Extra‐cerebral oxygenation influence on near‐infrared‐spectroscopy‐determined frontal lobe oxygenation in healthy volunteers: a comparison between <scp>INVOS</scp>‐4100 and <scp>NIRO</scp>‐200<scp>NX</scp>

Sørensen, Henrik; Rasmussen, Peter; Siebenmann, Christoph; Zaar, Morten; Hvidtfeldt, Morten; Ogoh, Shigehiko; Sato, Kohei; Kohl‐Bareis, Matthias; Secher, Niels H.; Lundby, Carsten

doi:10.1111/cpf.12142

Cited by 36 publications

(25 citation statements)

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“…This interpretation should be experimentally quantified during LBNP with direct measures of oxygen extraction via arterialjugular venous oxygen measurements across the brain, and direct assessment of CBF [e.g., via duplex Doppler ultrasound of the extracranial vessels (46)]. Additionally, NIRS is a noninvasive method to obtain measurements of ScO 2 , and concentrations of HbO 2 and dHb within the cerebral tissue, but it also may be contaminated by changes in oxygenation of the skin (11,18,41,42). For this study, we used a spatially resolved NIRS device with four emitters that were 2.0, 2.5, 3.0, and 3.5 cm from the detector, compared with only two emitters on many other NIRS devices.…”

Section: Discussionmentioning

confidence: 99%

The role of cerebral oxygenation and regional cerebral blood flow on tolerance to central hypovolemia

Kay

Rickards

2016

American Journal of Physiology-Regulatory, Integrative and Comp

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Kay VL, Rickards CA. The role of cerebral oxygenation and regional cerebral blood flow on tolerance to central hypovolemia. Am J Physiol Regul Integr Comp Physiol 310: R375-R383, 2016. First published December 16, 2015 doi:10.1152/ajpregu.00367.2015Tolerance to central hypovolemia is highly variable, and accumulating evidence suggests that protection of anterior cerebral blood flow (CBF) is not an underlying mechanism. We hypothesized that individuals with high tolerance to central hypovolemia would exhibit protection of cerebral oxygenation (ScO2), and prolonged preservation of CBF in the posterior vs. anterior cerebral circulation. Eighteen subjects (7 male/11 female) completed a presyncope-limited lower body negative pressure (LBNP) protocol (3 mmHg/min onset rate). ScO2 (via near-infrared spectroscopy), middle cerebral artery velocity (MCAv), posterior cerebral artery velocity (PCAv) (both via transcranial Doppler ultrasound), and arterial pressure (via finger photoplethysmography) were measured continuously. Subjects who completed Ն70 mmHg LBNP were classified as high tolerant (HT; n ϭ 7) and low tolerant (LT; n ϭ 11) if they completed Յ60 mmHg LBNP. The minimum difference in LBNP tolerance between groups was 193 s (LT ϭ 1,243 Ϯ 185 s vs. HT ϭ 1,996 Ϯ 212 s; P Ͻ 0.001; Cohen's d ϭ 3.8). Despite similar reductions in mean MCAv in both groups, ScO2 decreased in LT subjects from Ϫ15 mmHg LBNP (P ϭ 0.002; Cohen's dϭ1.8), but was maintained at baseline values until Ϫ75 mmHg LBNP in HT subjects (P Ͻ 0.001; Cohen's d ϭ 2.2); ScO2 was lower at Ϫ30 and Ϫ45 mmHg LBNP in LT subjects (P Յ 0.02; Cohen's d Ն 1.1). Similarly, mean PCAv decreased below baseline from Ϫ30 mmHg LBNP in LT subjects (P ϭ 0.004; Cohen's d ϭ 1.0), but remained unchanged from baseline in HT subjects until Ϫ75 mmHg (P ϭ 0.006; Cohen's d ϭ 2.0); PCAv was lower at Ϫ30 and Ϫ45 mmHg LBNP in LT subjects (P Յ 0.01; Cohen's d Ն 0.94). Individuals with higher tolerance to central hypovolemia exhibit prolonged preservation of CBF in the posterior cerebral circulation and sustained cerebral tissue oxygenation, both associated with a delay in the onset of presyncope.posterior cerebral artery; middle cerebral artery; lower body negative pressure HEMORRHAGE DUE TO TRAUMA IS one of the leading causes of morbidity and mortality worldwide in both the civilian and military settings (1, 2, 13, 22, 32). A major factor contributing to death and disability from severe blood loss is poor tissue perfusion and oxygenation of the vital organs (1, 13, 22). Prolonged cerebral hypoperfusion can lead to neuronal cell death, and if the patient survives, long-term cognitive impairment and physical disability (32). Understanding cerebral hemodynamic responses to blood loss is an essential target for improving survival to hemorrhagic injury, and developing effective therapeutic interventions (35). As there is considerable variability in survival time following hemorrhagic injuries (40), as well as tolerance to simulated hemorrhage (7,15,24,26), it is crucial to determine the rol...

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Section: Discussionmentioning

confidence: 99%

The role of cerebral oxygenation and regional cerebral blood flow on tolerance to central hypovolemia

Kay

Rickards

2016

American Journal of Physiology-Regulatory, Integrative and Comp

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“…The pigs were placed prone. A wide portion of the parietal scalp region was removed to avoid contamination by extracranial blood [24][25][26][27], and one NIRS probe (NIRO-200; Hamamatsu Photonics, Hamamatsu, Japan) was placed on the center of the parietal skull ( Fig. 1a).…”

Section: Animal Preparationmentioning

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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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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“…Recently, NIRS has been introduced as a method to evaluate cerebral autoregulation noninvasively. We reason that if other causes such as direct pharmacological effects of the vasoactive agents, extracranial contamination of the NIRS signal, [26][27][28][29][30] or patient-related or intraoperative confounders would be accountable for the paradoxical reactions, those reactions would have occurred in every patient. 11,[15][16][17][18]25 Especially when autoregulation is determined during rapid blood pressure changes induced by intravenous boluses of vasoactive agents, S c O 2 changes other than those because of CBF changes (change in hemoglobin, temperature, and others) are considered to be negligible.…”

Section: Divergent Effects Of Phenylephrine and Snp On Cox (18%)mentioning

confidence: 99%

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

et al. 2015

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Extra‐cerebral oxygenation influence on near‐infrared‐spectroscopy‐determined frontal lobe oxygenation in healthy volunteers: a comparison between INVOS‐4100 and NIRO‐200NX

Cited by 36 publications

References 32 publications

The role of cerebral oxygenation and regional cerebral blood flow on tolerance to central hypovolemia

The role of cerebral oxygenation and regional cerebral blood flow on tolerance to central hypovolemia

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

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

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