Based on the information you've shared, the child's capillary blood glucose level of 46 mg/dL (2.55 mmol/L) is below the normal range of 70-110 mg/dL (4.0-11.0 mmol/L). In this situation, an essential action for the nurse would be to provide immediate medical attention. They should notify the healthcare team, closely monitor the child's condition, and follow the appropriate protocols for managing low blood glucose levels.