A 17-year-old primigravida with severe hypertension of pregnancy has been receiving magnesium sulfate iv for three hr. the latest assessment reveals deep tendon reflexes (dtr) of +1, flushing, blood pressure of 150/100 mmhg, a pulse of 92 beats/min, a respiratory rate of 10 breaths/min, and urine output of 20 ml/hr. which action would be most appropriate?