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Comment by snek_case | Hacker News Reader

This article suggests that inflammation in response to the surgery is the problem, but as far as I know, anesthesia itself is very dangerous. It can reduce the amount of oxygen the brain is getting for several hours, and if the brain doesn't get enough oxygen, neurons can die. Some of the cognitive changes following anesthesia could be brain tissue death due to the anesthesia itself. Careful dosage and monitoring is required, and you should probably get local anesthesia if possible.

Anesthesia kills brain cells, but what does it mean? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5119529

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IIRC there are still post-operative cognitive problems in major surgeries done without general anesthesia, suggesting that there's something else going on too. (I don't doubt that anesthesia plays some role, though.)

edit: Found the reference: https://www.frontiersin.org/articles/10.3389/fpsyt.2018.0075....

"More convincingly, a recent study demonstrated that open abdominal surgery under local anesthesia caused increases in hippocampal IL-6, TNFα, and memory impairments (71), suggesting that anesthesia per se is not necessary for the production of neuroinflammation and subsequent development of POCD."

"As seen in observational studies, a prospective randomized clinical trial comparing the use of general vs. spinal anesthesia in extracorporeal shock wave lithotripsy showed no significant difference in the incidence of POCD defined by a neurocognitive battery (142), suggesting that surgery and not anesthesia causes POCD."

But according to those quotes there was still anesthesia administered in all cases, just not always general anesthesia.

So the possibility of anesthesia being the cause has not been ruled out by the studies you quote.

You're right, of course. It's just much less clear to me why local anesthesia would be implicated in cognitive impairment. But the brain is a complex thing, so I suppose my intuitions don't count for much!

Don't forget that most surgery also involves antibiotics which can be another cause of trauma, particularly to the microbiome. Changes to the microbiome have been shown to have cognitive effects recently.

Are all types of general anesthesia equally dangerous? I believe that some of them work in different ways. I suspect we could find a less dangerous way.

I agree. It's a bit tricky to study these things because you can't necessarily (ethically) assign people to different trial groups and use different dosages, but just recording data on what type of anesthesia was used and doing a subsequent followup a few months later could already be valuable.

I believe the culprit is "Pump Head". Not the inflammation thing they mention, not the anesthesia.

Heart lung bypass machines, ECMO systems, they all use non-pulsatile continuous flow pumps. These pumps do not have the same pressure curve and higher pressure pulses that the native circulation does. This causes blood to not make it all the way down to the capillaries, and therefore starves brain tissue that is fed by the smallest of the capillaries.

To solve this problem, a company I helped called Ventriflo has been working to build a pulsatile pump that can be used for both ECMO and cardiopulmonary bypass uses.

https://ventriflo.com/

Eh, this doesn't sound good for all the people that were on ECMO because of covid.

They only put people under ECMO when there's no other way they will survive so I think it's a pretty good deal.

Sure, but you have to put things in context. ECMO is used as a last recourse for life preservation when death is highly likely. I wouldn't be too worried about cognitive impairment if the alternative was to die.

No.

That's such a tiny, tiny, tiny percentage of surgeries and the risks being discussed are present without any heart-lung bypass being involved, ever.

That's not to say it's not an issue for people undergoing such a procedure, but it's just not what's being discussed here.

Thank you!

The article you reference is specifically on very young mice, and does not attempt to prove that this happens in adult brains of mice or humans.

I have a genetic phenotype which make the use of propofol dangerous for me (partial CPT1A deficiency). I found this out the hard way while getting an endoscopy. It affected my serum glucose levels for a week and they had to give me glucose during the procedure.

So yes, besides the inflammation, anesthetics are a problem.

My father definitely suffered after recent vascular surgery. They had to put him under a second time because of a bleed and do the whole procedure again. Hasn’t been the same since.

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