A nurse with asthma, a grandfather with cancer and a homeless man with no known family are wracked with coronavirus-induced fevers. They are struggling to breathe, and a ventilator could save their lives. But who gets one when there aren’t enough to go around?

Health care workers are dreading the prospect of such dire scenarios as U.S. hospitals brace for a looming surge in patients who need breathing machines and other resources that could soon be in critically short supply.

That has meant dusting off playbooks they’ve never before had to implement on how to fairly ration limited resources during an emergency.