2021 SfNIRS Virtual Meeting Q&A: Oral session – topic 2 (fNIRS in Clinical Applications)

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WabnitzHeidrun
WabnitzHeidrun (@wabnitzheidrun)
4 days ago
Continuous EEG-fNIRS in Neurological Intensive Care: Monitoring Hemodynamic Changes Associated with Abnormal EEG Patterns" Read more »

Great talk, interesting!
Which steps are needed before such a method could enter clinical routine?

PengKe
PengKe (@pengke)
Reply to  WabnitzHeidrun
4 days ago

Hi Dr. Wanitz!

Thanks so much for your interest!

I have to say that what I have presented was mostly about feasibility, i.e. whether we are able to conduct continuous EEG-fNIRS in neuroICU or not. Therefore, we had a limited patient number and used mostly offline analysis. To enable EEG-fNIRS as a routine monitoring technique in the neuroICU, I think at least the following items need to be addressed:

1 – More validation with a much larger sample size and more types of abnormal events with different characteristics. For example, in our study of periodic discharges we only had 3 patients with frequency = 0.3Hz, 0.6Hz and 0.8Hz, and saw a distorted hemodynamic response as the frequency increased. We would ideally need many more patients with PD frequencies from e.g. 0.2Hz -> 2.5Hz to see whether that trend in the changes of hemodynamic responses still holds.

2 – Studies on the relationship of the fNIRS-measured hemodynamic response to treatment outcome. We will need to prove to the clinicians that the abnormalities we see on fNIRS data has a direct impact on the final treatment outcome. For example, if we see a hypoxic state with seizures and that patient was left untreated, the outcome will be worse than if the clinician treated the patient as fNIRS signaled the hypoxic problem.

3 – Development on the more online processing analytical methods. We will not have sufficient time to do these kinds of offline filtering, GLM, or PCA. If EEG-fNIRS is used in real-time in the neuroICU. The clinicians will need to know whether a pattern should to be treated within minutes of seeing that pattern, especially for those events like seizures which can cause permanent damage.

Let me know what you think!

Ke

Ilias Tachtsidis
Ilias Tachtsidis (@i-tachtsidisucl-ac-uk)
4 days ago
Continuous EEG-fNIRS in Neurological Intensive Care: Monitoring Hemodynamic Changes Associated with Abnormal EEG Patterns" Read more »

Very interesting work. Regarding the metabolic hypothesis you might want to have a look at our recent paper in newborns (not adults) Front Pediatr. 2016; 4: 83. 2016 Aug 10. doi: 10.3389/fped.2016.00083 PMCID: PMC4978952
PMID: 27559538 Changes in Cerebral Oxidative Metabolism during Neonatal Seizures Following Hypoxic–Ischemic Brain Injury. Subhabrata Mitra et al.

We have observed a deleterious effect of repeated seizures that seem to deplete brain tissue substrate/energy availability that can lead to further injury.

PengKe
PengKe (@pengke)
Reply to  Ilias Tachtsidis
4 days ago

Thank you Dr. Tachtsidis! We will definitely check those papers.

In fact we observed a similar pattern in adult patients as well. We found out that it seemed for seizures, not only the duration was important, but where the seizure was located in timing also affected a lot its hemodynamic response. Factors such as how much time of the resting period before a seizure, and how long was the seizure preceding the current seizure might also play an important role. I did not have time to mention in the presentation but we were actually trying to some correlation analyses relating the hemodynamic response to all those factors.

Ilias Tachtsidis
Ilias Tachtsidis (@i-tachtsidisucl-ac-uk)
4 days ago
First Application of Wearable HD-DOT to Study Functional Connectivity During Sleep in the Newborn Brain Cot-side" Read more »

Julie your HbO-HbR correlation/anti-correlation map a great addition and i hope more people do that; well done. Keeping in mind that these infants were sleeping why you had issues with movement noise? and the 3min sections you analysed were only down to practical reasons finding stable data?

Ilias Tachtsidis
Ilias Tachtsidis (@i-tachtsidisucl-ac-uk)
4 days ago
Elucidating dynamic autoregulation of cerebral blood flow and oxygenation during carotid endarterectomy using diffuse correlation spectroscopy and near-infrared spectroscopy" Read more »

Kutlu what were the absolute StO2 and HbT values (not the changes) between controlateral and ipsilateral site? and did you see any connection between the absolute value and the level of changes when clamping and unclamping?

Ilias Tachtsidis
Ilias Tachtsidis (@i-tachtsidisucl-ac-uk)
4 days ago
Simultaneous monitoring of cerebral blood flow, oxygen consumption and the oxidation state of cytochrome c oxidase" Read more »

Daniel what excellent data. You need to have a look at this paper: J Cereb Blood Flow Metab. 2014 Mar; 34(3): 514–521. Propofol compared with isoflurane inhibits mitochondrial metabolism in immature swine cerebral cortex
Masaki Kajimoto and colleagues

The hypothesis is that the relationship of cytochrome vs CMRO2 should be a sigmoid type function; however the upper and lower limits of that sigmoid relationship will depend on the insult and/or injury. Suggestion, instead of fitting a linear line between CMRO2 and oxCCO try to find points of deflection.

Daniel Milej
Daniel Milej (@dmilej)
Reply to  Ilias Tachtsidis
3 days ago

Thank you. To be honest, the relationship between oxCCO and CMRO2 looks like it can be modelled with sigmoid function, but we were not sure if it is accurate or it is just due to noise in both parameters! I will check the paper you mentioned and try to find a better model to fit the data.