Three out of four U.S. hospitals surveyed are already treating patients with confirmed or suspected COVID-19, according to a federal report that finds hospitals expect to be overwhelmed as cases rocket toward their projected peak. A report due out Monday from a federal watchdog agency warns that different, widely reported problems are feeding off each other in a vicious cycle. Such problems include insufficient tests, slow results, scarcity of protective gear, the shortage of breathing machines for seriously ill patients and burned-out staffs anxious for their own safety. “There’s this sort of domino effect,” said Ann Maxwell, an assistant inspector general at the Department of Health and Human Services. “These challenges play off each other and exacerbate the situation. There’s a cascade effect.” The inspector general’s report is based on a telephone survey of 323 hospitals around the country, from March 23-27. With hundreds of new coronavirus cases daily, the situation is becoming more dire for many the nation’s 6,000 hospitals. Others can still scramble to prepare. “Hospitals reported that their most significant challenges centered on testing and caring for patients with known or suspected COVID-19, and keeping staff safe,” the report concluded.