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Nguyen TN, Wu W, Woldermichael E, Toronov V, Lin S. Hyperspectral near-infrared spectroscopy assessment of the brain during hypoperfusion. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-6. [PMID: 30877717 PMCID: PMC6975180 DOI: 10.1117/1.jbo.24.3.035007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 01/23/2019] [Indexed: 05/10/2023]
Abstract
Two-thirds of out-of-hospital cardiac arrest patients, who survive to hospital admission, die in the hospital from neurological injuries related to cerebral hypoperfusion. Therefore, noninvasive real-time monitoring of the cerebral oxygen metabolism in cardiac arrest patients is extremely important. Hyperspectral near-infrared spectroscopy (hNIRS) is a noninvasive technique that measures concentrations of the key chromophores in the brain, such as oxygenated hemoglobin, deoxygenated hemoglobin, and cytochrome C oxidase (CCO), an intracellular marker of oxygen consumption. We tested hNIRS on 10 patients undergoing transcatheter aortic valve insertion, where rapid ventricular pacing (RVP) is required to temporarily induce sudden hypotension and hypoperfusion that mimic cardiac arrest. Using multidistance hNIRS, we found that tissue oxygen saturation changes in the cerebral tissue were lower than those in the scalp during RVP. CCO redox changes were detected in cerebral tissue but not in the scalp during RVP. We have demonstrated that hNIRS is feasible and can detect sudden changes in cerebral oxygenation and metabolism in patients during profound hypotension.
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Affiliation(s)
- Thu Nga Nguyen
- Ryerson University, Faculty of Science, Department of Physics, Toronto, Ontario, Canada
- Address all correspondence to Thu Nga Nguyen, E-mail:
| | - Wen Wu
- St. Michael’s Hospital, Li Ka Shing Knowledge Institute, Toronto, Ontario, Canada
- University of Toronto, Department of Medicine, Toronto, Ontario, Canada
| | - Ermias Woldermichael
- Ryerson University, Faculty of Science, Department of Physics, Toronto, Ontario, Canada
| | - Vladislav Toronov
- Ryerson University, Faculty of Science, Department of Physics, Toronto, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology, Toronto, Ontario, Canada
| | - Steve Lin
- St. Michael’s Hospital, Li Ka Shing Knowledge Institute, Toronto, Ontario, Canada
- University of Toronto, Department of Medicine, Toronto, Ontario, Canada
- Institute for Biomedical Engineering, Science and Technology, Toronto, Ontario, Canada
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Harms F, Stolker RJ, Mik E. Cutaneous Respirometry as Novel Technique to Monitor Mitochondrial Function: A Feasibility Study in Healthy Volunteers. PLoS One 2016; 11:e0159544. [PMID: 27455073 PMCID: PMC4959702 DOI: 10.1371/journal.pone.0159544] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 07/04/2016] [Indexed: 01/16/2023] Open
Abstract
Background The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) is proposed as a potential clinical non-invasive tool to monitor mitochondrial function. This technique has been evaluated in several animal studies. Mitochondrial respirometry allows measurement in vivo of mitochondrial oxygen tension (mitoPO2) and mitochondrial oxygen consumption (mitoVO2) in skin. This study describes the first use of a clinical prototype in skin of humans. Methods The clinical prototype was tested in 30 healthy volunteers. A self-adhesive patch containing 2 mg 5-aminolevulinic acid (ALA) was applied on the skin of the anterior chest wall (sternal) for induction of mitochondrial protoporphyrin IX and was protected from light for 5 h. MitoPO2 was measured by means of oxygen-dependent delayed fluorescence of protoporphyrin IX. MitoVO2 was determined by dynamic mitoPO2 measurements on the primed skin, while locally blocking oxygen supply by applying local pressure with the measurement probe. MitoPO2 was recorded before and during a 60-s period of compression of the microcirculation, at an interval of 1 Hz. Oxygen consumption (i.e. the local oxygen disappearance rate) was calculated from the decay of the mitoPO2 slope. Results Oxygen-dependent delayed fluorescence measurements were successfully performed in the skin of 27 volunteers. The average value (± SD) of mitoPO2 was 44 ± 17 mmHg and mean mitoVO2 values were 5.8 ± 2.3 and 6.1 ± 1.6 mmHg s-1 at a skin temperature of 34°C and 40°C, respectively. No major discomfort during measurement and no long-term dermatological abnormalities were reported in a survey performed 1 month after measurements. Conclusion These results show that the clinical prototype allows measurement of mitochondrial oxygenation and oxygen consumption in humans. The development of this clinically applicable device offers opportunities for further evaluation of the technique in humans and the start of first clinical studies.
