A state panel voted unanimously Wednesday to increase the rates hospitals can charge by 1.65 percent, but the medical institutions say the amount is inadequate and will collectively drive hospitals into the red. The Maryland Hospital Association said the decision will cause operating margins to plummet to negative 0.24 percent. The association had pushed for a rate hike of 2.43 percent, which would have also pushed down margins, but still left hospitals operating in positive territory. Members of the Maryland Health Services Cost Review Commission said they preferred the lower rate hike proposed by their staff.