A client with intestinal obstruction has a nasogastric tube to low intermittent suction and is receiving an intravenous (IV) infusion of lactated Ringer's at 100 mL/hour.Which finding is most important for the nurse to report to the healthcare provider? Reference Range: Potassium (3.5 to 5 mEq/L (3.5 to 5 mmol/L).