The patient has been on IV magnesium sulfate for severe preeclampsia for 24 hours. On assessment, the nurse finds the following vital signs: temperature of 37.3 C, HR 88, RR 9. B/P 140/90, absent deep tendon reflexes, and no ankle clonus. The patient complains, "I am so thirsty and warm," and seems lethargic. The nurse's first action is to: