Vasopressors and reduced cerebral oxygenation determined by NIRS: An illusion ??

Science is great…but can be cruel. I have been lucky enough to work on a really interesting and relevant clinical issue since my postdoc years, that is the influence of vasopressors on cerebral oxygenation.

I have published 3 papers with data coming from postdoc work on that issue and another paper got recently published with data from my own lab.

Still, it is not a secret that extracranial contamination may have an important influence on the NIRS-determined cerebral oxygenation, especially when vasopressors are administered. We recently had a friendly debate about that issue here.

Well, this last paper recently published by my colleagues Shigehiko Ogoh et al. in Anesthesia & Analgesia hit me hard yesterday:

A decrease in spatially resolved near-infrared spectroscopy-determined frontal lobe tissue oxygenation by phenylephrine reflects reduced skin blood flow

This well-written paper is just another piece of evidence against the influence (whether direct or indirect) of vasopressors (phenylephrine and norepinephrine) on cerebral oxygenation, at least when determined by NIRS…

Other evidence has recently been published by my Danish friends and colleagues:

Cutaneous vasoconstriction affects near-infrared spectroscopy determined cerebral oxygenation during administration of norepinephrine.

Extra-cerebral oxygenation influence on near-infrared-spectroscopy-determined frontal lobe oxygenation in heatlhy volunteers: a comparison between INVOS-4100 and NIRO-200NX.

External carotid artery flow maintains near-infrared spectroscopy-determined frontal lobe oxygenation during ephedrine administration

So the question is: Does the reduction in NIRS-determined cerebral oxygenation following vasopressors administration is merely an illusion ?

I recently had an exchange of emails (one of many exchanges on that issue!) with Henrik Sørensen, the lead author of a couple of these papers, and he had these words:

You forced us to come up with some new ideas after your vasopressor-studies in CPH (Copenhagen), now we have forced you to come up with some new ideas too.

Challenge accepted !


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