Convoy

Lana and I also sleep quite a bit, but four hours later we are both awake and alive. Lana has a blood test tomorrow (we both do them every week, except mine are faked), so we will know how well this worked for her.

The blood tests — come back completely normal for her weekly dialysis regimen. I can’t commit to doing just her every other day, but I do commit to doing this once every four weeks if not more often. That way we will work out any kinks with the process. Ultimately I have to figure out how to support multiple people of the same blood type and then multiple people of different blood types. At scale (multiple vampires, with each focused on a single blood type), this will be easier but the process has to bootstrap on me until then. Lana’s blood type is ‘O’, so we need some more ‘O’ s to scale up.

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THE RING

It is my anniversary — A year ago today I woke up to the vampiric April Fool’s day prank. Amusingly it is also Friday, so I have a normal dialysis session before my weekend off, although Sunday is a cave dialysis day. We have finally reached twelve people, all of whom are homeless, do dialysis, have Type-O blood, and know Lana. She gets the commission for all of them. I visit homeless people fairly often, but I am not part of the tribe and they do not trust me enough to even provide the information we need to include them in the program. They do trust Lana: besides being homeless herself she does provide medical assistance to other homeless people. A doctor without borders of sorts, except the border is between the haves and the have-nots vs. geographical.

I built out a fairly nice ‘medical space’ within the Pico Pico House building. Other people help me sporadically with building houses, but no one but me has keys, so no one else can open the ‘iron door’ that holds thirteen comfortable chairs and a lot of tubing connecting them all together.

The space looks like a discussion ring — twelve chairs ring around a single chair in the center. They are spaced about two feet apart for easy access to the left and right arm of a participant. The chairs themselves are quite wide and deep: almost three feet in both directions when not reclined. They are about five feet deep when reclined. So the total perimeter is around 60 feet where the seats are seven feet from the center. The space is thirty by thirty, so supporting this layout isn’t a problem. We could probably pack twice as many in the space if we slid chairs after wiring up the patient, kind of like sliding library shelves.

But space is not a problem and with 12 people in the room, this

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represents $6K per session. If we could run eight shifts (MWF and THS at 6AM, 10AM, 2PM, and 6PM) totaling 24 sessions per week, we would make $150K a week, or over $7M a year. The rent would not be a problem. It would require eight vampires and the costs for consumables, but vampires are actually pretty inexpensive: they don’t work for peanuts, but a few pints will do nicely. Anything beyond that is fun money.

I don’t actually charge the 12 people anything: this is still just once a month so the costs are not prohibitive. The patients are happy to have a possible backup for dialysis and it actually turns out that we are doing a better job of cleaning their blood than the clinic technology does. Plus they actually know each other reasonably well, and without the noise of the machines they can talk and get to know each other even better. Or maybe it is just we don’t have televisions for them to zone-out with.

The startup, running, and shutdown — of cave dialysis is a balancing act. With twelve patients, each is producing a maximum of 400mL/m or 5L (10 pints) per minute in aggregate. I can run 5L/m continuously but am not an unlimited reservoir: I have about the same 5 liter capacity as a normal person. Maybe I can go all the way to 6 liters. And I start out at about 1L if it has been two days since my last facility dialysis (taking a pint a patient was always a theoretical maximum in case I came in like the walking dead). So ideally I replenish to 5 liters (and get rid of any residual blood of a type that is incompatible with the patient) and then hold at that 5 liter level until all the patients are done: for each liter in, I put a liter back out… whether someone is ready for it or not.

To handle this balancing act, we have a 10 liter vampire-input and 50 liter vampire-output reservoir per blood type to deal with transitions and stutters. The v-input reservoir is filled and held at 5 liters by an Arduino control system that controls the peristaltic pump

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speeds on a per-patient and per-vampire level. The output reservoir is managed similarly, but is simpler to balance since there is only one input and plenty of capacity. The only issue that pairs the input to the output is if the vampire expires. In that case, the input is pumped directly to the output and returned to the patients. It is not cleansed, but it is better than losing another pint (one in the vampire, one in the reservoir). I have never expired… yet. But the system needs to be fault tolerant when lives are at stake.

Swapping blood types requires a set of valve changes and accepting a bit of flushed contaminated blood if there is an incompatibility. Putting ‘O’ into an ‘A’ isn’t a problem, so that transition just ignores the possibility of residual ‘O’ blood. When the blood is incompatible, the system is run into the flush tank until an insignificant amount of residual is left. This ‘contaminated blood’ is stored in the 50 liter flush tank and effectively represents part of the blood cost for the cave dialysis service. This contaminated blood can be returned to the one or more vampires at the end of a session/shift since vampires are not affected by heterogenous blood types of any kind.

The dialysis centers may work this way also, but I have never been let into the back room. At the start of a cave dialysis it does appear I have heterogeneous blood.

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