Machines that pump blood

I donated blood again, on Wednesday. While I was waiting to get screened a guy who works there approached me and asked if I could donate double red cells. The requirements are to be 150lb and some height I can't remember, but it's under the 6'2" which people tell me I am; I fit the requirements. I said I could, and we did the whole screening process. I had good iron levels and heart rate, but my blood pressure was a little higher than normal (120/80) but still relatively good. I sat down at this machine, got the needle put in, and it started taking my blood. About half a liter later it filtered my red blood cells from the plasma (which was bright yellow, a good thing I am told) and then the machine pushed saline solution back into my body, followed by the plasma. The saline is cold, and my plasma has cooled off considerably from being out of my body for so long, and all this cold liquid going into my bloodstream starts to make me cold. Then, it starts all over again, taking another half liter of blood. This time, after the saline went in, and the plasma got started, my vein clotted. This is bad, since the machine is still pushing fluid up the tube and into my arm. I start to get this large bump where the needle's going in, which I am told is the plasma collecting under my skin (what else could it be? the beginning of a new forearm?). It gets to be about 2 inches across and an inch or so high. It doesn't hurt, but it feels bad anyway; it felt like there was pressure under my skin (which there was) and I started wondering how much pressure my skin could contain before busting. The guy taking my blood turns off the pump, and the bump in my skin eventually fades away. This, however, means that I lose most of the plasma I would have gotten back. So I'm out a liters worth of red blood cells and about a half liter of plasma. They patch me up, give me donuts and drinks, and a t-shirt, and I go on my way, trying to figure out the easiest way to get warm without burning myself too badly.