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Eleveld N, Esquivel-Franco DC, Drost G, Absalom AR, Zeebregts CJ, de Vries JPPM, Elting JWJ, Maurits NM. The Influence of Extracerebral Tissue on Continuous Wave Near-Infrared Spectroscopy in Adults: A Systematic Review of In Vivo Studies. J Clin Med 2023; 12:jcm12082776. [PMID: 37109113 PMCID: PMC10146120 DOI: 10.3390/jcm12082776] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/04/2023] [Accepted: 04/05/2023] [Indexed: 04/29/2023] Open
Abstract
Near-infrared spectroscopy (NIRS) is a non-invasive technique for measuring regional tissue haemoglobin (Hb) concentrations and oxygen saturation (rSO2). It may be used to monitor cerebral perfusion and oxygenation in patients at risk of cerebral ischemia or hypoxia, for example, during cardiothoracic or carotid surgery. However, extracerebral tissue (mainly scalp and skull tissue) influences NIRS measurements, and the extent of this influence is not clear. Thus, before more widespread use of NIRS as an intraoperative monitoring modality is warranted, this issue needs to be better understood. We therefore conducted a systematic review of published in vivo studies of the influence of extracerebral tissue on NIRS measurements in the adult population. Studies that used reference techniques for the perfusion of the intra- and extracerebral tissues or that selectively altered the intra- or extracerebral perfusion were included. Thirty-four articles met the inclusion criteria and were of sufficient quality. In 14 articles, Hb concentrations were compared directly with measurements from reference techniques, using correlation coefficients. When the intracerebral perfusion was altered, the correlations between Hb concentrations and intracerebral reference technique measurements ranged between |r| = 0.45-0.88. When the extracerebral perfusion was altered, correlations between Hb concentrations and extracerebral reference technique measurements ranged between |r| = 0.22-0.93. In studies without selective perfusion modification, correlations of Hb with intra- and extracerebral reference technique measurements were generally lower (|r| < 0.52). Five articles studied rSO2. There were varying correlations of rSO2 with both intra- and extracerebral reference technique measurements (intracerebral: |r| = 0.18-0.77, extracerebral: |r| = 0.13-0.81). Regarding study quality, details on the domains, participant selection and flow and timing were often unclear. We conclude that extracerebral tissue indeed influences NIRS measurements, although the evidence (i.e., correlation) for this influence varies considerably across the assessed studies. These results are strongly affected by the study protocols and analysis techniques used. Studies employing multiple protocols and reference techniques for both intra- and extracerebral tissues are therefore needed. To quantitatively compare NIRS with intra- and extracerebral reference techniques, we recommend applying a complete regression analysis. The current uncertainty regarding the influence of extracerebral tissue remains a hurdle in the clinical implementation of NIRS for intraoperative monitoring. The protocol was pre-registered in PROSPERO (CRD42020199053).
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Affiliation(s)
- Nick Eleveld
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
| | - Diana C Esquivel-Franco
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
| | - Gea Drost
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
- Department of Neurosurgery, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
| | - Anthony R Absalom
- Department of Anaesthesiology, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
| | - Clark J Zeebregts
- Department of Surgery, Division of Vascular Surgery, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
| | - Jean-Paul P M de Vries
- Department of Surgery, Division of Vascular Surgery, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
| | - Jan Willem J Elting
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
| | - Natasha M Maurits
- Department of Neurology, University Medical Centre Groningen, University of Groningen, Postbus 30001, 9700 RB Groningen, The Netherlands
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Evaluation of fNIRS signal components elicited by cognitive and hypercapnic stimuli. Sci Rep 2021; 11:23457. [PMID: 34873185 PMCID: PMC8648757 DOI: 10.1038/s41598-021-02076-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 10/18/2021] [Indexed: 11/08/2022] Open
Abstract
Functional near infrared spectroscopy (fNIRS) measurements are confounded by signal components originating from multiple physiological causes, whose activities may vary temporally and spatially (across tissue layers, and regions of the cortex). Furthermore, the stimuli can induce evoked effects, which may lead to over or underestimation of the actual effect of interest. Here, we conducted a temporal, spectral, and spatial analysis of fNIRS signals collected during cognitive and hypercapnic stimuli to characterize effects of functional versus systemic responses. We utilized wavelet analysis to discriminate physiological causes and employed long and short source-detector separation (SDS) channels to differentiate tissue layers. Multi-channel measures were analyzed further to distinguish hemispheric differences. The results highlight cardiac, respiratory, myogenic, and very low frequency (VLF) activities within fNIRS signals. Regardless of stimuli, activity within the VLF band had the largest contribution to the overall signal. The systemic activities dominated the measurements from the short SDS channels during cognitive stimulus, but not hypercapnic stimulus. Importantly, results indicate that characteristics of fNIRS signals vary with type of the stimuli administered as cognitive stimulus elicited variable responses between hemispheres in VLF band and task-evoked temporal effect in VLF, myogenic and respiratory bands, while hypercapnic stimulus induced a global response across both hemispheres.
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