Near-Infrared Spectroscopy-Derived Dynamic Cerebral Autoregulation in Experimental Human Endotoxemia-An Exploratory Study

Nick Eleveld; Cornelia W E Hoedemaekers; C Ruud van Kaam; Guus P Leijte; Judith M D van den Brule; Peter Pickkers; Marcel J H Aries; Natasha M Maurits; Jan Willem J Elting

doi:10.3389/fneur.2021.695705

Near-Infrared Spectroscopy-Derived Dynamic Cerebral Autoregulation in Experimental Human Endotoxemia-An Exploratory Study

Front Neurol. 2021 Sep 10:12:695705. doi: 10.3389/fneur.2021.695705. eCollection 2021.

Authors

Affiliations

¹ Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.
² Department of Intensive Care Medicine, Radboud University Medical Center, Radboud University, Nijmegen, Netherlands.
³ Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, Radboud University, Nijmegen, Netherlands.
⁴ Department of Intensive Care Medicine, School of Mental Health and NeuroSciences (MHeNS), University Medical Center Maastricht (MUMC+), Maastricht University, Maastricht, Netherlands.

Abstract

Cerebral perfusion may be altered in sepsis patients. However, there are conflicting findings on cerebral autoregulation (CA) in healthy participants undergoing the experimental endotoxemia protocol, a proxy for systemic inflammation in sepsis. In the current study, a newly developed near-infrared spectroscopy (NIRS)-based CA index is investigated in an endotoxemia study population, together with an index of focal cerebral oxygenation. Methods: Continuous-wave NIRS data were obtained from 11 healthy participants receiving a continuous infusion of bacterial endotoxin for 3 h (ClinicalTrials.gov NCT02922673) under extensive physiological monitoring. Oxygenated-deoxygenated hemoglobin phase differences in the (very)low frequency (VLF/LF) bands and the Tissue Saturation Index (TSI) were calculated at baseline, during systemic inflammation, and at the end of the experiment 7 h after the initiation of endotoxin administration. Results: The median (inter-quartile range) LF phase difference was 16.2° (3.0-52.6°) at baseline and decreased to 3.9° (2.0-8.8°) at systemic inflammation (p = 0.03). The LF phase difference increased from systemic inflammation to 27.6° (12.7-67.5°) at the end of the experiment (p = 0.005). No significant changes in VLF phase difference were observed. The TSI (mean ± SD) increased from 63.7 ± 3.4% at baseline to 66.5 ± 2.8% during systemic inflammation (p = 0.03) and remained higher at the end of the experiment (67.1 ± 4.2%, p = 0.04). Further analysis did not reveal a major influence of changes in several covariates such as blood pressure, heart rate, PaCO₂, and temperature, although some degree of interaction could not be excluded. Discussion: A reversible decrease in NIRS-derived cerebral autoregulation phase difference was seen after endotoxin infusion, with a small, sustained increase in TSI. These findings suggest that endotoxin administration in healthy participants reversibly impairs CA, accompanied by sustained microvascular vasodilation.

Keywords: cerebral perfusion; dynamic cerebral autoregulation; human endotoxemia model; near-infrared spectroscopy; sepsis.

Associated data

ClinicalTrials.gov/NCT02922673