The American Red Cross says the chronic blood shortage has gotten so bad that it’s ill prepared to handle any surge in hospital trauma cases in central Ohio. A single trauma case can require up to 40 units of blood. As of yesterday, the office in Columbus had just 30 units of o-negative blood. That’s the blood type that can be given to any recipient. Central Ohio Red Cross spokeswoman Catherine West says the agency sent out an urgent appeal for donors last week. Usually that does the trick, but daily collections have still been less than the goal. Last month, hospitals in Connecticut were asked to delay elective surgeries because of a blood shortage. National Red Cross spokeswoman Lesly Hallman says supplies are low nationwide, so regions no longer can bail each other out in emergencies.