As he coughed into his sleeve, Stahma comfortingly slid her hand from his shoulder along his upper back, between his shoulder blades. It wasn't a situation she was used to helping in, but she was doing the best she could. Stahma was more used to being the buffer between her hot tempered husband and everyone else, including their son. She wasn't used to helping someone who was ill, but she offered comfort, letting Ukitake know she was there and wasn't going to simply leave him alone.
Unless he requested it, of course, but until then she would be there at his side to do whatever she could to make him more comfortable and relaxed in the situation.