Noninvasive Cerebrovascular Autoregulation Assessment in Traumatic Brain Injury: Validation and Utility

Lang, E; Lagopoulos, Jim; Griffith, Jane; Yip, Kwok; Mudaliar, Yugan; Mehdorn, H. Maximilian; Dorsch, Nicholas W.C.

doi:10.1089/08977150360517191

Cited by 76 publications

(53 citation statements)

References 26 publications

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“…Indeed, the role of ICP in the assessment of dynamic AR remains controversial. However, the three studies comparing dynamic AR determination by CPP or by MABP found significant agreement between both methods (26,36,37). These results support the notion that MABP may reliably replace CPP or ICP for noninvasive assessment of dynamic AR.…”

Section: Discussionmentioning

confidence: 62%

Rapid Assessment of Cerebral Autoregulation by Near-Infrared Spectroscopy and a Single Dose of Phenylephrine

et al. 2011

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Rapid bedside determination of cerebral blood pressure autoregulation (AR) may improve clinical utility. We tested the hypothesis that cerebral Hb oxygenation (Hb Diff ) and cerebral Hb volume (Hb Total ) measured by near-infrared spectroscopy (NIRS) would correlate with cerebral blood flow (CBF) after single dose phenylephrine (PE). Critically ill patients requiring artificial ventilation and arterial lines were eligible. During rapid blood pressure rise induced by i.v. PE bolus, ⌬Hb Diff and ⌬Hb Total were calculated by subtracting values at baseline (normotension) from values at peak blood pressure elevation (hypertension). With the aid of NIRS and bolus injection of indocyanine green, relative measures of CBF, called blood flow index (BFI), were determined during normotension and during hypertension. BFI during hypertension was expressed as percentage from BFI during normotension (BFI%). Autoregulation indices (ARIs) were calculated by dividing BFI%, ⌬Hb Diff , and ⌬Hb Total by the concomitant change in blood pressure. In 24 patients (11 newborns and 13 children), significant correlations between BFI% and ⌬Hb Diff (or ⌬Hb Total ) were found. In addition, the associations between Hb-based ARI and BFI%-based ARI were significant with correlation coefficients of 0.73 (or 0.72). Rapid determination of dynamic AR with the aid of cerebral Hb signals and PE bolus seems to be reliable. (Pediatr Res 69: 436-441, 2011) I ntact cerebral blood pressure autoregulation (AR) describes the intrinsic ability of the brain to maintain cerebral blood flow (CBF) during changes in cerebral perfusion pressure. Diverse factors, such as age of patient, illness, injury, or vasoactive drugs, have been found to impair this ability-often to an unpredictable extent. Patients with impaired or even absent AR are at increased risk for inadequate CBF and consequently for cerebral ischemia. Measuring AR may provide clinically useful information and permit more individualized critical care. Several recent studies have demonstrated the potential of so-called dynamic AR to predict outcome in adult (1) or pediatric TBI (2) and in premature infants (3). In addition, monitoring of dynamic AR may allow determination of optimal cerebral perfusion pressure (4) and determination of treatment efficacy in controlling intracranial pressure (ICP) after head injury (5). Finally, AR-guided treatment of cerebral perfusion pressure in patients suffering severe head trauma carries the potential to improve outcome (6) and has therefore been recommended in the new adult guidelines (7). Nevertheless, further work is needed to delineate the clinical utility of AR determination in critical illness, especially for the child and newborn.Determination of the classic, steady state (or static) AR in intensive care medicine remains cumbersome and time consuming. In contrast, determination of the short-latency cerebrovascular response (or dynamic AR) to rapid perfusion pressure changes has been shown to be easily performed at the bedside and allows for repetitive...

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Section: Discussionmentioning

confidence: 62%

Rapid Assessment of Cerebral Autoregulation by Near-Infrared Spectroscopy and a Single Dose of Phenylephrine

et al. 2011

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“…' Lang et al (2003) showed that this index is valid if BP is used instead of cerebral perfusion pressure in these patients. This obviates the need for the invasive measurement techniques to determine intracranial pressure.…”

Section: Correlation Indexmentioning

confidence: 97%

Cerebral Autoregulation: An Overview of Current Concepts and Methodology with Special Focus on the Elderly

Beek

Claassen

Rikkert

et al. 2008

J Cereb Blood Flow Metab

418

372

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Cerebral autoregulation (CA) refers to the properties of the brain vascular bed to maintain cerebral perfusion despite changes in blood pressure (BP). Whereas classic studies have assessed CA during changes in BP that have a gradual onset, dynamic studies quantify the fast modifications in cerebral blood flow (CBF) in relation to rapid alterations in BP. There is a lack of standardization in the assessment of dynamic CA. This review provides an overview of the methods that have been applied, with special focus on the elderly. We will discuss the relative merits and shortcomings of these methods with regard to the aged population. Furthermore, we summarize the effects of variability in BP on CBF in older people. Of the various dynamic assessments of CA, a single sit-tostand procedure is a feasible and physiologic method in the elderly. The collection of spontaneous beat-to-beat changes in BP and CBF allows estimation of CA using the technique of transfer function analysis. A thorough search of the literature yielded eight studies that have measured dynamic CA in the elderly aged < 75 years. Regardless of the methods used, it was concluded from these studies that CA was preserved in this population.

