Noninvasive Measurement of Cerebral Blood Flow and Blood Oxygenation Using Near-Infrared and Diffuse Correlation Spectroscopies in Critically Brain-Injured Adults
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This study assesses the utility of a hybrid optical instrument for noninvasive transcranial monitoring in the neurointensive care unit. The instrument is based on diffuse correlation spectroscopy (DCS) for measurement of cerebral blood flow (CBF), and near-infrared spectroscopy (NIRS) for measurement of oxy- and deoxy-hemoglobin concentration. DCS/NIRS measurements of CBF and oxygenation from frontal lobes are compared with concurrent xenon-enhanced computed tomography (XeCT) in patients during induced blood pressure changes and carbon dioxide arterial partial pressure variation.
Seven neurocritical care patients were included in the study. Relative CBF measured by DCS (rCBFDCS), and changes in oxy-hemoglobin (ΔHbO2), deoxy-hemoglobin (ΔHb), and total hemoglobin concentration (ΔTHC), measured by NIRS, were continuously monitored throughout XeCT during a baseline scan and a scan after intervention. CBF from XeCT regions-of-interest (ROIs) under the optical probes were used to calculate relative XeCT CBF (rCBFXeCT) and were then compared to rCBFDCS. Spearman’s rank coefficients were employed to test for associations between rCBFDCS and rCBFXeCT, as well as between rCBF from both modalities and NIRS parameters.
rCBFDCS and rCBFXeCT showed good correlation (r s = 0.73, P = 0.010) across the patient cohort. Moderate correlations between rCBFDCS and ΔHbO2/ΔTHC were also observed. Both NIRS and DCS distinguished the effects of xenon inhalation on CBF, which varied among the patients.
DCS measurements of CBF and NIRS measurements of tissue blood oxygenation were successfully obtained in neurocritical care patients. The potential for DCS to provide continuous, noninvasive bedside monitoring for the purpose of CBF management and individualized care is demonstrated.
KeywordsNear-infrared spectroscopy Diffuse correlation spectroscopy Cerebral blood flow Xenon CT Neurocritical care
We are grateful for the contributions of Mark Burnett who initiated the earliest protocols in the neurointensive care unit that led to this study. We also thank Dalton Hance, Justin Plaum, and neurointensive care unit nurses and radiology staff at HUP for technical assistance. Finally, we acknowledge helpful technical discussions with Mary Putt, Rickson Mesquita, and David Minkoff.
Sources of Support (if applicable), name(s) of grantor(s), grant or contract numbers, name of author who received the funding, and specific material support given are as follows: National Institute of Heath: NS-054575 (MNK, JAD), NS-060653 (AGY), NS-045839 (JAD), HL-077699 (AGY), RR-02305 (AGY, JAD), and ED-26979 (TD). Thrasher Foundation: NR-0016 (TD).
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