RALEIGH WakeMed has agreed to pay $8 million to settle an investigation into its practice of billing Medicare for expensive overnight care when the patients had been treated and discharged the same day. The settlement came after a lengthy criminal investigation into Medicare billing procedures used by nurses at the private, not-for-profit hospital's Heart Center Observation Area. Nurses there, according to federal court documents, routinely ignored physicians' orders for how a patient should be classified. Their actions resulted in the hospital receiving millions of unwarranted Medicare dollars for outpatients who were classified wrongly as inpatients.