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“…Intact, partially impaired, or completely disrupted cerebral autoregulation has been reported, and various degrees of impairment have prognostic relevance. 1, 3,13,17,25,32 The pressure reactivity index (PRx), which is an index calculated from a moving correlation coefficient between mean ABP and ICP, has gained wide acceptance in ICU settings, and it has generated a large number of publications.…”

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confidence: 99%

“…2, 3,14,17,[27][28][29] It is clinically most attractive because it does not require an external stimulus or patient manipulation, and routinely monitored data can be used for clinical research. The PRx has been reported to correlate with outcome after traumatic brain injury (TBI), 14,17 and it is used for online calculation of the optimal cerebral perfusion pressure (CPPopt).…”

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confidence: 99%

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Short pressure reactivity index versus long pressure reactivity index in the management of traumatic brain injury

Lang

Kasprowicz

Smielewski

et al. 2015

JNS

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A rteriAl blood pressure (ABP), intracranial pressure (ICP), cerebral blood flow velocity measured with transcranial Doppler ultrasonography, and cerebral microcirculation assessed by laser Doppler flow are periodical biological signals that can be continuously monitored and recorded in both routine and ICU settings by using invasive and noninvasive techniques and devices. 5,12,16,30,32 These biological signals will show frequency peaks within certain frequency bands.6,11 They can be categorized into two groups: 1) the B waves that occur at approximately 0.5-3 cycles per minute, which corresponds to a frequency of 0.008-0.05 Hz;5,16,23 and 2) M waves, which occur at approximately 4-9 cycles per minute, which corresponds to a frequency of 0.07-0.15 Hz. 7,12,22 The 6 ventiabbreviatioNs ABP = arterial blood pressure; CPPopt = optimal cerebral perfusion pressure; GCS = Glasgow Coma Scale; GOS = Glasgow Outcome Scale; ICP = intracranial pressure; IQR = interquartile range; L-PRx = long pressure reactivity index; PVS = persistent vegetative state; TBI = traumatic brain injury. obJect The pressure reactivity index (PRx) correlates with outcome after traumatic brain injury (TBI) and is used to calculate optimal cerebral perfusion pressure (CPPopt). The PRx is a correlation coefficient between slow, spontaneous changes (0.003-0.05 Hz) in intracranial pressure (ICP) and arterial blood pressure (ABP). A novel index-the so-called long PRx (L-PRx)-that considers ABP and ICP changes (0.0008-0.008 Hz) was proposed. methods The authors compared PRx and L-PRx for 6-month outcome prediction and CPPopt calculation in 307 patients with TBI. The PRx- and L-PRx-based CPPopt were determined and the predictive power and discriminant abilities were compared. results The PRx and L-PRx correlation was good (R = 0.7, p < 0.00001; Spearman test). The PRx, age, CPP, and Glasgow Coma Scale score but not L-PRx were significant fatal outcome predictors (death and persistent vegetative state). There was a significant difference between the areas under the receiver operating characteristic curves calculated for PRx and L-PRx (0.61 ± 0.04 vs 0.51 ± 0.04; z-statistic = -3.26, p = 0.011), which indicates a better ability by PRx than L-PRx to predict fatal outcome. The CPPopt was higher for L-PRx than for PRx, without a statistical difference (median CPPopt for L-PRx: 76.9 mm Hg, interquartile range [IQR] ± 10.1 mm Hg; median CPPopt for PRx: 74.7 mm Hg, IQR ± 8.2 mm Hg). Death was associated with CPP below CPPopt for PRx (c 2 = 30.6, p < 0.00001), and severe disability was associated with CPP above CPPopt for PRx (c 2 = 7.8, p = 0.005). These relationships were not statistically significant for CPPopt for L-PRx. coNclusioNs The PRx is superior to the L-PRx for TBI outcome prediction. Individual CPPopt for L-PRx and PRx are not statistically different. Deviations between CPP and CPPopt for PRx are relevant for outcome prediction; those between CPP and CPPopt for L-PRx are not. The PRx uses the entire B-wave spectrum for index calculation, whereas the ...

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Noninvasive Cerebrovascular Autoregulation Assessment in Traumatic Brain Injury: Validation and Utility

Cited by 76 publications

References 26 publications

Rapid Assessment of Cerebral Autoregulation by Near-Infrared Spectroscopy and a Single Dose of Phenylephrine

Rapid Assessment of Cerebral Autoregulation by Near-Infrared Spectroscopy and a Single Dose of Phenylephrine

Cerebral Autoregulation: An Overview of Current Concepts and Methodology with Special Focus on the Elderly

Short pressure reactivity index versus long pressure reactivity index in the management of traumatic brain injury

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