PE Protocol and Neurology References
At my last plasma exchange, I paid closer attention to the tubing, which was a clue on how the anti-coagluation is done. The Cobe Spectra plasmapheresis machine has three tubes that combine right at the withdrawal point. One line delivers saline and a second delivers the anti-coagulant. These mix with the blood as it is being withdrawn down the third line. In other words, the anti-coagulant is mixed with my blood as soon as possible. When my blood returns, a calcium gluconate solution is mixed in just shortly before it enters. It should be easy enough to calculate how fast to infuse the calcium gluconate, to counter-balance the calcium the anti-coagulant binds up. Unless you are having a blood pressure crash or were low on calcium to start, you should not need extra calcium during the procedure, at least not so quickly that you get that warm sensation.
I have never had my blood pressure drop 2 hours after the procedure. I have had it drop alarmingly during (usually right at the end) and immediately after the procedure, though. I usually have a mild drop at the end, sometimes to the point where they need to give either extra saline or more concentrated albumin. One way to get extra saline is to do what my nurse call a “double rinse-back”. A “rinse-back” is when they rinse the blood out of the machine and back into you. So double just means they do it twice.
I could not find the reference text I was thinking of, which is [I]Peripheral[/I] [I]Neuropathy[/I], 3rd edition (Saunders, Philadelphia), by P. J. Dyck, P. K. Thomas, J. W. Griffin, et. al. (eds.). However, I did find two other books that had similar information. Their information is from these two papers:[INDENT]Dyck PJ, Daube J, O’Brien P, et. al. “Plasma exchange in chronic inflammatory demyelinating polyradiculoneuropathy” [I]New England Journal of Medicine[/I] 1986; [B]314[/B]:461-463.
Hahn AF, Bolton CF, Pillay N, et. al. “Plasma-exchange therapy in chronic inflammatory demyelinating polyneuropathy. A double-blind, sham-controlled, cross-over study” [I]Brain[/I] 1996; [B]119[/B]:1055-1066.
[/INDENT]Hahn’s study was the one with the information about the onset time of symptoms. The study was relatively small, 18 patients, with 15 patients completing the blinded study. Of those 15, 12 had very large improvements. The other three apparently did not. Of the 12, eight relapsed within 7 to 14 days after the last PE. Subsequent PE was effective in reversing the relapse. To increase the time between PE rounds, some form of immunosuppression (prednisone, cyclophosphamide in her case) was needed.
By the way, I tried CellCept in 2006, for a full five months. It was not sufficiently effective; it perhaps increased the time between PE rounds by 2 or 3 days. I switched to azathioprine and prednisone and continued PE. That combination works for me. A typical dose for mild suppression of azathioprine is 2 mg/kg/day. By upping the dose by about 15%, I appear to have reduced my prednisone need to about 0.8 mg/kg/week with PE every 6 weeks. I am trying to reduce the prednisone to 0 and would agree to a larger dose of azathioprine if it did the job. I would even take the anti-rejection amounts (3 mg/kg/day). Transplant patients take that amount, but typically they take more than one anti-rejection drug, increasing their risk considerably.