At 6:04 p.m. on Tuesday night, the staff at EvergreenHealth in Washington State got another warning: Two more patients with respiratory troubles were on their way to an emergency ward that had already been flooded with coronavirus patients. Doctors, nurses, technicians and respiratory therapists rushed to get each other prepared, handing out blue gloves, tying on each other’s yellow gowns and helping fit white helmets inflated by clean air — the visors opaque from the repeated cleanings with bleach they had undergone over the past brutal week.