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Affiliation(s)
- Floor Harms
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
- * E-mail:
| | - Robert Jan Stolker
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
| | - Egbert Mik
- Department of Anesthesiology, Laboratory of Experimental Anesthesiology, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
- Department of Intensive Care, Erasmus University Medical Center Rotterdam, ‘s-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
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Rackebrandt K, Gehring H. Calibration and evaluation of a continuous wave multi-distance NIRS system in simulated desaturation investigations. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/3/035017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Mitra S, Bale G, Mathieson S, Uria-Avellanal C, Meek J, Tachtsidis I, Robertson NJ. Changes in Cerebral Oxidative Metabolism during Neonatal Seizures Following Hypoxic-Ischemic Brain Injury. Front Pediatr 2016; 4:83. [PMID: 27559538 PMCID: PMC4978952 DOI: 10.3389/fped.2016.00083] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/27/2016] [Indexed: 01/01/2023] Open
Abstract
Seizures are common following hypoxic-ischemic brain injury in newborn infants. Prolonged or recurrent seizures have been shown to exacerbate neuronal damage in the developing brain; however, the precise mechanism is not fully understood. Cytochrome-c-oxidase is responsible for more than 90% of ATP production inside mitochondria. Using a novel broadband near-infrared spectroscopy system, we measured the concentration changes in the oxidation state of cerebral cytochrome-c-oxidase (Δ[oxCCO]) and hemodynamics during recurrent neonatal seizures following hypoxic-ischemic encephalopathy in a newborn infant. A rapid increase in Δ[oxCCO] was noted at the onset of seizures along with a rise in the baseline of amplitude-integrated electroencephalogram. Cerebral oxygenation and cerebral blood volume fell just prior to the seizure onset but recovered rapidly during seizures. Δ[oxCCO] during seizures correlated with changes in mean electroencephalogram voltage indicating an increase in neuronal activation and energy demand. The progressive decline in the Δ[oxCCO] baseline during seizures suggests a progressive decrease of mitochondrial oxidative metabolism.
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Affiliation(s)
- Subhabrata Mitra
- Department of Neonatology, Institute for Women's Health, University College London , London , UK
| | - Gemma Bale
- Department of Medical Physics and Biomedical Engineering, University College London , London , UK
| | - Sean Mathieson
- Department of Neonatology, Institute for Women's Health, University College London , London , UK
| | - Cristina Uria-Avellanal
- Department of Neonatology, Institute for Women's Health, University College London , London , UK
| | - Judith Meek
- Department of Neonatology, Institute for Women's Health, University College London , London , UK
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London , London , UK
| | - Nicola J Robertson
- Department of Neonatology, Institute for Women's Health, University College London , London , UK
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Caldwell M, Hapuarachchi T, Highton D, Elwell C, Smith M, Tachtsidis I. BrainSignals Revisited: Simplifying a Computational Model of Cerebral Physiology. PLoS One 2015; 10:e0126695. [PMID: 25961297 PMCID: PMC4427507 DOI: 10.1371/journal.pone.0126695] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 04/07/2015] [Indexed: 02/06/2023] Open
Abstract
Multimodal monitoring of brain state is important both for the investigation of healthy cerebral physiology and to inform clinical decision making in conditions of injury and disease. Near-infrared spectroscopy is an instrument modality that allows non-invasive measurement of several physiological variables of clinical interest, notably haemoglobin oxygenation and the redox state of the metabolic enzyme cytochrome c oxidase. Interpreting such measurements requires the integration of multiple signals from different sources to try to understand the physiological states giving rise to them. We have previously published several computational models to assist with such interpretation. Like many models in the realm of Systems Biology, these are complex and dependent on many parameters that can be difficult or impossible to measure precisely. Taking one such model, BrainSignals, as a starting point, we have developed several variant models in which specific regions of complexity are substituted with much simpler linear approximations. We demonstrate that model behaviour can be maintained whilst achieving a significant reduction in complexity, provided that the linearity assumptions hold. The simplified models have been tested for applicability with simulated data and experimental data from healthy adults undergoing a hypercapnia challenge, but relevance to different physiological and pathophysiological conditions will require specific testing. In conditions where the simplified models are applicable, their greater efficiency has potential to allow their use at the bedside to help interpret clinical data in near real-time.
