Assessment of Cerebral Autoregulation Patterns with Near-infrared Spectroscopy during Pharmacological-induced Pressure Changes

Moerman, Annelies T.; Vanbiervliet, V; Wesemael, Astrid Van; Bouchez, Stefaan; Wouters, Patrick; Hert, Stefan De

doi:10.1097/aln.0000000000000715

Cited by 41 publications

(32 citation statements)

References 36 publications

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“…The cerebral oximetry index (COx), calculated as the Spearman's correlation coefficient between the MAP and the cerebral TOI, was used to quantify cerebral autoregulation [4][5][6][7][8][9]. Spinal cord autoregulation was quantified in a similar fashion to the COx, by calculating the thoracic or lumbar spinal cord oximetry index (T-SOx or L-SOx, respectively).…”

Section: Assessment Of Cerebral and Spinal Cord Autoregulationmentioning

confidence: 99%

“…The central nervous system (CNS) is thought to exhibit robust autoregulation to maintain adequate blood flow [1][2][3]. Recently, cerebral autoregulation was evaluated using nearinfrared spectroscopy (NIRS) in several studies [4][5][6][7][8][9], which treated cerebral oxygenation as a surrogate indicator of cerebral blood flow. NIRS estimates mixed tissue hemoglobin oxygen saturation levels of the arterial, venous, and capillary blood within the field of view [10,11], which allows the oxygen supply-and-demand balance to be evaluated under differing conditions.…”

Section: Introductionmentioning

confidence: 99%

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Spinal cord autoregulation using near-infrared spectroscopy under normal, hypovolemic, and post-fluid resuscitation conditions in a swine model: a comparison with cerebral autoregulation

et al. 2020

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Background: Few studies have investigated spinal cord autoregulation using near-infrared spectroscopy (NIRS). Here, we assessed spinal cord autoregulation under normal, hypovolemic, and post-fluid resuscitation conditions compared with cerebral autoregulation. Methods: Ten pigs (36.1 ± 1.1 kg) were anesthetized with 2.5% isoflurane, before phenylephrine administration at 0.5, 1, 2, and 5 μg kg −1 min −1 in a stepwise fashion at 10-min intervals (baseline), followed by similar administration of sodium nitroprusside (SNP). Hypovolemia was induced by a 600-ml bleed (25% estimated total blood volume). Only phenylephrine was readministered (same protocol). Hypovolemia was reversed by infusing 600 ml hydroxyethyl starch, before readministering phenylephrine and SNP. The relationships between mean arterial pressure (MAP) and cerebral, thoracic, and lumbar spinal cord tissue oxygenation indices (TOIs) were evaluated. Results: Thoracic and lumbar spinal cord TOIs were approximately 15% and 10% lower, respectively, than the cerebral TOI at similar MAPs. The average relationship between MAP and each TOI showed an autoregulatory pattern, but negative correlations were observed in the cerebral TOI during phenylephrine infusion. A 600-ml bleed lowered each relationship < 5% and subsequent fluid resuscitation did not change the relationship. Individual oxygenation responses to blood pressure indicated that the spinal cord is more pressure-passive than the cerebrum. Paradoxical responses (an inverse relationship of tissue oxygenation to MAP) were observed particularly in cerebrum during phenylephrine infusion and were rare in the spinal cord.Conclusions: Spinal cord autoregulation is less robust than cerebral autoregulation and more pressure-dependent. Similar to cerebral oxygenation, spinal cord oxygenation is volume-tolerant but is more sensitive to hypotension.

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Section: Assessment Of Cerebral and Spinal Cord Autoregulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spinal cord autoregulation using near-infrared spectroscopy under normal, hypovolemic, and post-fluid resuscitation conditions in a swine model: a comparison with cerebral autoregulation

et al. 2020

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“…The propofol/remifentanil protocol was as our current practice, aiming at a quick reversal of anaesthesia to help postoperative neurological assessment, but hypotension occurred at least once in each of the included patients. Although there is no consensual trigger to treat intraoperative hypotension by vasopressors, mean arterial pressure (MAP) was currently considered in the literature, with threshold values either of 60 mm Hg, or 70%‐to‐90% of baseline . MAP values below 70% of baseline and 55 mm Hg are possible risk factors respectively for ischaemic stroke, and for renal/myocardial injury in non‐cardiac/non‐neurosurgical surgery .…”

Section: Discussionmentioning

confidence: 99%

“…Although there is no consensual trigger to treat intraoperative hypotension by vasopressors, mean arterial pressure (MAP) was currently considered in the literature, with threshold values either of 60 mm Hg, 5,6,12 or 70%-to-90% of baseline. 6,[13][14][15][16] MAP values below 70% of baseline and 55 mm Hg are possible risk factors respectively for ischaemic stroke, 17 and for renal/myocardial injury in non-cardiac/nonneurosurgical surgery. 18 During CEA, a target between baseline values and 20% above baseline has been suggested in a review; 4 this trigger was used in the abovementioned observational study during CEA.…”

Section: Discussionmentioning

confidence: 99%

Compared effects on cerebral oxygenation of ephedrine vs phenylephrine to treat hypotension during carotid endarterectomy

