Noninvasive Monitoring of Cerebrovascular Reactivity with Near Infrared Spectroscopy in Head-Injured Patients

Zweifel, Christian; Castellani, Gianluca; Czosnyka, Marek; Helmy, Adel; Manktelow, Anne; Carrera, Emmanuel; Brady, Kenneth Martin; Hutchinson, Peter J.; Menon, David; Pickard, John D.; Smielewski, Peter

doi:10.1089/neu.2010.1388

Cited by 143 publications

(135 citation statements)

References 23 publications

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“…Functional MRI has shown NIRS measurement to be consistent with changes in deoxyhemoglobin concentration and regional cerebral blood volume [74]. The CBF autoregulation can be assessed using NIRS [75] and an NIRS-based autoregulation index, derived from ICP and blood pressure waveforms, has been developed [76]. Despite these validation studies, NIRS remains fundamentally limited in its application, since a small sample volume of the frontal cortex (1.5 cm 3 at a depth of 1.5 cm) is used to represent global cerebral perfusion.…”

Section: Principles Of Cerebral Oximetrymentioning

confidence: 99%

Effects of Positioning on Cerebral Oxygenation

Soeding

2013

Curr Anesthesiol Rep

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Postural change during anesthesia has a complex effect on the systemic and cerebral circulations which can potentially decrease cerebral blood flow and oxygenation. Cerebral oximetry is emerging as a monitor of cerebral perfusion with widespread application in many types of surgery. The technology is based on the differential absorption of oxygenated and deoxygenated hemoglobin to near-infrared light. However, the dynamic coupling that exists between cerebral arterial, venous and cerebrospinal fluid volumes may influence oximetric readings during postural change. Interpretation of cerebral oxygen saturation measurement must account for these changes in cerebral physiology if monitoring is to predict neurological outcome.

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Section: Principles Of Cerebral Oximetrymentioning

confidence: 99%

Effects of Positioning on Cerebral Oxygenation

Soeding

2013

Curr Anesthesiol Rep

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“…Some studies indicate a correlation between data from NIRS and TCD and suggest that NIRS may be more sensitive than TCD for detecting compromised cerebral oxygenation. 37,38 In patients with a new focal neurological deficit, NIRS detected decreased cerebral oxygenation in the affected region and a rise in oxygenation after treatment with an inotrope. 39,40 However, others have found no such correlation.…”

Section: Jugular Bulb Oximetrymentioning

confidence: 99%

Multimodal Monitoring in Subarachnoid Hemorrhage

Sandsmark

Kumar

Park

et al. 2012

Stroke

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In severely injured patients, the immediate goal of resuscitation is restoration and maintenance of adequate tissue metabolism by ensuring sufficient delivery of fuel, typically oxygen and glucose, to meet cellular metabolic demands. In neurocritical care, traditional goals of resuscitation-intracranial pressure (ICP), cerebral perfusion pressure (CPP), and the clinical examination-have been extrapolated from those of general critical care. These variables are analogous to central venous pressure, mean arterial pressure, and urine output and are similarly crude. These distant surrogates for cerebral perfusion do not account for dynamic changes in cerebral autoregulation, tissue metabolic rate, cellular fuel use, and microcirculatory dysfunction, all of which impact tissue metabolic health. Although standard, it seems intuitively obvious that a uniform approach of maintaining ICP Ͻ20 mm Hg and CPP Ͼ60 mm Hg is overly simplistic. This approach does not address either significant baseline differences in patient physiology nor the complex, dynamic, and variable pathophysiological changes that ensue after severe brain injury. A more tailored therapeutic strategy that responds to multiple simultaneously measured and more relevant physiological variables is logically appealing. Until recently, however, the requisite individual patient physiology was inaccessible at the bedside.The emergence of technology that allows for continuous real-time bedside monitoring of cerebral physiology marks a new era in neurocritical care. These monitors facilitate assessment of therapeutic efficacy and may provide more relevant physiological end points for resuscitation. Combining these monitors in a multimodal approach allows for the practice of goal-directed cerebral resuscitation that emphasizes the individual patient's unique neurological and systemic physiology.

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“…-PRx can be estimated noninvasively using near infrared spectroscopy. Total hemoglobin or hemoglobin volume correlated with ABP (with the same time averaging and correlating scales as for PRx), producing noninvasive equivalents of PRx: THx and HVx [16,20]. They allow calculation of 'optimal ABP,' so far used in cardiac surgery [2] and brain protection of preterm neonates [8].…”

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confidence: 99%

Pressure reactivity index: journey through the past 20 years

Czosnyka

Smielewski

2017

Acta Neurochir

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Autoregulation after traumatic brain injury can be monitored continuously using simple signal processing of intracranial pressure and arterial blood pressure. The pressure reactivity index (PRx) showed several benefits when it was applied to continuous brain monitoring. Among them, a positive and strong correlation with the outcome and possibility of calculation of 'optimal cerebral perfusion pressure' have been listed. For this methodology, prospective clinical trials are missing-few of them are planned in the near future.Keywords Traumatic brain injury . Intracranial pressure . Arterial blood pressure . Optimal cerebral perfusion pressureThe pressure-reactivity index was first described in 1995. Originally, we were inspired by the presentation of Erhard Lang and Randal Chestnut during the ICRAN conference at Gold Coast, Australia (1994). They reported that they could read a state of cerebral autoregulation from relative changes in mean arterial blood pressure (ABP) and intracranial pressure (ICP). They told us that it was enough to ask a research nurse to sit in front of a bedside monitor and instruct her to observe trends of ABP and ICP. The nurse needed to report when the values were changing in the same or opposite directions. When we arrived home, we programmed our computers, running ICM (intensive care monitor) software [7], to calculate a moving correlation coefficient from 30 consecutive 10-s averages of ICP and ABP waveforms. We called this the PRx index (pressure reactivity index) [6].The rationale for averaging ICP and ABP waveforms over 10 s was that only slow waves, of frequencies lower than 0.05 Hz, can carry information about autoregulation [11]. Simple averaging is a sufficient method of filtration of all faster components (mainly respiratory and pulsatile), which do not contain or contain only a little of any autoregulationrelated signatures.The rationale for calculating the correlation coefficient from 5-min-long buffers (30 samples of 10 s produce correlation window of 5 min) is that longer periods (e.g., 30 or 60 min) may include too many reactions to drugs, nursingrelated variations, metabolic reactions, etc. They are all not related to cerebral autoregulation and would produce distortion of the PRx.When a few years later a postgraduate student from S w i t ze r l an d , L uz i u s S t e i n er ( no w P r o f e s s o r o f Anaesthesiology at University of Basel), came to our Laboratory of Brain Physics in Cambridge, asking whether he could be given a PhD project on PRx, we first took it for a joke. However, over the next 3 years we were proven very wrong. Works of Luzius and other clinical neuroscientists who followed in his footsteps brought to light perhaps the most important advantage of PRx, its ability to guide the management of cerebral perfusion pressure. The concept was so simple to understand and so appealing in the clinical setting that many more people than we initially anticipated embraced it enthusiastically and developed it further.After 20 years, summarizing the mile...

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Noninvasive Monitoring of Cerebrovascular Reactivity with Near Infrared Spectroscopy in Head-Injured Patients

Cited by 143 publications

References 23 publications

Effects of Positioning on Cerebral Oxygenation

Effects of Positioning on Cerebral Oxygenation

Multimodal Monitoring in Subarachnoid Hemorrhage

Pressure reactivity index: journey through the past 20 years

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