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Affiliation(s)
- Matthew Caldwell
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Tharindi Hapuarachchi
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology, University College London, London, UK
| | - David Highton
- Neurocritical Care Unit, University College Hospitals, London, UK
| | - Clare Elwell
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Martin Smith
- Neurocritical Care Unit, University College Hospitals, London, UK
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
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Svenmarker S, Häggmark S, Johansson G, Axelsson B, Wiklund U, Haney M. Regional changes in cerebral blood flow oxygenation can indicate global changes in cerebral blood flow during coronary artery occlusion in juvenile pigs. Physiol Meas 2014; 35:1439-50. [PMID: 24901340 DOI: 10.1088/0967-3334/35/7/1439] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Near infrared spectroscopy (NIRS) is a widely employed method for assessment of regional cerebral oxygenation (RcStO2). RcStO2 values are expected to vary with changes in the relative amount of oxyhaemoglobin. The present experimental study aimed to assess the response of RcStO2 to controlled alterations of carotid blood flow (CQ). Landrace pigs were anesthetized followed by surgical preparation. Cyclic variations in cardiac output were accomplished by intermittently occluding the main stem of the left coronary artery. A flow measurement probe for assessing CQ was placed around the left carotid artery. One NIRS probe was placed on the left ipsilateral forehead to assess regional cerebral oximetry. Simultaneous registration of CQ and RcStO2 was conducted. There was a strong correlation for variation in CQ and RcStO2 signal values. Based on coherence analysis the fraction of power of the RcStO2 that was coherent with the CQ signal reached 0.84 ± 0.12 (P < 0.05) for frequencies lower than 0.1 Hz. The agreement of the sample-to-sample co-variation, as assessed by the Pearson correlation coefficient, was 0.83 ± 0.08 (P < 0.05). One explanatory component for variations in cerebral oxygenation verified by NIRS should be attributed to variations in the cerebral blood flow.
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Affiliation(s)
- S Svenmarker
- Department of Surgical and Perioperative Sciences, Heart Centre, Umeå University, SE-901 85 Umeå, Sweden
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8
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Monitoring cerebral oxygenation during balloon occlusion with multichannel NIRS. J Cereb Blood Flow Metab 2014; 34:347-56. [PMID: 24301292 PMCID: PMC3915216 DOI: 10.1038/jcbfm.2013.207] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 10/25/2013] [Accepted: 10/30/2013] [Indexed: 01/22/2023]
Abstract
We report on oxygenation changes noninvasively recorded by multichannel continuous-wave near infrared spectroscopy (CW-NIRS) during endovascular neuroradiologic interventions requiring temporary balloon occlusion of arteries supplying the cerebral circulation. Digital subtraction angiography (DSA) provides reference data on the site, timing, and effectiveness of the flow stagnation as well as on the amount and direction of collateral circulation. This setting allows us to relate CW-NIRS findings to brain specific perfusion changes. We focused our analysis on the transition from normal perfusion to vessel occlusion, i.e., before hypoxia becomes clinically apparent. The localization of the maximal response correlated either with the core (occlusion of the middle cerebral artery) or with the watershed areas (occlusion of the internal carotid artery) of the respective vascular territories. In one patient with clinically and angiographically confirmed insufficient collateral flow during carotid artery occlusion, the total hemoglobin concentration became significantly asymmetric, with decreased values in the ipsilateral watershed area and contralaterally increased values. Multichannel CW-NIRS monitoring might serve as an objective and early predictive marker of critical perfusion changes during interventions-to prevent hypoxic damage of the brain. It also might provide valuable human reference data on oxygenation changes as they typically occur during acute stroke.
