Please be careful when plumbing external connections into the human circulatory system. Several important security mechanisms are bypassed, and there's much more complexity to blood than is initially obvious.
While true, cold saline IV’s are useful for both dehydration and lowering core body temperature.
I want a device that hooks into my circulatory system and diverts my blood flow through it, filtering out microplastics and other shit that shouldn't be there, and then cooling it down slightly before putting it back in.
You want dialysis?
Donate plasma, it works reasonably well. If you have antibodies you want to keep it might be bad though because those count as the plasma and get taken out.
there is more tubing. ice water enema is a thing, drinking cold drinks ofc but perhaps the nasal cavity can be repurposed?