Aliane

Dualé

Guesmi

et al. 2017

Clin Exp Pharma Physio

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While both ephedrine and phenylephrine are currently used to treat hypotension occurring during carotid endarterectomy (CEA) under general anaesthesia, phenylephrine may have deleterious effects on the cerebral watershed, due to its exclusively vasoconstrictive action. In this controlled, double-blind randomised trial, we compared the effects of ephedrine and phenylephrine administered in a standardised algorithm to treat the first hypotensive event occurring since induction of anaesthesia until carotid cross-clamping. The algorithm consisted of 1-to-3 boluses of 6 mg of ephedrine or 50 μg of phenylephrine, after a goal-directed fluid therapy. In case of failure, the treatment switched to the other study drug. Cerebral tissue oxygen saturation (SctO ) was monitored by near infrared spectroscopy (NIRS), and the primary outcome was the restoring effect of SctO (ipsilateral to surgery) to baseline values. Secondary postoperative outcomes were: contralateral SctO , neurological outcomes, and plasma S100B protein measured at discharge from post-anaesthesia care unit. Ephedrine treatment provided a higher rate of restoration of ipsilateral SctO than phenylephrine (93.2% vs 85.1%, P=.034); this was also noted for contralateral SctO (93.5% vs 90.7%, P=.026). The gain in SctO on the lowest value during hypotension was also higher under ephedrine than phenylephrine (6.4% vs 4.3% ipsilateral, 5.1% vs 4% contralateral), but not significantly so. Clinical outcomes were unaffected by the treatment, but S100B protein plasma concentration was higher in the phenylephrine group. To conclude, this pilot trial, focusing on intermediate outcomes, suggests that ephedrine should be preferred to phenylephrine to treat hypotension during CEA.

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“…Although we have considered the case where the intact region displays a positive slope and is therefore a confounder to the traditional correlation-based COx approach, it should be noted that distinct (paradoxical) negative slopes have also been observed in intact regions [26] for cardiac surgery patients. In this instance, the traditional COx method will tend to produce values at +1 and −1 for the impaired and intact regions respectively and hence the gradient adjustment method described here would not be necessary (although it could still prove useful in accentuating the difference in noisy data).…”

Section: Discussionmentioning

confidence: 99%

Gradient adjustment method for better discriminating correlating and non-correlating regions of physiological signals: application to the partitioning of impaired and intact zones of cerebral autoregulation

Addison

Antunes

Montgomery

et al. 2016

J Clin Monit Comput

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Cerebral blood flow (CBF) is regulated over a range of systemic blood pressures by the cerebral autoregulation (CA) control mechanism. This range lies within the lower and upper limits of autoregulation (LLA, ULA), beyond which blood pressure drives CBF, and CA function is considered impaired. A standard method to determine autoregulation limits noninvasively using NIRS technology is via the COx measure: a moving correlation index between mean arterial pressure and regional oxygen saturation. In the intact region, there should be no correlation between these variables whereas in the impaired region, the correlation index should approximate unity. In practice, however, the data may be noisy and/or the intact region may often exhibit a slightly positive relationship. This positive relationship may render traditional autoregulation limit calculations difficult to perform, resulting in the need for manual interpretation of the data using arbitrary thresholds. Further, the underlying mathematics of the technique are asymmetric in terms of the results produced for impaired and intact regions and are, in fact, not computable for the ideal case within the intact region. In this work, we propose a novel gradient adjustment method (GACOx) to enhance the differences in COx values observed in the intact and impaired regions. Results from a porcine model (N = 8) are used to demonstrate that GACOx is successful in determining LLA values where traditional methods fail. It is shown that the derived GACOx indices exhibit a mean difference between the intact/impaired regions of 1.54 ± 0.26 (mean ± SD), compared to 0.14 ± 0.10 for the traditional COx method. The GACOx effectively polarizes the COx data in order to better differentiate the intact and impaired zones and, in doing so, makes the determination of the LLA and ULA points a simpler and more consistent task. The method lends itself to the automation of the robust determination of autoregulation zone limits.

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Assessment of Cerebral Autoregulation Patterns with Near-infrared Spectroscopy during Pharmacological-induced Pressure Changes

Abstract: In this study, paradoxical changes in ScO2 after pharmacological-induced pressure changes occurred exclusively in patients with intact cerebral autoregulation, corroborating the hypothesis that these paradoxical responses might be attributable to a functional cerebral autoregulation.

Cited by 41 publications

References 36 publications

Spinal cord autoregulation using near-infrared spectroscopy under normal, hypovolemic, and post-fluid resuscitation conditions in a swine model: a comparison with cerebral autoregulation

Spinal cord autoregulation using near-infrared spectroscopy under normal, hypovolemic, and post-fluid resuscitation conditions in a swine model: a comparison with cerebral autoregulation

Compared effects on cerebral oxygenation of ephedrine vs phenylephrine to treat hypotension during carotid endarterectomy

Gradient adjustment method for better discriminating correlating and non-correlating regions of physiological signals: application to the partitioning of impaired and intact zones of cerebral autoregulation

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