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Cutaneous respirometry by dynamic measurement of mitochondrial oxygen tension for monitoring mitochondrial function in vivo. Mitochondrion 2013; 13:507-14. [DOI: 10.1016/j.mito.2012.10.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 09/19/2012] [Accepted: 10/02/2012] [Indexed: 11/23/2022]
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Kolyva C, Ghosh A, Tachtsidis I, Highton D, Cooper CE, Smith M, Elwell CE. Cytochrome c oxidase response to changes in cerebral oxygen delivery in the adult brain shows higher brain-specificity than haemoglobin. Neuroimage 2013; 85 Pt 1:234-44. [PMID: 23707584 PMCID: PMC3898943 DOI: 10.1016/j.neuroimage.2013.05.070] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/05/2013] [Accepted: 05/13/2013] [Indexed: 11/19/2022] Open
Abstract
The redox state of cerebral mitochondrial cytochrome c oxidase monitored with near-infrared spectroscopy (Δ[oxCCO]) is a signal with strong potential as a non-invasive, bedside biomarker of cerebral metabolic status. We hypothesised that the higher mitochondrial density of brain compared to skin and skull would lead to evidence of brain-specificity of the Δ[oxCCO] signal when measured with a multi-distance near-infrared spectroscopy (NIRS) system. Measurements of Δ[oxCCO] as well as of concentration changes in oxygenated (Δ[HbO2]) and deoxygenated haemoglobin (Δ[HHb]) were taken at multiple source-detector distances during systemic hypoxia and hypocapnia (decrease in cerebral oxygen delivery), and hyperoxia and hypercapnia (increase in cerebral oxygen delivery) from 15 adult healthy volunteers. Increasing source-detector spacing is associated with increasing light penetration depth and thus higher sensitivity to cerebral changes. An increase in Δ[oxCCO] was observed during the challenges that increased cerebral oxygen delivery and the opposite was observed when cerebral oxygen delivery decreased. A consistent pattern of statistically significant increasing amplitude of the Δ[oxCCO] response with increasing light penetration depth was observed in all four challenges, a behaviour that was distinctly different from that of the haemoglobin chromophores, which did not show this statistically significant depth gradient. This depth-dependence of the Δ[oxCCO] signal corroborates the notion of higher concentrations of CCO being present in cerebral tissue compared to extracranial components and highlights the value of NIRS-derived Δ[oxCCO] as a brain-specific signal of cerebral metabolism, superior in this aspect to haemoglobin. NIRS was used to measure oxidised cytochrome c oxidase (Δ[oxCCO]) in healthy brain. Δ[oxCCO] changed in the same direction as changes in cerebral oxygen delivery. Magnitude of Δ[oxCCO] response increased with increasing light penetration depth. Corresponding haemoglobin changes showed no dependence on light penetration depth. NIRS-measured Δ[oxCCO] has higher brain specificity than haemoglobin.
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Affiliation(s)
- Christina Kolyva
- Dept. of Medical Physics and Bioengineering, University College London, London, UK.
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Kolyva C, Ghosh A, Tachtsidis I, Highton D, Smith M, Elwell CE. Dependence on NIRS source-detector spacing of cytochrome c oxidase response to hypoxia and hypercapnia in the adult brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 789:353-359. [PMID: 23852515 PMCID: PMC4037984 DOI: 10.1007/978-1-4614-7411-1_47] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Abstract
Transcranial near-infrared spectroscopy (NIRS) provides an assessment of cerebral oxygen metabolism by monitoring concentration changes in oxidised cytochrome c oxidase Δ[oxCCO]. We investigated the response of Δ[oxCCO] to global changes in cerebral oxygen delivery at different source-detector separations in 16 healthy adults. Hypoxaemia was induced by delivery of a hypoxic inspired gas mix and hypercapnia by addition of 6 % CO2 to the inspired gases. A hybrid optical spectrometer was used to measure frontal cortex light absorption and scattering at discrete wavelengths and broadband light attenuation at 20, 25, 30 and 35 mm. Without optical scattering changes, a decrease in cerebral oxygen delivery, resulting from the reduction in arterial oxygen saturation during hypoxia, led to a decrease in Δ[oxCCO]. In contrast, Δ[oxCCO] increased when cerebral oxygen delivery increased due to increased cerebral blood flow during hypercapnia. In both cases the magnitude of the Δ[oxCCO] response increased from the detectors proximal (measuring superficial tissue layers) to the detectors distal (measuring deep tissue layers) to the broadband light source. We conclude that the Δ[oxCCO] response to hypoxia and hypercapnia appears to be dependent on penetration depth, possibly reflecting differences between the intra- and extracerebral tissue concentration of cytochrome c oxidase.
