Wouter van Snippenburg

Intensivist - - #FOAMcc

[Wouter van Snippenburg @snippenburg]

@IM_Crit_ This is so untrue. Uncomfortable truth is we have very little influence, most patients either survive or die regardless of the minutiae of what we do.

[Wouter van Snippenburg @snippenburg]

@PulmCrit E.g. https://t.co/EhpXKzc2MB and https://t.co/mmVu4xvd05 and https://t.co/dKHU9GMMO0

[Wouter van Snippenburg @snippenburg]

@PulmCrit That's a harsh take. And contrary to the evidence I know. As stated before, there's decades of experience with SDD in the Netherlands. No sign of increasing resistance. If anything, there's a signal towards a decrease, probably due to lower overall antibiotic use.

[Wouter van Snippenburg @snippenburg]

@icmteaching @thinkingcc @khaycock2 @msiuba @pulmcrit

[Wouter van Snippenburg @snippenburg]

Inspired by @icmteaching, I built a Windkessel web app (URL below) entirely by "vibe coding": describing intent, visuals, and physiology in plain language and iterating with an LLM (ChatGPT 5.2 in this case, Plus account). Just ideas, feedback, and rapid refinement.

🧵 1/9

[Wouter van Snippenburg @snippenburg]

9/9 Immediate disclaimer with regard to the Windkessel app: it's valid enough for my use as a didactic tool (i.e. show that MAP increases with increase in resistance, pulse pressure increases with decrease in compliance etc), but don't use it for clinical decision making.

[Wouter van Snippenburg @snippenburg]

@PulmCrit Only if suspicion of alcoholism or malnutrition

[Ashley Miller @icmteaching]

Why I’m rethinking extubation timing in fluid-overloaded ICU patients (a physiology thought experiment 🧵👇

[Wouter van Snippenburg @snippenburg]

@icmteaching Though after some further reading I came across https://t.co/gcX1jkzkHX (abstract), which supports your stance. Decrease in lymph flow, increase in EVLW with PEEP in sheep. Might still be decrease in filtration < decrease in lymph outflow, either way resulting in more lung water.

[Wouter van Snippenburg @snippenburg]

@icmteaching Yes, but total area where filtration happens is diminished if part of the vessel is choked, so I guess net effect would depend on proximal increase in filtration vs decrease in choked part (assuming there was filtration there when in WZ3, which I understand might not hold).

[Wouter van Snippenburg @snippenburg]

@icmteaching Maybe you're right regarding absolute Pcap proximal to collapse point, but transcapillary pressure by definition is near 0 in choked part of a West zone 2 capillary. So no or minimal filtration there. I think that has more and opposing effect than increase in proximal Pcap.

[Wouter van Snippenburg @snippenburg]

Let's start with something obvious https://t.co/nTjENKy6y4

[Wouter van Snippenburg @snippenburg]

1/ Why is CRRT prescribed in mL/kg/h instead of mL/min/1.73m² like eGFR? Because this way, it scales clearance to match small solute volume of distribution (Vd).

[Wouter van Snippenburg @snippenburg]

Out of curiosity and so I can decide whether I should make some educational CRRT posts: who decides the CRRT settings in your ICU? E.g. blood flow rate, citrate dose, substitution, dialysate rate.

[Wouter van Snippenburg @snippenburg]

5/5 Of course Vd = 0.5 L/kg is itself a simplification. Vd still varies with obesity, capillary leak, fluid overload, and solute properties. Weight-based CRRT dosing doesn’t eliminate t½ variability, but it minimizes it better than a BSA indexed or fixed mL/min dose.

[Wouter van Snippenburg @snippenburg]

1/ Why is CRRT prescribed in mL/kg/h instead of mL/min/1.73m² like eGFR? Because this way, it scales clearance to match small solute volume of distribution (Vd).

[Wouter van Snippenburg @snippenburg]

4/ When clearance scales proportional to Vd, half-life stays equal. Remember: t½ = 0.693 × Vd / Cl. If Vd = ... L/kg and Cl = ... mL/kg/h, the kg terms cancel eachother out. For Vd = 0.5 L/kg (total body water) and Cl = 25 mL/kg/h, t½ becomes 13.9h regardless of weight.