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

Donnelly, Joseph E.; Aries, Marcel; Czosnyka, Marek

doi:10.1586/14737175.2015.996552

Cited by 73 publications

(60 citation statements)

References 106 publications

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“…Over the past 2 decades, the clinical assessment of CA has transitioned from intermittent testing to continuous monitoring [4,6–9]. Czosnyka et al proposed that the relationship between the spontaneous, slow changes in mean arterial blood pressure (ABP) and ICP may shed light on the relationship between CPP and cerebral blood flow (CA), giving rise to the development of the pressure reactivity index (PRx) [10].…”

Section: Introductionmentioning

confidence: 99%

Cerebrovascular pressure reactivity monitoring using wavelet analysis in traumatic brain injury patients: A retrospective study

et al. 2017

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BackgroundAfter traumatic brain injury (TBI), the ability of cerebral vessels to appropriately react to changes in arterial blood pressure (pressure reactivity) is impaired, leaving patients vulnerable to cerebral hypo- or hyperperfusion. Although, the traditional pressure reactivity index (PRx) has demonstrated that impaired pressure reactivity is associated with poor patient outcome, PRx is sometimes erratic and may not be reliable in various clinical circumstances. Here, we introduce a more robust transform-based wavelet pressure reactivity index (wPRx) and compare its performance with the widely used traditional PRx across 3 areas: its stability and reliability in time, its ability to give an optimal cerebral perfusion pressure (CPPopt) recommendation, and its relationship with patient outcome.Methods and findingsFive hundred and fifteen patients with TBI admitted in Addenbrooke’s Hospital, United Kingdom (March 23rd, 2003 through December 9th, 2014), with continuous monitoring of arterial blood pressure (ABP) and intracranial pressure (ICP), were retrospectively analyzed to calculate the traditional PRx and a novel wavelet transform-based wPRx. wPRx was calculated by taking the cosine of the wavelet transform phase-shift between ABP and ICP. A time trend of CPPopt was calculated using an automated curve-fitting method that determined the cerebral perfusion pressure (CPP) at which the pressure reactivity (PRx or wPRx) was most efficient (CPPopt_PRx and CPPopt_wPRx, respectively).There was a significantly positive relationship between PRx and wPRx (r = 0.73), and wavelet wPRx was more reliable in time (ratio of between-hour variance to total variance, wPRx 0.957 ± 0.0032 versus PRx and 0.949 ± 0.047 for PRx, p = 0.002). The 2-hour interval standard deviation of wPRx (0.19 ± 0.07) was smaller than that of PRx (0.30 ± 0.13, p < 0.001). wPRx performed better in distinguishing between mortality and survival (the area under the receiver operating characteristic [ROC] curve [AUROC] for wPRx was 0.73 versus 0.66 for PRx, p = 0.003). The mean difference between the patients’ CPP and their CPPopt was related to outcome for both calculation methods. There was a good relationship between the 2 CPPopts (r = 0.814, p < 0.001). CPPopt_wPRx was more stable than CPPopt_PRx (within patient standard deviation 7.05 ± 3.78 versus 8.45 ± 2.90; p < 0.001).Key limitations include that this study is a retrospective analysis and only compared wPRx with PRx in the cohort of patients with TBI. Prior prospective validation is required to better assess clinical utility of this approach.ConclusionswPRx offers several advantages to the traditional PRx: it is more stable in time, it yields a more consistent CPPopt recommendation, and, importantly, it has a stronger relationship with patient outcome. The clinical utility of wPRx should be explored in prospective studies of critically injured neurological patients.

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Section: Introductionmentioning

confidence: 99%

Cerebrovascular pressure reactivity monitoring using wavelet analysis in traumatic brain injury patients: A retrospective study

et al. 2017

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“…7 However, depending on the nature of the pathology, this decrease in CPP can be somewhat compensated for by an active cerebral vasodilation such that CBF can be maintained despite decreases in CPP -a process known as cerebral autoregulation. [8][9][10][11] Recent studies indicate that the CBF response to a sustained decrease in CPP caused by a decrease in arterial blood pressure (ABP) or an increase in ICP has key physiological differences. [12][13][14] For example, Bragin et al 12,13 measured the cerebral haemodynamic response to sustained decrements of CPP (30 minutes at each level of ICP) and found when the decrease in CPP was brought about by an increased ICP, the lower limit of autoregulation was around 30 mm Hg, whereas with decreases in CPP brought about by a decreased ABP, the lower limit of autoregulation was around 50 mm Hg.…”

Section: Introductionmentioning

confidence: 99%

Cerebral haemodynamics during experimental intracranial hypertension

Donnelly

Czosnyka

Harland

et al. 2016

J Cereb Blood Flow Metab

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Intracranial hypertension is a common final pathway in many acute neurological conditions. However, the cerebral haemodynamic response to acute intracranial hypertension is poorly understood. We assessed cerebral haemodynamics (arterial blood pressure, intracranial pressure, laser Doppler flowmetry, basilar artery Doppler flow velocity, and vascular wall tension) in 27 basilar artery-dependent rabbits during experimental (artificial CSF infusion) intracranial hypertension. From baseline ($9 mmHg; SE 1.5) to moderate intracranial pressure ($41 mmHg; SE 2.2), mean flow velocity remained unchanged (47 to 45 cm/s; p ¼ 0.38), arterial blood pressure increased (88.8 to 94.2 mmHg; p < 0.01), whereas laser Doppler flowmetry and wall tension decreased (laser Doppler flowmetry 100 to 39.1% p < 0.001; wall tension 19.3 to 9.8 mmHg, p < 0.001). From moderate to high intracranial pressure ($75 mmHg; SE 3.7), both mean flow velocity and laser Doppler flowmetry decreased (45 to 31.3 cm/s p < 0.001, laser Doppler flowmetry 39.1 to 13.3%, p < 0.001), arterial blood pressure increased still further (94.2 to 114.5 mmHg; p < 0.001), while wall tension was unchanged (9.7 to 9.6 mmHg; p ¼ 0.35).This animal model of acute intracranial hypertension demonstrated two intracranial pressuredependent cerebroprotective mechanisms: with moderate increases in intracranial pressure, wall tension decreased, and arterial blood pressure increased, while with severe increases in intracranial pressure, an arterial blood pressure increase predominated. Clinical monitoring of such phenomena could help individualise the management of neurocritical patients.

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“…These relate closely to the four questions posed by Donnelly et al (2015): (1) what is it? These relate closely to the four questions posed by Donnelly et al (2015): (1) what is it?…”

Section: Cerebral Autoregulation Tomorrowmentioning

confidence: 78%

Cerebral Autoregulation

Payne

2016

SpringerBriefs in Bioengineering

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SpringerBriefs present concise summaries of cutting-edge research and practical applications across a wide spectrum of fields. Featuring compact volumes of 50 to 125 pages, the series covers a range of content from professional to academic. Typical topics might include: A timely report of state-of-the art analytical techniques, a bridge between new research results, as published in journal articles, and a contextual literature review, a snapshot of a hot or emerging topic, an in-depth case study, a presentation of core concepts that students must understand in order to make independent contributions.More information about this series at

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

Cited by 73 publications

References 106 publications

Cerebrovascular pressure reactivity monitoring using wavelet analysis in traumatic brain injury patients: A retrospective study

Cerebrovascular pressure reactivity monitoring using wavelet analysis in traumatic brain injury patients: A retrospective study

Cerebral haemodynamics during experimental intracranial hypertension

Cerebral Autoregulation

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