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Affiliation(s)
- Christina Kolyva
- Department of Medical Physics and Bioengineering, University College London, London, UK.
| | - Arnab Ghosh
- Neurocritical Care Unit, University College Hospitals, London, UK
| | - Ilias Tachtsidis
- Department of Medical Physics and Bioengineering, University College London, London, UK
| | - David Highton
- Neurocritical Care Unit, University College Hospitals, London, UK
| | - Martin Smith
- Neurocritical Care Unit, University College Hospitals, London, UK
| | - Clare E Elwell
- Department of Medical Physics and Bioengineering, University College London, London, UK
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12
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Ghosh A, Kolyva C, Tachtsidis I, Highton D, Elwell CE, Smith M. Reduction of cytochrome C oxidase during vasovagal hypoxia-ischemia in human adult brain: a case study. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 789:21-27. [PMID: 23852472 PMCID: PMC4038000 DOI: 10.1007/978-1-4614-7411-1_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Near-infrared spectroscopy (NIRS)-derived measurement of oxidized cytochrome c oxidase concentration ([oxCCO]) has been used as an assessment of the adequacy of cerebral oxygen delivery. We report a case in which a reduction in conscious level was associated with a reduction in [oxCCO]. Hypoxaemia was induced in a 31-year-old, healthy male subject as part of an ongoing clinical study. Midway through the hypoxaemic challenge, the subject experienced an unexpected vasovagal event with bradycardia, hypotension and reduced cerebral blood flow (middle cerebral artery blood flow velocity decrease from 70 to 30 cm s(-1)) that induced a brief reduction in conscious level. An associated decrease in [oxCCO] was observed at 35 mm (-1.6 μM) but only minimal change (-0.1 μM) at 20-mm source-detector separation. A change in optical scattering was observed, but path length remained unchanged. This unexpected physiological event provides an unusual example of a severe reduction in cerebral oxygen delivery and is the first report correlating change in clinical status with changes in [oxCCO].
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Affiliation(s)
- Arnab Ghosh
- Neurocritical Care Unit, University College Hospitals, WC1N 3BG, London, UK.
| | - Christina Kolyva
- Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK
| | - Ilias Tachtsidis
- Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK
| | - David Highton
- Neurocritical Care Unit, University College Hospitals, WC1N 3BG, London, UK
| | - Clare E Elwell
- Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK
| | - Martin Smith
- Neurocritical Care Unit, University College Hospitals, WC1N 3BG, London, UK
- Medical Physics & Bioengineering, University College London, WC1E 6BT, London, UK
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Ghosh A, Elwell C, Smith M. Review article: cerebral near-infrared spectroscopy in adults: a work in progress. Anesth Analg 2012; 115:1373-83. [PMID: 23144435 DOI: 10.1213/ane.0b013e31826dd6a6] [Citation(s) in RCA: 182] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Near-infrared spectroscopy (NIRS) has potential as a noninvasive brain monitor across a spectrum of disorders. In the last decade, there has been a rapid expansion of clinical experience using NIRS to monitor cerebral oxygenation, and there is some evidence that NIRS-guided brain protection protocols might lead to a reduction in perioperative neurologic complications after cardiac surgery. However, there are no data to support the wider application of NIRS during routine surgery under general anesthesia, and its application in brain injury, where it might be expected to have a key monitoring role, is undefined. Although increasingly sophisticated apparatuses, including broadband and time-resolved spectroscopy systems, provide insights into the potential of NIRS to measure regional cerebral oxygenation, hemodynamics, and metabolism in real-time, these innovations have yet to translate into effective monitor-guided brain protection treatment strategies. NIRS has many potential advantages over other neuromonitoring techniques, but further investigation and technological advances are necessary before it can be introduced more widely into clinical practice.
