Johannes Enevoldsen

I am on the job market and wanted to advertise myself here! 🤠

Looking for full-time or contracting roles!

Historically, my work spans population dynamics, healthcare informatics, robust adaptive controls, software engineering, and community engagement. 🧪

#STEMjobs #academicsky #publichealth

"If CO increases, EtCO2 rises, CO2 elimination increases, PaCO2 falls and this is also sustained."

The problem here is that if CO2 elimination increases, without a matching increase in production, dissolved CO2 will drop with a constant rate (elimination - production)

In ROSC, there is definitely an increase in CO2 production to maintain the new EtCO2.

I dont see how an increase in EtCO2 is not directly proportional to the amount of exhaled CO2 (unless the patient suddenly gets obstructive).

So when people use/study EtCO2 as indicator of fluid responsiveness, they look for a *temporary* increase in EtCO2? This is the model that makes sense to me, but I could not find it specified in any of the papers.

CaCO2 refers to the average CO2 in blood (arterial + venosus), right? The arterial concentration increase with ⬆️CO.

VCO2 = Exhaled + ΔCavCO2

At steady state the dissolved part is constant, so VCO2 = exhaled CO2.

I see how better V/Q will get EtCO2 closer to PaCO2.

But how can we sustain a higher EtCO2, if production is constant?
Assuming a square capnography curve, EtCO2 must be directly proportional to the volume of exhaled CO2, which must equal the production of CO2 (at steady state).

I don't understand the relationship between CO and ETCO2.

ETCO2 increases with rising CO, if ventilation and CO2 production is constant.

Is this just temporary?
We can't exhale more CO2 than we produce.

#anSky #medSky
@doctorhelgi.bsky.social
@load-dependent.bsky.social
@jm-l.bsky.social

There's a puzzle I've found annoying so I thought I'd let you find it annoying too: kucharski.substack.com/p/why-the-tu...

I find it more acceptable if it's formulated as: You ask a person with two kids: "is at least one of your kids a boy born on a Tuesday?" They say "yes". What is the probability that they have two boys?

Ah 👌 det giver jo egentligt god mening. TIL

Ok. Mit eksempel var grammatisk forkert ☺️ " ... med dens krig"

Men er den oprindelige overskrift ikke stadig god nok?

Er det ikke korrekt? "dansker banker" er grundled i sætningen.

Sætningen kunne forsættes "... med deres krig"

Small blog post on how to automate model building for mechanical systems using ModelingToolkit. #julialang

michielstock.github.io/posts/2025/p...

Drowning Doesn’t Look Like Drowning Drowning is not the violent, splashing call for help that most people expect.

Thanks for the reminder @janemunday.bsky.social. Every summer, I repost this article DROWNING DOES NOT LOOK LIKE DROWNING. To date, I know of FOUR kids who were saved after someone who'd clicked on the link learnt how to spot actual drowning. Take time to read and pass on.

slate.com/technology/2...

Great ... though it would have been nice to make this show 0✅

I have the same problem. If I only ever intend putting it on GitHub, is it reasonable to just ignore it? Escaping all these characters will make the code a lot less readable.

Thank you. With such praise, it is hard not to:
RSS: jenevoldsen.com/index.xml

It would be a reasonable regulatory mechanism, that lactate signals increased oxygen demand and raises CO, though I don't know whether it is possible, or even meaningful, to distinguish whether lactate is both fuel and a signal, or just fuel.

Cardiovascular effects of lactate in healthy adults - PubMed https://clinicaltrials.gov/ct2/show/NCT04710875 . Registered 1 December 2020.

Just found that the same group also did this study, showing that lactate increases CO in healthy adults. pubmed.ncbi.nlm.nih.gov/39825426/

bsky.app/profile/johs...

Absolutely fascinating! We know the heart switches to lactate as energy substrate in shock, could there be a clinical benefit from lactate infusion in human cardiogenic shock? #emimcc #cccsky

Incredible effect sizes. Do we know what lactate does in a healthy heart? From a teleological perspective, it would make sense that lactate has a positive inotropic effect, regardless of it being a substrate. Simply as a signal of hypoperfusion.

I'm sorry you had to experience that. Unfortunately I don't know what determines which treatment is tried first, or whether e.g. cardioversion can be expected to work if the condition reoccurs, when it didn't work the first time.

My cardiac arrhythmia simulation now also simulates how a reentrant loop can be terminated by increasing refractory time as suggested by @empoisonpharmd.bsky.social

Direct link to the updated part:
jenevoldsen.com/posts/excita...

✨ It's new samwho visual essay o'clock! ✨

Reservoir sampling is one of my favourite algorithms. It allows you to sample from a set without knowing the size of that set.

I try to assume no prior knowledge, and use no scary math notation. Just beautiful visuals.

Let me know what you think! ❤️

I just want to say I use this constantly at the bedside when dealing with patients who have arrythmias to explain how they propagate.

would LOVE LOVE a model where increasing refractory terminates reentrant rhythm so I can show how diltiazem terminates SVT.

such an amazing tool, thank you

Thank you! So nice to learn that it is actually read and used.

Good idea with a sim, where the arrhythmia is stopped with meds. It shouldn't be too hard to make a sim, where refractory time can be prolonged.

I'll give you a heads up when I find the time to implement it.

A 10-minute movie in a 6.3-second looping GIF.

Movie: Sprite Fright (#Blender open movie): studio.blender.org/projects/spr...

Code (#JuliaLang and @makie.org)
gist.github.com/JohannesNE/2...

For AVNRT, some people just have a physiological variant where the AV node is split in a slow pathway and a fast pathway.

For VF and AFib, there are many proposed mechanisms, slow repolarization could occur in areas with ischemia. Reduced conduction due to e.g. fibrosis plays a large role as well.

Thanks. Just scrolled through some of your articles. Really impressive! I look forward to doing a deeper dive in the coming days.