A nurse is about to administer a medication via a client's nasogastric (NG) tube. What is the priority safety check before administration?

NG TUBE MEDICATION SAFETY — VERIFY PLACEMENT: Before instilling ANY medication or feeding through an NG tube, VERIFY PLACEMENT to ensure the tube is in the stomach, not the lungs (a dislodged tube in the airway could cause aspiration of medication/feeding into the lungs — potentially fatal). VERIFICATION METHODS: Check the external tube length marking against the documented baseline; aspirate gastric contents and check pH (gastric pH typically ≤ 5); X-ray is the gold standard for initial placement; observe aspirate characteristics; the auscultation 'whoosh' test alone is NOT reliable; MEDICATION ADMINISTRATION via NG: Verify placement; check tube patency; use liquid forms when available; crush only compatible tablets (never crush enteric-coated or extended-release); administer medications separately, flushing between each (prevents interactions and clogging); flush with water before and after (typically 15-30 mL adult); keep head of bed elevated; LPN role: verify placement before every use, administer correctly, flush appropriately, monitor for complications.