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Affiliation(s)
- Arnab Ghosh
- Department of Neurocritical Care, Box 30, The National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BGUK
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Kolyva C, Tachtsidis I, Ghosh A, Moroz T, Cooper CE, Smith M, Elwell CE. Systematic investigation of changes in oxidized cerebral cytochrome c oxidase concentration during frontal lobe activation in healthy adults. BIOMEDICAL OPTICS EXPRESS 2012; 3:2550-66. [PMID: 23082295 PMCID: PMC3469997 DOI: 10.1364/boe.3.002550] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/10/2012] [Accepted: 06/30/2012] [Indexed: 05/02/2023]
Abstract
Using transcranial near-infrared spectroscopy (NIRS) to measure changes in the redox state of cerebral cytochrome c oxidase (Δ[oxCCO]) during functional activation in healthy adults is hampered by instrumentation and algorithm issues. This study reports the Δ[oxCCO] response measured in such a setting and investigates possible confounders of this measurement. Continuous frontal lobe NIRS measurements were collected from 11 healthy volunteers during a 6-minute anagram-solving task, using a hybrid optical spectrometer (pHOS) that combines multi-distance frequency and broadband components. Only data sets showing a hemodynamic response consistent with functional activation were interrogated for a Δ[oxCCO] response. Simultaneous systemic monitoring data were also available. Possible influences on the Δ[oxCCO] response were systematically investigated and there was no effect of: 1) wavelength range chosen for fitting the measured attenuation spectra; 2) constant or measured, with the pHOS in real-time, differential pathlength factor; 3) systemic hemodynamic changes during functional activation; 4) changes in optical scattering during functional activation. The Δ[oxCCO] response measured in the presence of functional activation was heterogeneous, with the majority of subjects showing significant increase in oxidation, but others having a decrease. We conclude that the heterogeneity in the Δ[oxCCO] response is physiological and not induced by confounding factors in the measurements.
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Affiliation(s)
- Christina Kolyva
- Medical Physics & Bioengineering, University College London,
London WC1E 6BT, UK
| | - Ilias Tachtsidis
- Medical Physics & Bioengineering, University College London,
London WC1E 6BT, UK
| | - Arnab Ghosh
- Neurocritical Care Unit, University College London Hospitals,
London WC1N 3BG, UK
| | - Tracy Moroz
- Medical Physics & Bioengineering, University College London,
London WC1E 6BT, UK
| | - Chris E. Cooper
- Biological Sciences, University of Essex, Colchester CO4 3SQ,
UK
| | - Martin Smith
- Medical Physics & Bioengineering, University College London,
London WC1E 6BT, UK
- Neurocritical Care Unit, University College London Hospitals,
London WC1N 3BG, UK
| | - Clare E. Elwell
- Medical Physics & Bioengineering, University College London,
London WC1E 6BT, UK
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Jelfs B, Banaji M, Tachtsidis I, Cooper CE, Elwell CE. Modelling noninvasively measured cerebral signals during a hypoxemia challenge: steps towards individualised modelling. PLoS One 2012; 7:e38297. [PMID: 22679497 PMCID: PMC3367969 DOI: 10.1371/journal.pone.0038297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 05/02/2012] [Indexed: 11/21/2022] Open
Abstract
Noninvasive approaches to measuring cerebral circulation and metabolism are crucial to furthering our understanding of brain function. These approaches also have considerable potential for clinical use “at the bedside”. However, a highly nontrivial task and precondition if such methods are to be used routinely is the robust physiological interpretation of the data. In this paper, we explore the ability of a previously developed model of brain circulation and metabolism to explain and predict quantitatively the responses of physiological signals. The five signals all noninvasively-measured during hypoxemia in healthy volunteers include four signals measured using near-infrared spectroscopy along with middle cerebral artery blood flow measured using transcranial Doppler flowmetry. We show that optimising the model using partial data from an individual can increase its predictive power thus aiding the interpretation of NIRS signals in individuals. At the same time such optimisation can also help refine model parametrisation and provide confidence intervals on model parameters. Discrepancies between model and data which persist despite model optimisation are used to flag up important questions concerning the underlying physiology, and the reliability and physiological meaning of the signals.
