynamic autoregulation (in both the frequency and time domains) is associated with poorer functional outcomes [44, 79,80].…”

Section: Premature Newbornsmentioning

confidence: 99%

Further understanding of cerebral autoregulation at the bedside: possible implications for future therapy

Donnelly

Aries

Czosnyka

2015

Expert Review of Neurotherapeutics

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Cerebral autoregulation reflects the ability of the brain to keep the cerebral blood flow (CBF) relatively constant despite changes in cerebral perfusion pressure. It is an intrinsic neuroprotective physiological phenomenon often suggested as part of pathophysiological pathways in brain research. However, despite increasing knowledge of this phenomenon for over 50 years, harnessing cerebral autoregulation as a basis for therapy remains an elegant concept rather than a practical reality. This raises the question is it useful to measure at the bedside or is it merely a scientific curiosity that is too complex and has little pragmatic relevance. In this article, we attempt to answer this question by demonstrating how cerebral autoregulation assessment can have prognostic value, indicate pathological states, and potentially even influence therapy with the use of the 'optimal cerebral perfusion pressure' paradigm. Evidence from the literature is combined with bedside clinical examples to address the following fundamental questions about cerebral autoregulation: What is it? How do we measure it? Why is it important? Can we use it as a basis for therapy?

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Section: Premature Newbornsmentioning

confidence: 99%

Further understanding of cerebral autoregulation at the bedside: possible implications for future therapy

Donnelly

Aries

Czosnyka

2015

Expert Review of Neurotherapeutics

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“…This parameter was called the "zero-fl ow" pressure (ZFP) or critical closing pressure [4,5]. The ZPF-model was proposed in 1951 by A. Burton [6] and was later developed by R. Dewey и S. Permutt [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…It was further determined that the fi rst two parameters constitute the value of ICP. Thus, the ZFP is determined by the following formula [4]:…”

Section: Introductionmentioning

confidence: 99%

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Zero-Flow Pressure of the Cerebral Microcirculatory Bed at Concomitant Traumatic Brain Injury

Trofimov¹,

Dobrzeniecki²,

Kalentyev³

et al. 2017

Ann Circ

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Zero-fl ow pressure (ZFP) is an important parameter of a microcirculation. The aim is to determine the status of the ZFP at concomitant traumatic brain injury with and without the development of intracranial hematomas. Material and Methods:The results of the treatment of 80 patients with severe head injury and polytrauma was studied. M:F -44:36. Their average age was 34.3 ± 14.5 years (min 15: max 73). Depending on the presence of intracranial hemorrhages the patients were divided into 2 groups. Wakefulness according to Glasgow Coma Score (GCS) was 10.4 ± 2.6 in the 1st group and 10.6 ± 2.8 in the 2nd group. The Injury Severity Score (ISS) was 32 ± 8 in the 1st group and 31 ± 11 in the 2nd group. Epidural hematomas were revealed in the 2nd group in 7 patients, subdural hematomas in 27 persons and multiple hematomas in 4 sufferers. All the sufferers were operated within the fi rst 3 days. During the fi rst day 30 patients (78.9%) were operated.All the patients were subjected to the transcranial Doppler of the both middle cerebral arteries and the evaluation of the mean arterial pressure. Based on the data obtained the cerebral perfusion pressure and the ZFP were calculated. The comparisons between the groups were performed by using the Student's t-criterion. Results:There was no signifi cant difference in ZFP between the left side and the right side in 1 st group (46.88±14.05 mmHg vs. 45.44±10.73 mmHg, respectively, t=0.45; р=0.65) The average ZFP values in each of the groups (with or without hematomas) appeared to be statistically signifi cantly higher than a mean value in control group (32,9 ± 3,6 mmHg, р<0.01). The intergroup comparison of the ZFP showed a statistically reliable increase in its level in the 2nd group on the side of the removed hematoma as compared with opposite side (56.02±21.68 mmHg vs. 45.43±16.71 mmHg, respectively, t=2.38; р=0.019p=0,019).

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“…Premature infants are commonly treated for low values of blood pressure based on mean ABP thresholds related to their gestational age (GA) (7)(8)(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).…”

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confidence: 99%

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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The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants

Cited by 28 publications

References 36 publications

Further understanding of cerebral autoregulation at the bedside: possible implications for future therapy

Further understanding of cerebral autoregulation at the bedside: possible implications for future therapy

Zero-Flow Pressure of the Cerebral Microcirculatory Bed at Concomitant Traumatic Brain Injury

Ontogeny of cerebrovascular critical closing pressure

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