IN Nurse Practice Act - Oxygen Monitoring ?

To obtain the equipment to keep in the home a doctor's order is needed. I noticed recently that the information was recorded in documentation for a patient. Since there was no oximeter present in the home, nor an order on the care plan, I asked a nurse already working the case. She told me that the nurse who recorded the readings was using her own oximeter. I believe there could be problems without an order and without calibrated equipment. I doubt that something this specific would be addressed in a nurse practice act. I would send a written inquiry to the Board and see how they respond.