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Affiliation(s)
- Beth Jelfs
- Department of Medical Physics and Bioengineering, University College London, London, United Kingdom.
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Boas DA, Franceschini MA. Haemoglobin oxygen saturation as a biomarker: the problem and a solution. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:4407-24. [PMID: 22006898 PMCID: PMC3263786 DOI: 10.1098/rsta.2011.0250] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Near-infrared spectroscopy measures of haemoglobin oxygen saturation are often used as an indicator of sufficient oxygen delivery to assess injury susceptibility and tissue damage. They have also often been used as a surrogate measure of oxygen metabolism. Unfortunately, these measures have generally failed to provide robust indicators of injury and metabolism. In this paper, we first review when haemoglobin oxygen saturation does work as a robust indicator, and then detail when and why it fails for assessing brain injury and breast cancer. Finally, we discuss the solution to obtain more robust measures of tissue injury and cancer by combining oxygen saturation measurements with measures of blood flow and volume to more accurately estimate oxygen metabolism.
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Affiliation(s)
- David A Boas
- Optics Division of the Martinos Center for Biomedical Imaging, Harvard Medical School, Massachusetts General Hospital, 149 13th St rm 2301, Charlestown, MA 02129, USA.
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Smith M. Shedding light on the adult brain: a review of the clinical applications of near-infrared spectroscopy. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:4452-69. [PMID: 22006901 DOI: 10.1098/rsta.2011.0242] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Near-infrared spectroscopy (NIRS) has potential as a non-invasive brain monitor in a wide range of clinical scenarios. In the last decade, there has been a rapid expansion of clinical experience using NIRS to monitor cerebral oxygenation, particularly in cardiac surgery, where there is some evidence that NIRS-guided brain protection protocols might lead to a reduction in peri-operative neurological complications. There are no data to support the wider application of NIRS to monitor cerebral oxygenation during routine anaesthesia and surgery, and its application in brain injury, where it might be expected to have a key monitoring role, is as yet undefined. Technological developments, including the introduction of broadband and time-resolved spectrometers that are capable of reliably measuring changes in oxidized cytochrome c oxidase, offer real potential for a single NIRS-based device to provide multi-site, regional monitoring of cerebral metabolic status as well as oxygenation and haemodynamics.
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Affiliation(s)
- Martin Smith
- Department of Neurocritical Care, The National Hospital for Neurology and Neurosurgery, University College London Hospitals, Queen Square, London WC1N 3BG, UK.
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Obrig H, Steinbrink J. Non-invasive optical imaging of stroke. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:4470-94. [PMID: 22006902 DOI: 10.1098/rsta.2011.0252] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The acute onset of a neurological deficit is the key clinical feature of stroke. In most cases, however, pathophysiological changes in the cerebral vasculature precede the event, often by many years. Persisting neurological deficits may also require long-term rehabilitation. Hence, stroke may be considered a chronic disease, and diagnostic and therapeutic efforts must include identification of specific risk factors, and the monitoring of and interventions in the acute and subacute stages, and should aim at a pathophysiologically based approach to optimize the rehabilitative effort. Non-invasive optical techniques have been experimentally used in all three stages of the disease and may complement the established diagnostic and monitoring tools. Here, we provide an overview of studies using the methodology in the context of stroke, and we sketch perspectives of how they may be integrated into the assessment of the highly dynamic pathophysiological processes during the acute and subacute stages of the disease and also during rehabilitation and (secondary) prevention of stroke.
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Affiliation(s)
- Hellmuth Obrig
- Department of Cognitive Neurology, University Hospital Leipzig, Liebigstraße 16, 04103 Leipzig, Germany.
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Current world literature. Neuroanaesthesia. Pain medicine. Regional anaesthesia. Curr Opin Anaesthesiol 2010; 23:671-8. [PMID: 20811177 DOI: 10.1097/aco.0b013e32833f3f68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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