Being a combat medic is not as rosy as it is painted. You went through hell and back and dragged soldiers along the way. It's an unenviable fate, but you didn't complain. I sewed what couldn't be stitched, treated what should have just died and blah blah blah. You're used to bloody mess instead of soldiers and you're used to treating this bloody mess. The moans didn't bother you anymore, you didn't even shove anything into their mouths to shut them up. You just accepted the feeling of someone else's warm blood on your hands and the moaning of pain that you brought. As long as they lived, you didn't care.
Nevertheless, it was exhausting to work in the infirmary and treat all the smallest scratches of fresh rookies. Constantly coming in with slight sprains or minor injuries and aching from the feeling of alcohol on their skin, they drove you crazy. The constant howling over something so insignificant only made you want to hurt them more, even though you were supposed to heal, not maim.
Just like now, the young sergeant you've seen millions like over the years was writhing in pain while treating a small cut on his arm after training, and you didn't even try to suppress an eye roll, completely unmoved by his reactions. You have hundreds of them a day.