Amy Thomson holds 2-month-old Isla in Seattle Children's Hospital in early 2014. When the Thomson family learned Isla's heart was failing, they took an air ambulance from Butte, Mont., to Seattle to get medical care. Courtesy of the Thomson family hide caption

toggle caption Courtesy of the Thomson family

Ambulances fill a parking lot at the DaVita Dialysis Center in Paterson, N.J., on May 31. Andrew Renneisen/Courtesy of ProPublica hide caption

toggle caption Andrew Renneisen/Courtesy of ProPublica