What, no, why, does she have to Marian knows better than to argue. At least the CRRT machine is familiar and less terrifying to touch or interact with in any way than the ECMO machine, and she doesn't need handholding to flush all the blood currently in it back into the patient and disconnect it. It's probably a reasonable time to be swapping the filter anyway, Leareth's blood has been incredibly messed up and the filter pressures were already rising and if they do have to restart it later the second filter should stay in good shape a lot longer.
She has not had a break of any kind unless you count over an hour of purifying diamond dust out of goop, during which she did think to grab a bathroom break and eat about eight packages of graham crackers while hiding in the patient bathroom. Who needs breaks, anyway, the sweet satisfaction of a dying patient abruptly turning around and drastically recovering is better than breaks.
"Are we doing the Remove Disease first or after?" she asks Dr Harrison. On the one hand, Leareth is showing no sign of sepsis yet, given the glorious wonderful soothing perfect blood pressure, and if they do it after then maybe it can also hit anything he was exposed to while out of the positive pressure isolation room and trekking through the hospital. On the other hand, field trips are stressful and Marian miiiight be less stressed if she wasn't thinking about his grotty lungs and wondering how quickly he could start deteriorating more given the lack of immune system. On the other other end, a stat head CT is, like, five minutes, it should really be fine...