Johanna was a superhero on Saturday and made a platelet donation at the blood bank near our house. For once I just got to hang out and watch, yay!
After answering a few eligibility questions, they put her in a recliner and started setting up the apheresis machinery that would be used to separate the platelets from her whole blood. The machine works by running her blood through a centrifuge which separates the different blood components by weight. Plasma floats to the top, platelets below that, etc. The centrifuge looks like a small washing machine drum and you could hear it spin up once the machine started (in the picture below, the centrifuge is inside the machine, underneath the maze of tubes). See that little yellow bag at the top left? Those are her platelets!
Once they extract the platelets, the rest of the blood is pumped back into the body. I guess in the old days it required 2 IVs, one in each arm for blood coming out and for blood going back in. Nowadays the machines are fancy enough that only one IV is needed and the machine cycles between pulling blood out and circulating it back in. Johanna said it sounds much worse than it is :) Though she said it required some attention to keep the blood pressure at the right amount, which she did by squeezing a little ball. Basically she had to watch the monitor to keep this little bar in the center of the graph. Too low and it was time to squeeze. Too high and it was time to back off.
All in all we were in and out in about 2 hours. They had lots of snacks and things to drink, and everyone was super nice. We went on a Saturday and I was blown away by the number of people who were donating -- I counted probably 10-15 people in the course of 2 hours. Apart from Johanna, everyone was donating whole blood, but one of the volunteers said they typically see about 3 platelet donors a day. Neat!
Go go jojo!