Assessing the relationship between the cerebral metabolic rate of oxygen and the oxidation state of cytochrome-c-oxidase

Milej, Daniel; Rajaram, Ajay; Suwalski, Marianne; Morrison, Laura; Shoemaker, Leena N.; Lawrence, Keith St.

doi:10.1117/1.nph.9.3.035001

Cited by 7 publications

(2 citation statements)

References 60 publications

(99 reference statements)

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“… 1 More recently, the combination of NIRS with diffuse correlation spectroscopy (DCS) 2 offers the opportunity to simultaneously measure multiple cerebral hemodynamic and metabolic parameters, including cerebral blood flow (CBF), blood volume, and markers of oxygen metabolism. 3 – 7 In addition to clinical bedside monitoring, 4 , 8 – 11 both DCS and NIRS have the temporal resolution to measure transient changes in cerebral hemodynamics in response to various physiological paradigms designed to assess the mechanisms regulating CBF. These paradigms include hypercapnia to assess chemoregulation, 3 head-up tilt, 12 and thigh-cuff release 13 , 14 to assess autoregulation related to vessel compliance and myogenic tone, and functional activation to assess neuronal control.…”

Section: Introductionmentioning

confidence: 99%

Using depth-enhanced diffuse correlation spectroscopy and near-infrared spectroscopy to isolate cerebral hemodynamics during transient hypotension

et al. 2023

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Combining diffuse correlation spectroscopy (DCS) and near-infrared spectroscopy (NIRS) permits simultaneous monitoring of multiple cerebral hemodynamic parameters related to cerebral autoregulation; however, interpreting these optical measurements can be confounded by signal contamination from extracerebral tissue.Aim: We aimed to evaluate extracerebral signal contamination in NIRS/DCS data acquired during transient hypotension and assess suitable means of separating scalp and brain signals.Approach: A hybrid time-resolved NIRS/multidistance DCS system was used to simultaneously acquire cerebral oxygenation and blood flow data during transient orthostatic hypotension induced by rapid-onset lower body negative pressure (LBNP) in nine young, healthy adults. Changes in microvascular flow were verified against changes in middle cerebral artery velocity (MCAv) measured by transcranial Doppler ultrasound.Results: LBNP significantly decreased arterial blood pressure (−18% AE 14%), scalp blood flow (>30%), and scalp tissue oxygenation (all p ≤ 0.04 versus baseline). However, implementing depth-sensitive techniques for both DCS and timeresolved NIRS indicated that LBNP did not significantly alter microvascular cerebral blood flow and oxygenation relative to their baseline values (all p ≥ 0.14). In agreement, there was no significant reduction in MCAv (8% AE 16%; p ¼ 0.09). Conclusion:Transient hypotension caused significantly larger blood flow and oxygenation changes in the extracerebral tissue compared to the brain. We demonstrate the importance of accounting for extracerebral signal contamination within optical measures of cerebral hemodynamics during physiological paradigms designed to test cerebral autoregulation.

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Section: Introductionmentioning

confidence: 99%

Using depth-enhanced diffuse correlation spectroscopy and near-infrared spectroscopy to isolate cerebral hemodynamics during transient hypotension

et al. 2023

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“…There is a growing interest in using optical methods, near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS), for bedside neuro-monitoring. Their combination 1 offers the opportunity to simultaneously measure multiple cerebral hemodynamic and metabolic parameters, including cerebral blood flow (CBF), blood volume, and markers of oxygen metabolism [2][3][4] .…”

Section: Introductionmentioning

confidence: 99%

Importance of depth-enhanced optical methods for measuring cerebral hemodynamics during transient hypotension

Milej,

Shoemaker,

Mistry

et al. 2023

Diffuse Optical Spectroscopy and Imaging IX

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Optical methods are well-suited for non-invasive bedside brain imaging: near-infrared spectroscopy (NIRS) for measuring brain oxygenation and diffuse correlation spectroscopy (DCS) for measuring cerebral blood flow. However, data obtained with those optical techniques are prone to signal contamination from extracerebral tissue. This study aimed to evaluate extracerebral signal contamination in trNIRS/multidistance DCS data acquired during transient hypotension and assess suitable means of separating scalp and brain signals. An in-house built hybrid system was used to acquire oxygenation and blood flow data simultaneously during transient orthostatic hypotension induced by rapid-onset lower body negative pressure (LBNP). In nine healthy young adults, LBNP significantly decreased arterial blood pressure (-18 ± 14%), scalp blood flow (-36 ± 25%), and scalp tissue oxygenation (all p ≤ 0.04 vs baseline).In contrast, LBNP had no significant effect on cerebral blood flow or oxygenation. This finding was confirmed by transcranial Doppler ultrasound, which found no significant changes (-8 ± 16%) in middle cerebral artery blood velocity during LBNP. These results demonstrate the importance of using depthenhanced methods when applying these optical technologies to physiological paradigms designed to test cerebral autoregulation that also affect systemic physiology.

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Effects of blood pressure on brain metabolism during cardiopulmonary bypass

Suwalski

Milej²,

Rajaram

et al. 2023

Clinical and Translational Neurophotonics 2023

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Assessing the relationship between the cerebral metabolic rate of oxygen and the oxidation state of cytochrome-c-oxidase

Cited by 7 publications

References 60 publications

Using depth-enhanced diffuse correlation spectroscopy and near-infrared spectroscopy to isolate cerebral hemodynamics during transient hypotension

Using depth-enhanced diffuse correlation spectroscopy and near-infrared spectroscopy to isolate cerebral hemodynamics during transient hypotension

Importance of depth-enhanced optical methods for measuring cerebral hemodynamics during transient hypotension

Effects of blood pressure on brain metabolism during cardiopulmonary bypass

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