Final answer:
A woman with severe preeclampsia should be monitored closely for signs of respiratory depression which can be a side effect of the magnesium sulfate infusion.
Step-by-step explanation:
When a woman with severe preeclampsia exhibits a respiratory rate of 10 breaths/min, the nurse should become concerned. A respiratory rate of 10 breaths/min is significantly lower than the normal range of 12-20 breaths/min, and it may indicate respiratory depression, which can be a serious side effect of the magnesium sulfate infusion.