Throughout last night, Lily continued desat'ing and this morning, started getting pale; doctors determined her hematocrit ('crit') levels were still low, around 22%*, so they administered Lily's sixth blood transfusion.
*22% of Lily's blood was composed of strictly red blood cells; this was determined by centrifuging a small vial of blood. 35% or above is generally OK.
Prior to the transfusion, doctors noticed that her reticulocyte ('retic'), or immature red blood cell count, was higher than they would expect (which is a good thing); it was so high, they ran a second blood test, which confirmed the high retic levels. A high retic count is good... it means that Lily's bone marrow is trying to create more red blood cells, which will ultimately lead to a higher/better overall crit level. Her bone marrow is yet too immature to generate enough hematocrits, though - hence the transfusion.
The downside about the transfusion is that is depletes all of her reticulocytes - transfused blood, from mature adults, contains about 1% of reticulocyte, whereas preemie blood should contain around 10%. More frequent transfusions means more frequent retic depletion, which tells the bone marrow to stop generating reticulocytes. I asked Dr. Gio if preemies ever become dependent on transfusion; they don't he said, for reasons I don't recall.
After transfusing, her blood oxygen levels stabilized and she stopped desat'ing as frequently - while I was visiting her, I held her for an hour and her blood oxygen was in the 90s almost the entire time! It did drop a bit at the end, but nothing like the past few days. It's still too early to say the transfusion was a 'success' - that will be determined by how well her new blood holds its crit count, and how fast her bone marrow generates new reticulocytes. Docs are giving her another blood test at midnight, at which point they'll determine whether she needs yet a seventh transfusion on Thursday. She would only need a seventh if for some reason the donor blood didn't provide enough hematocrits - if it didn't, the seventh blood transfusion would come from the same donor (not good to switch donor bloods so quickly). Each transfusion increases the volume of Lily's blood by about 10%... only 10%, because they are essentially transfusing concentrated red blood cells... almost pure hematocrits.
So - she's still tolerating feeds at 7ml/hr, she gained 30 grams last night, and it appears that the doctors are making progress in determining the cause of the blood oxygen volatility; at the very least, it seems the transfusion reduced the severity and frequency of the swings. Lily also hasn't had any bradycardia's since the transfusion!
We have a lot to be positive about - Lily is still fighting, and she's still holding the battle line!