Hemodiealysis (222.r.3)

FIVE HUNDRED The thought came to me — during one of my sessions. I watched the pump of the dialysis machine spinning as it pushed my blood through the tubes, into the membrane, and then back to my body. Spin spin. Pump pump. Flow flow. The machine would do this for four hours and an amount of blood equivalent to two-times the amount of water in the patient’s body would be processed. The blood picks up new ‘dirty’ water from the body each time it cycles through. At least that is the theory around hemodialysis.

But that is not what is really happening. My blood (cleansed of undesirables) is put through a switchable manifold into the proper line to go to one of the twelve different patients I am supporting.

Essentially, this is just a fancy way to do a two-way blood transfusion between me and that patient. Why do we need the middle men and machines?

• The next piece of the puzzle — was to understand that pump: how do you buy or make a ‘roller pump’ (formally a ‘peristaltic pump’) since that pump seems to be necessary for the transfusion?

A quick google search and some conversations with a college friend made it clear this was not an issue: I could easily get a ‘patient pump’ capable of the 500mL/minute maximum flow rate. To support a vampires flow rate would require a pump capable of 6L/minute, but that is only about twice as expensive. And the concept I was working on does not require that rate to begin with: it could easily be a oneto-one speed of transfer. The patient gives me their blood and I send it directly back — after wandering through the nooks and crannies of my cardiovascular system — with the blood moving at that 500mL/minute flow rate.

In less than four hours, a single patient and I would have exchanged blood. The patient would get kidney-clean blood to enable them to live and I would get… what? Payment? It would need to be at least a half-liter (a pint) of their blood for me to live also.

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