Karen Duffy has been a nurse caring for new mothers and babies at Brockton Hospital for more than 30 years. Sometimes, she said, she does not get to spend as much time with a patient as she wants to, or feels like she has to split her attention among too many patients. “You go home, when you’ve had too many patients, and say, ‘Did I give that med?’ ” Duffy said. “You second-guess yourself.”